Biology 1202B Lecture Notes - Lecture 6: Post-Translational Modification, Activation Energy, Covalent Bond

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marcusnandu

26 Feb 2019

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Document Summary

Enzymes speed up the rate of reaction by lowering the activation energy. Cofactors: required for enzymes and proteins, can be inorganic and organic (vitamins, minerals) In drug design, companies focus on drugs that are competitive inhibitors for the normal substrate: the right enzymes need to be targeted for the drug to competitively inhibit properly. Less substrate available means higher affinity, consequently increasing km. Graph 1: rate of reaction vs enzyme concentration. As enzyme concentration is increased, the rate of reaction increases linearly under the assumption that there is unlimited. If the substrate supply is limited, than the graph will adopt a parabolic shape, and eventually reach zero. Graph 2: rate of reaction vs substrate concentration. The rate of reaction will continue to increase as the substrate concentration inceases and plateau under the assumption that the enzyme supply is limited. Likewise, if more enzymes were added to the reaction, than the trend would be linear.

Related Questions

Enzyme Activity

1. Briefly explain the principle of spectrophotometry.

2. Which of the following statements is true about enzymes?(check all correct answers)

		__ enzymes act on (are specific for) one or just a fewsubstrates
		__ enzymes can be denatured (loose their tertiary/quaternarystructure and activity) by extreme conditions such as heat, high orlow pH,or presence of organic solvents
		__most enzymes are DNA
		__ enzymes are protein
		__enzymes perform best at specific conditions of temperature, pHand salt concentration 5. Which enzymes break the following macromolecules? Match the following with their correponding answers: ___ Nucleic acids A. proteases or proteinases such as pepsin ___ Cellulose B. none ___ Triglycerides C. lipases ___ Proteins D. amylases ___ Starch E. nucleases 6.Match the following enzymes totheir products. Answers ___ pepsin, trypsin and other digestive proteases A.Nucleotides ___ salivary and pancreatic amylases and other enzymes B. AminoAcids ___ lipases C. Monosaccharides ___ nucleases D. fatty acids and glycerol 7. Based on experiments, what is the effect of extremeconditions of pH and temperature (boiling tube) on enzymeactivity? 8. ATP stores energy in the form of___ ___ Chemical energy ___ Kinetic energy ___ Thermal energy ___ Activation energy 9. An allosteric site in anenzyme is____ __ the site where reactions occur __ the site that binds aregulator __ the site that binds thesubstrate __ the site that binds the product 10. Enzymes increase the rate of reactions by making thetransition state less stable. __ True __ False 11. Enzymes increase the rate of reactions by placing reactingparts of the molecule in favorable positions. __ True __ False 12. Which of the followingis a mechanism for regulation of enzymes? __ covalent modification __ feedback inhibition __ allosteric regulation __ all of the above 13. Which of the following represents a correct order of eventsin an enzyme catalytic cycle? 1.enzyme changes shape 2.substrate binds to active site 3.substrate is converted to products 4. products are released from activesite __ 1>2>3>4 __ 2>1>3>4 __ 3>2>1>4 __ 2>4>3>1

cyancicada301

What are the correct answers to the parts of this quiz marked incorrect? (that is my one question. Please take your time. I value accuracy over speed. )

IncorrectQuestion 2

0 / 1 pts
Studies done by Buchner showed that ground-up yeast cells were able to convert sugar to alcohol. The components of the mixture that were responsible for this transformation were

DNA molecules.

enzymes.

lipids.

carbohydrates.

Bloom's Level: 2. Understand
Learning Outcome: 06.01
Section: 06.01
Topic: History of Microbiology

IncorrectQuestion 3
0 / 1 pts
Bacteria that can absorb light energy and convert it into ATP are commonly called

cytochromes.

lysosomes.

chemotrophs.

phototrophs.

cytochromes AND chemotrophs.

Bloom's Level: 1. Remember
Learning Outcome: 06.02
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 4
0 / 1 pts
The readily usable energy currency of cells is

electricity.

the electron transport system.

ATP.

CTP.

the electron transport system AND CTP.

Bloom's Level: 1. Remember
Learning Outcome: 06.02
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 5
0 / 1 pts
NAD in its reduced form is symbolized as

NADH.

