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College > Genetics test 4 > Flashcards

Genetics test 4 Flashcards

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
Q

gain-of-function mutations

A

hypermorph
neo morph
usually domiant

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25
Q

hypermorph

A

increased gene product

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26
Q

neo morph

A

causes protien to have new functions

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27
Q

suppressor mutation

A

second mutation that reverts or relieves effects of a previous mutation
intragenic
intergenic

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28
Q

intragenic

A

occurs within the same gene

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29
Q

intergenic

A

occurs in the genome

30
Q

somatic mutations

A

occur in any cell germ cells; not heritable

31
Q

germ-line mutations

A

occur in gamets; inherited
autosomal mutations
X-linked and Y-linked mutations

32
Q

autosomal mutations

A

occur within genes located on autosomes

33
Q

X-linked and Y-linked mutations

A

occur within genes located on X and Y chromosome, respectively

34
Q

spontaneous mutations

A

changes in nucleotide sequence of genes that occur naturally
often occur during enzymatic process of DNA replication

35
Q

induced mutations

A

result from influence of extraneous factors
these are called mutagens
natural or artifical agents
radiation and UV

36
Q

ames test

A

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
Q

DNA transposons

A

move their location without going through RNA intermediate stage
inverted terminal repeats (ITRs) are located at ends of transposable elements

38
Q

retrotransposons

A

TEs that move within genome using RNA intermediate
copy and paste transposition method
resemble retroviruses
LTR (long terminal repeats) and non-LTR

39
Q

LINEs and SINEs

A

Long interspersed elements and short interspersed elements
34% of human genome
TEs have implications in human genetics

40
Q

Insertions of TEs in various locations and thier effects:

A

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
Q

what is a gene

A

genes are specific segments of DNA that are expressed

42
Q

prokaryotic gene sequence

A

lack introns (dense little genomes)
often organized in operons
polycistronic mRNA common
translated and transcribed at the same time (co-transcriptionally)

43
Q

eukaryote gene sequence

A

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
Q

4 types of RNA

A

mRNA
tRNA
rRNA
snRNA

45
Q

mRNA

A

messenger RNA

46
Q

rRNA

A

ribosomal RNA
RNA molecules that form a structural and enymatic component of the ribosome
most abundant RNA in the cell

47
Q

tRNA

A

transfer RNA
adaptor RNA molecules that bind to individual amino acids and transfer them to the nascent polypetide chain in the ribosome
translation

48
Q

snRNA

A

small nuclear RNA
located in nucleus
not protien coding
not in prokaryotes

49
Q

RNA’s have a primary, secondary and tertiary structure

A

primary - nucleotide sequence
secondary - stem and loops
teritary - 3D structure

50
Q

central dogma

A

SIr Francis Crick
the idea that information in the cell flows from DNA to RNA to protien (and not the other wat)

51
Q

How do we trnascribe RNA prokaryotes

A

initiation
elongation
termination

52
Q

general rules of transcription

A

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
Q

DNA footprinting

A

RNA polymerase (or other protiens) bound to DNA
DNAse digests unbound/unused DNA
Separate polymerase from DNA
Check for which DNA is left

54
Q

Rho dependent termination

A

Rho binds sequences in mRNA
Rho is a helicase
Rho catches up to RNAPol
Rho unwinds the RNA/DNA duplex
RNAPol is ejected

55
Q

Arthur kornberg

A

discovered DNA Pol1
Showed DNA synthesis in vitro

56
Q

Roger Kornberg

A

Professor at Standford
RNA Pol II

57
Q

Thomas Kornberg

A

Professor at UCSF
Discovered DNA Pol II and Pol III

58
Q

TFIID

A

contains TATA binding protien, first TF to bind promoter

59
Q

TFIIB

A

stabilizes TFIID binding and recruits polymerase

60
Q

TFIIE

A

steps on the gas (loads and activates TFIIH, activates RNAPOL CTDK)

61
Q

TFIIH

A

helicase containing TF

62
Q

Assemble a Pre-Initiation complex on the promoter

A

TFIID binds to TATA region
TFIIA binds TFIIB
TFIIB brings RNA polII with TFIIF riding jockey
TFIIE joins
brings TFIIH

63
Q

what happens after Pre-Initiation complex

A

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
Q

5’ methyl cap functions

A

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
Q

unlike in prokaryotes the transcripts requires modifications before translation

A

5-cap
3’ poly-a-tail
splicing
RNA editing

66
Q

3’ poly-a-tail

A

increases transcript stability
nuclear export and initiation of translation
also part of the termination of transcription

67
Q

splicing

A

major way eukaryotes use to increase transcript diversity
create protien diversity
can cause muscle hypertrophy

68
Q

RNA editing

A

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
Q

homoplymers

A

synthetic RNA that only contains U or C
Possible codon: UUU or CCC
one amino acid incorporated

70
Q

Heteropolymers

A

synthetic RNA contains UC repeats
codons: UCU, CUC

71
Q

nirenberg and leder

A

ribosomal filter assay
feed trinucleotides to in vitro translation systems, each with one radiolabeled amino acid

72
Q

rules of the code

A

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

College (8 decks)

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