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History of Microbiology. Domains of Life. Endosymbiotic Theory. Mitochondria and chloroplast have their own circular genome Also have 70S ribosomes This is evidence that organelles were originally bacteria taken up by a predatory eukaryote ancestor. Endosymbiotic Theory.

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endosymbiotic theory
Endosymbiotic Theory
  • Mitochondria and chloroplast have their own circular genome
  • Also have 70S ribosomes
  • This is evidence that organelles were originally bacteria taken up by a predatory eukaryote ancestor
endosymbiotic theory1
Endosymbiotic Theory

Eukaryotic predatory ancestor

Begins to produced energy for host, evolving into current mitochondrion

Digestion

No Digestion

Uptake into cell

Bacteria

plasma membrane
Plasma Membrane

Polar Headgroup

Hydrophobic Tail

membrane
Membrane

O

O

C

O

C

C

O

O

bacterial cell wall
Bacterial Cell Wall

Techoic Acid

Peptidoglycan

O-

polysaccharide

Core-

polysaccharide

LPS

Endotoxin

Porin

Lipoprotein

GRAM -

GRAM +

peptidoglycan and lysozyme
Peptidoglycan and Lysozyme
  • Peptidoglycan is composed of β(14) linked N-acetylglycosamine (G) and N-Acetylmuramic acid (M), amino acids (lysine, diaminopimelic acid = DAP)
  • Crosslinking = Strength
  • Lysozyme breaks β(14) bonds-therefore selective for Cell Wall of Bacteria
  • Archaepseudomurein is composed of β(13) linked N-acetylglycosamine and N-Acetylalosaminuronic acid
  • Lysozyme insensitive
cell wall synthesis
Cell Wall Synthesis
  • Divisome complex: Fts proteins for FtsZ ring defining division plane
  • FtsI synthesizes peptidoglycan (wall bands show border for new synthesis)
  • Glycanpentapeptide precursor must be transported across cell membrane first (Bactoprenol)
cell wall synthesis1
Cell Wall Synthesis

M

G

M

G

M

G

M

Transpeptidation crosslinks glycan layers – inhibited by Penicillin

G

M

M

G

FtsI

Bactoprenol

M

G

flagellum
Flagellum

Flagellin

Hook

LPS

L

P

Peptidoglycan

H+

MS

C

Cytoplasm

-Powered by proton gradient

-Flagellin added to terminus end

chemotaxis
Chemotaxis

Cells can either “run” to move or “tumble” to change orientation. Attractants increase frequency of “runs”, repellents increase frequency of “tumbles”

regulation of chemotaxis
Regulation of Chemotaxis
  • 1)Response to signal
    • Need Membrane Protein to bind attractant/repellent (MCP = Methyl-accepting Chemotaxis Protein)
    • Need to relay the signal to flagellum: CheA which undergoes auto-phosphorylation to CheA-P
    • Also CheW involved
chemotaxis 1
Chemotaxis (1)

Attractant

Repellent

MCP

MCP

Slows auto-phosphorylation

Speeds auto-phosphorylation

CheA CheA-P

CheA CheA-P

regulation of chemotaxis1
Regulation of Chemotaxis
  • 2)Control of Flagellar Rotation
  • - CheA-P transfers P to CheY CheY-P causes flagellar motor to Tumble = no movement (CW rotation)
  • CheZ removes P from CheY so that it cannot bind motor CCW rotation = Run
chemotaxis 2
Chemotaxis (2)

Attractant

Repellent

MCP

MCP

Slows auto-phosphorylation

Speeds auto-phosphorylation

CheA CheA-P

CheA CheA-P

CheZ

CheY-P

CheY

Cannot Bind Motor

Binds Motor

CCW spin = Run

CW spin = Tumble

chemotaxis 3
Chemotaxis (3)

