Genetics Flashcards
(130 cards)
1
Q
DNA is a polymer consisting of deoxyribonucleoside monophosphates covalently linked by _____ bonds
A
3’ 5’ phosphodiester bonds
2
Q
2 antiparallel strands of DNA are joined By ____ bonds
A
Hydrogen
3
Q
Highly repetitive sequences (TG-rich) at the end of the chromosomes
A
Telomeres
4
Q
Percent if cellular DNA located in mitochondria
A
1%
5
Q
Structural form of DNA
Right handed helix
11 base per turn
Moderately dehydrated B form
A
A DNA
6
Q
Structural form of DNA
Right handed helix
10 residues per turn
A
B DNA
7
Q
Structural form of DNA
Left handed
A
Z DNA
8
Q
Structural form of DNA
12 base pairs per turn
A
Z DNA
9
Q
Structural form of DNA
Found in areas of alternating purines and pyrimidines
A
Z DNA
10
Q
Polymer consisting of purine and pyrimidine ribonucleotides linked by 3’ 5 phosphodiester bonds
A
RNA
11
Q
Sugar moiety of DNA
A
Deoxyribose
12
Q
DNA OR RNA
Double stranded
A
DNA
13
Q
DNA OR RNA
SINGLE stand
A
RNA
14
Q
DNA OR RNA
Chargaffs rule does NOT apply
A
RNA
15
Q
DNA OR RNA
Stabel
A
DNA
16
Q
DNA OR RNA unstable
A
RNA
17
Q
DNA OR RNA
Cannot be hydrolyzed by alkali due to the absence of 2 OH group
A
DNA
18
Q
DNA OR RNA
Cam be hydrolyzed by alkali due to 2’3’ cyclic diesters of the mononucleotides
A
RNA
19
Q
Copies genetic info from DNA
serves as template for protein synthesis
A
mRNA
20
Q
mRNA structure in eukaryotes
A
Methylguanosine cap at 5’ 3end
Poly(A) tail at the 3’ end
21
Q
Contributes to formation of ribosomes which act as the site for protein synthesis
A
rRNA
22
Q
Adapter molecule that translates the nucleotide sequence if mRNA into specific AA
A
TRNA
23
Q
Contains anticodons
A
TRNA
24
Q
Cloverleaf appearance in 2D
A
Trna
25
Acceptor arm of TRNA terminates at what nucleotide
tRNA
26
Involved in rRNA and mRNA processing and gene regulation (eg removal of introns)
Small nuclear RNA
27
Micro RNA
| Silencing RNA
Noncoding regulatiry RNA
28
DNA replication occurs in what phase of cell cycle
S phase
29
Each strand becomes part of daughter strand
| Ech stand serves as template for complementary daughter strand
Semi conservative process
30
Steps in DNA replication
| Origin of replication is recognized by ___
ORC origin recognition complex
| DNAa protein in E coli
31
Steps in DNA replication
| Unwinds double helix in a process driven by ATP
Helicase
32
Steps in DNA replication
| Maintains separatikn of parent strands
Single stranded DNA binding proteins
33
Relieves torsio al strain that result from helicase-induced unwinding
Topoisomerase
34
Swivelase
Topoisomerase type I
35
Gyrase
Type II topoisomerase
36
Topoisomerase inh by fluoroquinolones
Type II (Gyrase)
37
Synthesizes short segments of complementary RNA primers
Primase
38
Steps in DNA replication
| Elongates DNA strand by adding new deoxyribonucleotides
DNA polymerase III
39
Direction of synthesis
5’ to 3’
40
Strand that is synthesized continuously
Leading stand
41
Strand that consists of okazaki fragments
Lagging
42
Direction for proof reading by exonucleases
5’ to 3’
43
Fills tha gap with deoxyribonucleotides
DNA pol I
44
Seals the nick by catalizing the formation of the last phosphodiester bond
Requiring hydrolysis of ATP
DNA ligase
45
DNA polymerase
Gap filling following DNA replication
Repair and recombination
I
46
DNA polymerase
Proof reading and repair
E coli
II
47
DNA polymerase
DNA repair
Eukaryotes
Beta
48
DNA polymerase
Mitochondrial synthesis
Eukaryotes
Gamma
49
DNA polymerase
| Processive, leading strand synthesis
III or epsilon
50
Primase
DNAG or alpha
51
Processive
Lagging stand synthesis
DNA polymerase
Delta
52
DNA lesion
| Errors that escaped proof reading
Mismatched strand
53
DNA lesion
| Exposure to UV light
Pyrimidine dimers
| Usually thymine
54
DNA lesion
| Spontaneous or deaminating compounds
Base alterations
| Eg cytosine to uracil or guanine to xanthine
55
DNA lesion
Ionizing radiation
Free radicals
Anti-tumor drugs
Double strand breaks
56
DNA lesion
| HNPCC (Lynch syndrome)
Mismatched strand
57
DNA lesion
| Xeroderma pigmentosum
Pyrimidine dimers
58
DNA lesion
| MUTYH-associated polyposis
Base alterations
59
DNA lesion
SCID
Breast CA susceptibility 1 and 2
Double strand breaks
60
Repair mechanism
| Mismatched strand
Mismatch repair
61
DNA lesion
| Pyrimidine dimers
Nucleotide excision repair
62
DNA lesion
| Base alteration
Base excision repair
63
DNA lesion
| Double stand breaks
Homologous recombination
64
Synthesis of RNA usinf DNA as template
Transcription
65
Enzyme for transcription
DNA-dependent RNA polymerase
66
rRNA
Pol I
67
tRNA, 5S rRNA
III
68
mRNA, lncRNA, miRNA, SnRNA
II
69
RNA binds to DNA promoter sequence
Initiation
70
Prmoter squence in prokaryotes
```
-35 sequence TTGACA
Pribnow box (TATAAT), about -10 bp
```
71
Promoter sequence in eukaryotes
TATA or Hogness box, about -25 bp
| CAAT box, about -70 to 80 bp
72
Occurs to create a transcriptionbubble in eukaryote initiation of transcriptiom
Unwinding of DNA
73
Local unwinding of the DNA continues in what direction
5’ to 3’
74
Step in transciption
| RNA ploymerase synthesizes RNA using nucleoside monophosphates releasing pyrophosphate each time
