Term
|
Definition
total of all chemical rxns in the cell
divided into catabolism & anabolism |
|
|
Term
|
Definition
- Energy-producing rxns
- provide ready source of reducing power (electrons)
- generate precursors for biosynthesis
- biodegradation & production of ATP
|
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|
Term
|
Definition
- synthesis of complex organic molecules from simpler ones
- requires energy from fueling rxns
- biosynthesis & consumes ATP
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|
Term
What is important about microbial metabolism? |
|
Definition
- have representatives in all 5 nutritional types
- contribute to cycling of elements in ecosystem
|
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|
Term
Microbial cells must do what kinds of work? |
|
Definition
chemical, transport, & mechanical work |
|
|
Term
|
Definition
synthesis of complex molecules |
|
|
Term
|
Definition
take up of nutrients, elimination of wastes, & maintenance of ion balances |
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Term
|
Definition
cell motility & movement of structures w/n cells |
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|
Term
A calorie is an energy unit.
Define calorie: |
|
Definition
amount of heat energy needed to raise 1 gram of water from 14.5-15.5 C° |
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|
Term
|
Definition
rxn is @ equilibrium when rate of fwd rxn = rate of reverse rxn |
|
|
Term
The equilibrium constant Keq expresses what? |
|
Definition
the equilibrium concentrations of products & reactants to one another |
|
|
Term
Describe the relationship between ΔG° and Equilibrium: |
|
Definition
Exergonic rxns: ΔG° is negative; proceeds spontaneously
Endergonic rxns: ΔG° is positive; nonspontaneous |
|
|
Term
What is the energy currency of the cell? |
|
Definition
Adenosine 5'-triphosphate (ATP) |
|
|
Term
What is the role of ATP in metabolism? |
|
Definition
- high energy molecule
- exergonic breakdown of ATP coupled w/ endergonic rxns to make them more favorable
- ATP + H20 --> ADP + Pi + H+
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|
Term
Many metabolic processes involve ______. |
|
Definition
oxidation-reduction rxns (electron transfers) |
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|
Term
How are electron carriers used to transfer electrons? |
|
Definition
from an electron donor to electron acceptor |
|
|
Term
|
Definition
transfer of electrons from a donor to an acceptor
- can result in energy release, which can be conserved & used to form ATP
- more electrons a molecule has, the more energy rich it is
|
|
|
Term
Electron Carriers are organized into what? |
|
Definition
the electron transport chain
first carrier is reduced & electrons moved to the next carrier and so on |
|
|
Term
Characteristics of Electron Carriers: |
|
Definition
- located in plasma membranes of chemoogranotrophs in bacteria & archaeal cells
- located in internal mitochondrial membranes in eukaryotic cells
- examples: NAD, NADP, & others
|
|
|
Term
|
Definition
Nicotinamide adenine dinucleotide |
|
|
Term
What does NADP stand for? |
|
Definition
Nicotinamide adenine dinucleotide phosphate |
|
|
Term
|
Definition
Flavin adenine dinucleotide |
|
|
Term
|
Definition
use iron to transfer electrons
(iron is part of a heme group) |
|
|
Term
Nonheme iron-sulfur proteins_________. |
|
Definition
can still use iron to transport electrons |
|
|
Term
|
Definition
- carry out rxns at physiological conditions so they proceed in a timely manner
- speed up rate @ which a rxn proceeds toward its final equilibrium
|
|
|
Term
|
Definition
substance that increases the rate of a rxn w/o being permanently altered |
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|
Term
Define protein catalysts: |
|
Definition
have great specificity for the rxn catalyzed & the molecules acted on |
|
|
Term
|
Definition
|
|
Term
|
Definition
substances formed by the rxn |
|
|
Term
Describe the structure of enzymes: |
|
Definition
- some composed solely of one or more polypeptides
- some have nonprotein components
|
|
|
Term
What is the transition-state complex? |
|
Definition
resembles both the substrates & the products |
|
|
Term
Define activation energy: |
