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MCAT > Biochemistry Ch 6. DNA and Biotechnology > Flashcards

Biochemistry Ch 6. DNA and Biotechnology Flashcards

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MCAT flashcards
1
Q

Deoxyribonucleic acid (DNA)

A

Macromolecule that stores genetic information all living organisms

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2
Q

Nucleosides

A

Contain a five carbon sugar bonded to a nitrogenous base

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3
Q

Nucleotides

A

Nucleosides with one to three phosphate groups added, in DNA contain deoxyribose, in RNA contain ribose

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4
Q

Deoxyribose

A

5 carbon sugar bonded to nitrogenous base In DNA

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5
Q

Ribose

A

5 carbon sugar bonded to nitrogenous base in RNA

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6
Q

5 nucleotides

A

Adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)

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7
Q

Adenine

A

A purine, pairs with T in DNA and U in RNA via two hydrogen bonds

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8
Q

Guanine

A

A purine, pairs with C in DNA and RNA via three hydrogen bonds

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9
Q

Thymine

A

A pyrimidine, pairs with A in DNA using two hydrogen bonds

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10
Q

Cytosine

A

A pyrimidine, pairs with G in DNA and RNA via three hydrogen bonds

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11
Q

Uracil

A

A pyrimidine, pairs with A in RNA using two hydrogen bonds

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12
Q

Watson-Crick model

A

How DNA is organized, the backbone is composed of alternating sugar and phosphate groups, always read 5’ to 3’, two strands with antiparallel polarity that are wound into a double helix

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13
Q

How is DNA always read

A

5’ to 3’

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14
Q

Antiparallel

A

-

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15
Q

Double helix

A

How two stands of DNA are wound

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16
Q

Purine

A

A and G, always pair with pyrimidines (A with T and G with C in DNA and A with U in RNA), biological aromatic heterocycle

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17
Q

Pyrimidine

A

U, T, and C, always pair with purines (A with T and G with C in DNA and A with U in RNA), biological aromatic heterocyle

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18
Q

Aromatic compounds

A

Cyclic, planar, and conjugated, contain 4n+2pi electrons

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19
Q

Huckels rule

A

Says aromatics contain 4n+2pi electrons where n is an integer

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20
Q

Heterocycles

A

Ring structures that contain at least two different elements in the ring

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21
Q

Chargaffs rules

A

States that purines and pyrimidines are equal in number in a DNA molecules and that because of base pairing, the amount of adenine equals the amount of thymine and the amount of cytosine equals the amount of guanine

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22
Q

B-DNA

A

most common DNA form with right handed helix

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23
Q

Z-DNA

A

Zigzag shape of DNA at a lower concentration, may be seen with high GC content or high salt concentration

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24
Q

Denatured

A

DNA strands that are pulled apart, can be done by heat, alkaline, pH, and chemicals like formaldehyde and urea

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25
Q

Reannealing

A

When DNA strands are brought back together after the removal of conditions that cause denaturing

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26
Q

Human chromosomes

A

DNA is organized into 46 chromosomes in human cells

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27
Q

Histone proteins

A

Proteins that DNA is wound around in eukaryotes to form nucleosomes, includes H2A, H2B, H3, and H4

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28
Q

Nucleosomes

A

DNA that is wrapped around histones, may be stabilized further by another histone protein (H1)

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29
Q

Chromatin

A

DNA and its associated histones in the nucleus

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30
Q

Heterochromatin

A

Dense, transcriptionally silent DNA that appears dark under light microscopy

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31
Q

Euchromatin

A

Less dense, transcriptionally active DNA that appears light under light microscopy

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32
Q

Telomeres

A

The ends of chromosomes, contain high GC content to prevent unraveling of the DNA, during replication, telomeres are slightly shortened although this can be partially reversed by the enzyme telomerase

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33
Q

Centromeres

A

Located in the middle of the chromosome and holds sister chromatids together until they are separated during anaphase in mitosis, also contain a high GC content to maintain a strong bond between chromatids

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34
Q

Replisome

A

aka replication complex, a set of specialized proteins that assist the DNA polymerases

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35
Q

Replication complex

A

A set of specialized proteins that assist the DNA polymerases

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36
Q

Origin of replication

A

Location where DNA is first unwound during replication by helicases

37
Q

Helicases

A

Unwind DNA, produce two replication forks at the origin of replication on either side of the origin

38
Q

Eukaryote origins of replication

A

Have linear chromosomes that contain many origins of replication

39
Q

Prokaryote origins of replication

A

Have a circular chromosome that contains only one origin of replication

40
Q

Replication forks

A

Formed on either side of the origin of replication by helicase at the beginning of DNA replication

41
Q

Single-stranded DNA-binding proteins

A

Keep unwound stands of DNA from reannealing or being degraded

42
Q

Supercoiling

A

Causes torsional strain on the DNA molecules which can be released by DNA topoisomerases

43
Q

DNA topoisomerases

A

Relieve torsional strain in supercoiled DNA by creating nicks

44
Q

Semiconservative

A

Describes DNA replication because one old parent strand and one new daughter strand is incorporated into each of the two new DNA molecules

45
Q

Parent strand

A

From original DNA molecule

46
Q

Daughter strand

A

New DNA strand

47
Q

Primase

A

Puts down a small RNA primer on a new DNA strand because DNA cannot be synthesized without an adjacent nucleotide to hook onto

