Cellular Division copyright cmassengale 1 Identical Daughter Cells Two identical daughter cells Parent Cell 2 Cell Division ✓All cells are derived from pre- existing cells ✓New cells are produced for growth and to replace damaged or old cells ✓Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) 3 Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules 4 P. 198 of TB The Purines (2 rings) Adenine Guanine The Pyrimidines (1 ring) Cytosine Thymine Uracil 5 Chromosomes 6 Prokaryotic Chromosome ✓The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane 7 Eukaryotic Chromosomes ✓All eukaryotic cells store genetic information in chromosomes ✓Most eukaryotes have between 10 and 50 chromosomes in their body cells ✓Human body cells have 46 chromosomes or 23 identical pairs 8 Chapter 8 Section 1 Chromosomes Chromosome Numbers, continued • Diploid and Haploid Cells – Cells having two sets of chromosomes are diploid (2n). – Haploid cells (1n) have only one set of chromosomes. Eukaryotic Chromosomes ✓Each chromosome is composed of a single, tightly coiled DNA molecule ✓Chromosomes can’t be seen when cells aren’t dividing and are called chromatin 10 Compacting DNA into Chromosomes ✓DNA is tightly coiled around proteins called histones 11 Chapter 8 Section 1 Chromosomes Chromosome Structure Chromosomes in Dividing Cells ✓Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids 13 Karyotype ✓A picture of the chromosomes from a human cell arranged in pairs by size ✓First 22 pairs are called autosomes ✓Last pair are the sex chromosomes ✓XX female or XY male 14 Boy or Girl? The Y Chromosome Decides Y - Chromosome X - Chromosome 15 Cell Reproduction 16 Types of Cell Reproduction ✓Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells ✓Mitosis & binary fission are examples of asexual reproduction ✓Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells ✓Meiosis is an example 17 Cell Division in Prokaryotes 18 Cell Division in Prokaryotes ✓ Prokaryotes such as bacteria divide into 2 Parent cell identical cells by the process of binary fission Chromosome ✓ Single chromosome replicates makes a copy of itself ✓ Cell wall forms Cell splits between the chromosomes dividing the cell 2 identical daughter cells 19 Prokaryotic Cell Undergoing Binary Fission 20 The Cell Cycle 21 Five Phases of the Cell Cycle ✓G1 - primary growth phase ✓S – synthesis; DNA replicated ✓G2 - secondary growth phase collectively these 3 stages are called interphase ✓M - mitosis ✓C - cytokinesis 22 Cell Cycle (P.155) DNA Copied Cells Mature Daughter Cells Cells prepare for Division Cell Divides into Identical cells 23 Interphase - G1 Stage ✓1st growth stage after cell division ✓Cells mature by making more cytoplasm & organelles ✓Cell carries on its normal metabolic activities 24 Interphase – S Stage ✓Synthesis stage ✓DNA is copied or replicated Two identical copies of DNA Original DNA 25 DNA Replication ✓DNA must be Original DNA copied or strand replicated before cell division Two new, identical DNA ✓Each new cell strands will then have an identical copy of the DNA 26 Interphase – G2 Stage ✓2nd Growth Stage ✓Occurs after DNA has been copied ✓All cell structures needed for division are made (e.g. centrioles) ✓Both organelles & proteins are synthesized 27 What’s Happening in Interphase? What the cell looks like Animal Cell What’s occurring 28 Mitosis 29 Mitosis ✓Division of the nucleus ✓Also called karyokinesis ✓Only occurs in eukaryotes ✓Has four stages ✓Doesn’t occur in some cells such as brain cells 30 Four Mitotic Stages ✓Prophase ✓Metaphase ✓Anaphase ✓Telophase 31 Early Prophase ✓Chromatin in nucleus condenses to form visible chromosomes ✓Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Nucleolus Cytoplasm Nuclear Membrane Chromosomes 32 Late Prophase ✓Nuclear membrane & nucleolus are broken down ✓Chromosomes continue condensing & are clearly visible ✓Spindle fibers called kinetochores attach to the centromere of each chromosome ✓Spindle finishes forming between the poles of the cell 33 Late Prophase Chromosomes Nucleus & Nucleolus have disintegrated 34 Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome 35 Review of Prophase What the cell looks like What’s happening 36 Spindle Fibers ✓The mitotic spindle form from the microtubules in plants and centrioles in animal cells ✓Polar fibers extend from one pole of the cell to the opposite pole ✓Kinetochore fibers extend from the pole to the centromere of the chromosome to which they attach ✓Asters are short fibers radiating from centrioles 37 Sketch The Spindle 38 Metaphase ✓Chromosomes, attached to the kinetochore fibers, move to the center of the cell ✓Chromosomes are now lined up at the equator Equator of Cell Pole of the Cell 39 Metaphase Asters at the poles Spindle Fibers Chromosomes lined at the Equator 40 Metaphase Aster Chromosomes at Equator 41 Review of Metaphase What the cell looks like What’s occurring 42 Anaphase ✓Occurs rapidly ✓Sister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers 43 Anaphase Sister Chromatids being separated 44 Anaphase Review What the cell looks like What’s occurring 45 Telophase ✓Sister chromatids at opposite poles ✓Spindle disassembles ✓Nuclear envelope forms around each set of sister chromatids ✓Nucleolus reappears ✓CYTOKINESIS occurs ✓Chromosomes reappear as chromatin 46 Comparison of Anaphase & Telophase 47 Cytokinesis ✓Means division of the cytoplasm ✓Division of cell into two, identical halves called daughter cells ✓In plant cells, cell plate forms at the equator to divide cell ✓In animal cells, cleavage furrow forms to split cell 48 Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell 49 Daughter Cells of Mitosis ✓Have the same number of chromosomes as each other and as the parent cell from which they were formed ✓Identical to each other, but smaller than parent cell ✓Must grow in size to become mature cells (G1 of Interphase) 50 Identical Daughter Cells What is the 2n or diploid number? 