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Molecular Genetics exam 1 > Molecular Genetics Exam 1 > Flashcards

Molecular Genetics Exam 1 Flashcards

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Biology 101 flashcards
1
Q

For a molecule to serve as the genetic material, it must be able to

A

replicate, store info, express info, and mutate

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2
Q

What is the genetic material?

A

what is transmitted from parent to offspring

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3
Q

Describe Griffiths experiment

A

used S (lethal) and R (non-lethal) bacteria; heat killed S bacteria combined with R bacteria and injected in mice; mice died and S bacteria was cultured suggesting something from the S turned R into S

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4
Q

Describe Avery, macleod, and mccartys experiment

A

used S (lethal) and R (non-lethal) bacteria; killed specific components of the S cells and combined the remaining components with R to inject in mice; mice that had DNA killed were the only ones to survive and no S bacteria was cultured from them suggesting that DNA was required to turn R into S

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5
Q

Describe Hershey-chase experiment

A

used viruses and radiolabeled either the DNA or protein coat; infected cells and looked to see where the radiolabel ended up after infection; when DNA was radiolabeled the label was found in the cell but when the protein was labeled there was nothing in the cells suggesting that viruses inject their DNA into the cell and this is what is used to make more viruses

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6
Q

What is the indirect evidence that supports the idea that DNA is the genetic material?

A

Distribution of DNA and mutagenesis

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7
Q

What is the direct evidence that supports the idea that DNA is the genetic material?

A

Recombinant DNA studies

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8
Q

Where are chromosomes located?

A

in the nucleus

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9
Q

Each chromosome contains one

A

long molecule of double stranded DNA

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10
Q

What are DNA markers used for?

A

To serve as landmarks that identify physical positions along a DNA molecule, such as DNA from a chromosome

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11
Q

What does DNA stand for?

A

Deoxyribose nucleic acid

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12
Q

What are the 3 major components of DNA?

A

Phosphate, sugar, and base

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13
Q

What is the difference between DNA and RNA?in regards to the sugar?

A

DNA does not have an OH, just an H, on the 2’ carbon

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14
Q

Nucleotides are___phosphates

A

mono

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15
Q

Nucleoside diphosphate has __ phosphate groups

A

2

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16
Q

Nucleoside triphosphate has __ phosphate groups

A

3

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17
Q

Bases that are purines and the number of rings

A

adenine and guanine, 2 rings

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18
Q

Bases that are pyrimidines and the number of rings

A

cytosine, thymine, and uracil, 1 ring

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19
Q

Parts of a nucleoside

A

Sugar and base

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20
Q

Nucleotides are linked by ____ bonds between the __ group on the c-3’ and the ___ group at the c-5’ position

A

Phosphodiaster, OH, phosphate

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21
Q

X-ray diffraction studies by ___ of DNA showed a 3,4 angstrom periodicity, characteristic of a helical structure

A

Rosalind Franklin

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22
Q

How many hydrogen bonds attract a and t?

A

2

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23
Q

How many hydrogen bonds attract g and c?

A

3

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24
Q

Chargaff’s rule

A

base pairing
A=T and C=G
Pyrimidines T+C=purines A+G

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25
Q

DNA becomes tightly packed when it

A

supercoils

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26
Q

Shape of Bacterial DNA

A

circular

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27
Q

What are nucleosomes?

A

a core of 8 histones

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28
Q

Simplest level of DNA

A

chromatin as a double stranded helical structure of DNA

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29
Q

DNA is complexed with histones to form ___

A

nucleosomes

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30
Q

Nucleosomes fold up to form a

A

30 nm fiber

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31
Q

30nm fibers that form loops ___ in length

A

300 nm

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32
Q

300 nm loops are compressed and folded to produce a

A

250 nm wide fiber

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33
Q

Tight coiling of the 250 nm fiber produces

A

the chromatid of a chromosome

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34
Q

Heterochromatin

A

condensed areas and are inactive because they either lack genes or contain genes that are compressed

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35
Q

euchromatin

A

uncoiled and active

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36
Q

what parts of the chromosomes are heterochromatin?

A

Telomeres, and centromeres

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37
Q

Centromeres

A

are the primary constrictions along eukaryotic chromosomes and mediate chromosomal migration during mitosis and meiosis

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38
Q

Telomeres

A

terminal heterochromatic caps that consist of short tandem repeats that contribute to stability and integrity of the chromosome

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39
Q

Does the telomere code for any genes?

A

no

40
Q

what is the sequence of telomere in humans?

A

TTAGGG

41
Q

What is the T loop?

A

The loop made by the telomere. It forms an overhang that protects from degradation. It involves many proteins

42
Q

What is meant by semiconservative replication?

A

1 original strand and one new strand

43
Q

What is Conservative replication?

A

when there is one complete double helix of old and one of new

44
Q

What is dispersive replication?

A

when there are chunks of old and new in a DNA molecule

45
Q

What was the meselson and stahl experiment?

A

They wanted to show how DNA was replicated so they labeled old nucleotides with 15n and new nucleotides with 14n then centrofuged them to find where they would be in the tube

46
Q

2 bands for the semiconservative

A

2 top bands

47
Q

2 bands for conservative model

A

1 on top and one at bottom

48
Q

2 bands for dispersive model

A

both in middle

49
Q

DNA replication is

A

semiconservative

50
Q

When does DNA replication occur?

A

The S phase of interphase

51
Q

When does growth occur?

