LearnSmart Chp. 13

Which of the following can cause spontaneous mutations?

- DNA replication - Transposon movement - Chemical change of a base

Which of the following ares probably carcinogenic?

- Ethylene dibromide - Tobacco smoke - X-rays - Ultraviolet radiation

Which of the following are activities of posttranscriptional control mechanisms?

- control of mRNA nuclear export speed - alternative mRNA splicing

Which of the following are possible consequences of a mutated DNA gene?

- different mRNA transcript - different protein product - different genotype - different phenotype

An operon includes:

- operator - structural genes - promoter

Which of the following have roles in transcriptional control of eukaryotic genes?

- repressors - mediator proteins - activators - DNA - transcription factors

Select the proteins that are required for the initiation of transcription by RNA polymerase in eukaryotes?

- transcription factor - transcription activator

Which of the following eukaryotic gene expression controls take place in the cytoplasm?

- translational control - posttranslational control

List the sequential order of steps to stop gene expression in a prokaryote:

1. A regulator gene is transcribed 2. A repressor binds to an operator 3. RNA polymerase cannot bind the promoter 4. Structural genes cannot be transcribed

What is the sequence of events that could cause cancer with a defective transcription factor?

1. a mutation occurs in the gene for a transcription factor 2. a transcription factor is translated, but misshapen 3. gene producing proteins to repress mitosis relies on transcription factor 4. a misshapen transcription factor cannot bind to gene to initiate transcription 5. a mitosis-repressing protein is missing, when mitosis should stop 6. cell division continues without check, making a mass of cells

Place these events in the correct sequence as they would occur during the functioning of the lac operon.

1. lactose binds to repressor 2. repressor unbinds from operator 3. RNA polymerase binds to the promoter 4. Enzymes for lactose metabolism are synthesized

List in sequential order the steps leading to transcription during transcriptional control of eukaryotic genes.

1. transcription factors bind to promoters 2. transcription activators bind to enhancers 3. mediator proteins bind transcription activators to transcription factors 4. RNA polymerase begins transcribing

List these eukaryotic gene control mechanisms in sequential order of their influence.

1. transcriptional control 2. posttransrictional control 3. translational control 4. posttranslational control

A certain gene excerpt has the sequence AAGGGTAACGA, then changes to CCGGGTAACGA. What just happened?

A gene mutation

The DNA sequence AAGTCTCAGGTC undergoes a frameshift mutation. Which of the following could be the new sequence of DNA?

AAGTCTCCAGGTC

The DNA sequence AAGTCTCAGGTC undergoes a point mutation. Which of the following could be the new sequence of DNA?

AAGTCTCTGGTC

______ is programmed cell death.

Apoptosis

The protein complex that not only assists with DNA replication, but also has the ability to repair spontaneous mutations is called ______.

DNA polymerase

______ enzymes restore the original base sequence to altered DNA strands.

DNA repair

Which of the following forms of chromatin would take up the most linear space (assuming same number of bases for each)?

Euchromatin

When chromatin is condensed, transcription is active.

False

______ is highly compacted chromatin not accessible for transcription.

Heterochromatin

Which of the following is the last chance of influencing gene expression?

Posttranslational control

During prokaryotic transcription, ______ binds to the promoter region.

RNA polymerase

Which of the following is NOT a level of eukaryotic gene expression control?

Replication control

______ operons are usually found in pathways producing proteins needed often by the cell.

Repressible

_______ mutations occur during normal biological processes such as movement of transposons or DNA replication errors.

Spontaneous

Which of these levels of eukaryotic gene control is the most critical?

Transcriptional control

Which of these levels of eukaryotic gene control occurs at euchromatin in the nucleus?

Transcriptional control

An exon in one pre-mRNA transcript could end up being an intron in an identical pre-mRNA transcript.

True

DNA repair enzyme correct mutations in one DNA strand by using the complimentary strand as a template.

True

Gene regulation is more complex in eukaryotes than prokaryotes.

True

In both prokaryotes and eukaryotes different genes are actively expressed at different times.

True

Mutagens may be chemical or physical in nature.

True

Some mutations may not affect the phenotype or functioning of an organism.

True

Transcription factors can either promote or repress transcription.

True

Repressible operons are normally ______ because their repressors are normally _______.

active; inactive

The series of intracellular events leading to destruction of the cell is called _____.

apoptosis

A(n) ______ is a mutagen that leads to the development of cancer.

carcinogen

Translational control occurs in the _____ of eukaryotic cells.

cytoplasm

Transcriptional control of gene expression works by:

deciding whether

The protein products of a certain bacterium depend upon its:

environment

Functional proteins are created from mRNA transcripts containing only:

exons

A ______ mutation is cause by the insertion or deletion of one or more bases, causing a change of the mRNA codon-reading sequence.

frameshift

A mutation that results in a different reading frame for the codons is called a

frameshift mutation

In which one of the following would gene regulation mechanisms be most complex?

fungi

Gene mutations called ______-line mutations occur in sex cells and could be passed to the next generation.

germ

A(n) ______ mutation is caused by some outside influence.

induced

An organism living in an environment free of mutagens would never experience _____ gene mutation.

induced

Chemical or physical agents that increase the chance of mutation are called ______.

mutagens

Chemical or physical agents that increase the chance of mutation are called _______.

mutagens

A gene _____ is a permanent change to the base sequence of DNA.

mutation

Posttranscriptional control takes place in the cell _____.

nucleus

The trp operon is an example of an operon that usually exists in the (on/off) ______ position.

on

A cancer-causing gene is called a(n) ______.

onocogene

A(n) ______ is a functional unit of structural and regulatory prokaryotic genes.

operon

Promoter, operators, and structural genes are the component of a(n) _____.

operon

A mutation that results in one base in the DNA being replaced by a different base is called a

point mutation.

The level of eukaryotic control of gene expression that involves how a protein product is handled in a cell is called ______ control.

posttranslational

Prior to transcription in prokaryotes, RNA polymerase binds to the ______ region of an operon.

promoter

Gene mutation can change a(n) ______ into a oncogene.

proto-onocogene

If a(n) ______ protein in bound to the ______ of an operon, transcription cannot occur because RNA polymerase cannot bind.

repressor; operator

Gene mutations called ______ mutations occur in body cells and would not be passed to the next generation.

somatic

A(n) ______ mutation can arise during normal biological processes.

spontaneous

A mutation in the tumor ______ gene could lead to uncontrolled cell division and a tumor.

suppressor