2 Chromosome number the same, but cells smaller than parent cell 51 Meiosis Formation of Gametes (Eggs & Sperm) 52 Facts About Meiosis ✓Preceded by interphase which includes chromosome replication ✓Two meiotic divisions --- Meiosis I and Meiosis II ✓Called Reduction- division ✓Original cell is diploid (2n) ✓Four daughter cells produced that are monoploid (1n) 53 Facts About Meiosis ✓Daughter cells contain half the number of chromosomes as the original cell ✓Produces gametes (eggs & sperm) ✓Occurs in the testes in males (Spermatogenesis) ✓Occurs in the ovaries in females (Oogenesis) 54 More Meiosis Facts ✓ Start with 46 double stranded chromosomes (2n) ✓After 1 division - 23 double stranded chromosomes (n) ✓After 2nd division - 23 single stranded chromosomes (n) ✓ Occurs in our germ cells that produce gametes 55 Why Do we Need Meiosis? ✓It is the fundamental basis of sexual reproduction ✓Two haploid (1n) gametes are brought together through fertilization to form a diploid (2n) zygote 56 Fertilization – “Putting it all together” 2n = 6 1n =3 57 Replication of Chromosomes ✓Replication is the process of duplicating a chromosome ✓Occurs prior to division ✓Replicated copies are called sister chromatids ✓Held together at centromere Occurs in Interphase 58 A Replicated Chromosome Gene X Homologs (same genes, different alleles) Sister Chromatids (same genes, same alleles) Homologs separate in meiosis I and therefore different alleles separate. 59 Meiosis Forms Haploid Gametes ✓ Meiosis must reduce the chromosome number by half ✓ Fertilization then restores the 2n number from mom from dad child too much! meiosis reduces genetic content The right number! 60 Meiosis: Two Part Cell Division Sister chromatids separate Homologs separate Meiosis I Meiosis II Diploid Haploid Haploid 61 Meiosis I: Reduction Division Spindle fibers Nucleus Early Prophase I (Chromosome number doubled) Late Prophase I Nuclear envelope Metaphase Anaphase Telophase I I I (diploid) 62 Prophase I Early prophase ✓Homologs pair. ✓Crossing over occurs. Late prophase ✓Chromosomes condense. ✓Spindle forms. ✓Nuclear envelope fragments. 63 Tetrads Form in Prophase I Homologous chromosomes (each with sister chromatids) Join to form a TETRAD Called Synapsis 64 Crossing-Over ✓ Homologous chromosomes in a tetrad cross over each other ✓ Pieces of chromosomes or genes are exchanged ✓ Produces Genetic recombination in the offspring 65 Homologous Chromosomes During Crossing-Over 66 Crossing-Over Crossing-over multiplies the already huge number of different gamete types produced by independent assortment 67 Metaphase I Homologous pairs of chromosomes align along the equator of the cell 68 Anaphase I Homologs separate and move to opposite poles. Sister chromatids remain attached at their centromeres. 69 Telophase I Nuclear envelopes reassemble. Spindle disappears. Cytokinesis divides cell into two. copyright cmassengale 70 Meiosis II Gene X Only one homolog of each chromosome is present in the cell. Sister chromatids carry identical genetic information. Meiosis II produces gametes with one copy of each chromosome and thus one copy of each gene. 71 Meiosis II: Reducing Chromosome Number Prophase II Metaphase Telophase II Anaphase 4 Genetically II II Different haploid cells 72 Prophase II Nuclear envelope fragments. Spindle forms. copyright cmassengale 73 Metaphase II Chromosomes align along equator of cell. copyright cmassengale 74 Anaphase II Equator Pole Sister chromatids separate and move to opposite poles. copyright cmassengale 75 Telophase II Nuclear envelope assembles. Chromosomes decondense. Spindle disappears. Cytokinesis divides cell into two. copyright cmassengale 76 Results of Meiosis Gametes (egg & sperm) form Four haploid cells with one copy of each chromosome One allele of each gene Different combinations of alleles for different genes along the chromosome 77 Gametogenesis Oogenesis or Spermatogenesis copyright cmassengale 78 Spermatogenesis ✓Occurs in the testes ✓Two divisions produce 4 spermatids ✓Spermatids mature into sperm ✓Men produce about 250,000,000 sperm per day 79 Spermatogenesis in the Testes Spermatid 80 Spermatogenesis 81 Oogenesis ✓Occurs in the ovaries ✓Two divisions produce 3 polar bodies that die and 1 egg ✓Polar bodies die because of unequal division of cytoplasm ✓Immature egg called oocyte ✓Starting at puberty, one oocyte matures into an ovum (egg) every 28 days 82 Oogenesis in the Ovaries 83 