M.2 - Genetics Lecture

The cross GE/ge × ge/ge produces the following progeny: GE/ge 404; ge/ge 396; gE/ge 97; Ge/ge 103. From these data, one can conclude that ________.

the G and E loci are linked

When a protoplast is infected by only the nucleic acid component of a virus, the infection is referred to as ________.

transfection

The form of DNA that is believed to be most biologically significant is ________.

B-DNA

As unwinding of the helix occurs during DNA replication, tension referred to as ________ is created ahead of the replication fork. This tension is relieved by the action of ________.

supercoiling; DNA gyrase

The relationship among a gene, a messenger RNA, and a protein is that ________.

genes make mRNA, which then make proteins

The protein shown below provides an example of which level of protein folding?

quaternary

In the Ames test, the clear region of no growth near the center of the plate (where the compound of interest is placed) typically indicates that the compound is:

lethal at high enough concentrations.

Assume that a cross is made between AaBb and aabb plants and that the offspring fall into approximately equal numbers of the following groups: AaBb, Aabb, aaBb, aabb. These results are consistent with which of the following?

independent assortment

Match the function of DNA on the left with the appropriate description on the right.

i.

expression

a.

stable maintenance and passage of information

ii.

variation

b.

duplication of genetic material

iii.

replication

c.

potential for alteration

iv.

storage

d.

production of a phenotype

Which of the choices below is correct?

i = d; ii = c; iii = b; iv = a

FISH can be used to determine the ________.

chromosomal location of specific genetic information

The protein product of the E. coli dnaE gene is a component of ________.

DNA polymerase III

A particular mRNA is 300 nucleotides long. If a mutation in the middle of the sequence changed a codon from a AAA to a UAA then what would be a reasonable prediction?

The protein coded by this mRNA would be shorter.

A protein is 300 amino acids long. Which of the following could be the number of total nucleotides in the section of DNA that codes for this protein? (Remember: DNA is double-stranded.)

1800

In the Ames test, the clear region of no growth near the center of the plate (where the compound of interest is placed) typically indicates that the compound is:

lethal at high enough concentrations.

The classic Hershey and Chase (1952) experiment that offered evidence in support of DNA being the genetic material in bacteriophages made use of which of the following labeled component(s)?

phosphorus and sulfur

The figure below is a nucleotide:

If this molecule were found in a DNA chain, the chemical group labeled (X) would be ________ and the chemical group labeled (Y) would be ________.

OH; H

DNA replication proceeds ________.

semiconservatively

What is the name given to the three bases in a messenger RNA that bind to the anticodon of tRNA to specify an amino acid placement in a protein?

codon

During initiation in bacterial translation, a particular mutation causes the premature binding of the large ribosome subunit to the small ribosome subunit. Which component of initiation is not working properly?

IF3

During the Ames test, his− bacteria are exposed to a chemical. If the bacteria remains his+, then what can we say about the chemical?

The chemical is not safe to consume because it is likely a mutagen.

At what stage of the meiotic cell cycle and during what chromosomal configuration does crossing over occur?

at the four-strand stage of meiosis, after synapsis of homologous chromosomes, and before the end of prophase I

Which type of rRNA can be found in both prokaryotes and eukaryotes?

5S

Which of the following statement about DNA replication in E. coli is correct?

There are two molecules of DNA polymerase III per replication fork.

When scientists were attempting to determine the structure of the genetic code, Crick and coworkers found that when three base additions or three base deletions occurred in a single gene, the wild-type phenotype was sometimes restored. These data supported the hypothesis that ________.

the code is triplet

If humans had 25 amino acids instead of 20 amino acids then how many aminoacyl tRNA synthetases would humans have?

25

A particular ________ carry the information for making a particular protein, but ________ can be used to make any protein.

gene and mRNA; a ribosome and a tRNA

In an analysis of the nucleotide composition of double-stranded DNA to see which bases are equivalent in concentration, which of the following would be true?

A + C = G + T

Which of the following terms accurately describes the replication of DNA in vivo?

semidiscontinuous

What is the name given to the three bases in a messenger RNA that bind to the anticodon of tRNA to specify an amino acid placement in a protein?

codon

During initiation in bacterial translation, a particular mutation causes the premature binding of the large ribosome subunit to the small ribosome subunit. Which component of initiation is not working properly?

IF3

In the Ames test, the clear region of no growth near the center of the plate (where the compound of interest is placed) typically indicates that the compound is:

lethal at high enough concentrations.

If complete linkage occurs, we expect ________.

to see only parental phenotypes in the F₂ of the appropriate test cross

Genetic functions in a eukaryote can be observed in ________.

chloroplasts, mitchondria, and the nucleus

The covalent linkage between the monomers in a dinucleotide is a(n) ________.

phosphodiester bond

If E. coli DNA polymerase III was able to initiate DNA synthesis opposite a single-stranded template, which molecule(s) would no longer be essential?

DNA polymerase I

When considering the initiation of transcription, one often finds consensus sequences located in the region of the DNA where RNA polymerase(s) binds. Which of the following is a common consensus sequence?

TATAAT

The primary structure of a protein is determined by ________.

the sequence of amino acids

The nuclear genetic code is considered universal with a few exceptions. Some of these exceptions are found when comparing the nuclear genetic code of humans to what?

human mitochondrial genetic code

The type of RNA modification that requires guide RNAs is ________.

RNA editing

By their experimentation using the Neurospora fungus, Beadle and Tatum were able to propose the far-reaching hypothesis that ________.

the role of a specific gene is to produce a specific enzyme

Select all that apply!

The universal nature of the genetic code had been supported by experiments including

• eukaryotic genes are correctly translated in bacteria.

• bacterial cell-free system correctly translates eukaryotic RNA.