|
Definition
energy required to form transition-state complex
(an enzyme speeds up by lowering activation energy) |
|
|
Term
Enzyme activity is significantly impacted by: |
|
Definition
substrate concentration, pH, and temperature |
|
|
Term
What is the effect of the substrate? |
|
Definition
- rate increases as substrate increases
- no further inc occurs after all enzyme molecules are saturated w/ substrate
|
|
|
Term
What is the effect of pH and temperature? |
|
Definition
- each enzyme has specific pH & temperature optima
- denaturation: loss of enzyme's structure & activity when temp & pH rise too much above optima
|
|
|
Term
What is a competitive inhibitor? |
|
Definition
directly competes w/ binding of substrate to active site |
|
|
Term
What is a noncompetitive inhibitor? |
|
Definition
- binds enzymes at site other than active site
- changes enzyme's shape so that it becomes less active
|
|
|
Term
Who discovered ribozymes? |
|
Definition
Thomas Cech & Sidney Altman |
|
|
Term
|
Definition
- RNA molecules that can catalyze rxns
- can catalyze peptide bond formation
- self-splicing
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|
|
Term
Characteristics of Metabolic Regulation: |
|
Definition
- important for conservation of energy & materials
- two major mechanisms: regulation of synthesis of particular enzyme (transciptional & translational) & direct stimulation or inhibition of activity of critical enzyme (post-translational)
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|
|
Term
Describe Post-translational regulation of enzyme activity: |
|
Definition
two important reversible control measures:
1. allosteric regulation
2. covalent modification |
|
|
Term
Describe allosteric regulation: |
|
Definition
- most regulatory enzymes
- activity altered by small molecule
|
|
|
Term
Characteristics of Allosteric Effector: |
|
Definition
- binds non-covalently at regulatory site
- changes shape of enzyme & alters activity of catalytic site
- can either inc or dec enzyme activity
|
|
|
Term
Describe Covalent Modification of Enzymes: |
|
Definition
- reversible on & off switch
- addition or removal of a chemical group (phosphate, methyl, adenyl)
|
|
|
Term
What are the advantages of the covalent modification of enzymes? |
|
Definition
- respond to more stimuli in varied & sophisticated ways
- regulation of enzymes that catalyze covalent modification adds 2nd level
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|
Term
Define feedback inhibition: |
|
Definition
inhibition of one or more critical enzymes in a pathway regulates entire pathway
also called end-product inhibition |
|
|
Term
Each end product regulates what? |
|
Definition
its own branch of the pathway &
the initial enzyme |
|
|
Term
|
Definition
energy release and conservation |
|
|
Term
What are the chemoorganotrophic fueling processes? |
|
Definition
- aerobic respiration
- anaerobic respiration
- fermentation
|
|
|
Term
Most respiration involves the use of what? |
|
Definition
electron transport chain
as electrons pass through ETC to final electron acceptor, proton motive force (PMF) is generated & used to synthesize ATP |
|
|
Term
Differentiate between the chemoorganic fueling processes of aerobic & anaerobic respiration: |
|
Definition
aerobic: final electron acceptor is oxygen
anaerobic: final electron acceptor is different exogenous acceptor such as NO3-, SO42-, CO2. Fe3+, or SeO42- |
|
|
Term
|
Definition
- uses organic electron acceptor
- no ETC; no proton motive force
- ATP synthesized only by substrate-level phosphorylation
|
|
|
Term
ATP is made primarily by what? |
|
Definition
oxidative phosphorylation |
|
|
Term
Many different energy sources are funneled into what? |
|
Definition
common degradative pathways; most pathways generate glucose or intermediates of the pathways used in glucose metabolism |
|
|
Term
Define Aerobic Respiration: |
|
Definition
process that can completely catabolize an organic energy source to CO2 using glycolytic pathways (glycolysis), TCA cycle, & ETC w/ O2 as final electron acceptor |
|
|
Term
What pathway describes the breakdown of glucose to pyruvate? |
|
Definition
The Embden-Meyerhof pathway (glycolysis) |
|
|
Term
What is the summary of Glycolysis: |