Even in presence of attractant/repellent it is still desirable to have some random movement

chemotaxis1
Chemotaxis
  • 3) Adaptation (temporally controlled)
  • -CheR (think regulation) adds methyls to MCP continuosly
  • -CheB removes methyls from MCP  Becomes very active when Phosporylated
  • Methylated MCP are responsive to Repellents, insensitive to Attractants
chemotaxis 31
Chemotaxis (3)

CheR Adds Methyls to MCP

Attractant

MCP

Does not slow auto-phosphorylation

Slows auto-phosphorylation

CheB (not very active)

CheB-P (active)

CheA CheA-P

CheA CheA-P

Demethylates MCP for a “reset”

CheY-P

CheY

Cannot Bind Motor

Binds Motor

CW spin = Tumble

CCW spin = Run

taxis
Taxis
  • A response to any number of stimuli
  • Phototaxis (light), aerotaxis (oxygen)
  • E.coli: Tar aspartate/malate attractants, Cobalt/Nickel repellents
molecular adaptations to environment
Molecular Adaptations to Environment
  • Hyperthermophiles: Protein Stability
    • Amino acid substitutions for “heat tolerant folds”: Maximize ionic forces (between +/-ve charges) of acidic/basic amino acids

-di-inositol phosphate, diglycerol phosphate, mannosylglycerate also produced to stabilize proteins

-

+

molecular adaptations to environment1
Molecular Adaptations to Environment
  • Hyperthermophiles: Membrane Stability
    • Bacteria have membranes enriched with SATURATED fatty Acids
    • Archae can have membrane monolayers (see before)

All single bonds in tails allows for close stacking to Maximize attractive forces

molecular adaptations to environment2
Molecular Adaptations to Environment
  • Psychrophiles: Membrane Stability
    • have membranes enriched with UNSATURATED fatty Acids

Cis Double Bond in tails causes bend which prevents close stacking increases fluidity

salt tolerance
Salt Tolerance
  • Halophiles are adapted to high salt concentration
    • aw = vapour pressure of air in equilibrium with solution/vapour pressure of air above pure water
    • Many ions in solution attract polar water away from its gaseous state in air
salt tolerance1
Salt Tolerance
  • Halophiles are adapted to high salt concentration

Organisms concentrate nutrients, therefore water diffuses into cell

Osmotic Pressure

Normal Conditions

Osmotic Pressure

High Salt concentrations draw water out of cell

What is a cell to do?

High Salt

salt tolerance2
Salt Tolerance
  • Halophiles are adapted to high salt concentration with COMPATIBLE SOLUTES

Halophile

Halophiles import/synthesize solutes to return osmotic pressure towards the cytoplasm

“Compatible Solutes” since they do not interfere with cell metabolic reactions (not toxic at high concentrations)

Osmotic Pressure

High Salt

oxygen tolerance
Oxygen Tolerance
  • Thioglycolate broth (reduces agent gets rid of molecular oxygen)
  • Resazurin indicates presence of O2 by turning Pink

Obligate Anaerobe – Can only grow in absence of oxygen

Obligate Aerobe – Can only grow in presence of oxygen

Facultative Aerobe – Can grow in absence of oxygen, but grows better with oxygen

Aerotolerant – Unaffected by oxygen content

Microaerophilic – Can only grow in presence of low oxygen

oxygen tolerance1
Oxygen Tolerance

Facultative Aerobe

Obligate Aerobe

O2 Present-Oxic Zone

O2 Absent - Anoxic Zone

Aerotolerant

Microaerophilic

Obligate Anaerobe

genetic regulation
Genetic Regulation

DNA

Transcriptional Regulation-positive/negative regulation, riboswitches

mRNA

Translational Regulation-Attenuation, RNAi

Enzyme Inhibition (allosterics)

enzyme inhibition
Enzyme Inhibition

Allosteric control

transcriptional regulation
Transcriptional Regulation

Positive Control-e.g. Maltose catabolism

Negative Control

Activator (protein) binds to Activator Binding Site(DNA sequence)

