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BIOL 112 > Week 6 (part 1 - ch. 3) > Flashcards

Week 6 (part 1 - ch. 3) Flashcards

1
Q

Define DNA

A

A linear polymer of four subunits; the information archive in all organisms.

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2
Q

Define double helix

A

The structure formed by two strands of complementary nucleotides that coil around each other.

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3
Q

What are the two major biological functions of DNA?

A

DNA stores information

DNA transmits genetic information from one generation to the next

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4
Q

Defien genetic information

A

Information carried in DNA, organized in the form of genes

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5
Q

Define genes

A

The unit of heredity; the stretch of DNA that affects one or more traits in an organism, usually through an encoded protein or noncoding RNA

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6
Q

Define gene expression

A

The production of a functional gene product.

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7
Q

Define gene regulation

A

The various ways in which cells control gene expression

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8
Q

What causes differences in genes?

A

the order of the individual sub units (bases) in the DNA

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9
Q

Define nucleotides

A

A constituent of nucleic acids, consisting of a 5-carbon sugar, a nitrogen-containing base, and one or more phosphate groups.

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10
Q

What does the elegant shape of the twisting strands rely on?

A

the structure of the DNA’s subunits aka nucleotides

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11
Q

What do nucleotides consist of (3 things)

A
  • a 5 carbon sugar
  • a base
  • one or more phosphate groups
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12
Q

Define sugar

A

The simplest carbohydrate molecule; also called a saccharide

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13
Q

Define base

A

A nitrogen-containing compound that makes up part of a nucleotide.

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14
Q

Define phosphate group

A

A chemical group consisting of a phosphorus atom bonded to four oxygen atoms.

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15
Q

What are the roles of the phosphate group and 5 carbon sugar in the DNA structure?

A

They form the backbone. Each sugar is linked to the phosphate group of the neighboring nucleotide

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16
Q

What is the role of the bases sticking out of the sugar on nucleotides?

A

They give the nucleotide its chemical identity

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17
Q

By convention, which direction are the carbon atoms on the sugar ring in DNA/RNA numbered?

A

clockwise

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18
Q

Define deoxyribose

A

The sugar in DNA.

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19
Q

Where is the base attached on the carbon ring in DNA/RNA?

A

it is attached to the 1’ carbon

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20
Q

Define purine

A

In nucleic acids, either of the bases adenine and gunanine, which have a double-ring structure

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21
Q

Define adenine (A)

A

A purine base.

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22
Q

define Guanine (G)

A

A purine base.

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23
Q

Define pyrimidine

A

In nucleic acids, any of the bases thymine, cytosine, and uracil, which have a single-ring structure.

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24
Q

Define thymine (T)

A

A pyrimidine base.

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25
Q

Define cytosine (C)

A

A pyrimidine base.

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26
Q

Define nucleoside

A

A molecule consisting of a 5-carbon sugar and a base.

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27
Q

a nucleoside with one or more phosphate groups constitutes a _____.

A

nucleotide

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28
Q

Why are nucleoside triphosphates particularly inmportant?

A

because they are the molecules that are used to form nucleotide polymers: DNA and RNA.

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29
Q

What other functions do nucleoside triphosphates do besides make up DNA and RNA?

A

They are carriers of chemical energy in the form of ATP and GTP

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30
Q

Define phosphodiester bond

A

A bond that forms when a phosphate group in one nucleotide is covalently joined to the sugar unit in another nucleotide.

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31
Q

_____ _____ are relatively stable and form the backbone of a DNA strand

A

Phosophodiester bonds

32
Q

What is the name of the C-O-P-O-C linkage?

A

Phosophodiester bond

33
Q

What gives DNA strands their polarity?

A

the phosphodiester linkage

34
Q

Define 5’ end

A

The end of a nucleic acid strand containing a free 5′ phosphate group.

35
Q

Define 3’ end

A

The end of a nucleic acid strand that carries a free 3′ hydroxyl.

36
Q

When a base sequence is stated without specifying the 5′ end, by convention the end at the left is the __ end

A

5’

37
Q

How would you specify a strand of DNA with the sequence TCGA with the T being nearest the hydroxyl group and the A being nearest the phosphate group?

A

5′-AGCT-3′ or equivalently 3′-TCGA-5′.

38
Q

How many base pairs are there per complete turn in the the double helix?

A

10

39
Q

What is the diameter or DNA?

A

2 nm

40
Q

Define major groove

A

The larger of two uneven grooves on the outside of a DNA duplex.

41
Q

Define minor groove

A

The smaller of two unequal grooves on the outside of a DNA duplex.

42
Q

What is the importance of minor and major groove in DNA?

A

proteins that interact with DNA often recognize a particular sequence of bases by making contact with the bases via the major or minor groove or both.

43
Q

Define antiparallel

A

Oriented in opposite directions; the strands in a DNA duplex are antiparallel.

44
Q

What does A pair with?

