Biochemistry 2280A Lecture 21: Topic 21

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pearraccoon570

14 Dec 2015

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Describe and differentiate between the different kinds of commonly observed dna damage. Predict which repair mechanism will be used to repair a particular instance of dna damage. Predict the consequences of dna damage that is not repaired before the next round of replication. Describe the role of translesion dna polymerases as they relate to. Dna damage = any unintended physical or chemical change in dna or its sequence. Dna molecules are huge and are prone to damage. To try to avoid changes in nucleotide sequence, cells have developed mechanisms for repairing dna damage. Mutations are not always bad, occasionally you get beneficial one, but the organism doesn"t know whether or not it will be beneficial. The cell wants to conserve the sequence of dna. Causes of dna damage: copying mistakes: dna polymerase makes an error about once every 107 nucleotides.

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QUESTION 1

A mutation caused by exposure to gamma rays is called a spontaneous mutation

	a.	True
	b.	False
	c.	Sometimes, depending on the type of base change
	d.	Gamma rays do not cause mutations

QUESTION 2

A recessive mutation affecting an essential biochemical pathway can be detected________

	a.	when the organism is heterozygous for that mutation.
	b.	when the organism is homozygous for that mutation.
	c.	in either homozygous or heterozygous conditions.
	d.	only by sequencing (recessive mutations never show a phenotype).

QUESTION 3

During DNA replication, the newly synthesized chain grows by adding

	a.	nitrogenous bases
	b.	the sugar-phosphate backbone
	c.	nucleosides
	d.	dNTPs

QUESTION 4

During replication, the DNA strand 5â- AAGTCTAGCCTAG -3â will serve as a template for the polymerization of:

	a.	5â- CTAGGCTAGACTT -3â
	b.	5â - TTCAGATCGGATC -3â
	c.	5â - GATCCGATCTGAA -3â
	d.	3â - AAGTCTAGCCTAG -5â

QUESTIOn 5

Given the following DNA sequences, select which statement(s) is(are) correct.

Sequence 1:

5â-TGGACGCTAA-3â

3â-ACCTGCGATT-5â

Sequence 2:

5â-AATCGCAGGT-3â

3â-TTAGCGTCCA-5â

Sequence 3:

5â-ACCTGCGATT-3â

3â-TGGACGCTAA-5â

	a.	Sequences 1 and 2 are the same
	b.	Sequences 1 and 3 are the same
	c.	Sequences 2 and 3 are the same
	d.	Sequences 1, 2 and 3 are all different

QUESTION 6

Repetitive sequences in the genome are hotspots for:

	a.	Deamination
	b.	Depurination
	c.	Thymine dimer formation
	d.	Replication errors

QUESTION 7

Select which statement(s) about the Ames test is(are) correct

	a.	it has been designed to understand mutation repair systems in Salmonella typhimurium
	b.	it uses mammalian liver extract
	c.	it allows to study whether chemical compounds or their enzymatic breakdown products are mutagenic
	d.	it is based on whether a chemical compound causes reversion mutations from his+ to his-
	e.	two of the above are correct
	f.	three of the above are correct

QUESTION 8

Select which statement(s) is(are) correct.

	a.	All DNA strands have a direction, and it is specified by the carbons in the sugar backbone.
	b.	All DNA strands have a direction, and it is specified by hydrogen bonds between nucleotides.
	c.	In order to form proper base pairs in a double stranded DNA molecule, the two strands must run in opposite directions.
	d.	A and C are correct.
	e.	B and C are correct.

QUESTION 9

Studies of gene mutation frequencies have shown that:

	a.	mutations are rare, and genomes are generally stable.
	b.	mutation frequencies differ among organisms and also between genes, suggesting certain genes are more susceptible to mutation.
	c.	mutation frequencies are consistent between organisms, and each region of DNA is equally susceptible to random mutations.
	d.	Both A and B are correct.
	e.	Both A and C are correct.