Effector (protein) binds to Operator (DNA sequence)

Induction-e.g. Lac operon

Repression-e.g. Arginine synthesis

Corepressors

bind effector protein  Stop transcription (anabolic/biosynthetic operons)

Inducers bind effector protein  Start transcription (catabolic/degradativeoperons)

transcriptional regulation1
Transcriptional Regulation

Negative Control

Positive Control

RNA Polymerase

RNA Polymerase

Repressor protein prevents binding of RNA Polymerase  Transcription Blocked

Activator protein promotes binding of RNA Polymerase  Transcription Proceeds

transcriptional regulation2
Transcriptional Regulation

Negative Control - Induction

Negative Control - Repression

RNA Polymerase

RNA Polymerase

Aporepressor cannot bind DNA  Transcription Proceeds

Repressor protein prevents binding of RNA Polymerase  Transcription Blocked

RNA Polymerase

RNA Polymerase

Repressor protein binds inducer, binding of RNA Polymerase allowed Transcription Proceeds

Co-repressor binds repressor protein, prevents binding of RNA Polymerase  Transcription Blocked

quorum sensing
Quorum Sensing

Example: AcylHomoserineLactone (AHL)

Cells in population excrete AHL

Quorum specific proteins expressed at critical AHL concentration

AHL Synthase expressed produces more AHL

AHL is taken up by neighbouring cells, binds AHL Activator protein

AHL activator protein promotes transcription

translational control
Translational Control
  • mRNA is ssRNAcan base pair with itself or bind other molecules
  • antisense RNA can base pair with part of mRNA and can block ribosomes from binding
  • Riboswitches: RNA can bind small molecules to change mRNA structure free up Ribosome Binding Site for translation
attenuation
Attenuation

Tryptophan Operon encodes 5 genes needed to synthesize tryptophan

DNA

5 genes

mRNA

5 internal ribosome binding sites

attenuation1
Attenuation
  • Transcription and Translation can occur simultaneously in E.Coli.
  • Rho-independent termination of transcription can terminate the mRNA molecule before any of the biosynthetic genes are transcribed
  • Signalled by stem-loop in RNA followed by multiple U’s
attenuation2
Attenuation

1

2

3

4

uuuuu

mRNA

4- can base pair with 3

Followed by multiple U’s

1- codes for trp and can base pair with 2

2- can base pair with 1 or 3

3- can base pair with 2 or 4

attenuation3
Attenuation

Tryptophan not available in cell Trp genes needed to synthesize more

RNA polymerase continues trp genes expressed

DNA

Ribosome Stalls since it can’t find the tryptophan “1” codes for

2 base pairs with 3

1

4

uuuuu

RNA polymerase

mRNA

2

3

1- codes for trp and can base pair with 2

3- can base pair with 2 or 4

4- can base pair with 3

Followed by multiple U’s

2- can base pair with 1 or 3

attenuation4
Attenuation

Tryptophan available in cell Trp genes NOT needed to synthesize any more

DNA

3 hybridizes with 4  signals attenuation

Ribosome continues since it can find the tryptophan “1” codes for, stops at stop codon

RNA polymerase drops off DNA

uuuuu

mRNA

1

2

3

4

1- codes for trp and can base pair with 2

3- can base pair with 2 or 4

4- can base pair with 3

Followed by multiple U’s

2- can base pair with 1 or 3

practice questions
Practice Questions
  • Who was the first person to observe bacteria? Who founded the study of Bacteriology?

