Exam 1

Review nucleosome and compaction

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Review telomerase animation

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Negative supercoiling:

1. Helps in the compaction of the chromosome 2. Creates tension that may be released by DNA strand separation

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

3' -> 5' exonuclease

How many base pairs would be expected within three turns of a molecule of DNA? 30 0.34 10 3.4 340 300

30

Which of the following DNA sequences is complementary to 5' TAGAC 3'? 5' TAGAC 3' 5' ATCTG 3' 5' GTCTA 3' 5' CAGAT 3' none of the above

5' GTCTA 3'

According to Chargaff's rule, which of the following statements about double-stranded DNA is TRUE? A = T and C = G A + G = C + T A + T = C + G A and B A, B, and C

A and B

A nucleosome is composed of

double-stranded DNA wrapped around an octamer of histone proteins

1. Eukaryotic chromosomes are usually circular.

false

1. Most bacterial species contain linear chromosomal DNA.

false

2. A typical eukaryotic chromosome is about one hundred thousand base pairs in length.

false

4. The short regions between adjacent bacterial genes are called repetitive sequences.

false

5. Bacterial chromosomes have multiple origins of replication.

false

6. Eukaryotic chromosomes contain a telomere that forms a recognition site for the kinetochore proteins.

false

7. Centromeres contain specialized sequences located at both ends of the linear chromosome.

false

An advantage of negative supercoiling in bacteria is that:

it promotes strand separation in small regions enhancing DNA replication and transcription

Which of the following is a characteristic of double-stranded DNA? 2 nanometers in width 10 base pairs per turn 0.34 nanometers per basepair A and B A, B and C

abc

The bacterial chromosome is found in a region of the cell called

nucleiod

The repeating structural unit within eukaryotic chromatin is the

nucleosome

Who used ball-and-stick models to deduce the secondary structure of a protein?

pauling

DNA polymerases cannot replicate the 5' end of circular chromosomes. the 3' end of circular chromosomes. the 5' end of linear chromosomes. the 3' end of linear chromosomes. both the 5' and 3' ends of linear chromosomes.

the 3' end of linear chromosomes.

Telomerase is unique because it contains a DNA molecule. an RNA molecule. different RNA molecules. different DNA molecules. both DNA and RNA molecules.

an RNA molecule.

The enzyme that travels along the leading strand assembling new nucleotides on a growing new strand of DNA is...

DNa polymerase

Who determined that, in DNA, the amount of A equals T and the amount of G equals C?

Chargaff

Which of the following synthesizes the daughter strands during DNA replication? DNA primase helicase RNA polymerase DNA polymerase topoisomerase

DNA polymerase

Okazaki fragments are involved in the replication of the leading strand in a replication bubble. True False

False

The newly-synthesized strand of DNA has exactly the same base sequence as that of its template strand. T/F

False

Who performed X-ray diffraction studies that helped to determine the structure of DNA?

Franklin and Wilkins

The enzyme that unwinds a segment of the DNA molecule is... DNA polymerase. DNA ligase. RNA primase. DNA polymerase III. helicase.

Helicase

Complimentary bases are held together by _____ bond

Hydrogen

Before the lagging strand can begin assembling new DNA nucleotides, which of the following must occur?

RNA primase constructs a short RNA primer.

Pulse and Chase exeriment

They figured out how many origins of replication there was in a chromosone molecule by radiation

Improper base-pairing during DNA replication causes a pause in chain elongation. True False

True

In the absence of telomerase activity, chromosomes are shortened slightly after every round of replication. True False

True

Synthesis of the daughter DNA strand from the leading strand template occurs in a 5' to 3' direction. True False

True

Telomeres consist of direct repeat sequences. True False

True

The Holliday model can be used to explain crossing over in meiosis. True False

True

Who deduced the structure of DNA, though they considered incorrect models along the way?

Watson and Crick

Which form of DNA is the predominant form found in living cells? B DNA Z DNA A DNA C DNA

b

What is the protein that promotes the binding of sister chromatids to each other through out S phase, G2 and the beginning of prophase?

cohesion

Which of the following prevents supercoiling of the DNA strands ahead of the replication bubble? helicase topoisomerase DNA binding proteins DnaA all of the above

topoisomerase

2. A typical bacterial chromosome is a few million base pairs in length.

true

3. Many eukaryotic species are diploid with two sets of chromosomes in somatic cells.

true

3. Most bacterial species contain a single type of chromosome, but it may be present in multiple copies. true correct

true

4. A typical eukaryotic chromosome contains between a few hundred and several thousand different genes.

true

5. Eukaryotic chromosomes contain many origins of replication that are interspersed about every 100,000 base pairs.

true

Following base removal, DNA polymerase can add nucleotides in the 5' to 3' direction. True False

true

After isomerization, cleavage by an endonuclease results in two nonrecombinant chromosomes, each containing a heteroduplex region. two nonrecombinant chromosomes, without heteroduplex regions. two recombinant chromosomes, each containing a heteroduplex region. two recombinant chromosomes, without heteroduplex regions. two chromosomes that are unchanged from the original chromosome.

two recombinant chromosomes, each containing a heteroduplex region.