Exam 2 (Ch. 5, 6, 13) Flashcards
What is metabolism?
The buildup and breakdown of nutrients within a cell.
Describe the two types of pathways of metabolism
catabolic - break down macromolecules into simple ones, releasing energy
anabolic - build up macromolecules by combining simple ones, using energy
catabolic reactions provide the energy needed for anabolic reactions
Tue or false: Many metabolic pathways can be beneficial rather than pathogenic
True
metabolic pathways are determined by
enzymes
what do catalysts do in chemical reactions?
speed up chemical reactions without being altered
what do enzymes do in chemical reactions?
- enzymes are biological catalysts; speed up the reaction
- act on a specific substrate
- lower the activation energy
substrate contacts the enzyme’s active site to form ____
an enzyme substrate complex
Substrate is transformed and rearranged into ___ which are released from the enzyme
products
competitive inhibitors fill the ___ of an enzyme and compete with the ___
active site, substrate
Noncompetitive inhibitors interact with the ___
allosteric site
what is feedback inhibition?
when an enzyme’s activity is inhibited by the enzyme’s end product
oxidation: ___ of electrons
removal
reduction: ___ of electrons
gain
what is a redox reaction?
an oxidation reaction paired with a reduction reaction
ATP is generated by the ___ of ADP with the input of energy
phosphorylation
what generates ATP?
The phosphorylation of ADP with the input of energy
describe oxidative phosphorylation
electrons are transferred from one electron carrier to another along the electron transport chain on a membrane that releases energy to generate ATP
what is photophosphorylation?
light energy is converted to ATP during oxidation from chlorophyll
most microorganisms oxidize ___ as primary energy source
carbohydrates
what are the three stages of the breakdown of carbohydrates?
- glycolysis
- citric acid cycle
- electron transport chain
Summarize glycolysis
first phase - glucose is broken down to glyceraldehyde and uses energy
second phase - glyceraldehyde is broken down to 2 pyruvate and releases energy in the form of ATP and NADH
summarize acetyl-coA synthesis
- pyruvic acid (from glycolysis) is oxidized and decarboxylation (loss of co2) occurs
- the resulting two-carbon compound attached to coenzyme A attaches to coenzyme A, forming acetyl coA and NADH
what is decarboxylatiob?
loss of co2
what is aerobic respiration?
- the production of energy from food in the presence of oxygen
- glucose + oxygen –> carbon dioxide + water + atp
in anaerobic respiration, the final electron acceptor in the electron transport chain is not __
O2
which yields more energy, aerobic or anaerobic respiration?
aerobic
what are three molecules that can be the final electron acceptors in anaerobic respiration?
-NO3-
-SO4 2-
CO3 2-
true or false: fermentation does not require oxygen
true
does fermentation release or use energy?
release
fermentation uses a ___ molecule as the final electron acceptor
organic
describe homolactic and heterolactic fermentation
homolactic - produces lactic acid
heterolactic -produces lactic acid and/or other compounds
summarize alcohol fermentation
- 2 pyruvate (from glycolysis) is used to produce co2 and ethanol
- acetaldehyde acts as an electron acceptor and the 2 NADH is oxidized to 2 NAD+
summarize lactic acid fermentation
- 2 pyruvate (from glycolysis) is used to produce 2 lactate
- pyruvate acts as an electron acceptor allowing NADH to be oxidized to NAD+
where does each glycolysis process occur in the cell?
citric acid - mitochondria
fermentation - cytoplasm
etc - mitochondria
what are physical requirements for growth?
- temperature
- ph
- osmotic pressure
what are chemical requirements for growth?
- carbon
- nitrogen, sulfur, phosphorous
- trace elements
how does temperature affect growth?
- affects 3-d structure of proteins
- if too low, membranes become rigid and fragile
- if too high, membranes become too fluid
describe the groups of microorganisms classified by their preferred temperature
psychrophiles - cold psychrotrophs - cold tolerant mesophiles - moderate thermophiles - hot hyperthermophiles - extreme hot
describe the groups of microorganisms classified by their preferred ph
acidophiles - 1
neutrophiles - 6.5 - 7.5
alkaliphiles - 11.5
describe hypertonic, hypotonic, and isotonic environments
hypertonic - higher concentration in solute than in the cell
hypotonic - lower concentration in solute than in the cell
isotonic - equal concentrations in solute and cell
hypertonic solutions cause ___
plasmolysis
toxic forms of oxygen are highly reactive and excellent ___ agents
oxidizing
what does oxidation do?
cause irreparable damage
what are two toxic forms of oxygen?
superoxide radicals o2-
peroxide anion h2o2
describe the types of bacteria classified by their oxygen requirements
obligate aerobes - require oxygen
facultative anaerobes - grow via fermentation or anaerobic respiration when oxygen is not available
obligate anaerobes - unable to use oxygen and most are harmed by it
aerotolerant anaerobes - tolerate but can’t use oxygen
microaerophiles - require oxygen concentration lower than air
what is quorum testing?
bacterial communication to control gene expression based on the number of individuals in the population
which enzymes are used to get rid of radicals?
sod, catalase
what is biofilm?
