Genetics Test 3 Flashcards
(144 cards)
1
Q
What did Avery, Macleod, and McCarthy (1944) do?
A
-Repeated Griffith’s experiment invitro
-Identified DNA as a transforming substance
2
Q
What are in chromesomes?
A
Proteins and nucleic acids
3
Q
What was Griffith’s (1928) Transformation experiment?
A
-Pneumonia bacteria study
-smooth lethal, rough nonlethal
-heat-killed smooth+ live rough = transformation observed
4
Q
What did Zinder and Lederberg (1952) do?
A
-used salmonella typhimurium
-demonstrated bacterial transduction with a bacteriophage
5
Q
What did Hershey and Chase (1952) do?
A
-Confirmed DNA as a genetic substance
-used radioactive markers, p32 and s35, in bacteriophage experiments
6
Q
is DNA a simple repetition of bases?
A
No
7
Q
What did Chargaff come up with?
A
equal proportions of A-T and G-C
8
Q
Describe Watson and Crick’s model
A
-Molecular structure based on X-ray crystallography
-double stranded DNA
-Antiparallel sugar phosphate backbone
-hydrogen bonds between bases
-B-form in living organisms, major and minor grooves
-replication involves unzipping
9
Q
Define Nucleoside
A
base with sugar
10
Q
Define Nucleotide
A
Base with sugar and phosphate
11
Q
What is RNA?
A
single stranded, ribose, uracil instead of thymine
12
Q
What is a purine?
A
-A,G
-double ring
-small name, big molecule
13
Q
What is a pyrimidine?
A
-T,C,U
-single ring
-big name, small molecule
14
Q
What groups are an amino?
A
-NH2
-A,C
15
Q
What groups are a ketone?
A
-Double bond O
-G,T,U
16
Q
Is A=U DNA or RNA?
A
RNA
17
Q
What is conservative replication?
A
One double helix of old DNA and one of new DNA
18
Q
What is semiconservative replication?
A
Two double helices, each with one old and one new DNA strand
19
Q
What is nonconservative (dispensive) replication?
A
Two double helices with a mixture of old and new DNA strands
20
Q
What was the Meselson and Stahl (1958) experiment?
A
-Used E coli grown in heavy (15N) and light (14N) nitrogen
-results supported semiconservative replication, after one round DNA was intermediate, after two rounds two bands appeared.
21
Q
What is specific to DNA rep in Prokaryotes?
A
-Bacteria have circular chrome
- lack organelles like mitochondria and chloroplasts
- No nuclear membrane, chrome are circular
22
Q
How and who observed semiconservative rep in Euk?
A
Taylor, used broad beans (Vicia faba) and autoradiographs of chrome
23
Q
What did Grunberg do?
A
Isolated RNA phosphorylase
24
Q
What did Kornberg do?
A
Isolated DNA polymerase from E. coli
25
What did Kornberg's experiments demonstrate?
used p32 labeled nucleotides, demonstrated 3' synthesis only, antipolar molecule
26
What did Cairns experiment do?
Labeled E. Coli DNA during rep, rep comes from single origin, occurs simultaneously as unzipping, and proceeds bidirectionally on each strand
27
How is Euk DNA rep different from pro?
Overall similar, but has multiple origins on each chrome
28
What are Okazaki fragments?
DNA rep is continuous in one direction (3' end) and discontinuous in the other (5' end)
29
Summarize the bubble model
unzipping from an origin, RNA primers, DNA synthesis, and joining by DNA ligase
30
What is the leading strand?
continuous synthesis
31
What is the lagging strand?
discontinuous synthesis with Okazaki fragments
32
What are telomers?
ends of linear chrome
33
What does telomerase do?
adds repetitive sequences to prevent shortening, prevents sticky ends in chrome fusion
34
What is heterochromatin?
inactive genes
35
What is euchromatin?
Active genes
36
What sequence does telomerase add?
TTAGGG
37
What are primers formed by?
primase
38
What does DNA pol do?
Synthesizes strands
39
What does an RNA polymerase (primase) create in the bubble model?