a)van Leeuwenhoek/Hooke

b)Hooke/Pasteur

c)Koch/Cohn

d) van Leeuwenhoek/Cohn

e) Winogradsky/Koch

practice questions1
Practice Questions
  • A chemolithoautotroph is an organism which:

a) Produces energy from light

b)Oxidizes inorganic compounds for energy, and uses CO2 as a carbon source

c) Produces energy from light and uses CO2 as a carbon source

d) Oxidizes inorganic compounds for energy and has organic carbon sources

practice questions2
Practice Questions
  • A new organism is discovered and is found to have the DNA organized in a discrete region. It is classified as a:

a) Bacteria

b) Prokaryote

c) Eukaryote

d) Archae

e) Could be any of the above

practice questions3
Practice Questions
  • The E. Coli genome is:

a) Circular

b) 2.7 million base pairs

c) 4.68 million base pairs

d) Has multiple Chromosomes

e) A and C

practice questions4
Practice Questions
  • Phototrophs

a) Are oxygenic

b) Produce energy from Light

c) Utilize Pigments

d) Can be anoxygenic

e) B, C, and D

practice questions5
Practice Questions
  • Some Bacteria are:

a) Responsible for the oxygenation of Earth

b) Multicellular

c) Protists

d) Obligate intracellular parasites like Deinococcus

e) A and C

practice questions6
Practice Questions
  • Methanogens are:

a) Euryarchaota

b) Archae

c) Methane producers

d) A, B, and C

e) B and C

practice questions7
Practice Questions
  • Which of the following are evidence for the Endosymbiotic Theory

a) Viruses can only reproduce in other cells

b) Endospores are resistant to desiccation and can survive long periods of time

c) Mitochondria and Chloroplasts are related to bacteria

d) Cyanobacteria produce oxygen and gain energy from light

e) None of the above

practice questions8
Practice Questions
  • Which of the following statements are true?

a) Morphology is a good indicator of physiology

b) Coccus refers to spiral shaped bacteria

c) The surface to volume ratio is greater for smaller organisms

d) All Prokaryotes are smaller than Eukaryotes

e) All of the above are false

practice questions9
Practice Questions
  • Which of the following make up the polar headgroup of phospholipids?

a) Fatty acid residues

b) Isoprene

c) Glycerol

d) Phosphate groups

e) C and D

practice questions10
Practice Questions
  • Membrane Proteins:

a) Process large molecules for transport

b) Can be embedded in the membrane

c) Contribute to electron transport reactions

d) Can be peripheral or integral

e) All of the above

practice questions11
Practice Questions
  • Which of the following are found in bacteria membranes?

a) Sterols

b) Ester-Linked fatty acids

c) Hopanoids

d) Ether-Linked fatty acids

e) B and C

practice questions12
Practice Questions
  • Which of the following are properties of transport proteins?

a) Can be saturated, and are specific

b) Are required for all small, non-polar molecules

c) Are Regulated by Biosynthesis

d) A, C

e)A, B, C

practice questions13
Practice Questions
  • Which of the following are found in both Gram positive and negative cell walls?

a) N-acetylmuramic acid

b) Techoic acid

c) Diaminopimelic acid

d) Lysozyme sensitive bonds

e) A, C, and D

practice questions14
Practice Questions
  • The peptidoglycan layer

a) Makes up 10% of the gram negative cell wall

b) Is a major component of archae cell walls

c) Is only found in Gram-positive baceteria

d) Contains core, and o-polysaccharides

e) Is not found in Staphylococcus aureus

practice questions15
Practice Questions
  • The periplasm:

a) Is in archae and is composed of pseudomurein

b) Has the consistency of gel

c) Contains endotoxin

d) Has very little protein

e) None of the above

practice questions16
Practice Questions
  • Gas vesicles are composed of 97% _____, and have ____ for crosslinking. Both of these proteins are ____ and allow the vesicles to be water tight and air _________.

a) GvpA, GvpB, hydrophobic, permeable

b) GvpC, GvpA, hydrophobic, permeable

c) GvpA, GvpC, hydrophilic, permeable

d) GvpC, GvpB, hydrophilic, tight

e) GvpA, GvpC, hydrophobic, permeable

practice questions17
Practice Questions
  • Endospores are high in _____, have very little ______, and can be stained _______.