Eukaryotic transcription is different than bacterial transcription because eukaryotic transcription ________.

requires the uncoiling of the chromatin fiber

Modular portions of a protein that fold into stable conformations with specific functional capabilities are referred to as ________.

protein domains

The genetic code is fairly consistent among all organisms. The term often used to describe such consistency in the code is ________.

universal

Which mRNA modification is likely absent if the mRNA is degrading prematurely from the 5′ end of the mRNA?

addition of the 7-methylguanosine cap to the 5′ end

What is the name of the protein that helps fold other proteins into their final and functional form?

chaperone

The nuclear genetic code is considered universal with a few exceptions. Some of these exceptions are found when comparing the nuclear genetic code of humans to what?

human mitochondrial genetic code

Which of the following intron groups is matched appropriately with a true statement?

Spliceosomal introns are removed using large protein-based enzyme complexes.

The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle-cell hemoglobin, what alteration is one likely to find?

valine instead of glutamic acid in the sixth position

Select the best answer!

An open reading frame (ORF)

is a DNA sequence that produces a funcional product.

Which mRNA modification is likely absent if the mRNA is degrading prematurely from the 5′ end of the mRNA?

addition of the 7-methylguanosine cap to the 5′ end

Which transcription factor binds directly to the TATA-box sequence?

TFIID

In bacteria and eukaryotes, a mutation is when ________.

the nucleotide sequence in a DNA molecule is directly changed

Tautomeric shifts ________.

can cause missense mutations due to mispairings

Adenine methylase is an enzyme used during mismatch repair (MMR). It helps determine which strand needs to be repaired by discriminating between template and new DNA strand. If this enzyme is mutated, how would MMR be affected

MMR would be hindered because both strands would be unmethylated and both would appear as new DNA strands and it would not be able to determine which strand has the error.

Select all that apply!

The Activator-Dissociation (Ac-Dc) system in maize

• was discovered by Barbara McClintock.

• refers to two mutations: Activator and Dissociation.

• As and Ds elements can move to new chromosomal locations.

A mutation that changes an amino acid-coding codon to a stop codon is classified as what kind of codon?

nonsense

Thymine dimers form when ________.

two thymines on the same strand and adjacent to each other bind together

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from ________.

xeroderma pigmentosum

Transposons, or jumping genes, are DNA elements that move within the genome. In which organismic groups are transposons found?

all organismic groups

Thymine dimers form when ________.

two thymines on the same strand and adjacent to each other bind together

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from ________.

xeroderma pigmentosum

Transposons, or jumping genes, are DNA elements that move within the genome. In which organismic groups are transposons found?

all organismic groups

At what stage is a mutation predicted to have the effect?

during early embryonic development

Which repair mechanism is most likely affected if the enzyme DNA glycosylase is not functioning properly?

base excision repair

Transposons, or jumping genes, are DNA elements that move within the genome. In which organismic groups are transposons found?

all organismic groups

In bacteria and eukaryotes, a mutation is when ________.

the nucleotide sequence in a DNA molecule is directly changed

Which of the following two mutagens that would be classified as base analogs?

5-Bromouracil and 2-amino purine

Which of the following diseases are caused by an expansion of trinucleotide repeats?

fragile X syndrome

Select all that apply!

DNA transposons

• move one location to another.

• abundant in eukaryotes.

In bacteria and eukaryotes, a mutation is when ________.

the nucleotide sequence in a DNA molecule is directly changed

Which of the following two mutagens that would be classified as base analogs?

5-Bromouracil and 2-amino purine

Which of the following diseases are caused by an expansion of trinucleotide repeats

fragile X syndrome

Select all that apply!

DNA transposons

• abundant in eukaryotes.

• move one location to another.

A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be which of the following?

frameshift

From the Luria-Delbruck fluctuation test, when would mutations arise in yeast cells to allow for survival in the presence of toxic levels of hydrogen peroxide?

Mutations are random and would have appeared prior to being exposed to hydrogen peroxide.

Adenine methylase is an enzyme used during mismatch repair (MMR). It helps determine which strand needs to be repaired by discriminating between template and new DNA strand. If this enzyme is mutated, how would MMR be affected?

MMR would be hindered because both strands would be unmethylated and both would appear as new DNA strands and it would not be able to determine which strand has the error.

Select all that apply!

The Activator-Dissociation (Ac-Dc) system in maize

• was discovered by Barbara McClintock.

• refers to two mutations: Activator and Dissociation.

• As and Ds elements can move to new chromosomal locations.

Mutations that arise in nature, from no particular artificial agent, are called ________.

spontaneous mutations

One would predict that bacteria that lack the enzyme photolyase would be more sensitive to what kind of mutagen?

UV light

Transposons, or jumping genes, are DNA elements that move within the genome. In which organismic groups are transposons found?

all organismic groups

A protein, like the lac repressor, is said to be ________ because when it binds lactose, it structurally changes and its chemical activity also changes.

allosteric

When referring to attenuation in regulation of the trp operon, it would be safe to say that when there are high levels of tryptophan available to the organism, ________.

transcriptional termination is likely

What term refers to clusters of bacterial genes that are under the control of a single regulatory region?

operon

Usually, bacteria only make tryptophan when tryptophan is absent or available in low concentration. However, a particular bacterial mutation makes tryptophan all the time whether or not tryptophan is present. What could explain this phenotype?

the terminator hairpin is unable to form

lacI codes for a(n) ________, and when lacI is mutated, the lac operon is ________.

repressor; constitutively expressed

Small noncoding RNAs regulate gene expression in bacteria by ________.

by both inhibiting and activating translation

Which binds to the operator of the lac operon?

repressor

What two important domains within a riboswitch involve the ligand-binding site?

aptamer and expression platform

Enzymes that are continuously produced are said to have a(n) ________ expression.

constitutive