exam 7 Flashcards Preview

AP Bio > exam 7 > Flashcards

Flashcards in exam 7 Deck (136)
Loading flashcards...
1
Q

T.H. Morgan

A

showed that genese exist as parts of chromosomes, the two chemical components of chromosomes–DNA and protein– emerged as the leading candidates for genetic material

2
Q

Frederick Griffith

A

studied two strains of the bacteria streptococcus pneumonia
concluded that the living R bacteria had been transformed into the pathogenic S bacteria by an unknown, heritable substance from the dead S cells that allowed R cells to make capsules

3
Q

transformation

A

change in genotype and phenotype due to the assimilation of external DNA by a cell

4
Q

bacteriophages

A

viruses that infect bacteria

5
Q

virus

A

little more than DNA enclosed by a protective coat, which is often simply protein
to produce more viruses, a virus must infect a cell and take over the cell’s metaboic machinery

6
Q

Hershey an Chase

A

used radioactive sulfur (protein) and phosphorus(DNA) to track the stuff of T2 phages that infect bacterial cells. they concluded that DNA was the heritable factor

7
Q

erwin chargaff

A

chargaff’s rules:

1) the base composition varies between species
2) within species, the number of A and T bases are roughly equal and the number of G and C bases are roughly equal

8
Q

Rosalind Franklin

A

X ray diffraction/crystolography to find shape of DNA

Watson and crick stole her thing

9
Q

double helix

A

shape of DNA that watson and crick coined

10
Q

antiparallel

A

their subunits run in opposite directions

11
Q

purine

A

2 ring

12
Q

pyrimidine

A

1 ring

13
Q

conservative model

A

the two parental strands reassociate after acting as template for new strands, thus restoring their parental double helix

14
Q

semiconservative model

A

the two strands of the parental molecule separate, and each functions as a template for synthesis of a new, complementary strand

15
Q

dispersive model

A

each strand of both daughter molecules conains a mixture of old and newly synthesized DNA

16
Q

Meselston and Stahl

A

cultured E. coli (details on experimient figure 13.11)

concluded that the semiconservative model was how DNA was replicated

17
Q

origins of replication

A

short stretches of DNA having a specific sequence of nucleotides to begin DNA replication

18
Q

replication fork

A

a Y shaped region where the parental strands of DNA are being unwound

19
Q

Helicases

A

enzymes that untwist the double helix at the replication forks, separating the two parental strands and making them available as template strands

20
Q

single-strand binding proteins

A

bind to the unpaired DNA strands and keep them from repairing

21
Q

topoisomerates

A

helps relieve the strain of twisting ahead of the replication fork
breaks, swivels, and rejoins DNA strands

22
Q

prokaryotic vs eukaryotic DNA replication

A

there is only 1 origin of replication and 1 replication fork in prokaryotic
there are multiple in eukaryotic
prokaryotic DNA is circular and the single replication fork moves in 2 directions

23
Q

primer

A

initial nucleotide chain that is produced during DNA synthesis is a short stretch of RNA
meant to attract DNA polymerase 3

24
Q

primase

A

enzyme that makes RNA primer

25
Q

DNA polymerase III

A

synthesizes DNA opposite from the template strnad

catalyzes the synthesis of new DNA by adding nucleotides to a preexisting chain.

26
Q

leading strand

A

the strand made by this mechanism:
dna pol 3 remains in the replication fork on the template strand and continuously adds nucleotides to the new complementary strand as the fork progresses
5-3 direction

27
Q

lagging strand

A

synthesized discontinuously, as a series of segments

28
Q

okazaki fragments

A

piece of DNA between 2 RNA primers

1,000 to 2,000 nucleotides long

29
Q

DNA ligase

A

enzyme that joins sugar phosphate backbones of all the Okazaki fragments into a continuous DNA strand

30
Q

DNA pol 1

A

replaces the RNA primers with DNA, adding to the 3’ end of fragment 2

31
Q

mismatch repair

A

other enzymes remove and replace incorrectly paired nucleotides resulting from replication errors