a) Calcium, acid soluble proteins, with special dyes

b) Dipicolinic acid, mRNA, never

c) Dipicolinic acid, mRNA, with special dyes

d) Enzyme activity, ribosomes, normally

e) Water, mRNA, with special dyes

practice questions18
Practice Questions
  • Which of the following are cell surface structures?

a) Glycocalyx

b) magnetosomes

c) Sulfur Globules

d) Pili

e) A and D

practice questions19
Practice Questions
  • Chemical Gradients are sensed

a) Temporally

b) In Chemotaxis

c) By Jedi

d) In response to light

e) A and B

practice questions20
Practice Questions
  • Which of the following are macronutients?

a) C

b) K

c) Ca

d) Na

e) All of the above

practice questions21
Practice Questions
  • Cell replication

a) Involves Fts proteins

b) Has variable generation times

c) Requires DNA replications

d) Can have generation times as low as 20 minutes

e) All of the above

practice questions22
Practice Questions
  • If there are 10 cells of an organism with a generation time of 1 hour, how many cells will there be: After 3 hours of logarithmic growth?

After 5 hours in stationary phase?

a) 80, 320

b) 10, 20

c) 30, 50

d) 80, 10

e) None of the above

practice questions23
Practice Questions
  • Which of the following are adaptations to environment?

a) Halophiles synthesizing compatible solutes

b) Halophiles developing a monolayer membrane

c) Thermophiles having membranes with saturated fatty acids

d) Psychrophiles having membranes with saturated fatty acids

e) A, and C

practice questions24
Practice Questions
  • Which of the following stabilizes proteins in thermophiles?

a) Amino acid substitutions to minimize ionic interactions between residues

b) Di-inositol phosphate

c) Compatible solutes

d) None of a, b, or c

e) a, b, and c

practice questions25
Practice Questions
  • The internal pH of most acidophiles

a) Is greater than 7

b) Is around neutral

c) Is less than 7

d) Can be as high as 9.5

practice questions26
Practice Questions
  • Water will

a) Flow out in an isotonic environment

b) Will always move into the cell in any conditions

c) Flow out in a hypotonic environment

d) Flow out in a hypertonic environment

e) Combine with LO2 to produce the next governor general

practice questions27
Practice Questions
  • The following shows which type of organism?

a) Obligate anaerobe

b) Facultative anaerobe

c) Obligate aerobe

d) Microaerophilic

e) None of the above

practice questions28
Practice Questions
  • Which is the reaction catalyzed by superoxide dismutase?

a) ATP  ADP + P

b) 2 H2O2 2 H2O + O2

c) 4 O2- + 4 H+ 2 H2O + 3 O2

d) 2 O2- + 2 H+ H2O2 + O2

e) All of the above

practice questions29
Practice Questions
  • Which of the following are levels of regulation?

a) Enzyme

b) Transcription

c) Transpeptidation

d) Translation

e) a, b, and d

practice questions30
Practice Questions
  • Feedback inhibition acts at the enzyme level of control, by inhibition a(n) _____ enzyme at the ______ of a metabolic pathway.

a) Constitutive/end

b) Allosteric/beginning

c) Allosteric/middle

d) Constitutive/beginning

e) Allosteric/end

practice questions31
Practice Questions
  • DAHP synthases are:

a) Involved in glutamic acid degradation

b) Isozymes

c) Subject to different regulatory control

d) Transcriptional control elements

e) B and C

practice questions32
Practice Questions
  • Negative control:

a) Includes the maltose degradation operon

b) Includes both the arginine biosynthesis and lacoperons

c) Is a translational level control

d) Can be regulated by inducers

e) B and D

practice questions33
Practice Questions
  • An activator protein:

a) Allows the transcription of the lacoperon

b) Is only active in the presence of an inducer

c) Must bind near the promoter

d) Is an example of positive control

e) None of the above

practice questions34
Practice Questions
  • DNA binding proteins

a) Include the lambda repressor

b) Can have two helices

c) Have inverted repeats

d) Can be dimers

e) All of the above

practice questions35
Practice Questions
  • A stem loop followed by a series of Uracils

a) Is part of Rho-dependant termination of transcription

b) Is involved in the regulation of the Trpoperon

c) Is a signal for translational termination

d) Is the only way to end transcription

e) All of the above

practice questions36
Practice Questions
  • Antisense RNA

a) Bind double stranded RNA

b) Are 1000s of nt long

c) Are down-regulated in order to turn target genes off

d) Always inhibit translation

e) None of the above

practice questions37
Practice Questions
  • Acylatedhomoserine lactones are:

a) Found in cell membranes

b) Involved in quorum sensing

c) Inhibit their own synthesis as part of feedback inhibition

d) Binds an activator protein

e) B and D

practice questions38
Practice Questions

uuuuu

  • This diagram of the trp leader peptide demonstrates:

a) A cell without any tryptophan

b) A cell with plenty of tryptophan

c) An attenuation signal

d) A and C

e) B and C

mRNA

1

2

3

4

practice questions39
Practice Questions
  • In low tryptophan conditions, the following regions would hybridize in the trp leader mRNA

a) 1 and 2, 3 and 4

b) 1 and 2, 2 and 3

c) Only 2 and 3

d) 1 and 4, 2 and 3

e) None of the above

practice questions40
Practice Questions
  • The role of CheB in chemotaxis is

a) Phosphorylation of MCP

b) Methylation of MCP

c) Phosphorylation of CheA

d) Demethylation of MCP

e) Demethylation of CheR

practice questions41
Practice Questions
  • Who was the first person to observe bacteria? Who founded the study of Bacteriology?

a)van Leeuwenhoek/Hooke

b)Hooke/Pasteur

c)Koch/Cohn

d) van Leeuwenhoek/Cohn

e) Winogradsky/Koch

practice questions42
Practice Questions
  • A chemolithoautotroph is an organism which:

a) Produces energy from light

b)Oxidizes inorganic compounds for energy, and uses C02 as a carbon source

c) Produces energy from light and uses C02 as a carbon source

d) Oxidizes inorganic compounds for energy, and organic carbon sources

practice questions43
Practice Questions
  • A new organism is discovered and it is found to have the DNA organized in a discrete region. It is classified as a:

a)Bacteria

b) Prokaryote

c) Eukaryote

d) Archae

e) Could be any of the above (could be describing a nucleus or a nucleoid)

practice questions44
Practice Questions
  • The E. Coli genome:

a) Is circular

b) Has 2.7 million base pairs

c) Has 4.68 million base pairs

d) Has multiple Chromosomes

e) A and C

practice questions45
Practice Questions
  • Phototrophs

a) Are oxygenic

b) Produce energy from Light

c) Utilize Pigments

d) Can be anoxygenic

e) B, C, and D

practice questions46
Practice Questions
  • Some Bacteria are:

a) Responsible for the oxygenation of Earth

b) Multicellular (eurkaryotes)

c) Protists (name for single celled eukaryotes)

d) Obligate intracellular parasites like Deinococcus (Deinococcus=radiation resistant, chlamydia are intracellular parasites)

e) A and C

practice questions47
Practice Questions
  • Methanogens are:

a) Euryarchaota

b) Archae

c) Methane producers

d) A, B, and C

e) B and C

practice questions48
Practice Questions
  • Which of the following are evidence for the Endosymbiotic Theory?

a) Viruses can only reproduce in other cells

b) Endospores are resistant to desiccation and can survive long periods of time

c) Mitochondria and Chloroplasts are related to bacteria

d) Cyanobacteria produce oxygen, and gain energy from light

e) None of the above

practice questions49
Practice Questions
  • Which of the following statements are true?