NAD.

NAD-.

NADP.

Bloom's Level: 1. Remember
Learning Outcome: 06.03
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 6
0 / 1 pts
The most common starting pathway for the breakdown of sugars is

respiration.

fermentation.

glycolysis.

oxidation.

Bloom's Level: 2. Understand
Learning Outcome: 06.04
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 7
0 / 1 pts
Which of the following processes generates the greatest amount of energy?

fermentation

aerobic respiration

the Entner-Duodoroff pathway

glycolysis

fermentation AND the Entner-Duodoroff pathway

Bloom's Level: 2. Understand
Learning Outcome: 06.05
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 8
0 / 1 pts
Fermentation

uses an inorganic molecule as the final electron acceptor.

uses an organic molecule as the final electron acceptor.

results in the production of a large amount of ATP.

is necessary in some organisms to produce reduced electron carriers.

uses an organic molecule as the final electron acceptor AND is necessary in some organisms to produce reduced electron carriers.

Bloom's Level: 2. Understand
Learning Outcome: 06.05
Section: 06.01
Topic: Microbial Metabolism

IncorrectQuestion 9
0 / 1 pts
The use of the suffix "ase" on a word denotes a(n)

substrate.

product.

enzyme.

electron acceptor.

substrate AND electron acceptor.

Bloom's Level: 1. Remember
Learning Outcome: 06.06
Section: 06.02
Topic: Microbial Metabolism

IncorrectQuestion 10
0 / 1 pts
Enzymes speed up reactions by

raising activation energy.

producing heat.

reducing entropy.

lowering activation energy.

raising activation energy AND reducing entropy.

Bloom's Level: 2. Understand
Learning Outcome: 06.06
Section: 06.02
Topic: Microbial Metabolism

IncorrectQuestion 11
0 / 1 pts
Most enzymes

are generalists and typically recognize a number of different substrates.

are specialists and typically recognize a single substrate.

are active over a wide pH range.

have several active sites.

are generalists and typically recognize a number of different substrates AND have several active sites.

Bloom's Level: 2. Understand
Learning Outcome: 06.06
Section: 06.02
Topic: Microbial Metabolism

IncorrectQuestion 12
0 / 1 pts
Allosteric enzymes

may bind two substrates.

are used to bind to other enzymes.

have an additional binding site that is involved in regulating enzyme activity.

are twice as fast as single site enzymes.

may bind two substrates AND are twice as fast as single site enzymes.

Bloom's Level: 2. Understand
Learning Outcome: 06.09
Section: 06.02
Topic: Microbial Metabolism

Question 13
1 / 1 pts
Feedback inhibition

is a means of regulating the amount of product produced.

often involves the use of allosteric enzymes.

involves inhibiting the last of a series of reactions.

results in raising the activation energy for the reaction.

is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.

Bloom's Level: 2. Understand
Learning Outcome: 06.10
Section: 06.02
Topic: Microbial Metabolism

IncorrectQuestion 14
0 / 1 pts
Coenzymes are derivatives of

minerals.

proteins.

lipids.

vitamins.

Bloom's Level: 1. Remember
Learning Outcome: 06.07
Section: 06.02
Topic: Microbial Metabolism

Question 15
1 / 1 pts
Environmental factors that may affect enzyme activity include

temperature

pH

salt

age

temperature, pH AND salt

Bloom's Level: 2. Understand
Learning Outcome: 06.08
Section: 06.02
Topic: Microbial Metabolism

Question 16
1 / 1 pts
Most enzymes function best at

acidic pH and high salt concentrations.

basic pH and low salt concentrations.

neutral pH and high salt concentrations.

slightly above pH 7 and low salt concentrations.

Bloom's Level: 2. Understand
Learning Outcome: 06.08
Section: 06.02
Topic: Microbial Metabolism

Question 17
1 / 1 pts
Mercury in mercurochrome inhibits growth

through competitive inhibition.

through a reversible action.

by oxidizing the sulfhydryl groups in cysteine.

by changing the shape of proteins.

by oxidizing the sulfhydryl groups in cysteine AND by changing the shape of proteins.