32
Q

nuclease

A

DNA cutting enzyme

33
Q

nucleotide excision repair

A

teams of enzymes detect and repair damaged DNA which distorts the DNA molecule
a nuclease enzyme cuts the damaged DNA strand at 2 points, and the damaged section is removed
repair synthesis by a DNA pol fills in thee missing nucleotides
DNA ligase seals the free end of the new DNA to the old DNA, making the strand complete

34
Q

telomeres

A

do not contain genes
the DNA consists of multiple repetitions of one short nucleotide sequence
buffer zone that protects the organism’s genes

35
Q

telomerase

A

catalyzes the lengthening of telomeres in eukaryotic germ cells, thus restoring their original length
not active in most human somatic cells but sows inappropriate activity in some cancer cells

36
Q

nucleoid

A

dense region of DNA in bacterium is not surrounded by a membrane

37
Q

chromatin

A

eukaryotic DNA and protein together in a complex called chromatin, fits into the nucleus through an elaborate, multilevel system of packing

38
Q

palendrome

A

same forward as it is backwards

favored to be cut by a restriction enzyme

39
Q

heterochromatin

A

interphase chromatin, visible as irregular clump with a light microscope

40
Q

euchromatin

A

less compacted more dispersed

41
Q

levels of organization in chromosme

A
DNA, double helix
Histones
Nucleosomes
30 nm fiber
looped domains (300 nm)
metaphase chromosome
42
Q

histones

A

proteins responsible for the first level of DNA packing in chromatin
small

43
Q

nucleosome

A

chromatin resembling beads on a string

each bead is a nucleosome, the basic unit of DNA packing; the string between beads is linker DNA

44
Q

nucleic acid hybridization

A

the base pairing of one strand of a nucleic acid to a complementary sequence on another strand

45
Q

genetic engineering

A

the direct manipulation of genes for practical purposes

46
Q

plasmids

A

small circular DNA molecules that replicate separately from the bacterial chromosome

47
Q

recombinant DNA

A

a DNA molecule formed when segments of DNA from 2 different sources–often different species–are combined in vitro (in a test tube) the plasmid is then returned to a bacterial cell, producing a recombinant bacterium. This single cell reproduces through repeated cell divisions to form a clone of cells, a population of genetically identical cell

48
Q

gene cloning

A

the production of multiple copies of a single gene

49
Q

restriction enzymes

A

enzymes that cut DNA molecules at a limited number of specific locations

50
Q

restriction site

A

a specific particular short DNA sequence that is cut by a restriction enzyme at precise points

51
Q

restriction fragments

A

fragments that yeild as a result of restriction enzymes making many cuts in a DNA molecule

52
Q

gel electrophoresis

A

a process that separates a mixture of nucleic acid fragments by length
short fragments move further
long fragments move closer

53
Q

sticky end

A

resulting double-stranded restriction fragments have at least 1 single stranded end called a sticky end

54
Q

cloning vector

A

2 DNA molecules that are joined together in gene cloning

55
Q

polymerase chain reaction

A

lots of copies of DNA
3 steps:
denaturation: heat briefly to separate DNA strands
Annealing: cool to allow primers to form hydrogen bonds with ends of target sequence
Extension: DNA polymerase adds nucleotides to the 3’ end of each primer

56
Q

DNA sequencing

A

once a gene is cloned, researchers can exploit the principle of complementary base pairing to determine the gene’s complete nucleotide sequence

57
Q

gene expression

A

process by which DNA directs synthesis of proteins

58
Q

transcription

A

the synthesis of RNA using information in the DNA

59
Q

messenger RNA

A

carries a genetic message from the DNA to the protien-synthesizing machinery of the cell

60
Q

translation

A

synthesis of a polypeptide using the information in the mRNA

61
Q

ribosomes

A

complex particles that facilitate the orderly linkage of amino acids into polypeptide chains
made of rRNA and proteins

62
Q

primary transcript

A

the initial RNA transcript from any gene, including those specifying RNA that is not translated into protein

63
Q

triplet code

A

the genetic instructions for a polypeptide chain written in the DNA as a series of non overlapping 3 nucleotide words
the series of words in a gene is transcribed into a complementary series of nonoverlapping three nucleotide words in mRNA whichis then translated into a chain of amino acids

64
Q

templatestrand

A

the genetic instructions for a polypeptide chain are written in the DNAas a series of nonoverlapping-three nucleotide words