a) Morphology is a good indicator of physiology

b) Coccus refers to spiral shaped bacteria

c) The surface to volume ratio is greater for smaller organisms

d) All Prokaryotes are smaller than Eukaryotes

e) All of the above are false

practice questions50
Practice Questions
  • Which of the following make up the polar headgroup of phospholipids?

a) Fatty acid residues

b) Isoprene

c) Glycerol

d) Phosphate groups

e) C and D (a and b are part of the hydrophobic tails in different organisms)

practice questions51
Practice Questions
  • Membrane Proteins:

a) Process large molecules for transport

b) Can be embedded in the membrane

c) Contribute to electron transport reactions

d) Can be peripheral or integral

e) All of the above

practice questions52
Practice Questions
  • Which of the following are found in bacteria membranes?

a) Sterols

b) Ester Linked fatty acids

c) Hopanoids

d) Ether Linked fatty acids

e) B and C

practice questions53
Practice Questions
  • Which of the following are properties of transport proteins

a) Can be saturated, and are specific

b) Are required for all small, non-polar molecules

c) Are Regulated by Biosynthesis

d) A, C

e) A, B, C

practice questions54
Practice Questions
  • Which of the following are found in both Gram positive and negative cell walls?

a) N-acetylmuramic acid

b) Techoic acid

c) Diaminopimelic acid

d) Lysozyme sensitive bonds

e) A, C, and D

practice questions55
Practice Questions
  • The peptidoglycan layer

a) Makes up 10% of the gram negative cell wall

b) Is a major component of archae cell walls

c) Is only found in Gram-positive bacteria

d) Contains core, and o-polysaccharides

e) Is not found in Staphylococcus aureus

practice questions56
Practice Questions
  • The periplasm:

a) Is in archae and is composed of pseudomurein

b) Has the consistency of gel

c) Contains endotoxin

d) Has very little protein

e) None of the above

practice questions57
Practice Questions
  • Gas vesicles are composed of 97% _____, and have ____ for crosslinking. Both of these proteins are ____ and allow the vesicles to be water tight and air _________.

a) GvpA, GvpB, hydrophobic, permeable

b) GvpC, GvpA, hydrophobic, permeable

c) GvpA, GvpC, hydrophilic, permeable

d) GvpC, GvpB, hydrophilic, tight

e) GvpA, GvpC, hydrophobic, permeable

practice questions58
Practice Questions
  • Endospores are high in _____, have very little ______, and can be stained _______.

a) Calcium, acid soluble proteins, with special dyes

b) Dipicolinic acid, mRNA, never

c) Dipicolinic acid, mRNA, with special dyes

d) Enzyme activity, ribosomes, normally

e) Water, mRNA, with special dyes

practice questions59
Practice Questions
  • Which of the following are cell surface structures?

a) Glycocalyx

b) magnetosomes

c) Sulfur Globules

d) Pili

e) A and D

practice questions60
Practice Questions
  • Chemical Gradients are sensed

a) Temporally

b) In Chemotaxis

c) By Jedi

d) In response to light

e) A and B

practice questions61
Practice Questions
  • Which of the following are macronutients?

a) C

b) K

c) Ca

d) Na

e) All of the above

practice questions62
Practice Questions
  • Cell replication

a) Involves Fts proteins

b) Has variable generation times

c) Requires DNA replication

d) Can have generation times as lows as 20 minutes

e) All of the above

practice questions63
Practice Questions
  • If there are 10 cells of an organism with a generation time of 1 hour, how many cells will there be:

After 3 hours of logarithmic growth?

