Genetics Chapter 7 - Mutations

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Forward mutation

A mutation that changes a wild-type allele to a mutant allele

Assume that a new low-calorie sweetener is developed. Before being approved for human consumption, the mutagenicity of the new molecule is determined with the Ames test. The results are shown. What conclusion is most consistent with these data?

The sweetener is not mutagenic but can be converted into strong mutagens.

true or false: Chemical agents can cause mutations by ethylating guanine residues in DNA.

True

true or false: Following base removal, DNA polymerase can add nucleotides in the 5'-to-3' direction.

True

true or false: The addition of a single base pair to the coding region of a gene can cause a frameshift mutation:

True

Classify the mutagens at left based on the type(s) of mutations they usually generate. (Each box is used at least once, and some boxes are used more than once.) Chromosomal rearrangements

X-rays

After a tautomeric shift in adenine,

adenine bonds with cytosine.

Classify the mutagens at left based on the type(s) of mutations they usually generate. (Each box is used at least once, and some boxes are used more than once.) Substitutions

- Hydroxylating agents - Alkylating agents - Deaminating agents - base analogs

Patients who have a defect in one of the DNA repair systems may have what?

- Increased chance of cancer - Increased number of skin lesions, such as freckles

Classify the mutagens at left based on the type(s) of mutations they usually generate. (Each box is used at least once, and some boxes are used more than once.) Deletions

- X-rays - Intercalating agents

Match each term to its correct definition or description.

180º rotation of a segment of a DNA molecule

In light repair,

the covalent bonds between the thymine dimers are broken.

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) Ultraviolet light, which produces __________________, and oxidation also damage DNA.

thymine dimers

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Emergency error-prone repair

- Michrohomology - mediated end joining results in large deletions - In bacteria, a sloppy DNA polymerase adds random bases opposite a region of DNA damage

Match each term to its correct definition or description. Transposable element

all DNA segments that move about in a genome, regardless of mechanism

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) In a test tube, the rate at which DNA polymerase incorporates an incorrect base into DNA is about ___________ bases.

1 in 10⁶

Drag each statement below to classify it as true or false. Six statements are true and four are false. True

- A forward mutation changed a wold type allele to a different allele - Only a small subset of mutations affect gene function - The ,station rate of a gene depends on gene size - A deletion is the loss of a block of one or more nucleotide pairs from a DNA molecule - A substitution is the replacement of one DNA base with another - Mendel studied the inheritance of germ-line mutations in pea plants

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Reversal pf base alterations

- Alkyltransferase removes methyl or ethyl groups from bases - Photolyse recognizes thymine dimers and severs the linkage between them

The set-up of Muller's experiment is shown in the diagram. Muller designed this experiment using fruit flies to determine if X-rays are mutagenic. What results did Muller obtain and what could he infer from the results of his experiment?

- As exposure to X-rays increased, the ratio of type 1 to type 2 outcomes increased. - X-rays induced random mutations in the parental males. - Increased X-ray exposure led to more recessive lethal mutations.

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) If any of these examples of DNA damage are not repaired before _____________________, the information content of DNA is changed __________________.

- DNA replication - permanently

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) __________________ is the removal of an amino group. Deamination of C to form U followed by DNA replication may result in a _____________ transition

- Deamination - C⋮G to T:A

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) _________________ occurs when an A or G base is excised from the DNA, leaving behind a site with no base. DNA polymerase will introduce a __________________ opposite the apurinic site.

- Depurination - random base

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Double-strand break repair

- Homologous recombination using a homolog or a sister chromatid as a template results in accurate repair - Nonhomologous end joining can result in small deletions and chromosome rearrangements

Drag each statement below to classify it as true or false. Six statements are true and four are false. False

- The rate of reverse mutation is higher than the rate of forward mutation - More point mutations are found in human eggs than in sperm - Mutations in somatic cells can be inherited by the progeny - A single point mutation can affect many genes

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) Naturally occurring radiation, such as _________________, can break the sugar-phosphate backbone and lead to _____________ of DNA bases.

- cosmic rays and X-rays - deletion

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. Use the figure as a reference to complete the sentences below using the given words and phrases. Hypothesis 1 stated that bacterial resistance occurs ______________________ to the bacteriophage. If this hypothesis is correct, different cultures of bacteria are expected to produce about ________________ of resistant colonies.

- in response to exposure - the same number

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) Other components of the replication machinery _______________ the rate of error and __________________ corrects residual replication mistakes.

- lower - methyl-directed mismatch repair

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. Use the figure as a reference to complete the sentences below using the given words and phrases. A prediction of Hypothesis 2, which states that resistance is due to __________________, is that different cultures will have __________________ of resistant colonies.

- random mutations - wide fluctuations in the number

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. Use the figure as a reference to complete the sentences below using the given words and phrases. Researchers observed that when __________ bacteria are grown in the presence of bacteriophage, viruses that infect and kill bacteria, _________ bacterial cells are resistant; they survive and divide by binary fission to produce ___________ of bacterial cells.

- wild-type - a few - colonies

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) In cells, the rate of error during replication is ________________ bases.