65
Q

codons

A

mRNA nucleotide triplets
64 codons
61 code for amio acids

66
Q

AUG

A

codes for Met and Start

67
Q

RNA polymerase

A

pries two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand, thus elongating the RNA polynucleotide. RNA polymerases can assemble a polynucleotide only in its 5’-3’ direction

68
Q

promoter

A

DNA sequence where RNA polymerase attaches and initiates transcription

69
Q

terminator

A

in bacteria, the sequence that signals the end of transcription

70
Q

trasncription unit

A

the stretch of DNA transcribed into an RNA molecule

71
Q

start point

A

the nucleotide where RNA synthesis actually begins

72
Q

stages of transcription

A

initiation
elongation
termination

73
Q

initiation

A

after RNA polymerase binds to the promote, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template strand

74
Q

Elongation

A

the polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5’-3’. in the wake of transcrition, the DNA strands re-form a double helix

75
Q

termination

A

eventually the RNA transcript is release, and the polymerase detaches from the DNA

76
Q

transcription factors

A

proteins that mediate the binding of RNA polymerase and the initiation of transcription

77
Q

transcription initiation complex

A

the whole complex of transcription factors and RNA polymerase 2 bound to the promoter

78
Q

TATA box

A

crucial DNA sequence in the promoter that only has T and A nucleotides

79
Q

RNA processing

A

both ends of the primary transcript are altered, also in most cases certin interior sections of the RNA molecule are cut out and the remaining parts are spliced together
these modifications produce an mRNA molecule ready for translation

80
Q

5’ cap

A

modified form of the Guanine nucleotide added onto the 5’ end after transcription of the first 20-40 nucleotides

81
Q

poly-A tail

A

at the 3’ end, adds 50-250 more adenine nucleotides

82
Q

functions of 5’ cap and poly A tail

A
  • facilitate the export of mature mRNA from the nucleus
  • help protect the mRNA from degradation by hydrolitic enzymes
  • help ribosomes attach to the 5’ end of the mRNA once the mRNA reaches the cytoplasm
83
Q

RNA splicing

A

removal of large portions of the RNA molecule that is initially synthesized

84
Q

introns

A

noncoding segments of nucleic acid that lie between coding regions
intervening sequences

85
Q

exons

A

other regions

eventually expressed and translated into amino acid sequences

86
Q

spliceosome

A

how is pre-mRNA splicing carried out? the removal of introns is accomplished by a large complex made of proteins and small RNAS called a spliceosome
this complex binds to several short nucleotide sequences along the intron
the intron is then released and rapidly degraded, and the splicosome joins ogether the two exons that flanked the intron

87
Q

ribozymes

A

RNA molecules that function as enzymes

88
Q

transfer RNA

A

transfer amino acids from the cytoplasmic pool of amino acids to a growing polypeptide in a ribosome

89
Q

anticodon

A

the particular nucleotide triplet that base-pairs to a specific mRNA codon on tRNA

90
Q

aminoacyl-tRNA synthases

A

enzymes that fit only a specific ombination of amino acid and tRNA
joins amino acid and tRNA through covalent bond

91
Q

ribosomal RNA (rRNA)

A

make up ribosome

92
Q

APE

A

A=arrival site
holds the tRNA carrying the next amino acid to be aded to the chain
P=protein building site
holds tRNA carrying the growing polypeptide chain
E=exit site
discharged tRNAs leave the ribosome from this site

93
Q

release factor

A

protein shaped like a tRNA, binds directly to the stop codon in the A site
the release factor causes the addition of a water molecule instead of an amino acid to the polypeptide chain
this reaction hydrolyzes the bond between the completed polypeptide and the tRNA in the P site, releasing the polypeptide through the exit tunnel of the large subunit

94
Q

phases of translation

A

codon recognition
peptide bond formation
translocation

95
Q

free vs bound ribosome

A

free ribosomes are suspended in the cytosol and mostly synthesize proteins that stay in the cytosol and function there
bound ribosomes are attached to the cytosolic side of the ER or to the nuclear envelope
bound ribosomes make up proteins of the endomembrane system

96
Q

signal peptide

A

the polypeptides of proteins destined for the endomembrane system or for secretion are marked by a signal peptide, which targets the protein to the ER.