Elongation
75
Termination signal that requires formation if hairpin loop
p-independent
76
Termination signal that requires p-protein to release RNA from DNA
P-dependent
77
Post transcriptional modifications
___ are removed
____ are spliced together
Introns
| Extrons
78
Post transcriptional modifications (4)
Additin of 7-methylgunaosine cap
Addition of poly(A) tail
Addition of -CCA tail
Methylation
Reduction
Deamination
And rearrangements of glycosidic bonds to create unual bases
79
Encodes Beta galactosidase
Z gene
80
Encodes galactosidase permease, a transport protein required for entry of lactise into the cell
Y gene
81
Encodes thiogalactoside transacetylase, whose function is unknown
A gene
82
Encodes thiogalactoside transacetylase, whose functions is unkown
A gene
83
Encodes a lac repressor protein that is constitutively expressed and located at a distant site in DNA
i Gene
84
Template for translation aka protein synthesis
mRNA
85
Adapter molecule in translation
tRNA
86
Total codons
64
87
Total codons that code for AA
61
88
Stop codons
UAG
UAA
UGA
89
Start of initiating codon for methionine in eukaryotes or formylmethionine in prokaryotes
AUG
90
Characteristics of the genetic code
| Multiple codons may code for the same AA
Degenerate
91
Characteristics of the genetic code
| A specific codon always codes for the same AA
Unambiguous
92
Characteristics of the genetic code
| The codons are read in a continuing sequence of nucleotide triplets until a translation stop codon is reached
Nonovelapping
93
Characteristics of the genetic code
It has beed conserved from very early stages of evolution with only slight difference in the manner in which the code translated
Universal
94
Contains the first codon for translation
tRNA
95
Before initiation, aminoacyl-tRNA synthetases attach AA to their respective tRNAs
Charging
96
Translation
| Site of incoming aminoacyl tRNA
A site
97
Translation initiation
| Occupied by peptidyl-tRNA
P site
98
Translation initiation
| Occupied by the empty tRNA
E site
99
A cyclic proces on the ribosome in which one AA at a time is added to the growing peptide chain
Elongation
100
Translation
Elongation Steps
Aminoacyl tRNA binds to _____ site except in the first aminoacyl-tRNA which binds to ____site
A site
| P site
101
Peptide bond formation is catalyzed by
Peptidyltransferase
102
Translation
Elongation Steps
Translocation of the ribosome on the ____
mRNA
103
Translation
Elongation Steps
Expulsion of the deacylated tRNA from
P and E site
104
Step in translation
| Occurs when one of the three termination codons moved into the A site
Termination
105
Step in translation
| Results in the release of the newly synthesized protein and dissociation of the ribosomes and mRNA
Termination
106
Addition of single AA to the polypeptide chain requires cleavage of four high energy bonds from ____ and ____
ATP and GTP
tRNA aminoacylation (ATP)
Loading of tRNA onto ribosome (GTP)
Translocation (GTP)
107
Post-translational modifications
Removal of excess AA
Phosphorylatiom
Glycosylation
Hydroxylation
108
Marks defective proteins for destructiom
Ubiquitin
109
Degrades defective proteins
Proteasomes
110
Peptide toxid alpha aminitin inhibits ______
RNA POL II
111
Diphtheria toxin inhibits ——- preventing translocation
| Results in local tissue translocation and pseudomembrane formation
Elongation Factor 2
112
2 Inhibitors of transcription
Rifampicin
| Dactinomycin
113
Inhibitors of transcription
| Binds to beta subunit of bacterial DNA-dependent RNA polymerase
Rifampicin
114
Inhibitors of transcription
| Binds to the DNA template and interferes with the movement of RNA polymerase during transcription
Dactinomycin
115
Protein synthesis inh
| Binds to 30s subunit and interferes with initiation
Streptomycin
| Aminoglycosides
116
Protein synthesis inh
| Prevents binding of aminoacyl tRNA to the A site
Tetracycline
117
Protein synthesis inh
| Inhibits prokaryotic peptidyltransferase
Chloramphenicol
118
Protein synthesis inh
| Bind to the 50s subunit and inhibits translocation
Clindamycin and macrolides
119
Types of point mutations
Transition
| Transversion
120
Purine to purine
| Pyr to pyr
Transition
121
Pur to pyr or
| Pyr to pur
Transversion
122
New codon codes for same AA
| No effect on protein
Silent mutation
123
New codon codes for diff AA
| Variable effects on protein
Missense
124
New codon is stop codon
Nonsense mutation
125
Deletion or addition of bases that should not bemmultiples of three
Shorter than normal usually non-functional protein
Frame shift mutation
126
Loss of large areas of chromosomes during unequal crossover in meiosis
Loss of function
Protein shorter than normal or entirely missing
Large segment deletion
127
Tay Sachs
Gaucher
B thalassemia
Splice donor or acceptor
128
Variable effects ranging from addition or deletion of a new AA to deletion of entire exon
Splice donor or acceptor
129
Huntingtong dse
Fragile X syndrome
Myotonic dystrophy
Triple repeat expansion
130
Diseases show anticipation in pedigree
| Expansions in coding regiond cause protein product to be longer than normal and unstable
Triple repeat expansion