Bloom's Level: 3. Apply
Learning Outcome: 06.10
Section: 06.02
Topic: Microbial Metabolism

IncorrectQuestion 18
0 / 1 pts
The term precursor metabolite refers to molecules that

activate cell components.

are used in biosynthesis.

result from cell activities.

are present but inactive.

Bloom's Level: 2. Understand
Learning Outcome: 06.11
Section: 06.03
Topic: Microbial Metabolism

IncorrectQuestion 19
0 / 1 pts
Glycolysis

requires oxygen.

produces 3 ATP molecules.

produces 4 molecules of NAD.

may occur under aerobic or anaerobic conditions.

produces 3 ATP molecules AND produces 4 molecules of NAD.

Bloom's Level: 2. Understand
Learning Outcome: 06.12
Section: 06.03
Topic: Microbial Metabolism

IncorrectQuestion 20
0 / 1 pts
The transition step

links glycolysis to the pentose phosphate pathway.

links the pentose phosphate pathway to the Entner-Duodoroff pathway.

links glycolysis to the TCA cycle.

takes place in the matrix of the nucleus.

Bloom's Level: 1. Remember
Learning Outcome: 06.11
Section: 06.03
Topic: Microbial Metabolism

Question 21
1 / 1 pts
The TCA cycle produces

ATP through substrate-level phosphorylation.

NADH.

FADH2.

precursor metabolites.

All of the choices are correct.

Bloom's Level: 1. Remember
Learning Outcome: 06.12
Section: 06.03
Topic: Microbial Metabolism

Question 22
1 / 1 pts
The electron transport system

requires a membrane.

utilizes the nuclear membrane of eukaryotes.

utilizes the mitochondrial membrane of prokaryotes.

generates a concentration gradient of protons.

requires a membrane AND generates a concentration gradient of protons.

Bloom's Level: 2. Understand
Learning Outcome: 06.13
Section: 06.04
Topic: Microbial Metabolism

IncorrectQuestion 23
0 / 1 pts
Which type of phosphorylation does not require a membrane?

Substrate-level phosphorylation

Oxidative phosphorylation

Photophosphorylation

All types of phosphorylation require a membrane.

Bloom's Level: 2. Understand
Learning Outcome: 06.13
Section: 06.04
Topic: Microbial Metabolism

Question 24
1 / 1 pts
Which pairing is incorrect?

A:T

G:C

A:U

A:G

Bloom's Level: 3. Apply
Learning Outcome: 07.01
Section: 07.01
Topic: Genetics

Question 25
1 / 1 pts
RNA is characterized by which one of the following features?

Deoxyribose.

Thymine.

Ribose.

Double-stranded.

Bloom's Level: 1. Remember
Learning Outcome: 07.01
Section: 07.01
Topic: Genetics

Question 26
1 / 1 pts
DNA is characterized by which of the following feature(s)?

Ribose.

Single-stranded.

Deoxyribose.

Thymine.

Deoxyribose AND thymine.

Bloom's Level: 1. Remember
Learning Outcome: 07.01
Section: 07.01
Topic: Genetics

Question 27
1 / 1 pts
Which of the following is/are true of DNA replication?

It starts at the origin of replication.

Nucleotides are added to the 3' end.

It requires an RNA primer to get started.

It utilizes polymerases.

All of the choices are true.

Bloom's Level: 2. Understand
Learning Outcome: 07.03
Section: 07.02
Topic: Genetics

Question 28
1 / 1 pts
Which is true about the RNA transcript?

It is formed using the DNA minus strand as a template.

It has the same 5'-3' orientation as the DNA positive strand.

It is made in short fragments that are then stitched together.

The template starts at the promoter region.

It is formed using the DNA minus strand as a template, it has the same 5'-3' orientation as the DNA positive strand AND the template starts at the promoter region.

Bloom's Level: 2. Understand
Learning Outcome: 07.04
Section: 07.03
Topic: Genetics

IncorrectQuestion 29
0 / 1 pts
How many nucleotides are in a codon?

1

2

3

4

5

Bloom's Level: 1. Remember
Learning Outcome: 07.05
Section: 07.03
Topic: Genetics

Question 30
1 / 1 pts
Which may be or is an RNA molecule?