|
Definition
glucose + 2ADP + 2Pi + 2NAD+
----------->
2 pyruvate + 2ATP + 2NADH + 2H+ |
|
|
Term
Characteristics of the Tricarboxylic Acid Cycle: |
|
Definition
- also called citric acid or Kreb's cycle
- common in aerobic bacteria, free living protozoa, most algae, & fungi
- major role is as source of carbon skeletons for use in biosynthesis
|
|
|
Term
|
Definition
- for each acetyl-CoA molecule oxidized, TCA cycle generates:
-2 molecules of CO2
-3 molecules of NADH
-one FADH2
-one GTP = one ATP |
|
|
Term
What is synthesized directly from oxidation of glucose to CO2? |
|
Definition
|
|
Term
|
Definition
when NADH & FADH2 (formed as glucose degraded) are oxidized in ETC |
|
|
Term
What is the mitochondrial ETC composed of? |
|
Definition
a series of electron carriers that operate together to transfer electrons from NADH & FADH2 to a terminal electron acceptor O2 |
|
|
Term
Describe the ETC in eukaryotes: |
|
Definition
in eukaryotes, chain carriers are w/n the inner mitochondral membrane |
|
|
Term
Electron transfer is accompanied by what? |
|
Definition
proton movement across inner mitochondrial membrane |
|
|
Term
Descibe Bacterial & Archaeal ETCs: |
|
Definition
- located in plasma membrane
- some resemble mitochondrial ETC, but many are different
|
|
|
Term
Define Oxidative Phosphorylation: |
|
Definition
process by which ATP is synthesized as the result of electron transport driven by the oxidation of a chemical energy source |
|
|
Term
What is the most widely accepted hypothesis to explain oxidative phosphorylation? |
|
Definition
|
|
Term
|
Definition
- ETC organized so protons move outward from the mitochondrial matrix as electrons are transported down the chain
- proton expulsion during ET results in the formation of a conc. gradient of protons (pH gradient) & charge gradient
- combined chemical & electrical potential difference represent proton motive force (PMF)
|
|
|
Term
What drives the formation of ATP? |
|
Definition
Diffusion of protons back across membrane
PMf drives ATP synthesis |
|
|
Term
|
Definition
- enzyme that uses PMF to catalyze ATP synthesis
- functions like rotary engine w/ conformational changes
|
|
|
Term
How can maximum ATP yield be calculated? |
|
Definition
- includes oxidation of NADH & FADH2
- ATP produced by substrate level phosphorylation
- theoretical maximum total yield of ATP during aerobic respiration is 38 but actual number closer to 30
|
|
|
Term
Describe Theoretical vs. Actual Yield of ATP: |
|
Definition
- amount of ATP produced during aerobic respiration varies depending on growth conditions & nature of ETC
- under anaerobic conditions, glycolysis only yields 2 ATP molecules
|
|
|
Term
Describe Anaerobic Respiration: |
|
Definition
- uses electron carriers other than O2
- generally yields less energy
|
|
|
Term
Characteristics of Fermentation: |
|
Definition
- oxidation of NADH produced by glycolysis
- pyruvate or derivative used as endogenous electron acceptor
- substrate only partially oxidized
- O2 not needed
- oxidative phosphorylation does not occur (ATP formed only by substrate-level phosphorylation)
|
|
|
Term
Describe the catabolism of other carbohydrates: |
|
Definition
- many different carbohydrates can serve as energy source
- carbohydrates can be supplied externally or internally (from internal reserves)
|
|
|
Term
Describe Lipid Catabolism: |
|
Definition
Triglycerides
- common energy sources
- hydrolyzed to glycerol & fatty acids by lipases
- glycerol degraded via glycolytic pathways
- fatty acids often oxidized via B-oxidation pathway
|
|
|
Term
What is the function of a protease? |
|
Definition
hydrolyzes protein to amino acids |
|
|
Term
|
Definition
- removal of amino group from amino acid
- resulting organic acids converted to pyruvate, acetyl-CoA or TCA cycle intermediate (can be oxidized via TCA cycle & can be used for biosynthesis)
|
|
|
Term
|
Definition
- energy from light trapped & converted to chemical energy
- a 2 part process
|
|
|
Term
What is the two-part process of photosynthesis? |
|
Definition
- light rxns in which light energy is trapped & converted to chemical energy
- dark rxns in which the energy produced in the light rxns is used to reduce CO2 & synthesize cell constituents
|
