BIOL 1201 (EXAM 3): DNA and RNA Structure

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DNA and RNA

Which of these is a difference between a DNA and an RNA molecule?

A . DNA contains uracil, whereas RNA
contains thymine.
B. DNA is double-stranded, whereas RNA
is single-stranded.
C. DNA is a polymer composed of
nucleotides, whereas RNA is a polymer composed of nucleic acids.
D. DNA contains nitrogenous bases,
whereas RNA contains phosphate
groups.
E. DNA contains five-carbon sugars,
whereas RNA contains six-carbon
sugars.

B. DNA is double-stranded, whereas RNA
is single-stranded.

DNA has sugar with (1) ______ oxygen atoms and RNA has a sugar with (2) ______ oxygen atoms

1. two
2. three

Which of these nitrogenous bases is found in DNA but not in RNA?

A.thymine
B. adenine
C. guanine
D. cytosine
E. uracil

A. Thymine

What are single ring structures called?

Pyrimidines

In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon

1' ... 5'

Nucleic acids are assembled in the _____ direction.

5' to 3'

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

After DNA replication is completed what happens?

each new DNA double helix consists of one old DNA strand and one new DNA strand

The first step in the replication of DNA is catalyzed by _____.

helicase

**The first step of DNA replication is unwinding the DNA double helix.

The action of helicase creates _____.

replication forks and replication bubbles

**A replication fork is the transition region between paired and unpaired DNA strands.

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

DNA polymerase can assemble DNA only in the 5' to 3' direction

**Since DNA polymerase can assemble DNA only in the 5' to 3' direction, the new strand complementary to the 3' to 5' strand must be assembled in short 5' to 3' segments, which are later joined together by ligase.

The synthesis of a new strand begins with the synthesis of a(n) _____.

RNA primer complementary to a preexisting DNA strand

An old DNA strand is used as a _____ for the assembly of a new DNA strand

template

**An old DNA strand is used as a template for the synthesis of a complementary new strand.

The backbone of a DNA strand is composed of

sugar-phosphate bonds

In DNA which nitrogenous base would pair with cytosine?

guanine

Hydrogen bonds must be broken during the process of DNA replication. These bonds occur between?

nitrogenous bases

What catalyzes DNA synthesis?

DNA Polymerase

Which of the following statements about DNA synthesis is true?

A. DNA polymerase adds dNTP monomers in the 3' to 5' direction.
B. Nucleotides are added in a random fashion to single-stranded DNA.
C. As DNA polymerase moves along the template strand, each new nucleotide provides a 5' hydroxyl group for the next reaction to occur.
D. Primers are short sequences that allow the initiation of DNA synthesis.

D. Primers are short sequences that allow the initiation of DNA synthesis.

Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?

phosphate groups

Which of the following enzymes creates a primer for DNA polymerase?

A. Topoisomerase
B. Helicase
C. Primase
D. Ligase

C. Primase

Which of the following statements about Okazaki fragments in E. coli is true?

A. They are usually 50 to 500 bases long.
B. They are synthesized in the 3' to 5' direction.
C. They are sealed together by the action of helicase.
D. They are formed on the lagging strand of DNA.

D. They are formed on the lagging strand of DNA.

Which enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?

Topoisomerase

True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.

True

**When the 3' end of one DNA strand points in the same direction as the 5' end of the other DNA strand, the strands are said to be antiparallel.

What is the process called that converts the genetic information stored in DNA to an RNA copy?

What is the process called that converts the genetic information stored in DNA to an RNA copy?

DNA does not store the information to synthesize which of the following?

organelles

Transcription begins at a promoter. What is a promoter?

a site in DNA that recruits the RNA polymerase

Which of the following statements best describes the promoter of a protein-coding gene?


A. The promoter is a site at which only RNA polymerase will bind.
B. The promoter is part of the RNA molecule itself.
C. The promoter is a nontranscribed region of a gene.
D. The promoter is a site found on RNA polymerase.

C. The promoter is a nontranscribed region of a gene.

What determines which base is to be added to an RNA strand during transcription?

Base pairing between the DNA template strand and the RNA nucleotides

What term best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

Complementary

What happens to RNA polymerase II after it has completed transcription of a gene?

It is free to bind to another promoter and begin transcription.

The backbone of a DNA strand is composed of

The backbone of a DNA strand is composed of

Hydrogen bonds must be broken during the process of DNA replication. These bonds occur between?

nitrogenous bases

During RNA processing a(n) _____ is added to the 5' end of the RNA.

modified guanine nucleotide

During RNA processing a(n) _____ is added to the 3' end of the RNA.

a long string of adenine nucleotides

Spliceosomes are composed of

snRNPs and other protein

The RNA segments joined to one another by spliceosomes are _____.

exons

Translation occurs in the _____.

cytoplasm

The direction of synthesis of an RNA transcript is _____.

5' —> 3'

What enzyme catalyzes the attachment of an amino acid to tRNA?

aminoacyl-tRNA synthetase

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG

The initiator tRNA attaches at the ribosome's _____ site.

P site

True or false? A codon is a group of three bases that can specify more than one amino acid.

false

true or false? A knock-out mutation results in a total absence of the mutated protein.

false

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

deletion

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?

One addition and one deletion mutation.

If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?

two

If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?

An addition mutation and a deletion mutation.

The operon model of the regulation of gene expression in bacteria was proposed by _____.

jacob and Monod

What is NOT a component of the lac operon?

regulator gene only

Regulatory proteins bind to _____.

the operator

In the presence of a regulatory protein the lac operon is _____.

not transcribed

Enzyme complexes that break down protein are called _____.

proteasomes

The nuclear membrane's role in the regulation of gene expression involves _____.

regulating the transport of mRNA to the cytoplasm

What is the function of a spliceosome?

RNA processing

Protein-phosphorylating enzymes' role in the regulation of gene expression involves _____.

protein activation

Nucleoli are present during what part of mitosis?

interphase

Cytokinesis often, but not always, accompanies _____.

telophase

Chromosomes become visible during _____.

prophase

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

anaphase

Spindle fibers attach to kinetochores during _____.

prometaphase

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids

During _____ both the contents of the nucleus and the cytoplasm are divided.

the mitotic phase

During _____ the cell grows and replicates both its organelles and its chromosomes.

interphase

Which of the following is a function of the S phase in the cell cycle?

The synthesis of sister chromatids

The copying of chromosomes occurs during which of the following phases of the cell cycle?

S phase

For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to M without gaps. Which of the following is likely to be true about dividing cells in early frog embryos?

The cells get smaller with each generation.

True or false? The M phase is characterized by the replication and division of a cell's chromosomes.

false

If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle?

34

Which of the following events would cause the cell cycle to arrest?

Poor nutrient condition

Human gametes are produced by _____.

meiosis

Human gametes are produced by _____.

23

How many sets of chromosomes does Haploid cells have?

1 set

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Meiosis I produces _____ cells, each of which is _____.

two....haploid

Meiosis II typically produces _____ cells, each of which is _____.

four....haploid

During _____ sister chromatids separate (meiosis)

anaphase II

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids. (meiosis)

telophase I

Synapsis occurs during _____. (meiosis)

prophase I

Homologous chromosomes migrate to opposite poles during _____. (Meiosis)

anaphase I

During _____ chromosomes align single file along the equator of a haploid cell.(Meiosis)

metaphase II

At the end of _____ and cytokinesis there are four haploid cells.(Meiosis)

telophase II

During _____ a spindle forms in a haploid cell.(Meiosis)

prophase II

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