AGCCTAC

GGGCCCA

GCCCUUA

AGCCTAC AND GGGCCCA

GGGCCCA AND GCCCUUA

Bloom's Level: 2. Understand
Learning Outcome: 07.01
Section: 07.01
Topic: Genetics

IncorrectQuestion 31
0 / 1 pts
Which molecule carries an anticodon?

DNA

mRNA

rRNA

tRNA

Bloom's Level: 1. Remember
Learning Outcome: 07.05
Section: 07.03
Topic: Genetics

Question 32
1 / 1 pts
AUG

is only used as the start codon.

codes for methionine.

determines the reading frame.

is one of the stop codons.

codes for methionine AND determines the reading frame.

Bloom's Level: 2. Understand
Learning Outcome: 07.05
Section: 07.03
Topic: Genetics

IncorrectQuestion 33
0 / 1 pts
The A-site

is found on the RNA polymerase enzyme.

is found on the 30S ribosome.

is found on the 70S ribosome.

is the amino acid site.

is found on the 70S ribosome AND is the amino acid site.

Bloom's Level: 1. Remember
Learning Outcome: 07.05
Section: 07.03
Topic: Genetics

IncorrectQuestion 34
0 / 1 pts
A stop codon

codes for the stop amino acid s-methyl-methionine.

forms a hairpin loop forcing the ribosome to fall off.

codes for no amino acid.

enhances the binding of the e-polymerase.

codes for the stop amino acid s-methyl-methionine AND forms a hairpin loop forcing the ribosome to fall off.

Bloom's Level: 2. Understand
Learning Outcome: 07.05
Section: 07.03
Topic: Genetics

IncorrectQuestion 35
0 / 1 pts
Some segments of the precursor mRNA in eukaryotes are non-coding and are called

exons.

introns.

integrans.

uselessans.

Bloom's Level: 1. Remember
Learning Outcome: 07.06
Section: 07.04
Topic: Genetics

Question 36
1 / 1 pts
Gene regulation may entail

turning on genes only when needed.

turning off genes when not needed.

turning on or off entire groups of genes.

All of the choices are correct.

Bloom's Level: 2. Understand
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

IncorrectQuestion 37
0 / 1 pts
The set of genes in bacteria that are linked together and transcribed as a single unit is referred to as a(n)

operon.

regulon.

operator.

repressor.

Bloom's Level: 1. Remember
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

Question 38
1 / 1 pts
The molecules that bind to a repressor and cause it to no longer bind to the operator are called

activators.

repressors.

introns.

inducers.

Bloom's Level: 2. Understand
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

Question 39
1 / 1 pts
Repressors

are involved in negative control.

are involved in positive control.

always bind to the promoter.

bind or do not bind to the operator depending on their shape (conformation).

are involved in negative control AND bind or do not bind to the operator depending on their shape (conformation).

Bloom's Level: 2. Understand
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

Question 40
1 / 1 pts
Activators

are involved in negative control.

are involved in positive control.

always bind to the promoter.

are allosteric proteins.

are involved in positive control AND are allosteric proteins.

Bloom's Level: 2. Understand
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

Question 41
1 / 1 pts
Signal transduction

is the relay of information about conditions outside a cell to inside the cell.

often relies on a two component system.

may involve phosphorylation of various molecules.

is used by certain pathogens to sense low magnesium conditions.

All of the choices are correct.

Bloom's Level: 2. Understand
Learning Outcome: 07.07
Section: 07.05
Topic: Genetics

IncorrectQuestion 42
0 / 1 pts

Quorum sensing

is used by bacteria to sense the density of cells.

is used by bacteria to sense the proximity of eukaryotic cells

is used by bacteria to limit the density of cells.

is used by eukaryotes to sense the presence of bacteria.

does not influence the expression of genes by a bacteria.

Quorum sensingBloom's Level: 2. UnderstandLearning Outcome: 07.07Section: 07.05Topic: Genetics

Question 43
1 / 1 pts
In DNA sequence analysis

the + strand of DNA is used.

the start codon is ATG.

ORFs are searched for.

codon usage is a helpful indicator for protein coding areas.

All of the choices are correct.

Bloom's Level: 2. Understand
Learning Outcome: 07.12
Section: 07.08
Topic: Genetics

IncorrectQuestion 44
0 / 1 pts
DNA replication is usually unidirectional.