A

in G1 and G2 of interphase

52
Q

what are the parts of mitosis?

A

prophase, metaphase, anaphase, telephase

53
Q

what does it mean by replication is bidirectional?

A

Replication occurs in both directions simultaneously with the leading and lagging strand

54
Q

How many strands are there on a fork that is replicating?

A

2

55
Q

Similarities and Differencences in origins and direction of replication in prokaryotes and eukaryoties

A

Pro-1 origin, bidirectional

Euk-More than 1, bidirectional

56
Q

what is the replication fork?

A

the point at which replication is actively occuring

57
Q

DNA polymerase

A

catalyzes the elongation of new DNA at replication fork but cannot initiate synthesis of a polynucleotide and can only add nucleotides to an existing 3’ end thus the unusual strand is a short RNA primer

58
Q

Primase

A

adds the primer to give DNA polymerase a 3’OH to begin replication at

59
Q

Difference between DNA and RNA

A

DNA only has an H at the 2’ c and RNA has a OH

60
Q

Synthesis only occurs in the ___ direction

A

5’ to 3’

61
Q

The ___ is replicated as a continuous strand and polymerase moves toward replication fork

A

Leading strand

62
Q

The ___ is replicated as a discontinuous strand and the polymerase moves away from replication fork

A

Lagging strand

63
Q

Topoisomerase aka gyrase

A

Alleviates the supercoiling and places single stranded nicks in the DNA which are then repaired

64
Q

Helicase

A

Unzips Double helix

65
Q

the lagging strand has ____ fragments

A

okazaki

66
Q

what makes up an Okazaki fragment

A

Newly senthesized DNA and RNA primer

67
Q

What happens to RNA primers in the Okazaki fragments?

A

RNA primers are removed and the space is filled in the DNA via a polymerase and then ligated to the strand using an enzyme known as ligase

68
Q

Why is the lagging strand left short?

A

When the primer is removed on the end and it cannot be filled in, the next round of replication will cause it to be short

69
Q

Why are telomeres indicated in aging?

A

Telomeres are thought to be the counting mechanism for the number of times a cell has replicated. When the telomeres reach a critically short length the cell will undergo apoptosis and the shortening would be close to deleting genes

70
Q

what do southern blots do?

A

look at DNA sequences and often show telomere shortening

71
Q

What is the enzyme that elongates telomeres?

A

telomerase

72
Q

In stem cells and cancer cells telomerase is

A

turned on

73
Q

How does topoisomerase work?

A

Introduces a double stranded break ahead of the replication fork and swivels the cleaved ends around the central axis to relieve the stress of helix unwinding

74
Q

What is PCR?

A

polymerase chain reaction. A rapid method of DNA cloning that copies a specific DNA sequence through in vitro reactions that can amplify target DNA sequences present in very small quantities

75
Q

What goes into the tube for PCR?

A

DNA primer, taq polymerase, heat, DNA template and dNTP

76
Q

What is the temperature at which 50 percent of pairs are denatured

A

melting temperature

77
Q

3 parts of PCR

A

denaturation, annealing, and extention

78
Q

what is denaturation?

A

temperature is increased to separate DNA strands

79
Q

What is annealing?

A

Temperature is decreased to allow primers to base pair to complementary DNA template

80
Q

What is extension?

A

Polymerase extends primer to form nascent DNA strand

81
Q

What do we use to analyze DNA?

A

Electrophoresis

82
Q

what is electrophoresis?

A

Seperates DNA and RNA fragments by size using polyacrylamide or agarose gels

83
Q

What are the 2 types of electrophoresis?

A

southern blots for DNA and northern blots for RNA

84
Q

why does DNA move to the + end in electrophoresis?

A

Phosphate groups of DNA make the DNA -

85
Q

Smaller fragments move more ___ through the gel

A

quickly

86
Q

Describe gel electrophoresis of DNA

A

Liquid gel is allowed to harden with an appropriately shaped mold in place to form slots for the samples. After electrophoresis, the DNA fragments, located at various positions in the gel, are made visible by immersing the gel in a solution containing a reagent that binds to or reacts with DNA.

87
Q

What do we use to see the DNA in the electrophoresis gel?

A

Ethidium bromide which binds to DNA and glows when exposed to UV light

88
Q

what are the sizes of the holes in agarose based on?

A

the percentages of agarose

89
Q

____ hold on to the single stranded DNA so that it does not form duplexes

A

Single strand binding proteins

90
Q

PCR is an in vitro version of

A

replication

91
Q

PCR buffer

A

create the correct environment for the reaction to occur (stimulating the cell/nucleus)

92
Q

Template DNA in PCR

A

what is being copied

93
Q

dNTPs in PCR

A

Nucleotides (bases) that make up the new strand

94
Q

Primers in PCR

A

Complementary to DNA and indicates the area to be copied; provides the free 3’ OH for DNA polymerase to begin

95
Q

Taq polymerase in PCR

A

DNA polymerase that adds nucleotides

96
Q

what is dideoxycy sequencing?

A

A primer distinguishes where to start. dNTPs are added along with dideoxyNTPs. When the polymerase adds ddNTPs the polymerization stops and lots of different fragment sizes are formed and separated by electrophoresis to identify bases

97
Q

What is next generation sequencing?

A

Bridge PCR Allows for the whole genome to be sequenced within a few hours by either flourecence or pH changes

Molecular Genetics exam 1 (6 decks)

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