smartbook 8

Place the steps in the expression phase of the CRISPR-Cas system in order. Start with the first step at the top.

1. The genes encoding pre-crRNA and tracrRNA are transcribed. 2. tracrRNAs bind to pre-crRNA due to complementary base pairing 3. pre-cRNA is cleaved into many small molecules 4. Each tracrRNA-cRNA complex binds to a Cas9 protein

CRISPR stands for , regularly , short, repeats.

Blank 1: clustered Blank 2: interspaced Blank 3: palindromic

The DNA sequence of the coding strand of a gene is depicted in the top of this figure. Below it are four different types of mutations. Which of them are transversion mutations?

C B A

During adaptation, what proteins in the CRISPR-Cas system are involved in recognizing and cleaving bacteriophage DNA into small pieces?

CAS 1 & 2

During the interference phase, which protein in the CRISPR-Cas system cleaves bacteriophage DNA?

CAS9

An immune type system in prokaryotes that protects against foreign invaders is called the ___-___ system.

CRISPR CAS

Which macromolecule is most likely to have played a central role in the emergence of proteins in an RNA world?

RNA

In modern cells, how does RNA function in protein synthesis?

Ribosomes containing rRNA provide a site for polypeptide synthesis. Transfer RNA (tRNA) molecules act as adaptors for polypeptide formation. Messenger RNA (mRNA) provides information for producing the sequence of a a polypeptide. A ribosomal RNA (rRNA) acts as a ribozyme to catalyze peptide bond formation.

Mutations in the 5'-UTR or 3'-UTR of an mRNA molecule are most likely to affect what?

The mRNA's ability to be translated The stability of the mRNA

Which of the following statements about promoter mutations is true?

Up promoter mutations cause the promoter sequence to be more like the consensus sequence Down promoter mutations decrease the affinity of transcription factors to the promoter

Which changes can cause a frameshift mutation?

a base addition & deletion

A germ-line mutation is one that occurs in ______.

a sperm or egg cell

Which of the following base changes is a transition mutation?

a to g

Which of the following base changes are transversion mutations?

a to t g to c a to c

In this figure, the normal DNA coding sequence of a gene is shown on top, along with four different mutations. Match the mutation to its appropriate description.

a. silent b. missense c. nonsense d. frameshift

In a neutral mutation, a negatively-charged amino acid is substituted for ______.

another negatively-charged amino acid

In the replica-plating experiment of the Lederbergs, bacterial colonies appeared ______ of the two secondary plates.

at the same location on each

A mutation that enhances the survival and/or reproductive success of an individual is referred to as a(n) ___ mutation.

beneficial

Mutations that occur in a promoter sequence can be divided into two types: ___ promoter mutations increase the transcription rate, while ___ promoter mutations decrease it.

blank 1: up blank 2: down

The region where two chromosome pieces break and re-attach to other chromosome pieces is called a chromosomal .

breakpoint

Mutations that affect the phenotype only under certain circumstances are called ______ mutations.

conditional

During the interference phase of the CRISP-Cas defense system, each spacer within a ______ is complementary to one of the strands of the bacteriophage DNA.

crRNA

A position effect can alter gene expression in cases when the gene is moved from a less condensed, or ______ chromosome, where it is active, to a very highly condensed, or ______ chromosome, where its expression may be turned off.

euchromatic ; heterochromatic

Which phase of the CRISPR-Cas defense system is depicted in this figure?

expression

True or false: Deleterious mutations that cause the death of a cell are called nonsense mutations.

false

The addition or deletion of a number of bases that is not a multiple of 3 causes a(n) mutation.

frameshift

A mutant allele is best defined as an allele that ______.

has a different DNA sequence from the wild-type

In this figure, two panels are shown. Panel I shows protein A. A first mutation inhibits the function of protein A. In Panel II a second mutation alters protein B to carry out the function of protein A. What is this an example of?

intergenic suppression

The restoration of protein function by a second mutation in a different gene is known as a(n) ______.

intergenic suppressor

A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) mutation.

missense

A mutation in a gene that causes an amino acid change in the encoded protein is called a ______ mutation.

missense

Which of these point mutations would likely have an inhibitory effect on protein function?

missense nonsense frameshift

The term ___ refers to an inherited change in the sequence of the genetic material.

mutation

A(n) __ mutation is a missense mutation that has no detectable effect on protein function

neutral

A change of one base for another is described as a base

point

The expression of an intact gene may be altered when it is moved to a new location. This is due to a(n) ______.

position effect

The eye color gene in this Drosophila mutant (panel b) has been relocated to a heterochromatic chromosome, which resulted in its inactivation. This change in the gene's location is said to have a(n)

position effect

A mutation that does not change the amino acid sequence of a polypeptide is known as a(n) ... mutation

silent

Mutations in body cells that do not go on to form gametes are known as ______ mutations.

somatic

The patch of white hair in this child is most likely caused by a ______ mutation.

somatic

A second mutation that occurs in a different site than the first mutation, and which converts the mutant back to the wild-type phenotype, is best referred to as a(n) mutation.

suppressor

A deleterious mutation is best defined as one that decreases the chance of ______.

survival and reproduction

A missense mutation in the β-globin gene is responsible for sickle cell disease. This mutation causes an altered polypeptide sequence where the sixth amino acid is changed from glutamic acid to ______.

valine

an intergenic suppressor mutation may involve which of the following?

A change in the expression of one gene that compensates for the loss-of-function mutation in another gene

Which of the following statements regarding somatic and germ-line mutations is true?

A germ-line mutation typically originates during meiosis whereas a somatic mutation typically originates during mitosis.

