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Genetics test 4 Flashcards

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1
Q

genome

A

the amount of DNA is a cell

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2
Q

eukaryotic genomes

A

multiple
linear
use protein scaffolds called histones and other non-histone protiens to organize and pack thier DNA

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3
Q

Histone core for the nucleosome

A

8 subunits
2 of each of the 4 types
H2A
H4
H3
H2B

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4
Q

chromatin

A

loosely packed
room for gene expression

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5
Q

heterochromatin

A

tightly packed
rarely expressed

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6
Q

special problems of multiple chromosomes: mitotic segregation

A
  • protiens attach to specific heterochromatin structures called centromeres to segregate chromosomes in mitosis
  • each species has its own centromere sequence, so they are functionally conserved, but not conserved at the level of sequence
  • centromeres can vary in lenght and sequence composition
  • can be visualized as a constriction of the chromosome in mitosis
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7
Q

DNA is packed into prokaryotic cells by a ____________________ and the generation of _____________. The protiens that make prokaryotic loop domains remain _________.

A

Combination of supercoiling
looped domains
poorly characterized

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8
Q

DNA is packed into eukaryotic cells into _________. There are several layers of packing including the ____, the ______________, looping and coiling of the fiber

A

chromatin
10nm fiber
30nm “solenoid” fiber

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9
Q

types of chromosomal mutation

A

deletion
duplication
translocation
inversion
fusion

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10
Q

types of mutations

A

point mutation
missense mutation
nonsense mutation
silent mutation
neutral mutation

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11
Q

mutation

A

an alteration in nucleotide sequence in genome
any base-pair change in sequence

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12
Q

point mutation

A

change from one base pair to another

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12
Q

missense mutation

A

results in new triplet code for different amino acid

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13
Q

nonsense mutation

A

results in triplet code for stop codon (translation terminated prematurely)

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14
Q

silent mutation

A

new triplet code stillcodes for same amino acid

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15
Q

neutral mutation

A

mutations in noncoding regions

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16
Q

base substitutions

A

transitions
transversions

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17
Q

transitions

A

pyrimidine repplaces pyrimidine, or purine replaces purine

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18
Q

transversions

A

purine and pyrimidine are interchanged

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19
Q

frameshift mutations

A

results from insertions or deletions of nucleotide
loss or addition of nucleotide causes shift in reading frame
frame od triplet reading during translation is altered