48
Q

DNA polymerase II

A

In prokaryotes, can synthesize a new strand of DNA, they read the template DNA 3’ to 5’ and synthesize the new stand 5’ to 3’

49
Q

DNA polymerases alpha, delta, and epsilon

A

In eukaryotes, can synthesize a new strand of DNA, they read the template DNA 3’ to 5’ and synthesize the new stand 5’ to 3’

50
Q

Eukaryote DNA polymerase types

A

Alpha, delta, and epsilon

51
Q

Leading strand

A

Requires only one primer and can then by synthesized continuously in its entirety

52
Q

Lagging strand

A

Requires many primers and is synthesized in discrete sections called Okazaki fragments

53
Q

Okazaki fragments

A

Discrete sections of DNA formed on the lagging strand

54
Q

DNA polymerase I

A

In prokaryotes, removes RNA primer and fills spot in with DNA

55
Q

Dna polymerase delta

A

In eukaryotes, removes RNA primer and fills spot in with DNA

56
Q

DNA ligase

A

Fuses the DNA strands together to create one complete molecule

57
Q

Oncogenes

A

Develop from mutations of proto-oncogenes and promote cell cycling, may lead to cancer

58
Q

Proto-oncogenes

A

Mutate into oncogenes

59
Q

Cancer

A

Unchecked cell proliferation with the ability to spread by local invasion or metastasize

60
Q

Metastasize

A

Migrate to distance sites via the bloodstream or lymphatic system

61
Q

Tumor suppressor genes

A

Code for proteins that reduce cell cycling or promote DNA repair, mutations of tumor suppressor genes can also lead to cancer

62
Q

Polymerase proofreading

A

During replication, DNA polymerase proofreads its work and excises incorrectly matched bases, the daughter strand is identified by its lack of methylation and corrected accordingly

63
Q

Mismatch repair

A

Also occurs during the G2 phase of the cell cycle, using the genes MSH2 and MLH1

64
Q

Nucleotide excision repair

A

Fixes helix-deforming lesions of DNA (such as thymine dimers) via a cut and patch process that requires an excision endonuclease

65
Q

Excision endonuclease

A

Necessary for nucleotide excision repair which fixes helix-deforming lesions of DNA (such as thymine dimers) via a cut and patch process

66
Q

Base excision repair

A

Fixes non deforming lesions of the DNA helix (such as a cytosine deamination) by removing a base, leaving an apurinic/apyrimidinic (AP) site

67
Q

Apurinic/apryrimidinic site

A

AP site, left when a base is removed during base excision repair

68
Q

AP endonuclease

A

Removes the damaged sequence when can be filled in with the correct bases

69
Q

Recombinant DNA

A

DNA composed of nucleotides from two different sources

70
Q

DNA cloning

A

Introduces a fragment of DNA into a vector plasmid, once the fragment binds to the plasmid, it can be introduced into a bacterial cell and permitted to replicate, generating many copies of the fragment of interest, one replicated, the bacterial cells can be used to create a protein of interest or can by lysed to allow for isolation of the fragment of interest from the vector

71
Q

Vector plasmid

A

-

72
Q

Restriction enzyme

A

aka restriction endonuclease - cuts both the plasmid and the fragment, which are left with sticky ends

73
Q

Sticky ends

A

-

74
Q

Vectors

A

Contain an origin of replication, the fragment of interest, and at least one gene for antibiotic resistance (to permit for selection of the colony after replication)

75
Q

DNA libraries

A

Large collections of known DNA sequences

76
Q

Genomic libraries

A

Contain large fragments of DNA, including both coding and nonvoting regions of the genome, they cannot be used to make recombinant proteins or for gene therapy

77
Q

cDNA libraries

A

aka expression libraries, contain smaller fragments of DNA and only include the eons of genes expressed by the sample tissue, they can be used to make recombinant proteins or for gene therapy

78
Q

Hybridization

A

The joining of complementary base pair sequences

79
Q

Polymerase chain reaction (PCR)

A

An automated process by which millions of copies of a DNA sequence can be created from a very small sample of hybridization

80
Q

Agarose gel electrophoresis

A

Can separate DNA molecules by size

81
Q

Southern blotting

A

Can be used to detect the presence and quantity of various DNA strands in a sample, after electrophoresis, the sample is transferred to a membrane that can be probed with simple stranded DNA molecules to look for a sequence of interest

82
Q

DNA sequencing

A

Uses dideoxyribonucleotides which terminate the DNA chain because they lack a 3’ -OH group, the resulting fragments can be separated by gel electrophoresis and the sequence can be read directly from the gel

83
Q

Didoxyribonucleotides

A

Terminate the DNA chain because they lack a 3’ -OH group

84
Q

Gene therapy

A

A method of curing genetic deficiencies by introducing a functional gene with a viral vector

85
Q

Transgenic mice

A

Created by integrating a gene of interest into the germ line or embryonic stem cells of a developing mouse, can be mated to select from the transgender

86
Q

Chimeras

A

Organisms that contain cells from two different lineages (such as mice formed by integration of transgenic embryonic stem cells into a normal mouse blastocyst)

87
Q

Knockout mice

A

Created by deleting a gene of interest

88
Q

Biotechnology ethics

A

Brings up a number of safety and ethical issues including pathogen resistance and the ethics of choosing individuals for specific traits

MCAT (67 decks)

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