1 in 10⁹

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. place the sentences in paragraph order. (Each box can be used only once, and not all boxes are used.)

1. Researchers observed that when wild-type bacteria are grown in the presence of bacteriophage, viruses that infect and kill bacteria, a few bacterial cells are resistant; they survive and divide by binary fission to produce colonies of bacterial cells. 2. To explain the observations, Luria and Delbruck devised an experiment to distinguish between two explanations for bacterial resistance. 3. Hypothesis 1 stated that bacterial resistance occurs in response to exposure to the bacteriophage. If this hypothesis is correct, different cultures of bacteria are expected to produce about the same number of resistant colonies. 4. A prediction of Hypothesis 2, which states that resistance is due to random mutations, is that different cultures will have wide fluctuations in the number of resistant colonies. 5. The experimental results suggest that mutations produce resistant cells, and that the cells become resistant before exposure to the bacteriophage.

DNA polymerases use their ________ activity to remove a mismatched base.

3' → 5' exonuclease

A region of DNA has six copies of a trinucleotide repeat. During one round of replication, the newly synthesized strand slips as shown in the diagram. If the loop is not repaired (cut out), how many repeats will be present in DNA if this newly synthesized strand is used as a template in the next round of replication?

8

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Substitution

A change of one base for another, different base

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) reverse mutation

A mutation that changes a mutant allele back to wild-type

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) SOS system

A system in bacteria that uses error-prone DNA polymerases.

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Methyl-directed mismatch repair

A system in bacteria that uses methyl groups on the parental DNA strand to determine which of two noncomplementary bases is correct.

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Insertion

Addition of a block of one or more nucleotide pairs.

Which of the following are involved in repair of DNA with thymine dimers? I. The enzyme photolyase II. Exposure to light III. Capture of energy to split the dimers

All of them: I & II & III

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Fluctuation test

An experiment performed by Luria and Delbriick to determine when resistance mutations occurred.

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Mutagen

Any agent that can cause mutations at a frequency higher than the spontaneous rate.

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Base excision repair

DNA glycosylases cleaver specific altered bases, such as uracil, from the DNA nucleotide

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Nucleotide excision repair

Enzyme complexes scan for distortions in DNA and remove nucleotides surrounding the damage

true or false: Only pyrimidine dimers are repaired by nucleotide excision repair.

False

In the Ames test, which samples are controls?

His− bacteria + distilled water + rat liver enzymes

Drag each description to the correct repair category. (Each box is used only one time. Some repair categories have more than one correct answer.) Methyl-directed mismatch repair

In E.coli, methyl groups on the parental strand indicate which mismatched base is correct

Classify the mutagens at left based on the type(s) of mutations they usually generate. (Each box is used at least once, and some boxes are used more than once.) Additions

Intercalating agents

Label this diagram by dragging the descriptions to the proper location.

Look at pic

Drag the terms on the left to their matching descriptions on the right. (Each box can be used only once, and not all boxes will be used.) Delation

Loss of a block of one or more nucleotide pairs.

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. Use the figure as a reference to complete the sentences below using the given words and phrases. To explain the observations, Luria and Delbruck devised an experiment to distinguish between two explanations for _____________________.

bacterial resistance

Luria and Delbrück tested two hypotheses regarding how bacterial resistance to bacteriophage infection arises. Use the figure as a reference to complete the sentences below using the given words and phrases. The experimental results suggest that mutations produce resistant cells, and that the cells become resistant __________________ to the bacteriophage.

before exposure

Match each term to its correct definition or description. Prototrophic

capable of growth on minimal medium

UV light damages DNA by causing

covalent bonds to form between thymine bases next to each other on the same DNA strand.

Complete each sentence using the words and phrases on the left. (Each box can be used only once, and not all boxes are used.) The information stored in DNA can change by natural processes that ______________ DNA.

damage

Match each term to its correct definition or description. Intercalators

flat planar molecules that sandwich between DNA bases

Match each term to its correct definition or description. Auxotrophic

grows on minimal medium only if supplemented

The proofreading function of DNA polymerase reduces the error rate from about one in a million base pairs to about one in a ________ base pairs.

hundred million

Label the diagram to review how base excision repair can remove a damaged base and replace it with the correct, intact base.

look at pic

Label this diagram by dragging the descriptions to the proper location. (same pic diff answers)

look at pic

Muller demonstrated that X-rays increase the mutation rate in fruit flies. Label this diagram of Muller's experiment.

look at pic

Match each term to its correct definition or description. Reverse mutation

mutant allele is changed to wild-type

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) DNA polymerase has a low rate of error because it has the ability to ______________ and fix mistakes.

proofread

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) A second source of mistakes by DNA polymerase is ___________________ which can occur when DNA polymerase is copying repetitive regions of DNA.

slipped mispairing

Complete each sentence using the words and phrases on the left. (Each box can be used only once and not all boxes are used.) One reason DNA polymerase makes mistakes is because of the existence of base ______________, alternate forms of bases that pair differently than the usual forms do.

tautomers