QUESTION 10

The compound 5-bromodeoxyuridine (BrdU) is a derivative of uracil, and if BrdU becomes incorporated during DNA replication, it pairs with adenine. This compound is best classified as which type of mutagen?

	a.	base analog
	b.	base inducer
	c.	intercalating agent
	d.	oxidative agent
	e.	alkylating agent

QUESTION 11

The rate of mutation of the fruit fly is higher than the rate of mutation of Algae

True

False

QUESTION 12

Thymine dimers are most commonly caused by which of the following?

	a.	X-rays
	b.	Alkylating agents
	c.	U.V. irradiation
	d.	DNA intercalating agents

QUESTION 13

What chemical group is found in the 3â end of a DNA strand?

	a.	an alcohol
	b.	a hydroxyl
	c.	a methyl
	d.	a phosphate

QUESTION 14

What chemical group is found in the 5â end of a DNA strand?

	a.	an alcohol
	b.	a hydroxyl
	c.	a methyl
	d.	a phosphate

QUESTION 15

Which is the correct order of molecules binding to DNA during DNA replication?

	a.	Helicase, SSB, primase, DNA pol III, DNA pol I, ligase
	b.	SSB, DNA pol I, ligase, helicase, DNA pol I, primase
	c.	primase, helicase, DNA pol III, ligase, DNA pol I, SSB
	d.	SSB, helicase, primase, DNA pol III, DNA pol I, ligase

QUESTION 16

Which statement(s) is(are) correct about strand slippage?

	a.	It can cause disorders such as Huntingon disease.
	b.	It is a process that causes mutations altering the number of DNA repeats.
	c.	It is a process that incorporates nucleotide base analogs and trinucleotide repeats.
	d.	a and b are correct.
	e.	b and c are correct.
	f.	a, b and c are correct.

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QuestionGroup: #21 Gene expression 2

Assigned as

Homework

The direct end result of gene expression is which of the following?

Amino acids

Translation

Proteins

Carbohydrates

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QuestionGroup: #22 Mutation

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Which of the following is the ways in which nucleotide mutations lead to altered proteins?

One nucleotide is substituted by another nucleotide, which can cause an early stop codon to be incorporated into the amino acid sequence resulting in a truncated protein.

One nucleotide is replaced by another nucleotide, which can change an amino acid in the protein sequence

Nucleotides are inserted into a nucleotide sequence causing a frameshift in the sequence.

All three choices may cause mutations.

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QuestionGroup: #23 Mutation 2

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Mutations are the result of which of the following?

Change in the normal nucleotide sequence in the DNA directly resulting in different carbohydrates

Change in the normal nucleotide sequence in the DNA directly resulting in different proteins

Change in the order of transfer RNA to messenger RNA so that the transfer RNA take over the role of Messenger RNA

Primarily an alteration in the sequence of nucleotides in the abnormal proteins

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QuestionGroup: #24 Cell division

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There are two major kinds of cell division. Which of the following plays a major role in promoting genetic diversity?

Meiosis since it causes the cells to make more daughter cells than mitosis

Mitosis since it causes the cells to duplicate and eventually have mutations

Meiosis since it causes the DNA sequences to be separated into new patterns in the daughter cells.

Mitosis since it essential for the ovaries in humans to separate and duplicate

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QuestionGroup: #25 Cancer

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Genes that slow down or stop the cell cycle are called...

Apoptotic genes

Oncogenes

Restriction genes

Tumor suppressor genes

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QuestionGroup: #26 Cancer2

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The common theme in the development of all cancers is...

Mutation

Evolution

Infection

Syncopation

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QuestionGroup: #27 Genetics

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Homework

Punnett's square is which of the following?

Example of all possible combinations of alleles

Example of all possible combinations of chromosomes

Example of only certain combination of alleles since some will not be expressed.

Example of all possible combinations of DNA

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QuestionGroup: #28 Embryo development

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Which of the following is the end of the cleavage phase?

A fetus

Formation of a blastocyst

Implantation to the lining of the uterus

Fewer number of cells

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QuestionGroup: #29 Development of organ system

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For organs to be differentiated, which of the following is the first step?

Stem cells trigger the development of differentiated cells

Tissues assemble into organ systems such as blood

Tissue specific genes in stem cells are triggered

Differentiated cells form tissues

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QuestionGroup: #30 Development and society

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A pregnant mother ingests a chemical which her mother said would be great for the baby. When the baby was born, it had a large head and flippers for arms. What caused this phenotype?

The chemicals were teratogens which influenced oxidative phosphorylation causing the changes in the phenotype.

The chemicals influenced the expression of different stem cells.

There is no way to assume the chemicals caused the phenotype since we have no data on other mothers who took this medicine. It could have been purely by chance.

The chemicals were teratogens which caused the baby to show early signs of evolution.

Biochemistry 2280A Lecture 21: Topic 21

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