Shared Flashcard Set

Details

Microbiology Test 2
Chapters 9-16
157
Microbiology
Undergraduate 3
02/24/2013

Additional Microbiology Flashcards

 


 

Cards

Term
What is metabolism?
Definition

total of all chemical rxns in the cell

 

 divided into catabolism & anabolism

Term
Define Catabolism:
Definition
  • Energy-producing rxns
  • provide ready source of reducing power (electrons)
  • generate precursors for biosynthesis
  • biodegradation & production of ATP
Term
Define Anabolism:
Definition
  • synthesis of complex organic molecules from simpler ones
  • requires energy from fueling rxns
  • biosynthesis & consumes ATP
Term
What is important about microbial metabolism?
Definition
  • have representatives in all 5 nutritional types
  • contribute to cycling of elements in ecosystem
Term
Microbial cells must do what kinds of work?
Definition
chemical, transport, & mechanical work
Term
What is chemical work?
Definition
synthesis of complex molecules
Term
What is transport work?
Definition
take up of nutrients, elimination of wastes, & maintenance of ion balances
Term
What is mechanical work?
Definition
cell motility & movement of structures w/n cells
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°
Term
Define equilibrium:
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 rxnsΔG° is negative; proceeds    spontaneously


Endergonic rxnsΔG° 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+
Term
Many metabolic processes involve ______.
Definition
oxidation-reduction rxns (electron transfers)
Term
How are electron carriers used to transfer electrons?
Definition
from an electron donor to electron acceptor
Term
Define redox reactions:
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
What does NAD stand for?
Definition
Nicotinamide adenine dinucleotide
Term
What does NADP stand for?
Definition
Nicotinamide adenine dinucleotide phosphate
Term
What does FAD stand for?
Definition
Flavin adenine dinucleotide
Term
Define cytochromes:
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
Define enzymes:
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
Define catalyst:
Definition
substance that increases the rate of a rxn w/o being permanently altered
Term
Define protein catalysts:
Definition
have great specificity for the rxn catalyzed & the molecules acted on
Term
Define substrates:
Definition
reacting molecules
Term
Define products:
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
Define ribozymes:
Definition
  • RNA molecules that can catalyze rxns
  • can catalyze peptide bond formation
  • self-splicing
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)
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
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
Define Catabolism:
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
What is fermentation?
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
Summarize the TCA cycle:
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
4 ATP molecules
Term
When is most ATP made?
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
Chemiosmosis
Term
Explain chemiosmosis:
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
What is ATP synthase?
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
Define deamination:
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
Define photosynthesis:
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
Define Chlorophyll:
Definition
major light-absorbing pigments
Term
What are accessory pigments?
Definition
transfer light energy to chlorophylls (e.g. carotenoids)
Term
Describe antennas:
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
Define Anabolism:
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
Define turnover:
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
macromolecules
Term
What is used by most autotrophs to fix CO2?
Definition
the Calvin cycle
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

Nitrogen 

 

 

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
Define purine:
Definition

cyclic nitrogenous bases consisting of 2 joined rings 

 

adenine & guanine

Term
Define pyrimidine:
Definition

cyclic nitrogenous bases consisting of single ring

 

uracil, cytosine, & thymine

Term
Define nucleoside:
Definition
nitrogenase base-pentose sugar
Term
Define nucleotide:
Definition
nucleoside-phosphate
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
acetyl-CoA
Term
Define phospholipids:
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
Define proteins:
Definition
enzymes & structural proteins
Term
Define genome:
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
Griffith
Term
In 1944, who showed that the transforming principle was DNA?
Definition
MacLeod & McCarty
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
Hershey & Chase
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
polymers
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
Function of Helicases:
Definition
unwind DNA strands
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
Function of DNA gyrase:
Definition

DNA topoisomerase

 

introduces negative supercoiling to help compact bacterial chromosome

Term
Function of primase:
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
Okazaki fragments
Term
____________ is needed for the synthesis of each new Okazaki fragment.
Definition
a new primer
Term
What are the events at the replication fork in E. coli?
Definition
  1. primase synthesizes RNA primer
  2. lagging & leading strands are synthesized
  3. DNA pol I removes RNA primers
  4. Okazaki fragments are joined by DNA ligase
Term
Function of DNA ligase:
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
telomerase
Term
Define gene:
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
Supporting users have an ad free experience!