BIO 111 DNA structure and replication

Cytosine makes up 30% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be thymine?

20

Given the nucleotide sequence 5' - CATTAGATCG-3' find the complementary DNA strand

3'-GTAATCTAGC-5'

Which would you expect of a eukaryotic cell lacking telomerase?

A reduction in chromosome length

Which answer correctly summarizes the findings of Erwin Chargraff?

A=T; G=C

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

Adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn

In the ladder analogy of the structure of DNA, the uprights are composed of

Alternating deoxyribose and phosphate groups

For a science project 2 students decided to repeat the Hershey and Chase experiment, with modifications. They decide that labeling the phosphates of the DNA wasn't good enough. Each nucleotide has only 1 phosphate, whereas each nitrogenous base has 2-5 nitrogens. Thus, labeling the nitrogenous base would provide a stronger label than labeling the phosphates. This experiment won't work because

Amino acids (and thus proteins) also have nitrogen atoms, this the radioactivity would not distinguish between DNA and proteins.

What is the function of DNA ligase

Covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.

The sub-units that constitute the backbones of a DNA molecule (rails in the ladder analogy) are held together by

Covalent bonds between sugar molecules and phosphate groups

Which enzyme catalyzes the elongation of a DNA strand in the 5'-3' direction

DNA polymerase III

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end.

The enzymes that actually catalyze the synthesis of a new DNA strand are called

DNA polymerases

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which?

Gaps left at the 5' end of the lagging strand because of the need for a 4' onto which nucleotides can attach

Which of the statements is true of chromatin

Heterochromatin is highly condensed, whereas euchromatin is less compact

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged

What kind of chemical bonds are found between paired bases of the DNA double helix?

Hydrogen

During DNA replication, synthesis of the lagging strand is discontinuous and forms short segments of DNA known as

Okazaki fragments

Replication in prokaryotes differs from replication in eukaryotes for which of the reasons?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many

It is unknown what the genetic material for the organisms that live on planet X is. Based on some observations, you suspect that on the planet, it is protein that serves as the genetic material.

Radioactive sulfur will be associated with infected cells but radioactive phosphorous will not.

The site on a replacing DNA molecule at which the old strands are being separated is known as the

Replication fork

DNA replication occurs during ___ of the cell cycle

S phase

All of the following elements are present in DNA except

Sulfur

Which of the following statements does not apply to the Watson and Crick model of DNA?

The 2 strands of the helix are held together by covalent bonds

What determines the nucleotide sequence of the newly synthesized strand during DNA replication

The nucleotide sequence of the template strand

All of the following were determined directly from x-ray diffracting photographs of crystallized DNA except

The specificity of base pairing

What is the function of DNA polymerase?

To add nucleotides to the end of a growing DNA strand

The nitrogenous bases____ contain 2 nitrogenous rings and are known as

adenine and guanine; purines

Since the 5' to 3' direction of one strand of the DNA molecule is opposite to that of the other, the strands are said to be

anti-parallel

A DNA nucleotide consists of

deoxyribose plus a base plus a phosphate

The base sequence of DNA in eukaryotic organisms

differs from 1 species to the next

The enzymes that break the H bonds between complementary base pairs during DNA replication are

helicases

The function of single-strand binding proteins in DNA replication is to

hold the unwound single strands apart so they do not kink

DNA replication is called semi-conservative because

one parent strand goes to each of the 2 daughter strands

The specific nucleotide sequence at which DNA replication is initiated is known as the

origin of replication

In the ladder analogy of DNA structure, the rungs of the ladder are

paired nitrogen bases.

During DNA replication, each strand acts as a ___ since it serves as a pattern for the generation of a new

template; complementary strand

If radioactive sulfur is used in the culture medium of bacteria that harbor phage viruses, it will later appear in the

viral coats