Molecular Genetics Test (Ch.4,5,6) Flashcards Preview

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Flashcards in Molecular Genetics Test (Ch.4,5,6) Deck (30)
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1

DNA is most often described as a double helix, which looks like a spiral ladder.

True

2

The anticodon for the mRNA codon AGC is UCG.

True

3

Some restriction endonucleases make zigzag cuts in double-stranded DNA leaving sticky ends.

True

4

Ribosomes move along mRNA in a 5'--> 3' direction

True

5

The mRNA transcription of a gene is made up of the same bases, in the same proportion, as the strand of DNA complementary to the template strand, except the thymine, will be replaced by the uracil.

True

6

Organisms without nuclease activity would replicate faster than other organisms since time would not be spent checking newly synthesized DNA and removing mismatched bases. The mutation rate would also be higher.

True

7

The fact that the genetic code is very similar in almost all organisms indicates that it evolved early in the history of life on earth.

True

8

The genetic code is very similar in

deer, maple trees, and bacteria

9

A nucleotide consists of

deoxyribose, a phosphate, and an amino acid.

10

A section of mRNA 6 codons long would most likely result in the addition of how many amino acids to a growing polypeptide (assume the stop codon is absent from the section of mRNA)?

6

11

An enzyme, which excises (=removes) a mismatched base in a newly synthesized strand of DNA, is called

an exonuclease or nuclease

12

The function of the polyadenine (=poly A) tail that is added to mRNA in eukaryotic cells is to

prvent degradation of the mRNA.

13

An adenine molecule bonds to its complementary base with

two hydrogen bonds

14

which of the following best describes mutations?

They are permanent changes in the DNA sequence of an organism.

15

Base pairing due to hydrogen bonding is fundamental to

both processes

16

DNA acts as a template (=guide) for transcription. Which of the following statements regarding the DNA of a gene being expressed is true?

After unwinding, only one of the DNA strands acts as a template.

17

The main support to the DNA molecule is provided by two backbones which run along the two sides of the double helix. These backbones link together

sugars and phosphates

18

An amino acid is

a building block of protein

19

The number of molecules of cytosine in a sample of DNA will always be the same as the number of molecules of

guanine

20

The splicing of the first-formed mRNA transcript by splicesomes is necessary because

introns need to be removed

21

The flow of genetic information is usually in which of the following directions?

DNA--> mRNA--> protein

22

(5') GGCATA (A)
(B) CCGTAT (C)
If the above is a representation of a piece of double-stranded DNA, what symbols should occupy the positions (A), (B) and (C)?

3',3',5'

23

Compare the two mRNA sequences below:
sequence 1- AUAUUCGGCAAUCCG
sequence 2-AUAUUCGGCAAUCG
This change could be a result of

deletion mutation

24

Which of the following is a correct representation of a segment of DNA?
1. 5'ATTC3', 3'ATTC5'
2. 5'AUUC3', 3'UAAG5'
3. 5'CCGG3', 5'GGCC3'
4. '5ATAG3', 3'TATC5'
5. 5'ACGA3',3'TGCT5'

4 and 5

25

If the percentage composition of thymine in a DNA molecule is 26%, what is the percentage composition of cytosine?

24%

26

The discovery of restriction endonucleases was crucial to the development of recombinant DNA technology because of these enzymes

cut DNA at specific and predictable sequences of bases.

27

The model of DNA structure proposed by Watson and Crick suggests a way in which the DNA molecule can replicate itself, because

each base is capable of specifying the base opposite to it in the double helix.

28

Consider the ends of the DNA fragments below. They have been produced by digestion of a single sequence of DNA using a number of restriction endonucleases.
1. 5' A 3'
3' TTCGA 5'
2. 5' G 3'
3' CAGCT 5'
3. 5'AATTC 3'
3' G 5'
4. 5'TCGAC 3'
3' G 5'
5. 5'GGG 3'
3' CCC 5'
Which of these ends are capable of base pairing and being joined by DNA ligase?

2. 5' G 3'
3' CAGCT 5'

4. 5'TCGAC 3'
3' G 5'

29

Complementary base pairing is the result of

hydrogen bonding

30

During DNA replication, one of the new strands of DNA is synthesized continuously, while the other is synthesized discontinuously as a number of separate fragments of DNA that are linked later by DNA ligase. This is because

DNA polymerase only synthesizes DNA in the 5'-3' direction.