After 5 hours in stationary phase?

a) 80, 320

b) 10, 20

c) 30, 50

d) 80, 10

e) None of the above

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Practice Questions
  • Which of the following are adaptations to environment?

a) Halophiles synthesizing compatible solutes

b) Halophiles developing a monolayer membrane

c) Thermophiles having membranes with saturated fatty acids

d) Psychrophiles having membranes with saturated fatty acids

e) A, and C

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Practice Questions
  • Which of the following stabilizes proteins in thermophiles?

a) Amino acid substitutions to minimize ionic interactions between residues

b) Di-inositol phosphate

c) Compatible solutes

d) None of a, b, or c

e) a, b, and c

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Practice Questions
  • The internal pH of most acidophiles

a) Is greater than 7

b) Is around neutral

c) Is less than 7

d) Can be as high as 9.5

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Practice Questions
  • Water will

a) Flow out in an isotonic environment

b) Will always move into the cell in any conditions

c) Flow out in a hypotonic environment

d) Flow out in a hypertonic environment

e) Combine with LO2 to produce the next governor general

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Practice Questions
  • The following shows which type of organism?

a) Obligate anaerobe

b) Facultative anaerobe

c) Obligate aerobe

d) microaerophilic

e) None of the above

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Practice Questions
  • Which is the reaction catalyzed by superoxide dismutase?

a) ATP  ADP + P

b) 2 H2O2 2 H2O + O2

c) 4 O2- + 4 H+ 2 H2O + 3 O2

d) 2 O2- + 2 H+ H2O2 + O2

e) All of the above

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Practice Questions
  • Which of the following are levels of regulation?

a) Enzyme

b) Transcription

c) Transpeptidation

d) Translation

e) a, b, and d

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Practice Questions
  • Feedback inhibition acts at the enzyme level of control, by inhibition a _____ enzyme at the ______ of a metabolic pathway.

a) Constitutive/end

b) Allosteric/beginning

c) Allosteric/middle

d) Constitutive/beginning

e) Allosteric/end

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Practice Questions
  • DAHP synthases are:

a) Involved in glutamic acid degradation

b) Isozymes

c) Subject to different regulatory control

d) Transcriptional control elements

e) B and C

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Practice Questions
  • Negative control:

a) Includes the maltose degradation operon

b) Includes both the arginine biosynthesis and lacoperons

c) Is a translational level control

d) Can be regulated by inducers

e) B and D

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Practice Questions
  • An activator protein:

a) Allows the transcription of the lac operon

b) Is only active in the presence of an inducer

c) Must bind near the promoter

d) Is an example of positive control

e) None of the above

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Practice Questions
  • DNA binding proteins

a) Include the lambda repressor

b) Can have two helices

c) Have inverted repeats

d) Can be dimers

e) All of the above

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Practice Questions
  • A stem loop followed by a series of Uracils

a) Is part of Rho-dependant termination of transcription

b) Is involved in the regulation of the Trpoperon

c) Is a signal for translational termination

d) Is the only way to end transcription

e) All of the above

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Practice Questions
  • Antisense RNA

a) Bind double stranded RNA

b) Are 1000s of nt long

c) Are down-regulated in order to turn target genes off

d) Always inhibit translation

e) None of the above

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Practice Questions
  • Acylatedhomoserine lactones are:

a) Found in cell membranes

b) Involved in quorum sensing

c) Inhibit their own synthesis as part of feedback inhibition

d) Able to bind an activator protein

e) B and D

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Practice Questions

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  • This diagram of the trp leader peptide demonstrates:

a) A cell without any tryptophan

b) A cell with plenty of tryptophan

c) An attenuation signal

d) A and C

e) B and C

mRNA

1

2

3

4

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Practice Questions
  • In low tryptophan conditions the following regions would hybridize in the trp leader mRNA

a) 1 and 2, 3 and 4

b) 1 and 2, 2 and 3

c) Only 2 and 3

d) 1 and 4, 2 and 3

e) None of the above

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Practice Questions
  • The role of CheB in chemotaxis is

a) Phosphorylation of MCP

b) Methylation of MCP

c) Phosphorylation of CheA

d) Demethylation of MCP

e) Demethylation of CheR