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20
Q

loss of function mutations

A

null mutation
recessive mutation
dominant negative mutation

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21
Q

null mutation

A

results in complete loss of function

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22
Q

recessive mutation

A

loss of function

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23
Q

dominant negative mutation

A

one allele may encode inactive gene product - interferes with function

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24
gain-of-function mutations
hypermorph neo morph usually domiant
25
hypermorph
increased gene product
26
neo morph
causes protien to have new functions
27
suppressor mutation
second mutation that reverts or relieves effects of a previous mutation intragenic intergenic
28
intragenic
occurs within the same gene
29
intergenic
occurs in the genome
30
somatic mutations
occur in any cell germ cells; not heritable
31
germ-line mutations
occur in gamets; inherited autosomal mutations X-linked and Y-linked mutations
32
autosomal mutations
occur within genes located on autosomes
33
X-linked and Y-linked mutations
occur within genes located on X and Y chromosome, respectively
34
spontaneous mutations
changes in nucleotide sequence of genes that occur naturally often occur during enzymatic process of DNA replication
35
induced mutations
result from influence of extraneous factors these are called mutagens natural or artifical agents radiation and UV
36
ames test
uses different strains of salmonella typhimurium - strain able to reveal presence of specific mutations assay measures frequency of reverse mutations in mutant gene carcinogens shown by Ames test to be strong mutagens rapid way to assess mutagenicity
37
DNA transposons
move their location without going through RNA intermediate stage inverted terminal repeats (ITRs) are located at ends of transposable elements
38
retrotransposons
TEs that move within genome using RNA intermediate copy and paste transposition method resemble retroviruses LTR (long terminal repeats) and non-LTR
39
LINEs and SINEs
Long interspersed elements and short interspersed elements 34% of human genome TEs have implications in human genetics
40
Insertions of TEs in various locations and thier effects:
coding region: translation disruptions intron: termination signal in intron can terminate transcription intron: splicing of RNA transcribed from a gene Genes transcription regulator region: effects gene expression identical TEs in genome: potential for transposon recombination
41
what is a gene
genes are specific segments of DNA that are expressed
42
prokaryotic gene sequence
lack introns (dense little genomes) often organized in operons polycistronic mRNA common translated and transcribed at the same time (co-transcriptionally)
43
eukaryote gene sequence
intron/extron structure significant upstream and downstream sequences that are not translated introns are spliced out must be post-transcirptionally modified to be exported to ribosomes in the cytosol translated only after processing and export
44
4 types of RNA
mRNA tRNA rRNA snRNA
45
mRNA
messenger RNA
46
rRNA
ribosomal RNA RNA molecules that form a structural and enymatic component of the ribosome most abundant RNA in the cell
47
tRNA
transfer RNA adaptor RNA molecules that bind to individual amino acids and transfer them to the nascent polypetide chain in the ribosome translation
48
snRNA
small nuclear RNA located in nucleus not protien coding not in prokaryotes
49
RNA's have a primary, secondary and tertiary structure
primary - nucleotide sequence secondary - stem and loops teritary - 3D structure
50
central dogma
SIr Francis Crick the idea that information in the cell flows from DNA to RNA to protien (and not the other wat)
51
How do we trnascribe RNA prokaryotes
initiation elongation termination
52
general rules of transcription
transcription initiation is directed by gene regulatory elements RNA polymerase synthesis ssRNA in the 5' to 3' direction NO PRIMER NEEDED ssRNA synthesized from the DNA template strand DNA nontemplate strand is not involved
53
DNA footprinting
RNA polymerase (or other protiens) bound to DNA DNAse digests unbound/unused DNA Separate polymerase from DNA Check for which DNA is left
54
Rho dependent termination
Rho binds sequences in mRNA Rho is a helicase Rho catches up to RNAPol Rho unwinds the RNA/DNA duplex RNAPol is ejected
55
Arthur kornberg
discovered DNA Pol1 Showed DNA synthesis in vitro
56
Roger Kornberg
Professor at Standford RNA Pol II
57
Thomas Kornberg
Professor at UCSF Discovered DNA Pol II and Pol III
58
TFIID
contains TATA binding protien, first TF to bind promoter
59
TFIIB
stabilizes TFIID binding and recruits polymerase
60
TFIIE
steps on the gas (loads and activates TFIIH, activates RNAPOL CTDK)
61
TFIIH
helicase containing TF
62
Assemble a Pre-Initiation complex on the promoter
TFIID binds to TATA region TFIIA binds TFIIB TFIIB brings RNA polII with TFIIF riding jockey TFIIE joins brings TFIIH
63
what happens after Pre-Initiation complex
TFIIH is the gas pedel starts unwinding the helix and starts the phosphorylation of the RNA pol C-terminal domain and the whole machine starts to move
64
5' methyl cap functions
protects the transcript from 5' exonuclease attack by making the 5' end look like a 3' end regualtes nuclear export of transcript through interaction with the CBC promotes correct binding to the ribosome for translation initiation promotes excision of the nearest intron
65
unlike in prokaryotes the transcripts requires modifications before translation
5-cap 3' poly-a-tail splicing RNA editing
66
3' poly-a-tail
increases transcript stability nuclear export and initiation of translation also part of the termination of transcription
67
splicing
major way eukaryotes use to increase transcript diversity create protien diversity can cause muscle hypertrophy
68
RNA editing
insertion/deletion editing - nucleotides are added/deleted from the total number of bases substitution editing - identities of individual nuclotide bases are altered can change the coding sequence before it gets to the ribosome
69
homoplymers
synthetic RNA that only contains U or C Possible codon: UUU or CCC one amino acid incorporated
70
Heteropolymers
synthetic RNA contains UC repeats codons: UCU, CUC
71
nirenberg and leder
ribosomal filter assay feed trinucleotides to in vitro translation systems, each with one radiolabeled amino acid
72
rules of the code
the code is a triplet code the code is continuous the code is nonoverlapping the code is almost universal the code is degenerate the code has a start and top codon wobble occurs in the tRNA anticodon

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