- slime produced by bacteria for protection from harmful environments
- used to share nutrients
- involved in 70% of infections
what are the steps of binary fission?
- cell elongates and dna is replicated
- plasma membrane begins to constrict and new wall is made
- cross-wall forms, completely separating the two dna copies
- cell separates
what is generation time?
- the time required for a cell to divide (one round of binary fission)
- binary fission doubles the number of cells each generation
describe the phases of growth
lag - no increase in number, intense protein synthesis
log - active division, exponential increase in number
stationary - bacteria approach carrying capacity, nutrients are being depleted
death - waste accumulates and nutrients are exhausted
describe chemically defined media and complex media
chemically defined - exact chemical composition is known
complex - extracts of yeast meat, plants; composition varies. ex. nutrient broth/agar
why is the streak plate method used?
to isolate pure cultures
how many cfu’s should be counted on one plate?
30-300
what kind of plate method allows microorganisms to grow on the surface and within the medium?
pour plate
what kind of plate method makes it easy to count bacteria
spread plate
true or false: viruses are acellular
true
what size are viruses?
20 nm to 1000 nm
the spectrum of host cells that a virus can infect is called __
host range
the host range is determined by __
specific host attachment sites and cellular factors
viruses that can infect bacteria are called __
bacteriophages
what is a virion?
a fully developed viral particle
a protein coat on a virion that encases genetic material is called a ___
capsid
what are capsomeres?
the subunits of a capsid
how does a virus acquire an envelope?
from the host cell
describe the lytic and lysogenic cycles
lytic - phage causes lysis and death of the host cell. generalized transduction
lysogenic - phage dna is incorporates in the host dna. phage conversion. specialized transduction
describe the steps of the lytic cycle
attachment - phage attaches by the tail fibers to the host cell
penetration - phage lysozyme opens the cell wall; tail sheath contracts to force the tail core and dna into the cell
biosynthesis - production of phage dna and proteins
maturation(assembly) - assembly of phage particles
release - phage lysozyme breaks the cell walls
what is a prophage
inserted phage dna
the lysogenic cycle results in ___ in which the host cell exhibits new properties
phage conversion
what is transduction?
the transfer of genetic information from one cell to another via a bacteriophage
generalized vs specialized transduction
generalized - a random piece of bacterial chromosome dna is transferred by the phage during the lytic cycle
specialized - a specific piece of bacterial chromosome is transferred, occurs at the end of lysogenic cycle
describe the steps of the lysogenic cycle
integration - prophage exists in galactose-using host
excision - phage genome excises, carrying with it the adjacent gal gene from the host
infection - phage infects cell that cannot utilize galactose (lacking gal gene)
recombination - along with the prophage, the bacterial gal gene becomes integrated into the new host’s dna
describe the steps of multiplication of animal viruses
attachment
entry - by endocytosis, or fusion, direct penetration
uncoating by viral or host enzymes
biosynthesis - production of nucleic acid and proteins
maturation - nucleic acid and capsid proteins assemble
release by budding or rupture/lysis
during biosynthesis, viruses synthesize capsid and other proteins in the cytoplasm using ___
host cell enzymes
what are the two host cell enzymes that viruses use for biosynthesis
ssDNA
dsDNA
describe the two strands of ssRNA
ssRNA +(sense)
ssRNA -(antisense)
-complimentary strands
-positive acts as mRNA to make viral proteins
-negative needs RdRp (polymerase) to make + strand
what is a retrovirus?
-virus that uses reverse transcriptase to transcribe dna from rna
abnormal, pathogenic agents that are transmissible and found in the brain are called ___
prions
true or false: prions are viruses
false
what are ways that prions are transmissible?
ingestion
transplant
surgical instruments
what are PrPc and PrPsc?
prpc - normal prion protein, on the cell surface
prpsc - misfolded version of prion protein, scrapie form, accumulates in the brain and forms plaques
what are the two lifecycles for viruses
lytic and lysogenic
summarize the citric acid cycle
the acetyl group from acetyl coA attaches to oxaloacetate to produce citrate. citrate is oxidized to produce two co2. atp, nadh and fadh2 is also produced
What is the fate of pyruvate in an organism that uses aerobic respiration
it is converted to acetyl coa
___ uses an organic molecule as the final electron acceptor
fermentation
what molecule is used to transport electrons to the etc in aerobic respiration?
nadh
true or false - cyclic photophosphorylation leads to o2 production
false
in prokaryotes, the etc is located in the
plasma membrane