Select the three phases of the CRISPR-Cas response.

Interference Expression Adaptation

What is the effect of a suppressor mutation?

It suppresses the phenotypic effect of another mutation.

Which phase of the CRISPR-Cas defense system is depicted in this figure?

adaptation

Because a bacterial cell must first be exposed to an agent to elicit a response, the CRISPR-Cas system is called a(n) ______.

adaptive defense system

The Lederbergs' replica-plating experiment demonstrated that ______.

bacteria mutate randomly prior to exposure to viruses

A mutant Drosophila fly can land on the side of a fly bottle when the bottle is incubated at 20-23o C but not at 24-27o C. This is an example of a(n) mutation.

conditional

Silent mutations are possible because the genetic code is ______.

degenerate

If an individual possesses a germ-line mutation, then ______ produced by the individual will carry the mutation. If an individual possesses a somatic mutation, then ______ produced by the individual will carry the mutation.

half of the gametes ; none of the gametes

An individual that is ______ for the sickle cell allele has a decreased chance of survival.

homozygous

Areas within a single gene that are more likely to mutate than other regions are called .

hot spots

What phase of the CRISPR-Cas defense system is depicted in this figure?

interference

Consider a mutation that causes a decreased activity in a particular protein. A second mutation alters the function of another protein that participates in the same cellular pathway, thereby overcoming the defect in the first protein. This is an example of a(n) ______.

intergenic

This figure shows an example of a(n) ___ mutation.

intragenic, suppressor

A mutation that results in the death of an organism is known as a(n) __ mutation.

lethal

An individual that has one copy of the sickle cell allele and one copy of the wild-type allele has an increased level of resistance to the disease

malaria

Sickle cell disease is caused by a ______ mutation in the gene for the ______ chain.

missense; β-globin

A mutation that results in a premature termination of the synthesis of a polypeptide is called a(n) ___ mutation.

nonsense

What type of mutations involve a change from a normal codon to a stop codon?

nonsense

The hypothesis states that the resistance of bacteria to T1 infection should arise as a result of exposure to T1 phage but not before.

physiological adaptation

A change in a single base pair in the genetic material is known as a(n)

point

A(n) ______ mutation refers to a mutation in which just one base is changed within the DNA sequence.

point

The CRISPR locus in prokaryotes contains a series of ______.

repeated sequences

What process likely accounts for the way DNA came into existence in an RNA world?

reverse transcription

Which of these mutations changes a mutant allele back to a wild-type allele?

reversion

A base substitution in which a purine and a pyrimidine are interchanged is called a(n) mutation.

transversion

The wild type genotype or phenotype is the one that is ______ found in nature.

typically

A breakpoint refers to the region ______.

where two chromosome pieces break and rejoin with other chromosome pieces

Which are examples of somatic mutations?

A mutation in an adult muscle cell A mutation in an embryonic kidney cell

Cells that give rise to the gametes such as eggs and sperm are called

germ cell

A mutation that occurs directly in a sperm or egg cell, or in one of their precursor cells, is referred to as a(n) - mutation.

germ-line

The restoration of function by a second mutation at a different site in the same gene is known as a(n) ______.

intragenic suppressor

In the CRISPR-Cas defense system, what triggers the expression phase?

A subsequent bacteriophage infection

In a natural population, a - genotype is the most common one.

wild type

This figure shows a technique known as .

replica plating

Order the genes commonly found in the CRISPR-Cas type II system. Start with tracr at the top.

1. tracr 2. Cas9 3. Cas1 4. Cas2 5. Crispr

Suppressor mutations that occur within the same gene as the first are called suppressors.

intragenic

In this figure, a gene's expression is changed due to its new location near regulatory sequences, which is an example of the effect.

position

The term germ line is used to describe the ______.

cells that produce sperm and eggs

An individual that has somatic regions with different genotypes is known as a genetic

mosaic

An allele that has a DNA sequence different from that of the wild-type is called a(n) __ allele.

mutant

According to the hypothesis, mutations can occur in any gene and do not require the exposure of an organism to an environmental condition or agent.

random mutation

What is responsible for silent mutations?

degeneracy of the genetic code

Match each component from the expression phase of the CRISPR-Cas system with the letters shown in the figure.

A. crRNA B. tracrRNA C. Cas9

This figure best illustrates what type of mutation?

base substitution

Rank these molecules according to catalytic activity, placing the molecule with the greatest catalytic ability on top.

1. proteins 2. rna 3. dna

What new functions would early cells have experienced by the introduction of proteins?

Greater catalytic ability than RNA Uptake of substances into living cells by membrane proteins Structural roles of proteins

If the patch of white hair in this child were larger, that would indicate a ______ mutation that occurred ______ during embryonic development.

somatic; earlier

A genetic mosaic is an individual that ______.

Has regions of the body that are genotypically different from each other

The red arrow in this figure points to a(n)

apurinic site

A silent mutation is a mutation that results in no ______.

change to the amino acid sequence of the polypeptide

Which region in the crRNA is complementary to a strand of bacteriophage DNA?

spacer

Replica plating is a technique in which ______.

bacterial colonies are transferred from one plate to another with a sterile piece of velvet cloth

Mutations in eukaryotic genes that change the recognition sequences may affect the order and/or number of exons contained in the mature mRNA.

splice

Errors in DNA replication are examples of ______ mutations, while mutations caused by ultraviolet light are ______ mutations.

spontaneous ; induced

A(n) ___ is a type of base substitution that involves a change of a pyrimidine to another pyrimidine, or a purine to another purine.

transition