BSC110 - Chapter 13 HW and Recharges (Fall 2026)

Bacteria produce the same protein products regardless of their environment.

False

The operon controls gene regulation in

prokaryotes

Promoters, operators, and structural genes are the components of a(n) __________.

operon

Which operon structure codes for the production of a repressor?

regulator gene

In prokaryotes, RNA polymerase binds to a short sequence of DNA called the

promoter

An increase in the environmental temperature would most likely cause a bacterium to

shift the expression of its proteins or enzymes

Operons are generally involved with

prokaryotic gene expression

Active repressors bind to operators which are sequences of

DNA

Which operon structure signals the start of transcription?

Promoter

Which operon structure codes for the enzymes involved in metabolic pathways of the operon?

Structural gene

The genes that code for a repressor protein in prokaryotes is known as a __________ gene.

regulator

Select the events that take place as a result of the trp operon when tryptophan is not present?

inactive repressor cannot bind operator

transcription of the trp operon takes place

T/F: RNA polymerase is able to bind to this structural gene's promoter.

True

The repressor can bind to an operator when a(n) __________ binds to it.

corepressor, co-repressor, or tryptophan

What type of pathway are repressible operons generally involved with?

anabolic pathways

What is the role of the operator?

Controls transcription of structural genes

RNA polymerase can bind to the promoter in the lac operon when

the repressor does not bind to the operator

lactose binds to the repressor

Genes that code for enzymes and proteins involved in the metabolic pathway of the operon are known as

structural genes

An inducible operon is activated by a(n)

inducer

What is the sequence of events that take place in the trp operon when tryptophan is present? Begin with the first event at the top of the list.

1. trytophan binds to the repressor

2. the repressor becomes activated

3. the repressor binds to the operator

4. transcription of the trp operon is halted

Since the CAP proteins, when active, promote the activity of the lac operon, they are said to exhibit __________ control over transcription.

positive

T/F: The trp operon is an example of a repressible operon.

True

What determines why a skin cell expresses differently than a hair cell?

The genes expressed in each cell

Repressible operons usually produce proteins that are

used often within the cell

Place these events in the correct sequence as they would occur during the functioning of the lac operon. Begin with the first event at the top of the list.

1. lactose binds to repressor

2. repressor unbinds from operator

3. RNA polymerase binds to the promoter

4. enzymes for lactose metabolism are synthesized

Which group of organisms will have their genes regulated?

Both Prokaryotes and Eukaryotes

The presence of an inducer activates a(n) __________ operon.

inducible

Of the 5 levels of eukaryotic gene expression, 3 occur in the __________ and 2 occur in the __________.

nucleus; cytoplasm

In bacteria, when glucose is present, the lac operon functions (less/more) __________; when glucose is absent, the lac operon functions (less/more) __________.

less; more

What are the levels of eukaryotic gene expression control?

Posttranscriptional control

Posttranslational control

Transcriptional control

Translational control

Chromatin structure

Even though the DNA is the same in all of the cells of a multicellular organism, cells will assume different features because they express different __________.

genes

Chromatin structure helps control gene expression by

allowing access to the DNA when it is not compacted

Pathways that produce proteins needed by the cell often contain __________ operons.

repressible

The highly compacted chromatin that is not accessible for transcription is called __________.

heterochromatin

T/F: Gene regulation occurs in both prokaryotic cells and eukaryotic cells.

True

Gene transcription is reduced on heterochromatin because it is inaccessible to

RNA polymerase

Posttranslational controls occurs in the __________ of eukaryotic cells.

cytoplasm

Which level of eukaryotic gene control is the most critical?

Transcriptional control

The first step of transcriptional control requires the presence of __________.

DNA

T/F: RNA polymerase would NOT be present in condensed eukaryotic chromatin.

