-Self feeders -Make their own organic mols from inorganic ones.
-Must aquire their organic mos in their diet.
-Source of energy for nearly all life on Earth -Enters web of life thru photosynthesis.
Aerobic Cell Respiration
-Main degradative metabolic pathway to break down glucose. -Complete breakdown of glucose to CO2 +H20 using O. -Main function is to provide the energy needed for ATP synthesis. -36 ATP/glucose
2 Mechanisms for ATP synthesis
1.Substrate-level phosphorylation-some enzymes in glycolysis and the Kreb's cycle can directly transfer a P group to ADP to form ATP. 2.Chemiosmosis-a H ion concentration gradient across a membrane drives ATP production. Involves an e transport chain and a channel protein.
Aerobic Respiration Occurs In 4 Stages
1.Glycolysis 2.Pyruvate Conversion/Oxidation 3.Kreb's Cycle 4.E Transport Chain
-In cytoplasm -Makes 2 pyruvates, 2 NADH, + 2ATP -If O is present, pyruvates are transported into the mitochondrial matrix.
-In mitochondrial matrix -Each 3-C pyruvate is converted into 2-C acetyl CoA w/ formation of CO2 + another NADH (occurs 2ce for ea. glucose broken down.
-In mitochodrial matrix -Ea AcetylCoA goes thru Kreb cycle+is broken down to CO2s. rest of Hs pull off+e+some H ions stored in NADH+FADH2. -1 ATP made per turn of cycle (cycle must go around 2ce/glucose) -End of Cycle: 10NADH, 2 FADH2 + 4 ATP
Electron Transport Chain
-Inner mitochondrial membrane. -All coenzymes give up their e+H ions for use by an e transport system in inner mitochondrial membrane. -E transport system has 3 big complexes ( proton pumps when chain is running), w/ 2 mobile e carriers that travel btw them.
Electron Transport Chain 2
-NADH gives up e to 1st complex. -FADH2 gives up e after 1st complex. -E passed from mol to mol until they reach final e acceptor:O. -O can accept 2 e, can pick up 2 protons to form H20. -When e transport chain is running, 3 complexes pump H ions into inter-membrane space.
Electron Transport Chain
-Then H ions move down conc. gradient to matrix thru membrane channel protein(ATP synthase) b/c its the enzyme that catalyzes the reaction: ADP+P->ATP. -Channel protein/enzyme couples diffusion of H ions thru it to formation of ATP by chemiosmosis.
-Don't use O. -Conversion of pyruvate to other subs is to regenerate NAD so it doesnt get tied up- no glucose could then be broken down. 1.Anaerobic cell respiration-similar to aerobic, but some inorganic sub other than O used as final e acceptor. 2.Fermentation-incomplete breakdown of glucose. -Final e acceptor is an organic mol. -Virtually identical to glycolysis, doesn't use O. -Occurs in cytoplasm. A)Alcohol fermentation- glucose-->pyruvate+NADH+2ATP-->ethanol+NAD B)Lactate fermentation- glucose-->pyruvate+NADH+2ATP-->lactate+NAD
-No nucleus. -Divide by binary fission. -Single circular chromosome copied;cell grows to 2ce its size, divides in two.
-Larger cells+more DNA (as linear chromosomes). -More complex division.
-Threadlike chromatin(complex of protein+long strand of DNA) -DNA strand looped around protein "spool" made of histones (looks like string of beads). -Ea histone w/ looped is nucleosome. -Coiled further to make chromatin fiber to make highly condensed portion visible chromosome. Heterochromatin: -never expressed -highly condensed part of chromosome. Euchromatin: -Expressed part of genetic material. -Condensed only during cell division. -Usually in looser chromatin form.
-Carried on a set of 23 chromosomes. -Body(somatic)cells have 2 sets of chromosomes= diploid cell (2N). -Cells have 2 of ea type of chromosome(homologous pairs). -Before cell division ea chromosome must duplicate self. -Condensed chromosomes at beginning of cell division,2 identical copies of chrom(sister chromatids) are attached by their centromeres.
-(Eggs + Sperm). -Haploid (IN). -Have only one set of chromosomes.
-Nondividing portion of cell cycle(90--95% of cell cycle). 1)G1-1st stage after division, growth of new cell. 2)S-synthesis of DNA, chromosomes duplicate. 3)G2-2nd growth period, preparations for cell division
-Division of nuclear contents.
-Division of cytoplasmic contents.
-Resting state in G1. -Some cells, neurons,+ muscle stay here permanently.
-Array of microtubules seen only in cell division. -Critical to chromosome separation.
-Basis of asexual reproduction(1 parent). -1 parent cell produces 2 daughter cells that are gen. identical to parent cell (Clones). -Chromosome #+content remain same for every generation.
-Duplicated chromosomes line up on spindle equator(metaphase plate). -Attach by kinectochores.
-Sister chomatids move to opp. poles of cell.
-Chromosomes reach opp poles, decondense, nuclear envelope reappears.
-Involves formation of cleavage furrow in animal cells. -Involves formation of cell plate in plant cells.
Cell Division Controlled By 2 Types of Proteins
-Cyclins +Cyclin. -Dependent protein kinases+a variety of genes that stimulate/inhibit cell division. -problems w/ any of these may lead to uncontrolled cell division (cancer).
-Forms basis of sexual reproduction along w/ fertilization. -Special type of nuclear division that cuts chromosome# in 1/2. (Reduction Division). -Occurs only in germ cells of reprod. organs to produce gametes(eggs+sperm). -Invovles replication of DNA + then 2 mr divisions. -Results in formation of 4 haploid gametes. -None are identical to original parent cell(diploid germ cell).
Meiosis Vs. Mitosis
1)Meiosis I: Prophase1:duplicated homologous chroms pair up(synapsis) Form synaptonemal complexes leading to crossing over. Exchange = amts of DNA btw nonsister chromatids. Metaphase1:paired homolgues line up on spindle equator. Anaphase1:duplicated homologues sep,move to opp poles. Telophase1:duplicated chroms reach opp poles. -Cytokinesis usually occurs. -Cell may/not go directly into Meiosis II. -Resting period called interkinesis.
Meiosis Vs. Mitosis (2)
2)Meiosis II: ProphaseII:spindle forms MetaphaseII:duplicated chroms line up single file on spindle equator. AnaphaseII:sister chromatidsmove to opp poles. TelophaseII:chroms reach opp poles of cell Nuclear envelopes reforn, cytokinesis. -Now 4 haploid cells-none identical to parent cell(b/c crossing over). -Proper chrom # is restored in fertilization.
Development of unfertilized egg into an adult.
Sources of Genetic Variation
1)Crossing over. 2)Independent assortment of maternal+paternal chroms. 3)Random fertilization. 4)Mutation-the only one that has nothing to do w/ sexual reproduction.