Oogenesis First polar body may divide (haploid) a Mitosis Oogonium (diploid) X A X Primary oocyte (diploid) X a X a a Polar bodies die X Meiosis I Meiosis II (if fertilization A occurs) X A X Secondary oocyte (haploid) Ovum (egg) Mature egg A X Second polar body (haploid) 84 Comparing Mitosis and Meiosis 85 Comparison of Divisions Mitosis Meiosis 2 Number of divisions 1 Number of daughter cells 2 4 Yes No Same as parent Half of parent Where Somatic cells Germ cells When Throughout life At sexual maturity Growth and repair Sexual reproduction Genetically identical? Chromosome # Role 86 Uncontrolled Mitosis ✓ If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors ✓ Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells 87 Chapter 11 Section 2 Gene Expression in Development and Cell Division Gene Expression in Development • The development of cells with specialized functions is called cell differentiation. • The development of form in an organism is called morphogenesis. • Both cell differentiation and morphogenesis are governed by gene expression. Chapter 11 Section 2 Gene Expression in Development and Cell Division Gene Expression in Development, continued • Homeotic Genes – Regulatory genes that determine where anatomical structures will be placed during development. • Homeobox Sequences – Within each homeotic gene, a specific DNA sequence known as the homeobox regulates patterns of development. – The homeoboxes of many eukaryotic organisms appear to be very similar. Chapter 11 Section 2 Gene Expression in Development and Cell Division Gene Expression, Cell Division, and Cancer • Mutations of proto-oncogenes, which regulate cell growth, or tumor-suppressor genes, which prevent cell division from occurring too often,may lead to cancer. • Cancer is the uncontrolled growth of abnormal cells. Chapter 11 Section 2 Gene Expression in Development and Cell Division Effect of Mutation on Gene Expression Chapter 11 Section 2 Gene Expression in Development and Cell Division Gene Expression, Cell Division, and Cancer, continued • Gene Expression in Cancer – Unlike normal cells, cancer cells continue to divide indefinitely, even if they become densely packed. – Cancer cells will also continue dividing even if they are no longer attached to other cells. • Causes of Cancer – A carcinogen is any substance that can induce or promote cancer. – Most carcinogens are mutagens, substances that cause mutations. Review of Mitosis 93 Draw & Learn these Stages 94 Draw & Learn these Stages 95 Name the Mitotic Stages: Interphase Name this? Prophase Telophase Name this? Metaphase Anaphase 96 Eukaryotic Cell Division ✓ Used for growth and repair ✓ Produce two new cells identical to the original cell ✓ Cells are diploid (2n) Prophase Metaphase Chromosomes during Metaphase of mitosis Anaphase Telophase Cytokinesis 97 Mitosis in Onion Root Tips Do you see any stages of mitosis? 98 Mitosis Quiz 99 Name the Stages of Mitosis: Early Anaphase Early prophase Metaphase Interphase Late Prophase Late telophase, Mid-Prophase Advanced cytokinesis Early Telophase, Begin cytokinesis Late Anaphase 100 Identify the Stages ? Early, Middle, & Late Prophase ? ? Metaphase Late Prophase Late Anaphase Anaphase ? ? Telophase ? ? Telophase & Cytokinesis 101 Locate the Four Mitotic Stages in Plants Anaphase Telophase Metaphase Prophase 102 Cellular Respiration ◼ A catabolic, exergonic, oxygen (O2) requiring process that uses energy extracted from macromolecules (glucose) to produce energy (ATP) and water (H2O). C6H12O6 + 6O2 → 6CO2 + 6H2O + energy glucose ATP 1 Section 1 Glycolysis and Fermentation Photosynthesis-Cellular Respiration Cycle Mitochondria ◼ Organelle where cellular respiration takes place. Outer membrane Inner membrane space Matrix Cristae Inner membrane 3 *In the presence of Oxygen: Aerobic Environment Cellular Respiration occurs: utilizes Glycolysis, Krebs cycle electron transport chain and chemiosmosis. Without the presence of Oxygen: Anaerobic environment Fermentation can take place through: * Alcoholic Fermentation -occurs in yeast *Lactic Acid Fermentation -specific conditions for humans -some bacteria     Occurs in the cytoplasm…specifically in the cytosol (semifluid portion of the cytoplasm) Glucose (6 C) ➔ 2 PGAL (3 C) ➔ 2 Pyruvic Acid (3 C) –also known a pyruvate Section 1 Glycolysis and Fermentation Glycolysis Section 1 Glycolysis and Fermentation Glycolysis • Cellular respiration begins with glycolysis, which takes place in the cytosol of cells. • During glycolysis, one glucose molecule is oxidized to form two 3-carbon pyruvic acid molecules. • A net yield of 2 ATP and 2NADH is produced for every molecule of glucose that undergoes glycolysis. • (Gross of 4 ATP – Cost of 2 ATP = Net yield of 2 ATP) Efficiency • Efficiency = Energy Required to make ATP Energy Released by Oxidizing Glucose • Eff of Glycolysis = 2 ATP * 7 kcal / 686 kcal = 2% • Eff of Cell Respiration = 38 ATP * 7kcal / 686 kcal = 39% Fermentation ◼ ◼ ◼ Occurs in cytosol when “NO Oxygen” is present (called anaerobic). Remember: glycolysis is part of fermentation. Two Types: 1. Alcohol Fermentation 2. Lactic Acid Fermentation 10 Section 1 Glycolysis and Fermentation Fermentation • If oxygen is not present, some cells can convert pyruvic acid into other compounds through additional biochemical pathways that occur in the cytosol. The combination of glycolysis and these additional pathways is fermentation. • Fermentation does not produce ATP, but it does regenerate NAD+, which allows for the continued production of ATP through glycolysis. • NAD = Nicotinamide adenine dinucleotide       Occurs in the cytoplasm Pyruvic Acid converted to another product with no further release of energy Example : Yeast 2 pyruvic acid ➔ 2 ethyl alcohol and CO2 Example : Humans/ some bacteria 2 pyruvic acid ➔ 2 Lactic acid Section 1 Glycolysis and Fermentation Two Types of Fermentation Acetylaldehyde Section 1 Glycolysis and Fermentation Fermentation, continued • Alcoholic Fermentation – Some plants and unicellular organisms, such as yeast, use a process called alcoholic fermentation to convert pyruvic acid into ethyl alcohol and CO2. – Bubbles in champagne and holes in bread are both from CO2. Alcohol Fermentation ◼ End Products: Alcohol fermentation 2 - ATP (substrate-level phosphorylation) 2 - CO2 2 - Ethanol’s 15 Alcohol Fermentation ◼ C C C C C C Plants and Fungi 2ADP +2 P beer and wine 2ATP 2NADH C C C Glycolysis 2 NAD+ → 2NADH 2 Pyruvic acid glucose copyright cmassengale 2 NAD+ C C 2 Ethanol 2CO2 released 16 Section 1 Glycolysis and Fermentation Fermentation, continued • Lactic Acid Fermentation – In lactic acid fermentation, an enzyme converts pyruvic acid into another three-carbon compound, called lactic acid. – LA Fermentation of harmless microorganisms produces cheese, buttermilk, yogurt, sour cream, and other dairy products. – LA Fermentation also occurs in muscle cells eventually leading to fatigue, pain, and cramps. Lactic Acid Fermentation ◼ End Products: Lactic acid fermentation 2 - ATP (substrate-level phosphorylation) 2 - Lactic Acids copyright cmassengale 18 Lactic Acid Fermentation ◼ Animals (pain in muscle after a workout). C C C C C C 2ADP +2 P 2ATP 2NADH C C C Glycolysis 2 NAD+ 2NADH 2 Pyruvic acid 2 NAD+ C C C 2 Lactic acid Glucose 19 Chapter 7 Section 1 Glycolysis and Fermentation Cellular Respiration Versus Fermentation Section 1 Glycolysis and Fermentation C6H12O6 + 6O2 ↔ 6CO2 + 6H2O (+ ATP) • Cellular respiration is the process by which cells break down organic compounds to produce ATP. • Both autotrophs and heterotrophs use cellular respiration to make CO2 and water from organic compounds and O2. • The products of cellular respiration are the reactants in photosynthesis; conversely, the products of photosynthesis are reactants in cellular respiration. • Cellular respiration can be divided into two stages: glycolysis and aerobic respiration.  Three major steps - Glycolysis - Krebs cycle - Electron Transport Chain Section 2 Aerobic Respiration Overview of Aerobic Respiration • In eukaryotic cells, the processes of aerobic respiration occur in the mitochondria. Aerobic respiration only occurs if oxygen is present in the cell. • The Krebs cycle occurs in the mitochondrial matrix. The electron transport chain (which is associated with chemiosmosis) is located within the inner membrane of the cristae. Breakdown of Cellular Respiration ◼ Four main parts (reactions). 1. Glycolysis (splitting of sugar) a. cytosol, just outside of mitochondria. 2. Grooming Phase a. migration from cytosol to matrix. copyright cmassengale 24 Breakdown of Cellular Respiration 3. Krebs Cycle (Citric Acid Cycle) a. mitochondrial matrix 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation a. Also called Chemiosmosis b. inner mitochondrial membrane. 25 2. Grooming Phase ◼ ◼ Occurs when Oxygen is present (aerobic). 2 Pyruvate (3C) molecules are transported through the mitochondria membrane to the matrix and is converted to 2 Acetyl CoA (2C) molecules. Cytosol 2 CO2 C C C Matrix C-C 2 Pyruvate 2 NAD+ 2NADH 2 Acetyl CoA 26 2. Grooming Phase ◼ End Products: grooming phase 2 - NADH 2 - CO2 2- Acetyl CoA (2C) 27 3. Krebs Cycle (Citric Acid Cycle) ◼ ◼ ◼ Location: mitochondrial matrix. Acetyl CoA (2C) bonds to Oxalacetic acid (4C - OAA) to make Citrate (6C). It takes 2 turns of the krebs cycle to oxidize 1 glucose molecule. Mitochondrial Matrix 28 Section 2 Aerobic Respiration The Krebs Cycle – • In the mitochondrial matrix, the pyruvic acid produced in glycolysis will react with coenzyme A to form acetyl CoA. Then, acetyl CoA enters the Krebs cycle. • One glucose molecule is completely broken down in two turns of the Krebs cycle. These two turns produce 4 CO2 molecules, 2 ATP molecules, and H atoms that are used to make 6 NADH and 2 FADH2 molecules. • FAD = flavin adenine dinucleotide 3. Krebs Cycle (Citric Acid Cycle) 2 Acetyl CoA (2C) Citrate (6C) OAA (4C) 2 FADH2 Krebs Cycle 4 CO2 (two turns) 6 NAD+ 2 FAD 6 NADH 2 ATP 2 ADP + P 30 3. Krebs Cycle (Citric Acid Cycle) ◼ Total net yield (2 turns of krebs cycle) 1. 2 - ATP (substrate-level phosphorylation) 2. 6 - NADH 3. 2 - FADH2 4. 