|
|
Term
Describe light rxns in oxygenic photosynthesis: |
|
Definition
- photosynthetic eukaryotes & cyanobacteria
- oxygen is generated & released into environment
- most important pigments are chlorophylls
|
|
|
Term
|
Definition
major light-absorbing pigments |
|
|
Term
What are accessory pigments? |
|
Definition
transfer light energy to chlorophylls (e.g. carotenoids) |
|
|
Term
|
Definition
- highly organized arrays of chlorophylls & accessory pigments
- captured light transferred to special rxn-center chlorophyll (directly involved in photosynthetic electron transport)
|
|
|
Term
What is oxygenic photosynthesis? |
|
Definition
noncyclic electron flow (ATP + NADPH made; noncyclic photophosphorylation)
cyclic electron flow (ATP made; cyclic photophosphorylation) |
|
|
Term
Describe the light rxn in anoxygenic photosynthesis: |
|
Definition
- H2O not used as an electron source so O2 not produced
- only 1 photosystem involved
- uses bacteriochlorophylls & mechanisms to generate reducing pwr
- carried out by phototropic green & purple bacteria
|
|
|
Term
Describe Bacteriorhodopsin-based phototrophy: |
|
Definition
- some archaea used type of phototrophy that involves bacteriorhodopsin (a membrane protein which functions as light-driven proton pump)
- proton motive force generated
- ETC not involved
|
|
|
Term
|
Definition
the use of energy from catabolism for biosynthetic pathways |
|
|
Term
Characteristics of Anabolism: |
|
Definition
- using a carbon source & inorganic molecules, organisms synthesize new organelles & cells
- antibiotics inhibit anabolic pathways
- great deal of energy needed for anabolism
|
|
|
Term
|
Definition
continual degradation & resynthesis of cellular constituents by nongrowing cells |
|
|
Term
Why is metabolism carefully regulated? |
|
Definition
for rate of turnover to be balanced by rate of biosynthesis |
|
|
Term
Describe the Principals Governing Biosynthesis: |
|
Definition
- macromolecules are synthesized from limited number of simple structural units (monomers)
- catabolic & anabolic pathways are not identical as some enzymes function in only one direction
- generation of precursor metabolites is critical step in anabolism
- carbon skeletons are used as starting substrates for biosynthetic pathways
|
|
|
Term
Large assemblies form spontaneously from ______________ by self-assembly. |
|
Definition
|
|
Term
What is used by most autotrophs to fix CO2? |
|
Definition
|
|
Term
In Eukaryotes, where does the fixation of CO2 by autotrophs occur? |
|
Definition
in the stroma of chloroplasts |
|
|
Term
Characteristics of the Calvin Cycle: |
|
Definition
consists of 3 phases
1. carboxylation phase
2. reduction phase
3. regeneration phase
three ATPs & two NADPHs are used during the incorporation of one CO2 |
|
|
Term
Describe the Carboxylation Phase: |
|
Definition
- catalyzed by enzyme ribulose 1,5-bisphosphate carboxylase (aka ribulose bisphosphate carboxylase/oxidase; rubisco)
- rubisco catalyzes addition of CO2 to ribulose 1,5-bisphosphate (RuBP) forming 2 molecules of 3-phosphoglycerate
|
|
|
Term
How are monosaccharides synthesized? |
|
Definition
several sugars are synthesized while attached to a nucleoside diphosphate with uridine diphosphate glucose |
|
|
Term
How are amino acids synthesized? |
|
Definition
many precursor metabolites are used as starting substrates for synthesis of amino acids
- carbon skeleton is remodeled
- amino group & sometimes sulfur are added
|
|
|
Term
What is a major component of protein, nucleic acids, coenzymes, & other cell constituents? |
|
Definition
|
|
Term
Nitrogen addition to carbon skeleton is an important step. What are some potential sources of nitrogen and why is it easily incorporated? |
|
Definition
- potential sources of nitrogen: ammonia, nitrate, or nitrogen (most cell use ammonia or nitrate)
- ammonia nitrogen easily incorporated into organic material b/c it is more reduced than other forms of inorganic nitrogen
|
|
|
Term
Describe assimilatory nitrate reduction: |
|
Definition
- used by bacteria to reduce nitrate to ammonia & then incorporate it into an organic form
- nitrate reduction to nitrite catalyzed by nitrate reductase
- reduction of nitrite to ammonia catalyzed by nitrite reductase
|