97
Q

signal-recognition particle

SRP

A

recognizes the signal peptide and binds to it, which halts sythesis momentarily
this particle functions as an escort that brings the ribosome to a receptor protein built into the ER membrane

98
Q

polyribosome

A

multiple ribosomes synthesizing the same mRNA strand into multiple versions of the same polypeptide
occurs in prokaryotic and eukaryotic cells

99
Q

mutations

A

changes to the genetic information of a cell or virus

100
Q

point mutations

A

small scale mutations of one or a few nucleotide pairs

101
Q

silent mutations

A

no observable afect on the phenotype

102
Q

missense mutations

A

change one amino acid o another

103
Q

nonsense mutation

A

translation is terminated prematurely

104
Q

nucleotide pair substitutions

A

least effect to most effect
silent
missense
nonsense

105
Q

nucleotide-pair insertion or deletion

A

least effect to most effect
3 nucleotide pair deletion
frameshift causing missense
frameshift causing immediate nonsense

106
Q

mutagens

A

number of physical and chemical angents that interact with DNA in ways that cause mutations

107
Q

operator

A

on-off switch that can control the whole cluster of functionally related genes

108
Q

operon

A

operator, promoter, and genes they control

109
Q

repressor

A

binds to the operator and blocks attachment of RNA polymerase to the promoter, preventing transcription of the genes

110
Q

regulatory gene

A

expressed continuously

produces inactive repressors

111
Q

corepressor

A

small molecule that cooperates with a repressor protein to switch an operon off

112
Q

repressible operon

A

trp

its transcription is usually ON but can be REPRESSED

113
Q

inducible operon

A

lac

transcription is usually OFF but can be INDUCED

114
Q

inducer

A

inactivates repressor

activates transcription

115
Q

cyclic AMP (cAMP)

A

accumulates when glucose is scarce

small organic molecule that binds to the regulatory protein CAP which is an activator

116
Q

activator

A

a protein that binds to DNA and stimulates transcription of a gene

117
Q

differential gene expression

A

the expression of different genes by cells with the same genome

118
Q

histone acetylation

A

the addition of acetyl -COCH3

promotes transcription by opening chromatin structure

119
Q

DNA methylation

A

addition of methyl groups can lead to a condensation of chromatin and reduce transcription
once methylated, genes usually stay that way through successful cell divisions

120
Q

epigenic inheritance

A

not directly involving nucleotide sequence

things outside DNA can alter things that are inherited

121
Q

control elements

A

segments of noncoding DNA having particular nucleotide sequences that serve as binding sites for the proteins called transcription

122
Q

proximal control elements

A

control elements located close to the promoter

123
Q

distal control elements

A

may be thousands of nucleotides upstream or downstream of a gene or within an intron

124
Q

enhancers

A

groups of distal control elements

125
Q

transcription initiation complex

A

formed on promoter and initiates transcription

126
Q

alternative RNA splicing

A

different mRNA molecules are produced from the same primary transcript
figure 15.12

127
Q

mRNA degradation

A

the life span of mRNA molecules in the cytoplasm is important in determining the pattern of protein

128
Q

micro RNAs (miRNAs)

A

single stranded mRNA molecules that are capable of bining to complementary sequences in mRNA molecules

129
Q

small interfering RNAs (siRNAS)

A

similar in size and unction to miRNAs

130
Q

RNA interference

A

the blocking of gene expression by siRNAs

131
Q

nucleic acid hybridization

A

the base pairing of one strand of a nucleic acid to the complementary sequence on another strand

132
Q

nucleic acid probe

A

the complementary smolecule, a short single stranded nucleic acid that can be either RNA or DNA

133
Q

in situ hybridization

A

probes dyed fluorescently to allow us to track mRNA

134
Q

reverse transcriptase-polymerase chain reaction

RT–PCR

A

turning sample sets of mRNAs into double-stranded DNAs with the corresponding sequences

135
Q

complementary DNA (cDNA

A

resulting double stranded DNA fro RT–PCR

136
Q

DNA microarray assays

A

a DNA microarray consists of tiny amounts of a large number of single stranded DNA fragments representing different genes fixed to a glass slide in a tightly spaced array, or grid. ideally these fragments represent all the genes in the genome of an organism