4 - CO2 31 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) ◼ ◼ ◼ Location: inner mitochondrial membrane. Uses ETC (cytochrome proteins) and ATP Synthase (enzyme) to make ATP. ETC pumps H+ (protons) across innermembrane (lowers pH in innermembrane space). Inner Mitochondrial Membrane 32 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) Outer membrane Inner membrane space Matrix Cristae Inner membrane 33 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) ◼ ◼ ◼ ◼ The H+ then move via diffusion (Proton Motive Force) through ATP Synthase to make ATP. All NADH and FADH2 converted to ATP during this stage of cellular respiration. Each NADH converts to 3 ATP. Each FADH2 converts to 2 ATP (enters the ETC at a lower level than NADH). 34 Chapter 7 Section 2 Aerobic Respiration Electron Transport Chain and Chemiosmosis, continued • As protons move through ATP synthase and down their concentration and electrical gradients, ATP is produced. O2 combines with the electrons and protons to form H2O. 1 NADH → 3 ATP And 1 FADH2 → 2 ATP → 18 ATP And 2 FADH2 → 4 ATP Thus: 6 NADH 4. ETC and Oxidative Phosphorylation (Chemiosmosis for NADH) higher H+ concentration Intermembrane Space 1H+ E 2H+ 3H+ T C NAD+ (Proton Pumping) Matrix ATP Synthase Inner Mitochondrial Membrane O2 H O 2 2H+ + 1/2 NADH + H+ H+ ADP + P H+ ATP lower H+ concentration 36 4. ETC and Oxidative Phosphorylation (Chemiosmosis for FADH2) higher H+ concentration Intermembrane Space 1H+ E T FADH2 + H+ FAD+ (Proton Pumping) Matrix 2H+ C 2H+ + 1/2O2 H+ ATP Synthase Inner Mitochondrial Membrane H2O ADP + P H+ ATP lower H+ concentration 37    Certain Carrier proteins are able to transfer Hydrogen ions from the matrix to the outer compartment where the concentration rises. Hydrogen ions flow down the concentration gradient through ATP synthase. This converts ADP to ATP Section 2 Aerobic Respiration Electron Transport Chain and Chemiosmosis, continued • The Importance of Oxygen – ATP can be synthesized by chemiosmosis only if e- continue to move along the ETC. – By accepting electrons from the last molecule in the electron transport chain, oxygen allows additional electrons to pass along the chain. – As a result, ATP can continue to be made through chemiosmosis. Section 2 Aerobic Respiration Electron Transport Chain and Chemiosmosis Section 2 Aerobic Respiration ETC and Chemiosmosis, continued • High-energy e- in H atoms from NADH and FADH2 are passed between molecules in the ETC along the inner mitochondrial membrane. Protons (hydrogen ions, H+) are also given up by NADH and FADH2. • As the e- move through the ETC, they lose energy. This energy is used to pump protons from the matrix into the space between the inner and outer mitochondrial membranes resulting in a high concentration gradient of protons and a charge gradient across the inner membrane. Maximum ATP Yield for Cellular Respiration (Eukaryotes) Glucose Cytosol Glycolysis 2 Acetyl CoA 2 Pyruvate Mitochondria Krebs Cycle 2NADH 2 ATP 6NADH 2FADH2 (substrate-level phosphorylation) 2NADH ETC and Oxidative Phosphorylation 2 ATP (substrate-level phosphorylation) 2ATP 6ATP 6ATP 18ATP 4ATP 38 ATP (maximum per glucose) 2ATP 42 Prokaryotes (Lack Membranes) Total ATP Yield 02 ATP - glycolysis (substrate-level phosphorylation) 06 ATP - converted from 2 NADH - glycolysis 06 ATP - converted from 2 NADH - grooming phase 02 ATP - Krebs cycle (substrate-level phosphorylation) 18 ATP - converted from 6 NADH - Krebs cycle 04 ATP - converted from 2 FADH2 - Krebs cycle 38 ATP - TOTAL ◼ 43 Section 2 Aerobic Respiration Summary of Cellular Respiration – P.142* Section 2 Aerobic Respiration A Summary of Cellular Respiration • Another Role of Cellular Respiration – Providing cells with ATP is not the only important function of cellular respiration. – Molecules formed at different steps in glycolysis and the Krebs cycle are often used by cells to make compounds that are missing in food. Module 4 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 1 1. Definitions a) Metabolism: The sum of chemical reactions that occur in living cells; the processes of catabolism and anabolism b) Catabolism: The processes by which a living organism obtains its energy and raw materials from nutrients(breaking down to YIELD energy) c) Anabolism: The processes by which energy and raw materials are used to build macromolecules and cellular structures (building up by USING energy) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 2  Catabolism provides the building blocks and energy for anabolism. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.1 3 An organic molecule(usually protein) that brings about a chemical change =the enzyme itself does not change =are reusable =are catalysts = are highly specific; will only function in one type of reaction =substance acted upon= SUBSTRATE =substances produced after reaction= PRODUCTS = site of attachment= ACTIVE SITE  Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 4  The turnover number is generally 1-10,000 molecules per second. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.4 5    A METABOLIC PATHWAY is a sequence of chemical reactions in which the PRODUCT of one reaction serves as the SUBSTRATE for the next reaction in a cell. Metabolic pathways are determined by enzymes. Enzymes are encoded by genes. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 6     Some enzymes need help binding with their substrates= use COFACTOR(non-protein) If cofactor is organic molecule= COENZYME EG: NAD,FAD,NADH,coenzyme A Enzymes requiring cofactor but without one bound= APOENZYME(protein) Apoenzyme with its cofactors(coenzymes)= HOLOENZYME Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 7 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.3 8  Temperature Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5a 9  pH Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5b10  Substrate concentration Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5c11  Competitive inhibition: INHIBITORS compete in binding to enzyme to decrease their activity Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7a, b12   Noncompetitive inhibition: INHIBITOR binds to enzyme at different location((ALLOSTERIC SITE),but still decreases activity. The stronger the concentration of the inhibitor, the more inhibition takes place Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7a, c13    Oxidation is the removal of electrons. Reduction is the gain of electrons. Redox reaction is an oxidation reaction paired with a reduction reaction. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.914  In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.1015    ATP(adenosine triphosphate): immediate energy source for cells Phosphorylation=adding a phosphate group to a protein ATP is generated by the phosphorylation of ADP(adenosine diphosphate). Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 16 Oxidative-Phosphorylation: =pairs of electrons are passed from one chemical substance to another =the energy released during the passage combines phosphate with ADP to form ATP  CHEMIOSMOSIS: the actual mechanism for ATP formation : =involves a chemical and transport(“osmosis”) process  Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 17 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.16.218 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 19   The breakdown of carbohydrates to release energy; referred to as “CELLULAR RESPIRATION”; uses oxygen= “aerobic” 3 types of aerobic respiration: ◦ Glycolysis(is aerobic and anaerobic) ◦ Krebs cycle/Citric acid cycle ◦ Electron transport chain Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 20   One of the most studied aspects of metabolism is the catabolism of glucose (a 6-carbon carbohydrate used for energy). Glycolysis:the breakdown of glucose into 2 molecules of pyruvic acid (a 3-carbon molecule that results from breakdown of glucose), releasing 2 molecules of ATP 2 ATP Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 21 Preparatory Stage Glucose 1   Glucose 6-phosphate 2 ATPs are used Glucose is split to form 2 Glucose-3phosphate 2 Fructose 6-phosphate 3 4 Fructose 1,6-diphosphate 5 Dihydroxyacetone phosphate (DHAP) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Glyceraldehyde 3-phosphate (GP) Figure 5.12.122 6 1,3-diphosphoglyceric acid     2 Glucose-3phosphate oxidized to 2 Pyruvic acid 4 ATP produced 2 NADH produced 2 ATP were used; so net gain of 2 ATP 7 3-phosphoglyceric acid 8 2-phosphoglyceric acid 9 Phosphoenolpyruvic acid (PEP) 10 Pyruvic acid Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.12.2 23  Most common and well-known type of glycolysis= Embden-Meyerhof pathway(named for its founders) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 24  Pentose phosphate pathway: ◦ Uses pentoses(monosaccharides) and NADPH ◦ Operates with glycolysis  Entner-Doudoroff pathway: ◦ Produces NADPH and ATP ◦ Does not involve glycolysis ◦ Pseudomonas, Rhizobium, Agrobacterium Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 25       Begins after pyruvic acid molecules in glycolysis are converted to slightly different compound(acetyl CoA) Pyruvic acid turns into 3 molecules of CO2 Acetyl CoA condenses to form citric acid Intermediate steps produce compounds(NAD and FAD)that store high energy electrons and 2 ATP molecules NAD and FAD are reduced(add hydrogen) to NADH and FADH which then carry the energy to next stage,forming 2 new ATP molecules Total of 4 ATP molecules(2 from glycolysis and 2 from Kreb’s cycle) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 26 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.13.227    A series of electron carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain. Uses coenzymes NAD, NADP, and FAD; changing 3 ADP to ATP by adding phosphate Energy released can be used to produce ATP by chemiosmosis. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 28 Pathway Eukaryote Prokaryote Glycolysis Cytoplasm Cytoplasm Intermediate step Cytoplasm Cytoplasm Krebs cycle Mitochondrial matrix Cytoplasm ETC Mitochondrial inner membrane Plasma membrane Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 29    Energy produced from complete oxidation of 1 glucose using aerobic respiration 36 ATP produced in eukaryotic cells 38 ATP produced in prokaryotic cells ATP produced NADH produced FADH2 produced Glycolysis 2 2 0 Intermediate step 0 2 Krebs cycle 2 6 2 Total 4 10 2 Pathway Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 30   Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O2). Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycles operations under anaerobic conditions. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 31    Breakdown by microorganisms of complex organic substances, especially CHOs, into CO2 and alcohol Does not require oxygen(anaerobic) Does not use the Krebs cycle or ETC Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 32 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.18b33   Alcohol fermentation. Produces ethyl alcohol + CO2 Lactic acid fermentation. Produces lactic acid. ◦ Homolactic fermentation. Produces lactic acid only. ◦ Heterolactic fermentation. Produces lactic acid and other compounds. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 34 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2035  Lipid Biosynthesis:anabolism(building lipids) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2936 Protein Extracellular proteases Deamination, decarboxylation, dehydrogenation Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino acids Organic acid Krebs cycle 37  Amino Acid and Protein Biosynthesis: anabolism(building protein) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.30a38  Used to identify bacteria. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 10.839 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2340 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2241      Carbohydrate anabolism using light as an energy source Takes place in organisms with chlorophyll ATP is one compound produced, but glucose is the major end-product Occurs in cell membrane of eukaryotic and prokaryotic organisms Prokaryotes= cyanobacteria(“blue-green algae”), green sulfur bacteria and purple sulfur bacteria Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 42 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2543 2 main groups of microorganisms: 1.Heterotroph: requires organic(has carbon) substrates to get its carbon from = “consumer” 2. Autotroph: self-sustained by producing food from inorganic(no carbon) compounds = “self-feeder” Add prefixes: “Photo-”: uses light as energy source “Chemo-”: break down chemicals for energy Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 44 Combine prefix with microorganism: 1. Photoheterotroph= obtains energy from light and must get carbon from others 2. Chemoheterotroph= obtains energy from the consumption of organic molecules 3. Photoautotroph= obtain energy from light while converting own carbon into organic materials 4. Chemoautotroph= obtain energy from oxidation of electron donating molecules in environment while surviving on own carbon Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 45 Nutritional type Energy source Carbon source Example Photoautotroph Light Inorganic Photoheterotroph Light Organic compounds Chemoautotroph Chemical Inorganic Iron-oxidizing bacteria. Chemoheterotroph Chemical Organic compounds Fermentative bacteria. Animals, protozoa, fungi, bacteria. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Oxygenic: Cyanobacteria plants. Anoxygenic: Green, purple bacteria. Green, purple nonsulfur bacteria. 46 Microbial Growth-module 4b Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 47  Microbial growth = increase in number of cells, not cell size The Requirements for Growth: Physical Requirements  Temperature ◦ Minimum growth temperature: cannot grow below this temperature ◦ Optimum growth temperature:grows best ◦ Maximum growth temperature: cannot grow above this temperature Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 48 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 49 • Grow with low temperatures • Grow between 0°C and 2030°C • Cause food spoilage 50 • pH • Most bacteria grow between pH 6.5 and 7.5 • Molds and yeasts grow between pH 5 and 6 • Acidophiles grow in acidic environments • Osmotic Pressure Most bacteria need a watery environment • Hypertonic environments:increase salt or sugar, cause plasmolysis(shrinks or shrivels up) = some need high salt: halophiles Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 51 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 52  Carbon ◦ Every organism must have carbon;energy source ◦ heterotrophs use organic carbon sources ◦ Autotrophs use own CO2  Nitrogen  Sulfur ◦ Need for synthesis of protein and nucleic acids ◦ Most bacteria decompose proteins for nitrogen ◦ Some bacteria use NH4+ (ammonium) or NO3− (nitrate) ◦ A few bacteria use N2 in nitrogen fixation   Phosphorus ◦ In DNA, RNA, ATP, and membranes ◦ PO43− (phosphate)is a source of phosphorus Trace Elements ◦ Inorganic elements required in small amounts ◦ Usually as enzyme cofactors ◦ In amino acids, thiamine, biotin ◦ Most bacteria decompose proteins 53 5 types : 1. Obligate aerobes: need large amts of O2 2. Facultative anaerobes: can metabolize aerobically when O2 is available, or anaeraobically when O2 not there 3. Microaerophiles: grow at low pressures of O2 4. Obligate anaerobes: cannot grow in presence of O2 5. Aerotolerant: cannot metabolize aerobically, but not harmed when O2 is present  Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 54 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 55 Culture Media  Culture Medium: liquid or solid prepared for microbial growth  Sterile: No living