RNA primer
40
Does RNA primer construction occur once or repeatdly?
repeatdly, as the DNA unwinds
41
What does DNA pol III do?
Builds DNA on the 3' end of the RNA primer using the existing DNA strand as a template
42
What doe DNA pol I do?
removes ribonucletides and replaces them with deoxyribonucleotides
43
What are DNA strands joined with?
DNA ligase
44
What is DNA pol III?
a Dimer
45
How does the leading strand travel?
Straight through, new DNA is made in a continuous fashion. The 3' end has traveled through the channel and the 5' end hasnt
46
How does the lagging strand travel?
Lops around so the 5' end is back towards the 5' end of the leading strand. The template then moves through the 3' end first.
47
What does the lagging strand result in?
Discontinuous DNA rep, when the DNA pol runs into an existing primer it stops, releases the template, and moves to a new starting position
48
What does Gyrase do?
Loosens the coiling
49
What does helicase do?
Unzips the DNA
50
What does the single stranded binding protein do?
Keeps from forming a double helix again
51
What is the Hayflick limit?
50 cell division in humans before the telomere is gone
52
What is a sticky end?
End region of a telomere has an unequal length, 3' is longer, if not resolved will result in chrome fusion
53
What is laid down using the old DNA as a template to prevent sticky ends?
RNA primer, extended using DNA polymerase α and δ
54
What is DNA wrapped around?
Protein structure called nucleosomes
55
What is a nucleosomes composed of?
Histone octomer (8 peptides)
56
What is a solenoid?
6 nuclesomes arranged in a disk like structure
57
What do stacked solenoid structures form?
A loop domain
58
What is satellite DNA?
Too much light DNA, composed of tandom repeats
59
How are primers formed?
Enzyme primase
60
How does DNA pol start synthesis?
Using a primer
61
What did Bateson's study of alcaptonurea show?
It is a recessive trait
62
What did Pastuer show?
Living organisms control chem rxns, yeast needed to make ethanol from grape juice
63
What did Buchner show?
Furthered Pastuer, component of living yeast resulted in ethanol production
64
What did Garrod show?
Genes control biochem rxns, biochem rxn determine phenotype
65
What did Sumner do?
isolated pure crystalline enzyme- urease
66
What is induced conformation?
conformational changes in the 3d structure may occur when the protein bind with some other chem
67
What was discovered about alcaptonurea in the 1920s?
result of a nonfunctional enzyme
68
What is Tyrosine?
Intitial substrate for a number of biochem pathways
69
What did beetle and Tatum do?
1-gene 1-enzy,e model in neurospora mutants
70
What did sub and horowitz do?
arginine pathway supports 1- gene 1-enzyme model
71
What did Pauling do?
In hemoglobin molecule 2 α and 2 β units, in sickle cell the β peptide was altered
72
What model did Pauling change?
altered the 1-gene 1-enzyme model to become 1-gene 1-peptide
73
Where is DNA in Euk cells?
Nucleus
74
Where does protein synthesis take place?
cytoplasm
75
Why does there have to be an intermediary?
DNA is only in nuc, protein synthesis in cytoplasm
76
How do you get from DNA to phenotype?
DNA->RNA->enxymes->biochem->phenotype
77
What was the theoretical argument of DNA code?
3-base code for 20 amino acids
78
What does it mean that the code was degenerate?
More than one word for each amino acid
79
What are the three models for code?
triplet, unambiguous, and degenerate
80
What is the triplet code nature? (Crick)
induced mutations in the t4 virus using acridine dyes, dyes fit between bases and cause one base addition or deletions, cause frameshift mutation
81
What suggested the genetics code is three bases long?
addition or deletion of three bases resulted to original frame
82
What did Nirenberg do?
Deciphered the first specific three base coding sequence
83
What did the triple binding assay lead to?
50 out of 64 codons
84
What are the stop codons?
USS, UAG, UGA
85
What is the wobble theory?
Third position in codon not critical
86
What is the start codon?
