bio 25

Proteins contain up *** amino acids and can be sequenced in any particular way

20

there are how many possible nitrogen-containing bases?

4

Which of the following DNA bases are purines?

Adenine and Guanine

cell division occurs when

Body growth Maintenance and repair Fighting infection Replacing worn/dead cells

Which of the following DNA bases are pyrimidines?

Cytosine and Thymine

The enzyme *** unwinds and "unzips" the double-stranded DNA by breaking the weak hydrogen bonds between the paired bases.

DNA helicase

In the 1940s, scientists had concluded that the genetic material was most likely either

DNA or Protein

The enzyme responsible for maintaining the complimentary natures of the DNA strands during DNA replication is

DNA polymerase

The synthesis of new DNA double helix molecules from a pre-existing parent molecule is called _______.

DNA replication

During cell division, each new cell requires an exact copy of the DNA contained in the chromosomes. The process of copying one DNA double helix into two identical double helices is called

DNA replication.

Select the enzyme(s) used by Avery et al. that prevented the transformation of R strain bacteria into virulent bacteria.

DNase

Which of the following were direct contributions of the work of James Watson and Francis Crick?

Determined that sugars and phosphates formed backbones in the DNA Determined that nucleotides were paired inside the double helix Discovered the double helix shape of deoxyribonucleic acid

Which of the following were direct contributions of the work of James Watson and Francis Crick?

Determined that sugars and phosphates formed backbones in the DNA Discovered the double helix shape of deoxyribonucleic acid Determined that nucleotides were paired inside the double helix

Select the findings of Erwin Chargaff regarding DNA composition.

G=C A = T pyrimidines = purines

complementary base pairing

Hydrogen bonding between particular purines and pyrimidines; responsible for the structure of DNA, and some RNA, molecules.

Which of the following are components of a nucleotide?

Nitrogen-containing base 5-carbon sugar (deoxyribose) Phosphate

DNA (deoxyribonucleic acid)

Nucleic acid polymer produced from covalent bonding of nucleotide monomers that contain the sugar deoxyribose; the genetic material of living organisms.

purine

Nucleotides with a double-ring structure; examples are adenine and guanine.

pyrimidine

Nucleotides with a single ring in their structure; examples are thymine, cytosine, and uracil

The short segments of DNA that are formed on the lagging strand during replication are called

Okazaki fragments

In Griffith's experiment, which bacterial strain underwent transformation into a lethal form by obtaining genetic material from the other?

R strain

By using various enzymes to degrade candidates for the genetic material, Avery etal. were able to eliminate *** and *** as potential candidates.

RNA & Proteins

Which scientist's X-ray diffraction data helped to demonstrate the double helix structure of DNA?

Rosalind Franklin

Why did early molecular geneticists know that the genetic material needed to be a stable molecule? (Choose all that apply.)

So it could be passed from one generation to the next. So it could be replicated accurately.

True or false: A purine base normally pairs with a pyrimidine base.

This statement is true: A (purine) pairs with T (pyrimidine) and G (purine) pairs with C (pyrimidine).

True or false: The DNA double helix involves two strands of nucleotides running in opposite directions.

True

Antiparrell

Two strands of DNA in double helix oriented in opposite directions to eachother

Rosalind Franklin (Fig. 25Aa), working with Maurice Wilkins at King's College, London, had just prepared an X-ray diffraction photograph of DNA (Fig. 25Ab, c). It showed that DNA is a double helix of constant diameter and that the bases are regularly stacked on top of one another.

Using these data, Watson and Crick deduced that DNA has a twisted, ladderlike structure. The sugar-phosphate molecules make up the sides of the ladder, and the bases make up the rungs. The double helices of the DNA molecule are antiparallel, meaning they are oriented in opposite directions. Further, they determined that if A is normally hydrogen-bonded with T, and G is normally hydrogen-bonded with C (Chargaff's rules), then the rungs always have a constant width, consistent with the X-ray photograph. Watson and Crick built an actual model of DNA out of wire and tin. This double-helix model does indeed allow for differences in DNA structure between species because the base pairs can be in any order. Also, the model suggests that complementary base pairing plays a role in the replication of DNA. As Watson and Crick pointed out in their original paper, "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material." When the Nobel Prize in Physiology or Medicine for the discovery of the double helix was awarded in 1962, the honor went to James Watson, Francis Crick, and Maurice Wilkins. Rosalind Franklin was not listed as one of the recipients. Tragically, Franklin developed ovarian cancer in 1956, and she died in 1958 at the age of 37. Franklin had not been nominated for the award, and according to the rules at that time, was ineligible for the Nobel Prize.

Which of the following are the two new nucleotides that have been created by the company Synthorx?

X & Y

There are four types of nucleotides because there are four different bases:

adenine (A) and guanine (G) are purines, while cytosine (C) and thymine (T) are pyrimidine

The new synthetic nucleotides have been inserted into the E.coli bacteria to increase the number of *** *** they can produce

amino acids

the term *** refers to the fact that the nucleotide strands in DNA are oriented in opposite directions.

anti parallel

the 2 DNA strands are

antiparallel

the rungs of the ladder are

complementary paired nitrogen bases

The two nucleotide strands in DNA wind around each other forming a shape called a(n)

double helix

DNA replication is called semiconservative because

each new DNA is one-half formed from the original molecule.

Cell division occurs whenever the body

grows or heals itself.

Which factors or combinations of factors in Griffith's experiments proved lethal to mice?

heat killed S strain bacteria and live R strain bacteria S strain bacteria

The enzyme that unwinds the DNA double helix so that replication can occur is called DNA

helicase

The two strands of a DNA double helix are held together by

hydrogen bonds

DNA is a chain of

nucleotides

DNA is a polymer of

nucleotides, each one having a phosphate group, the sugar deoxyribose, and a nitrogen-containing base.

Select the characteristics that researchers suspected the genetic material would have prior to the discovery that the genetic material was DNA.

passes from one generation to the next ability to store information accurate replication

DNA is a chain of nucleotides. Each nucleotide is a complex of three subunits—

phosphoric acid (phosphate), a pentose sugar (deoxyribose), and a nitrogen-containing base.

The enzyme that assists with complementary base pairing and adding new nucleotides to the growing strand during DNA replication is DNA

polymerase

Hershey and Chase used radioactive sulfur in order to label *** during the experiments that demonstrated that DNA was the genetic material.

protein

A chemist, Erwin Chargaff, had determined in the late 1940s that regardless of the species under consideration, the number of purines in DNA always equals the number of

pyrimidines. Further, the amount of adenine equals the amount of thymine A=T, and the amount of guanine equals the amount of cytosine G=C. These findings came to be known as Chargaff's rules.

Select the result of the Hershey and Chase experiment that demonstrated DNA to be the genetic material.

radioactive DNA is taken up by bacteria

The production of two DNA copies from a single original DNA molecule is called DNA

replication

helix

spiral

the sides of the ladder are

sugar-phosphate backbone

G always pairs with C by forming *** *** bonds

three hydrogen

The production of mRNA from a DNA template occurs during

transcription

A always pairs with T forming *** *** bonds

two hydrogen

Rosalind Franklin's X-ray diffraction photograph demonstrated that DNA

was a double helix