|
|
Term
Describe Nitrogen Fixation: |
|
Definition
- reduction of atmospheric nitrogen to ammonia
- catalyzed by nitrogenase (found onlyl in bacteria & archaea)
|
|
|
Term
What is the relationship between microbes and purines/pyrimidines? |
|
Definition
most microbes can synthesize their own purines and pyrimidines |
|
|
Term
|
Definition
cyclic nitrogenous bases consisting of 2 joined rings
adenine & guanine |
|
|
Term
|
Definition
cyclic nitrogenous bases consisting of single ring
uracil, cytosine, & thymine |
|
|
Term
|
Definition
nitrogenase base-pentose sugar |
|
|
Term
|
Definition
|
|
Term
Where can phosphorus be found? |
|
Definition
can be found in nucleic acids as well as proteins, phospholipids, ATP, and some coenzymes
most common sources are inorganic phosphate & organic phosphate esters |
|
|
Term
How is inorganic phosphate incorporated? |
|
Definition
incorporated through the formation of ATP by
- phosphorylation
- oxidative phosphorylation
- substrate-level phosphorylation
|
|
|
Term
What is the significance of lipids? |
|
Definition
- major required component in cell membranes
- most bacterial & eukaryotic lipids contain fatty acids
|
|
|
Term
What is the significance of fatty acids? |
|
Definition
synthesized then added to other molecules to form other lipids such as triaclyglycerols & phospholipids |
|
|
Term
What are fatty acids synthesized from? |
|
Definition
|
|
Term
|
Definition
major components of eukaryotic & bacterial cell membranes |
|
|
Term
Define ribonucleic acid (RNA): |
|
Definition
expresses the information in DNA |
|
|
Term
Define Deoxyribonucleic acid (DNA): |
|
Definition
storage molecule for genetic instructions to carry out metabolism & reproduction |
|
|
Term
|
Definition
enzymes & structural proteins |
|
|
Term
|
Definition
- all DNA present in a cell or virus
- bacteria & archaea generally have 1 set (haploid - 1N)
- eukaryotes have 2 sets (diploid - 2N)
|
|
|
Term
In 1928, who observed the change of non-virulent organisms into virulent ones as a result of "transformation"? |
|
Definition
|
|
Term
In 1944, who showed that the transforming principle was DNA? |
|
Definition
|
|
Term
In 1952, who used bacteriophage T2 infection as a model and labeled DNA with 32P protein coat labeled with 35S so only DNA entered the cell? |
|
Definition
|
|
Term
What is the central concept? |
|
Definition
- the pathway from DNA to RNA to protein is gene expression
- it is conserved in all cellular forms of life
|
|
|
Term
Describe the flow of genetic information from one generation to the next: |
|
Definition
- DNA stores genetic information
- information is duplicated by replication & is passed on to the next generation
|
|
|
Term
Describe gene expression and how DNA is divided into genes: |
|
Definition
- transcription yields a ribonucleic acid (RNA) copy of specific gene
- translation uses info in messenger RNA to synthesize a polypeptide
- also involves activities of transfer RNA & ribosomal RNA
|
|
|
Term
The nucleic acids DNA & RNA are __________ of nucleotides. |
|
Definition
|
|
Term
How do the structures of DNA & RNA differ? |
|
Definition
- the nitrogenous bases they contain
- the sugars they contain
- whether they are single or double stranded
|
|
|
Term
What are the bases and sugar of DNA? |
|
Definition
adenine, guanine, cytosine, & thymine
sugar is deoxyribose |
|
|
Term
Describe the structure of DNA regarding its backbone & covalent bonds: |
|
Definition
- sugar phosphate backbone
- covalent bonds b/n the 3' hydroxyl of one sugar & a 5' hydroxyl of an adjacent sugar
|
|
|
Term
Describe the structure of DNA regarding its two complementary strands: |
|
Definition
- double-stranded helix
- base pairing:
2H bonds-adenine (purine) & thymine (pyrimidine)
3H bonds-guanine (purine) & cytosine (pyrimidine)
- major & minor grooves form when the 2 strands twist around each other
|
|
|
Term
What are the bases and sugar of RNA? |
|
Definition
adenine, guanine, cytosine, & uracil
sugar is ribose |
|
|
Term
Describe the structure of RNA regarding bond types and number of strands: |
|
Definition
phosphodiester bonds
most RNA molecules are single-stranded but some are double-stranded |
|
|
Term