A

T

45
Q

What does G pair with?

A

C

46
Q

What does T pair with?

A

A

47
Q

What does C pair with?

A

G

48
Q

Each base pair contains a ____ and a _____

A

purine

pyrimidine

49
Q

Why does the precise pairing of bases maintain the structure of the double helix?

A

because pairing two purines would cause the backbones to bulge and pairing two pyrimidines would cause them to narrow

50
Q

Define complementary

A

Describes the relationship of purine and pyrimidine bases, in which the base A pairs only with T and G pairs only with C

51
Q

Because they form specific pairs, the bases A and T are said to be _____, as are the bases G and C

A

complementary

52
Q

The specificity of base pairing is brought about by ____ _____ that form between A and T and between G and C

A

hydrogen bonds

53
Q

How many hydrogen bonds do A and T share?

A

two

54
Q

How many hydrogen bonds do G and C share?

A

Three

55
Q

What two things can disrupt hydrogen bonding?

A

high pH or high temperatures

56
Q

Define base stacking

A

Stabilizing hydrophobic interactions between bases in the same strand of DNA.

57
Q

What is one of the most important features of DNA structure?

A

There is no restriction on the sequence of bases along a DNA strand

58
Q

What do the base pairing rules imply?

A

%A = %T and %G = %C

and that the percentage of purines equals the percentage of pyrimidines

59
Q

Many of the double-stranded DNA molecules in prokaryotic cells are ___ and form _____

A

circular

supercoils

60
Q

Define supercoils

A

A coil of coils; a circular molecule of DNA can coil upon itself to form a supercoil.

61
Q

Supercoiling is caused by enzymes called _____ that cleave, partially unwind, and reattach a DNA strand, which puts ____ on the DNA double helix.

A

topoisomerases

strain

62
Q

Define topoisomerases

A

Any one of a class of enzymes that regulates the supercoiling of DNA by cleaving one or both strands of the DNA double helix, and later repairing the break.

63
Q

Supercoils relieve the ___ and help to preserve the 10 base pairs per turn in the double helix.

A

strain

64
Q

n eukaryotic cells, most DNA molecules in the nucleus are _____, and each individual molecule forms one _____

A

linear

chromosome

65
Q

Define chromosome

A

In eukaryotes, the physical structure in which DNA in the nucleus is packaged; used more loosely to refer to the DNA in bacterial cells or archaeons.

66
Q

Double-stranded DNA molecules in eukaryotes are usually packaged with proteins called ______, and others, to form a complex of DNA and proteins referred to as ______

A

histones

chromatin

67
Q

Define chromatin

A

A complex of DNA, RNA, and proteins that gives chromosomes their structure; chromatin fibers are either 30 nm in diameter or, in a relaxed state, 10 nm.

68
Q

What are the main differences between RNA and DNA

A
  • the sugar in RNA is ribose whereas the sugar in DNA is deoxyribose (which is why RNA is less stable than DNA)
  • RNA is less stable than DNA
  • in RNA the base uracil replaces thymine
  • while the 5′ end of a DNA strand is typically a monophosphate, the 5′ end of an RNA molecule is typically a triphosphate
  • RNA is usually a shorter strand than DNA
  • RNA is usually single stranded
69
Q

Why is a deoxyribose called a 2’-deoxyribose?

A

Because the oxygen is missing of the 2’ carbon atom

70
Q

What is the covalent bond which links monomers together?

A

a phosphodiester bond

71
Q

What is the difference between structural polarity and bond polarity

A

structural: difference in EN of two ends of a molecule
Bond: difference in EN between two atoms bonded together

72
Q

What is the name of the enzyme that forms at the start of transcription?

A. 	RNA polymerase
B. 	DNA polymerase
C. 	DNA gyrase
D.	 RNA helicase
A

A. RNA polymerase

73
Q

What genetic material is made during the process of transcription?

A.	mRNA
B.	tRNA
C.	rRNA
D.	All of the above
A

D. All of the above

74
Q

If the first nucleotide after the promoter on the top DNA strand is changed from G to T, what would the resulting nucleotide be on the mRNA?

A.	C
B.	A
C.	G
D.	T
A

B. A

75
Q

If you made a change in the promoter sequence in the DNA, what would happen at the RNA level?

A.	The RNA polymerase would not be able to
	recognize and bind the DNA, so no RNA would
	be made.
B.	The DNA helicase would not be able to
	recognize and bind the DNA, so the RNA
	would not be made.
C.	The mutation of the DNA would be carrier
	through to the RNA sequence.
D.	Nothing, the RNA would be made as usual.
A

A. The RNA polymerase would not be able to recognize and bind the DNA, so no RNA would be made.

76
Q

If the first nucleotide after the promoter on the bottom DNA strand is changed from C to T, what would the resulting nucleotide be on the mRNA?

A.	A
B.	U
C.	C
D.	T
A

A. A

BIOL 112 (12 decks)

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