Lecture 7 Flashcards by amanda kastel

true or false

bacteria are the smallest living cells

TRUE

0.1-10 micrometers

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are bacteria prokaryotic cells or eukaryotic cells?

prokaryotic

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nearly ALL bacteria have….

a rigid cell wall

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what is the size of cell respiration in prokaryotes and in eukaryotes?

prokaryotes – the cell membrane

eukaryotes – the mitochondria

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bacteria can be classified by which 6 things?

-appearance

-requirements for their growth

-their metabolism

-biochemistry

-antigenicity

-genotype

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what do you mean that bacteria can be classified by their appearance?

their shape and their gram stain

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what do you mean that bacteria can be classified based on the requirements for their growth?

the specific nutrients they need and can be selective on the media they grow in

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what do you mean that bacteria can be classified based on their metabolism?

if they’re aerobic, anaerobic, or facultative (does aerobic if oxygen is present, but capable of switching to fermentation in absence of oxygen)

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what do you mean that bacteria can be classified based on their biochemistry?

their proteases and enzymes

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what do you mean that bacteria can be classified by their antigenicity?

by their recognition by the immune system

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the cytoplasm of prokaryotes is rich in ____ ribosomes

70s

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name the different shapes of bacteria

coccus (circular)

bacillus (rod shaped)

curved (coil/spiral)

OTHER – helical or club

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name 4 FUNCTIONS of the bacterial cell wall

-maintains shape, strength, and rigidity

-protects against osmotic lysis

-allows for ATTACHMENT to (host) cells and to other surfaces

-provides PROTECTION against the immune system

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explain the difference between the gram positive and the gram negative bacterial cell wall

gram positive: has THICK layer of peptidoglycan that serves as the cell wall. has plasma membrane inside.

gram negative: has outer and inner membrane. has thinner layer of peptidoglycan in the periplasmic space.

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using GRAM STAIN is an easy way to determine what?

if the bacteria has a thick or thin cell wall. the stain stays in the THICK cell wall (cell wall)

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name the 4 steps of using gram stain

Crystal violet
gram iodine
decolorizer (alcohol or acetone)
safranin red

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when using the 4 step process of gram stain, what color will gram-positive be? what about gram negative?

gram positive — purple

gram negative – red

2 EXCEPTIONS
-some gram-positive bacteria are easily decolorized

-some gram-negative can retain the crystal violet color and appear somewhat gram positive

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the CAPSULE of bacteria is also known as the __ layer

slime layer

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what is the COMPOSITION of the capsule of bacteria?

polysaccharide or polypeptide

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what is the term for the space between the 2 membranes of certain bacteria? which bacteria have this? what is it composed of?

space = periplasm

only in gram negative bacteria

composition = proteins and oligosaccharides in solution

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what is the nucleoid? which bacteria have it?

nucleoid = DNA with associated RNA and proteins

both gram positive and gram negative bacteria have it

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what are plasmids composed of?

DNA

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Which bacteria have endospore?

NOT gram negative

gram positive can have it or not have it

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an ENDOSPORE consists of….

all cell components + dipicolinate and special envelope components

true or false gram positive bacteria does not have an outer membrane

TRUE

Which type of bacteria has a high lipid content? explain

gram NEGATIVE this is so because it has both an outer and inner membrane, and gram positive only has inner membrane

which is RESISTANT to cell wall disruption and WHY? (gram positive or gram negative)

gram negative is resistant to cell wall disruption. -has an outer membrane

which is relatively featureless? (has few proteins) -gram positive or gram negative

gram positive -- only has 1 membrane for proteins to be inserted into

explain the structure of a cell wall

composed of peptidoglycan. has rigid glycan (polysaccharide; carbon based) chains that are crosslinked by flexible peptide bridges

which 2 classes of antibiotics inhibit bacterial cell wall synthesis?

penicillins and cephalosporins

which type of bacteria (gram positive or gram negative) has a feature that makes it resistant to antibiotics that breakdown the cell wall? explain

gram negative they have an outer membrane to protect the cell wall

LPS is part of which bacteria? explain its structure

gram NEGATIVE has CORE of polysaccharide O side chain Lipid A

what gives bacteria motility?

flagella

only _________ bacteria form spores

GRAM POSITIVE

What is the function of spores

to protect the bacteria. they are vegetative. they have many layers

name 4 methods of bacterial metabolism

aerobic respiration anaerobic respiration glycolysis (fermentation) pentose phosphate pathway (generates NADPH)

can aerobe bacteria ferment?

What happens if anaerobes are exposed to O2?

they're killed

what do anaerobes do in the absence of O2?

They ferment

explain what facultative bacteria can do in the presence and absence of oxygen

presence of oxygen -- they respire absence of oxygen -- they ferment

what are "microaerophilic" bacteria?

they grow BEST at LOW O2 AND can grow without O2

give an example of a microaerophilic bacteria?

campylobacter jejuni

the metabolic end products of bacterial metabolism can be used to do what?

identify certain bacteria

what is facilitated diffusion? does it require energy?

moving from high to low concentration with the help of a transmembrane protein does NOT require energy

name 2 transport mechanisms of bacteria

facilitated diffusion and active transport

explain active transport

uses a gated pore. once a particle binds to the protein gating the pore, it transports it in, using ATP and breaking it down into ADP and Pi

what is the function of secretion systems?

through use of secretion systems, bacteria can deliver their proteins and toxins to the interstitial fluid and into cells

which type of bacteria have secretion systems?

both gram positive and gram negative

as mentioned, both gram positive and gram negative bacteria have secretion systems. is there any difference? if so, explain

YES the secretion system is simpler in gram positive bacteria -- only have ONE transmembrane protein (remember: gram positive only has 1 membrane while gram negative has 2)

how many and what are the names of the secretion systems in gram positive and in gram negative bacteria?

gram positive -- 2 types gram negative -- 5 types gram positive = Tat and Sec gram negative = types 1-5 type I = direct transport type II = 2-step process type III = nanosyringe type IV = nanosyringe type V = 2 step process

in gram negative bacteria, which type(s) of secretion systems involve a chaperone protein?

types III and V

bacterial DNA is found in what configuration? what does this mean about bacterial replication?

bacterial DNA is a circular, double helix therefore, to replicate the DNA must be unwound for the polymerase to come in and replicate the bacterial genome

where does bacterial DNA replication start and end?

starts at "origin of replication", ends at "ter" region

once 2 forks are generated in bacterial DNA replication, they need to be unlinked by which enzyme? what happens if they're not unlinked?

topoisomerase if not unlinked, the bacterial cell will die

what can you say about the clinical aspects of topoisomerase

it is the target of many antibiotics (such as cipro). targeting topoisomerase prevents bacterial DNA replication and thus causes it to die

true or false in bacterial translation (mRNA--> protein) there is 1 ribosome for each mRNA transcript

FALSE there are MANY ribosomes for a single mRNA transcript

How many steps are there in bacterial protein translation? name them

initiation elongation peptidyl transferase translocation