chapter 12 biology Flashcards


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1

The main reason scientists thought that proteins, rather than DNA, were the carriers of genetic material in the cell was:

the large number of possible amino acids combinations

2

In the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:

was an example of the genetic exchange known as transformation

3

The first experimenters to use Griffith's transformation assay to identify the genetic material were:

Avery, MacLeod, and McCarty

4

Which of the following statements about DNA is false?

DNA is only found in eukaryotic cells

5

The bacteriophages used in Alfred Hershey's and Martha Chase's experiments showed that:

DNA was injected into bacteria

6

The two molecules that alternate to form the backbone of a polynucleotide chain are:

sugar and phosphate

7

Chargaff determined that DNA from any source contains about the same amount of guanine as __________.

cytosine

8

__________ used x-ray diffraction to provide images of DNA.

Franklin

9

X-ray diffraction studies are used to determine:

the distances between atoms of molecules

10

X-ray crystallography showed that DNA:

was a helix

11

__________ determined the structure of the molecule DNA.

Waston and Crick

12

The information carried by DNA is incorporated in a code specified by the:

specific nucleotide sequence of the DNA molecule

13

Why is DNA able to store large amounts of information?

Its nucleotides can be arranged in a large number of possible sequences

14

The portion of the molecule in box 5 of Figure 12-1 is:

a phosphate

15

In Figure 12-1, the portion of the molecule in box __________ is a pyrimidine.

1

16

The portion of the molecule in box 3 of Figure 12-1 is:

a purine

17

Hydrogen bonds can form between guanine and __________, and between adenine and __________.

cytosine; thymine

18

Two chains of DNA must run in __________ direction(s) and must be __________ if they are to bond with each other.

antiparallel; complementary

19

Which of the following nucleotide sequences represents the complement to the DNA strand
5¢ - AGATCCG- 3¢?

3¢-TCTAGGC-5¢

20

When DNA copies itself,

the two stands separate and both serve as templates

21

Which of the following best describes semiconservative replication?

A DNA molecule consists of one parental strand and one new strand

22

The final product of DNA replication is:

two DNA molecules, each of which contains one new and one old DNA strand

23

Who first confirmed that the replication of DNA was semiconservative?

Meselson and Stahl

24

If DNA replication rejoined the 2 parental strands, it would be termed:

conservative

25

Meselson and Stahl separated DNA from different generations using:

the mutation is corrected by the DNA polymerase enzyme

26

When a DNA molecule containing a wrong base at one location in one strand is replicated:

The mutation is copied into one of the two daughter molecules

27

Which of the following causes the unwinding of the DNA double helix?

DNA helicase

28

A replication fork:

is a Y shaped structure where both DNA strands are replicated simultaneously

29

In replication, once the DNA strands have been separated, reformation of the double helix is prevented by:

single strand binding proteins

30

Enzymes called __________ form breaks in the DNA molecules to prevent the formation of knots in the DNA helix during replication.

topoisomerases

31

What prevents knot formation in replicating DNA?

topoisomerase

32

Which of the following adds new nucleotides to a growing DNA chain?

DNA polymerase

33

Why does DNA synthesis only proceed in the 5¢ to 3¢ direction?

Because DNA polymerases can only add nucleotides to the 3c end of a polynucleotide strand

34

The 5¢ end of each Okazaki fragment begins with:

A separate RNA primer

35

DNA primase is the enzyme responsible for:

making short strands of RNA at the site of replication initiation

36

The DNA strand that is replicated smoothly and continuously is called the:

leading strand

37

In DNA replication, the lagging strand:

is synthesized as a series of Okazaki fragments

38

Okazaki fragments are joined together by:

DNA ligase

39

How is the chromosome of a bacterial cell replicated?

The circular DNA molecule is replicated from one origin of replication bidirectionally

40

How are the chromosomes of a eukaryote cell replicated?

The linear DNA molecules are replicated from multiple origins of replication bidirectionally

41

Refer to Figure 12-2. The correct designation for the DNA strand labeled C is:

A strand serving as a template

42

Refer to Figure 12-2. The segments labeled F are responsible for:

initiating DNA synthesis

43

Refer to Figure 12-2. The enzyme represented by the letter D is responsible for:

linking short DNA segments

44

Refer to Figure 12-2. The structures represented by the letter E are called:

Okazaki fragments

45

Which of the following statements concerning nucleotide excision repair is FALSE?

it is a type of mismatch repair

46

__________, the ends of eukaryotic chromosomes, shorten with every cell replication event.

telomeres

47

The ends of eukaryotic chromosomes can be lengthened by:

telomerase

48

When cultured normal human cells were infected with a virus that carried the genes that coded for a subunit of telomerase:

the cells underwent more cell divisions than normal

49

Cancerous cells differ from noncancerous cells in that cancerous cells:

can maintain telomere length as they divide

50

Mismatch repair occurs when

enzymes remove incorrectly-paired nucleotides