AUG
87
Is genetic code universal?
yes
88
Describe the genetic code model
Triplet, unambiguous, degenerate code, no commas, non-sense codons, universal
89
What is transcription?
Transcribe DNA to RNA
90
What is translation?
RNA to protein
91
What is the core enzyme made up of?
5 peptides: α α β β’ω
92
What does a single RNA pol do?
handles mRNA, rRNA, tRNA
93
When is holoenzyme formed?
when the σ peptide binds to the core enzyme.
94
When is σ involved?
only in transcription initiation
95
What is the transcprition bubble?
unwinding in DNA double helix
96
What is the template strand?
transcription always proceeds from the same DNA strand for a particular gene
97
What is the mRNA product complementary strand?
The template strand=anti sense strand , and identical to the non template strand=sense strand
98
What is a closed-promoter complex?
initial binding between the polymerase and a promoter
99
What is a open promoter complex?
single stranded DNA available as a template for transcription
100
What terms is gene structure given in?
coding strand
101
What is the promoter region?
DNA sequence to which RNA polymerase binds to initiate transcription of a gene
102
Where are promoters found?
5' UTR upstream region of the coding sequence
103
Where are the promoter regions in pro?
-35 and -10
104
Where is TATA box?
TATAAT is at -10
105
Where IS GACA box?
TTGACA is at -35
106
How long does aborted initiation continue?
until 10 nucleotides synthesized
107
What is template strand used for?
RNA synthesis
108
What is Rho-independant termination?
newly synthesized mRNA molecule forms hairpin loop followed by run of U's
109
What is Rho-dependant termination?
Rho factor disrupts RNA-DNA interaction
110
RNA pol I transcribe to
rRNA(5.8s, 18s, 28s)
111
RNA pol II transcribe to
mRNA
112
RNA pol III transcribe to
tRNA and 5s rRNA
113
What 6 general transcription factors are required for initiation of transcription by RNA pol II
TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH
114
What are aborted starts?
many cycles before transcription elongation
115
What is the 5' mG cap
methlylated guanine at 5' end
116
Describe the elongation process
progressive and continuous
117
mRNA termination
poly-A signal recognition, poly-A polymerase adds A
118
rRNA termination
resembles Rho-dependant termination, RNA pol I pausing
119
tRNA termination
poly-T signal, pol III termination without additional factors
120
Define Translation
process where ribosomes create proteins from mRNA
121
What is mRNA decoding?
ribosomes decode mRNA to produce a polypeptide
122
What is initiation?
-Ribosomes assemble around mRNA
-first tRNA attached at start codon
123
What is elongation?
-tRNA transfers amino acids to polypeptide
-ribosome moves to next mRNA codon
124
What is translocation?
movement to the next mRNA codon
125
What happens at termination?
ribsomes releases polypeptide at stop codon
126
Where is translation in bacteria?
cytoplasm
127
Where is translation in euk?
cytosol or endoplasmic reticulum
128
What does mRNAdo?
carries genetic info from DNA to ribosomes
129
what is tRNA?
transports amino acids to ribosomes
130
What does a ribosome do?
facilitate mRNA decoding and protein synthesis
131
What is aminoacyl tRNA synthetases
catalyze tRNA and amino acid bonding
132
what do release factors do?
trigger termination and release of proteins
133
What does phosphorylation of elF2 do?
regulate protein synthesis
134
What does 4EBP do?
binds to elF4E, regulates protein synthesis
135
What are codon?
3 nucleotide sequences on mRNA
136
What are amino acids?
matched to codons by tRNA
137
What is euk initation?
cap-dependent (5' cap) or cap independent (IRES)
138
How are genes in pro organized?
polycistronic groups
139
how are polycistronic genes controlled?
by a single regulatory element
140
positive inducible system
chemical binds to R protein causing binding to lac O and positive transcription
141
negative repressible system
chemical binds to R protein causing binding to lac O and negative transcription
142
positive repressible system
chemical prevents R protein from binding to lac O leading to negative transcription
143
negative inducible system
chemical prevents R protein from binding to lac O, starting transcription
144
DO genes transcribe continuously regardless of product prescence?
yes