True

False

Bloom's Level: 2. Understand
Learning Outcome: 07.03
Section: 07.02
Topic: Genetics

IncorrectQuestion 45
0 / 1 pts
There are 4 functional types of RNA.

True

False

Bloom's Level: 1. Remember
Learning Outcome: 07.04
Section: 07.03
Topic: Genetics

Question 46
1 / 1 pts
Antisense RNA is the complement of the plus strand and may be useful in inhibiting translation.

True

False

Bloom's Level: 2. Understand
Learning Outcome: 07.11
Section: 07.07
Topic: Genetics

IncorrectQuestion 47
0 / 1 pts
A drug that inhibits the activity of bacterial DNA gyrase ______ be a good antibiotic because _______.

would; it would inhibit all DNA synthesis

would NOT; it would inhibit all DNA synthesis, even our own cell's DNA synthesis

would; it would selectively inhibit bacterial DNA synthesis due to differences between bacterial/human gyrase

would NOT; the DNA replication machinery could still function, even with impaired DNA gyrase enzyme

Bloom's Level: 5. Evaluate
Learning Outcome: 07.03
Section: 07.02
Topic: Genetics

IncorrectQuestion 48
0 / 1 pts
The regulatory protein

binds to the promoter region of DNA.

may inhibit or enhance transcription.

may control translation of the operon.

affects the activity of the DNA polymerase.

binds to the promoter region of DNA AND affects the activity of the DNA polymerase.

Bloom's Level: 2. Understand
Learning Outcome: 07.09
Section: 07.06
Topic: Genetics

Question 49
1 / 1 pts
The source of variation among microorganisms that were once identical is

antibiotic resistance.

virulence factors.

sigma factors.

mutation.

Bloom's Level: 1. Remember
Learning Outcome: 08.02
Section: 08.01
Topic: Genetics

Question 50
1 / 1 pts
The characteristics displayed by an organism in any given environment is its

genotype.

archaetype.

mutatotype.

phenotype.

Bloom's Level: 2. Understand
Learning Outcome: 08.01
Section: 08.01
Topic: Genetics

Question 51
1 / 1 pts
Transposons

are informally known as jumping genes.

may cause insertion mutations.

may cause knockout mutations.

were first recognized in plants.

All of the choices are correct.

Bloom's Level: 2. Understand
Learning Outcome: 08.05
Section: 08.02
Topic: Genetics

Question 52
1 / 1 pts
The largest group of chemical mutagens consists of

radiation.

base analogs.

nitrous acid.

alkylating agents.

Bloom's Level: 1. Remember
Learning Outcome: 08.06
Section: 08.03
Topic: Genetics

Question 53
1 / 1 pts
Nitrous acid most frequently causes mutations by

substituting oxygen for hydrogen bonds.

converting keto groups to amino groups.

altering the bonding ratios of nitrogen bases.

converting cytosine to uracil.

Bloom's Level: 2. Understand
Learning Outcome: 08.06
Section: 08.03
Topic: Genetics

IncorrectQuestion 54
0 / 1 pts
Chemical mutagens that mimic the naturally occurring bases are called

nitrogen mustards.

alkylating agents.

base analogs.

nitrous oxide.

Bloom's Level: 1. Remember
Learning Outcome: 08.06
Section: 08.03
Topic: Genetics

IncorrectQuestion 55
0 / 1 pts
Irradiation of cells with ultraviolet light may cause

4 nucleotides to covalently bind together.

thymine dimers.

adenine complementary base pairing with cytosine.

the addition of uracil.

Bloom's Level: 2. Understand
Learning Outcome: 08.08
Section: 08.03
Topic: Genetics

Question 56
1 / 1 pts
Thymine dimers are dealt with by

no repair mechanisms.

photoreactivation repair.

SOS repair.

excision repair.

photoreactivation repair AND excision repair.

Bloom's Level: 2. Understand
Learning Outcome: 08.11
Section: 08.04
Topic: Genetics

IncorrectQuestion 57
0 / 1 pts
X-rays

have no effect on DNA.

cause thymine trimers.

cause single and double strand breaks in DNA molecules.

make the DNA radioactive.