microbes  Inoculum: Introduction of microbes into medium  Culture: Microbes growing in/on culture medium Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 56 • Complex polysaccharide • Used as solidifying agent for culture media in Petri plates • Generally not metabolized by microbes • Liquefies at 100°C • Solidifies ~40°C Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 57 • Chemically Defined Media: Exact chemical composition is known • Complex Media: exact composition is not known(extracts and digests of yeasts, meat, or plants) • Nutrient broth • Nutrient agar Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 58 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 59 Reducing media  Contain chemicals (thioglycollate or oxyrase) that deplete the O2 levels in the medium  Heated to drive off O2 Anaerobic jar Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 60 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 61 Candle jar CO2-packet Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 62 • Suppress unwanted microbes and encourage desired microbes. • Salts , dyes, and antibiotics used to inhibit growth of unwanted organisms Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 63 Make it easy to distinguish colonies of different microbes by noting visible changes in the medium(use red dye in agar that some bacteria take up)  Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 64 • Encourages growth of desired microbe adding a nutrient that enhances the growth of the bacteria • Assume a soil sample contains a few phenol-degrading bacteria and thousands of other bacteria • Inoculate phenol-containing culture medium with the soil and incubate • Transfer 1 ml to another flask of the phenol medium and incubate • Transfer 1 ml to another flask of the phenol medium and incubate • Only phenol-metabolizing bacteria will be growing • A pure culture contains only one species or strain • A colony is a population of cells arising from a single cell or spore or from a group of attached cells • A colony is often called a colony-forming unit (CFU) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 65 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 66    Refrigeration: days to weeks Deep-freezing with liquid nitrogen: -50°to 95°C: weeks to years Lyophilization (freeze-drying so that all water is removed):turns to a powder: years Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 67   Binary fusion: cell separates Budding: new cell grows off original cell Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 68 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 69  Serial dilutions of a sample: place sample in tube and allow to grow, then multiply by dilution factor Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 70  Inoculate Petri plates from serial dilutions Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 71  After incubation, count colonies on plates that have 25-250 colonies (CFUs) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 72  Used for smaller populations: measures the waste byproducts produced(gas) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 73  Direct Microscopic Count Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 74 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 75  Turbidity(cloudiness): measures how much light travels through the culture Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 76 Module 4C Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 77 • Sterilization: Removal of all microbial life • Commercial Sterilization: Killing C. botulinum endospores • Disinfection: reducing the number of or inhibiting the growth of microorganisms • Antisepsis: Removal of pathogens from living tissue(external) • Degerming: Removal of microbes from a limited area • Sanitization: Lower microbial counts on eating utensils • Biocide/Germicide: Kills microbes • Bacteriostasis: Inhibiting, not killing, microbes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 78    Sepsis refers to microbial contamination. Asepsis is the absence of significant contamination. Aseptic surgery techniques prevent microbial contamination of wounds. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 79 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 80 • Number of microbes • Environment (organic matter, temperature, biofilms) • Time of exposure • Microbial characteristics 81 Alteration of membrane permeability  Damage to proteins  Damage to nucleic acids Physical Methods of Microbial Control  • Heat • Thermal death point (TDP): Lowest temperature at which all cells in a culture are killed in 10 min. • Thermal death time (TDT): Time to kill all cells in a culture • Decimal reduction time (DRT): Minutes to kill 90% of a population at a given temperature Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 82   Moist heat: boiling,autoclave, pastuerization Autoclave: Steam under pressure Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 83       Pasteurization reduces spoilage of organisms and pathogens Equivalent treatments 63°C for 30 min High-temperature short-time 72°C for 15 sec Ultra-high-temperature: 140°C for
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