True

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

Transcription activator

Transcription factors

Heterochromatin will have

more inactive genes than euchromatin

What structure will the transcription factors bind to?

promoter

Heterochromatin is not transcribed because

it is inaccessible to RNA polymerase

What are some of the activities of posttranscriptional control mechanisms?

control of mRNA nuclear export speed

alternative mRNA splicing

Which level of genetic control would override the others?

transcriptional

Posttranscriptional control takes place in the cell __________.

nucleus

What substance is required in eukaryotes that experience genetic control?

DNA

Eukaryotic cells have translational control occur in the

cytoplasm

What is the role of the transcription factors?

Assist in the binding of RNA polymerase to the promoter

When the activators, enhancers, and mediators come in contact with the transcription factors, the DNA forms a shape called a

loop

What can posttranslational control allow a cell to do?

Influence gene expression

Alternative mRNA splicing takes place at which level of eukaryotic gene control?

posttranscriptional control

Regulation that controls the way mRNA transcripts are processed in the nucleus are called __________ control.

posttranscriptional

The level of eukaryotic control of gene expression that involves the control of the mRNA transcript in the cytoplasm of the cell is called __________ control.

translational; translation

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

posttranslational control

Where does translational control begin?

When mRNA reaches the cytoplasm

T/F: Posttranslational control is the last chance of influencing gene expression.

True

What is the most direct consequence of a gene mutation?

The organism's DNA is changed.

Mutations that occur in sex cells which can be passed to the next generation are known as __________ -line mutations.

germ

Mutations that occur in body cells and are not passed to the next generation are called __________ mutations.

somatic

A mutation that happens for no apparent reason (bad luck) is considered a

spontaneous mutation

Environmental influences, like toxic chemicals or radiation, are said to cause __________ mutations.

induced

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

A gene mutation

T/F: Spontaneous mutations resulting from errors in DNA replication are rare because DNA polymerase proofreads newly synthesized DNA.

True

What is true about germ-line mutations?

They can be passed down to the next generation

They occur in the sex cells

Which protein complex assists with DNA replication and also has the ability to repair spontaneous mutations?

DNA polymerase

Which group of cells experience mutations that can lead to cancer?

somatic cells

Identify the potential mutagen(s).

Radiation

Organic chemicals

Gene mutations that occur during normal biological processes such as movement of transposons or DNA replication are called __________ mutations.

spontaneous

A carcinogen is a type of mutagen that leads to the development of __________.

cancer

What are some of the factors that can lead to an induced mutation?

exposure to toxins

exposure to radiation

Which structure will remove thymine dimers from the DNA strand so the strand can be repaired?

DNA repair enzymes

What are some of the factors that can cause spontaneous mutations?

Transposon movement

DNA replication

Chemical change of a base

What tasks will DNA polymerase do?

Proofreads the new DNA strand for errors

Corrects errors in the DNA strand

Environmental factors such as radiation and organic chemicals can affect the nucleotide base composition of DNA and are therefore referred to as __________.

mutagens; carcinogens

Mutagens that lead to the development of cancer are called __________.

carcinogens

When one base in a DNA sequence is altered, it is known as a __________ mutation.

point

Enzymes that restore the original base sequence to altered DNA strands are known as

DNA repair enzymes

A type of point mutation where one nucleotide is replaced with another, incorrect nucleotide, is called a base __________.

substitution

What type of mutation in the DNA sequence can lead to sickle cell disease?

base substitution

What protein complex assists with DNA replication and also has the ability to repair spontaneous mutations?

DNA polymerase

The insertion of one or more bases that results in a change to the mRNA codon-reading structure is called a __________ mutation.

frameshift

Frameshift mutations are usually __________ harmful than/as point mutations.

more

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

AAGTCTCTGGTC

If a DNA sequence that is supposed to be AAA gets changed to ATA, what specific type of mutation has occurred?

Base substitution

What are possible consequences of a mutated DNA gene?

different phenotype

different genotype

different mRNA transcript

different protein product

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

AAGTCTCCAGGTC

Which type of mutation is likely to have the most dramatic effect on an organism or cell?

Frameshift mutation

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

point mutation