There are 3 different types of RNA which may differ from each other in function, site of synthesis, & in structure. What are these 3 types? |
|
Definition
- messenger RNA (mRNA)
- ribosomal RNA (rRNA)
- transfer RNA (tRNA)
|
|
|
Term
Describe the structure of protein: |
|
Definition
- polymers of amino acids linked by peptide bonds
- amino acids have central carbon with a C-terminal (carboxyl group), N-terminal (amino group), and side chains
- amino acids can be polar, non-polar, or charged depending on the side chain
|
|
|
Term
Explain the process of DNA replication: |
|
Definition
- involves numerous proteins which help ensure accuracy
- 2 strands separate w/ each serving as a template for synthesis of a complementary strand
- synthesis is semi-conservative in which each daughter cell obtains 1 old (parent) & 1 new strand
|
|
|
Term
Describe the patterns of DNA synthesis for Bacteria, Archaea, & Eukaryotes: |
|
Definition
- Bacteria: DNA in most is circular; bidirectional replication from single origin & replication fork is where DNA is unwound
- Archaea: circuar but may have more than one origin
- Eukaryotic: linear chromosome w/ many replication forks
|
|
|
Term
Compare/Contrast the Replication Machinery of Bacteria, Archaea, & Eukaryotes: |
|
Definition
- Bacteria like E. Coli consists of at least 30 proteins
- Archaea has more similarities to eukaryotic replication machinery
- overall process similar in all
|
|
|
Term
Descibe the general process of replication machinery: |
|
Definition
- DNA pol catalyzes synthesis of complementary strand of DNA
- DNA synthesis is in 5' --> 3' direction resulting w/ formation of a phosphodiester bond
|
|
|
Term
What do the enzymes of replication machinery require? |
|
Definition
- template that directs synthesis of complementary strand
- a primer such as DNA or RNA strand
- Deoxyribonucleoside triphosphates (dNTPs) such as dATP, dTTP, dCTP, & dGTP
|
|
|
Term
What is a DNA polymerase holoenzyme? |
|
Definition
- complex of 10 proteins
- catalyze DNA synthesis
- proofreading for fidelity
|
|
|
Term
|
Definition
|
|
Term
Function of single-stranded binding proteins (SSB): |
|
Definition
keep strands apart for replication to occur |
|
|
Term
Function of DNA topoisomerases: |
|
Definition
break one or both strands of DNA to relieve tension from rapid unwinding of double helix & prevent supercoiling |
|
|
Term
|
Definition
DNA topoisomerase
introduces negative supercoiling to help compact bacterial chromosome |
|
|
Term
|
Definition
synthesizes short complementary strands of RNA (about 10 nucleotides) to serve as primers needed by DNA polymerase |
|
|
Term
What direction does DNA pol synthesize? |
|
Definition
in the 5' to 3' direction only |
|
|
Term
The lagging strand is synthesized in short fragments called __________? |
|
Definition
|
|
Term
____________ is needed for the synthesis of each new Okazaki fragment. |
|
Definition
|
|
Term
What are the events at the replication fork in E. coli? |
|
Definition
- primase synthesizes RNA primer
- lagging & leading strands are synthesized
- DNA pol I removes RNA primers
- Okazaki fragments are joined by DNA ligase
|
|
|
Term
|
Definition
forms a phosphodiester bond b/n 3' hydroxyl of the growing strand & 5' phosphate of Okazaki fragment |
|
|
Term
When does replication stop? |
|
Definition
when replisome reaches termination site on DNA |
|
|
Term
What are catenanes and when do they form? |
|
Definition
interlocked rings
form when the two circular daughter chromosomes do not separate |
|
|
Term
What allows strands to separate? |
|
Definition
topoisomerases temporarily break the DNA molecules so the stands can separate |
|
|
Term
What enzyme found in eukaryotes can synthesize DNA using an RNA template thus solving the "end" replication problem? |
|
Definition
|
|
Term
|
Definition
- basic unit of genetic info
- nucleic acid sequence that codes for a polypeptide, tRNA, or rRNA
- linear sequence of nucleotides w/ a fixed start point & end point
- codons are found in mRNA & code for single amino acids
|
|
|
Term
Define the Reading Frame of gene structure: |
|
Definition
- organization of codons such that they can be read to give rise to a gene product
- most do not overlap but the exception is some viruses which have overlapping reading frames
|
|
|