Ch 6: DNA and Biotechnology Flashcards

1
Q

Nucleosides

A

contain a 5-carbon sugar bound to a nitrogenous base

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2
Q

nucleotides

A

nucleosides w 1-3 phosphate groups added

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3
Q

___ in DNA contain deoxyribose and in RNA contain ribose

A

nucleotides

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4
Q

Nucleotides are abbrev A,C,G,T,U

A
adenine
cytosine
guanine
thymine
uracil
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5
Q

Watson-Crick model says backbone of DNA is

A

organized alternating sugar and phosphate groups and is always read 5-3’

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6
Q

purines

A

A and G

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7
Q

pyrimidines

A

C,U,T

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8
Q

A pairs with

A

T or U

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9
Q

G three hydro bond with

A

C

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10
Q

purine and pyrimidines are biologically aromatic heterocycles meaning

A

aromatic - cyclic, planar, conjugated, 4n+2pi electrons (Huckels rule where n needs to come out 0 or positive even integer when set equation equal to numb pi electrons in molecule)

heterocycles - ring structure that contains at least two different element in the ring

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11
Q

Chargaff’s rule

A

purines and pyrimidines are equal in number in a DNA molecule and that because of base pairing the amount of adenine equals the amount of thymine,and C=G

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12
Q

most DNA is ___ which forms righ handed helix

A

B-DNA

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13
Q

low concentrations of DNA are in ___ with a zig zag shape, may be seen with hgih GC-content or high salt concentration

A

Z-DNA

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14
Q

What can denature DNA and then allow it to reanneal when gone

A

heat, alkaline pH, chemicals like formaldehyde and urea can cause denaturation of DNA

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15
Q

DNA organized into ___ chromosomes in the human cells

A

46

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16
Q

in eukaryotes, DNA is wound around ____ to form ____ which may be stabilized by another ____

A
histone proteins (H2A, H2B, H3, H4)
nucleosomes
histone protein (H1)
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17
Q

DNA and its associated histones as a whole make up ____ in the nucleus

A

chromatin

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18
Q

heterochromatin

A

dense, transcriptionally active DNA that appears dark under the light microscopy

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19
Q

euchromatin

A

less dense, transcriptionally active DNA that appears light under the light microscopy

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20
Q

telomeres

A

end of chromosomes; high GC content to prevent unraveling of DNA

during replication, telomeres are slightly shortene. although this can partially be reversed by the enzyme telomerase

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21
Q

centromeres

A

located in the middle of chromosomes and hold sister chromatids together until they are seperated during anaphase in mitosis. they also contain a high GC content to maintain a strong bond between chromatids

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22
Q

replisome (replication complex)

A

is a set of specialized proteins that assist the DNA polymerases

23
Q

Origin of replication

A

when DNA is replicated it is unwound here by helicases
this produces two replication forks on either side of the origin

prokaryotes - circular chromosome with one OOR
eukaryotes - linear chromosome with many origin of replication

24
Q

unwound strands are kept from reannealing or being degraded by

A

single-stranded DNA-binding proteins

25
Q

__causes torisonal strain on the DNA molecule, which can be released by ____, which creates nicks in the DNA molecule

A

supercoiling

DNA topoisomerase II (DNA gyrase)

26
Q

DNA replication is ___ for one old parent strand and one new daughter strand are incorporated into each of the two new DNA molecules

A

semiconservative

27
Q

DNA cannot be synthesized without ____ so a small RNA primer is put down by ____

A

an adjacent nucleotide to hook onto

primase

28
Q

DNA polymerase 3 (prokaryotes) or DNA polymerase alpha and gamma (eukaryotes)

A

can then synthesize a new strand of DNA

read DNA temple 3 -5’ and synthesize new strand 5-3

29
Q

leading strand needs only

A

one primer and can by synthesized continuously

30
Q

lagging strand needs

A

many primers and synthesized in sections called Okazaki fragments

31
Q

RNA primers can be removed later by ____ and filled in with DNA by _____

A

DNA polymerase 1 (prok) or RNase H (euk)

DNA polymerase 1 (prok) or DNA polymerase gamma (euk)

32
Q

DNA ligase

A

can fuse the DNA strands together to create one complete molecule

33
Q

Oncogenes

A

develop from mutations of proto-oncogenes and promote cell cycling. they may lead to cancer which is unchecked cell proliferation with the ability to spread by local invasion or metastasize

34
Q

Tumor suppressor genes

A

code for proteins that reduce cell cycling or promote DNA repair

35
Q

during replication, _____ proofreads its work. the ____ is identified by its lack of ____ and corrects accordingly

A

DNA polymerase
daughter strand
methylation

36
Q

Mismatch repair also occurs during ___ of the cell cycle and uses genes MSH2 and MLH1

A

G2

37
Q

Nucleotide excision repair fixes

A

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

38
Q

Base excision repair fixes

A

nondeforming lesions of the DNA helix (such as cytosine deamination) by removing the base, leaving an apurinic/apyrimidinic (AP) site. An AP endonuclease then removes the damaged sequence which can be filled in with the correct bases

39
Q

Recombinant DNA is

A

DNA composed of nucleotides from two different sources

40
Q

DNA cloning introduces a fragment of DNA into a

A

vector plasmid

41
Q

building of the cloning, ____ cuts both the plasmid and the fragment, which are left with sticky ends. once a 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

A

Restriction enzyme

42
Q

vectors contain

A

OOR, fragment of interest, one gene of antibodic resistance to permit for selection of that colony after replication

once replicated bacterial cells can be used to create a protein of interest or can be lysed to allow for isolation of the fragment of interest from the vector

43
Q

DNA libraries

A

large collections of known DNA sequences

genonmic and cDNA libraries are two examples

44
Q

Genomic libraries

A

contain large fragments of DNA including both coding and non coding regions of the genome. They CANT be used to make recombinant proteins or for gene therapy

45
Q

cDNA libraries (expression libraries)

A

contain smaller fragments of DNA and only include the exons expressed by the sample tissue. CAN be used to make recombinant proteins or for gene therapy

46
Q

Hybridization

A

is the joining of complementary bp sequences

47
Q

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

A

Polymerase Chain Reaction (PCR)

48
Q

DNA molecules can be seperated by size using

A

agarose gel electrophoresis

49
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 single-stranded DNA molecules to look for a sequence of interest

50
Q

DNA sequencing uses____ which terminate the DNA chain bc they lack a 3’-OH. The resulting fragment can be seperated by _____ and the sequence can be read directly from the gel

A

dideoxyribonucleotides

gel electrophoresis

51
Q

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

A

gene therapy

52
Q

created by integrating a gene of interest into the germ line of the embryonic stem cells of a developing mouse

A

transgenic mice

and they can be mated to select for the transgene

53
Q

chimeras

A

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

54
Q

created by deleting a gene of interest

A

knockout mice