Bloom's Level: 1. Remember
Learning Outcome: 08.08
Section: 08.03
Topic: Genetics

IncorrectQuestion 58
0 / 1 pts
DNA repair mechanisms occur

only in prokaryotes.

only in eukaryotes.

in both eukaryotes and prokaryotes.

in neither eukaryotes or prokaryotes.

Bloom's Level: 1. Remember
Learning Outcome: 08.09
Section: 08.04
Topic: Genetics

IncorrectQuestion 59
0 / 1 pts
Antibiotics

cause mutations to occur.

may act as alkylating mutagens.

provide an environment in which pre-existing mutants survive.

increase the rate of spontaneous mutation.

Bloom's Level: 2. Understand
Learning Outcome: 08.12
Section: 08.05
Topic: Genetics

IncorrectQuestion 60
0 / 1 pts
Prokaryotic cell mutations can be observed very quickly because the prokaryotic chromosome is

diploid.

polyploid.

haploid.

polysomal.

Bloom's Level: 2. Understand
Learning Outcome: 08.02
Section: 08.01
Topic: Genetics

Question 61
1 / 1 pts
The diploid character of eukaryotic cells may mask the appearance of a mutation since

this may be a frame shift.

the mutation is often reversible.

the mutation may be palindromic.

the matching chromosome may carry the dominant gene.

Bloom's Level: 2. Understand
Learning Outcome: 08.02
Section: 08.01
Topic: Genetics

IncorrectQuestion 62
0 / 1 pts
A clever technique that streamlines the identification of auxotrophic mutants is

gas chromatography.

replica plating.

direct selection.

reversion.

Bloom's Level: 2. Understand
Learning Outcome: 08.12
Section: 08.05
Topic: Genetics

IncorrectQuestion 63
0 / 1 pts
To increase the proportion of mutants in a population of bacteria one may use

direct selection.

replica plating.

penicillin enrichment.

individual transfer.

Bloom's Level: 2. Understand
Learning Outcome: 08.12
Section: 08.05
Topic: Genetics

Question 64
1 / 1 pts
Bacteria that have properties of both the donor and recipient cells are the result of

UV light.

SOS repair.

frame shift mutations.

genetic recombination.

Bloom's Level: 2. Understand
Learning Outcome: 08.13
Section: 08.06
Topic: Genetics

IncorrectQuestion 65
0 / 1 pts
The mechanism by which genes are transferred into bacteria via viruses is called

ellipsis.

replica plating.

transformation.

transduction.

conjugation.

Bloom's Level: 1. Remember
Learning Outcome: 08.14
Section: 08.07
Topic: Genetics

IncorrectQuestion 66
0 / 1 pts
In conjugation the donor cell is recognized by the presence of

an F plasmid.

a Y chromosome.

diploid chromosomes.

an SOS response.

an F plasmid AND diploid chromosomes.

Bloom's Level: 2. Understand
Learning Outcome: 08.15
Section: 08.08
Topic: Genetics

IncorrectQuestion 67
0 / 1 pts
Gene transfer that requires cell-to-cell contact is

transformation.

competency.

conjugation.

functional genomics.

Bloom's Level: 2. Understand
Learning Outcome: 08.15
Section: 08.08
Topic: Genetics

Question 68
1 / 1 pts
The transfer of vancomycin resistance from Enterococcus faecalis to Staphylococcus aureus is thought to have involved

conjugation.

transformation.

transduction.

transposons.

conjugation AND transposons.

Bloom's Level: 2. Understand
Learning Outcome: 08.17
Section: 08.09
Topic: Genetics

IncorrectQuestion 69
0 / 1 pts
Double-stranded DNA enters the recipient cell during transformation.

True

False

Bloom's Level: 2. Understand
Learning Outcome: 08.13
Section: 08.06
Topic: Genetics

Question 70
1 / 1 pts
Plasmids often carry the information for antibiotic resistance.

True

False

Bloom's Level: 2. Understand
Learning Outcome: 08.16
Section: 08.09
Topic: Genetics

Quiz Score: 31 out of 70

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

Biology 1202B Lecture Notes - Lecture 6: Post-Translational Modification, Activation Energy, Covalent Bond

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