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Biology > Genetics > Flashcards

Genetics Flashcards

1
Q

telomers

A

non-coding DNA sequence that protects the rest of the chromosomes from degradation by being degraded itself
chromosomes shorten after each replication event due to end-replication problem

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2
Q

end-replication problem

A

ends of chromosome shortens slightly after each replication event because the lagging strand usually can’t put a primer on the last little portion of DNA

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3
Q

miRNA

A

microRNA

small, noncoding eukaryotic or viral RNA molecules that bind complementary sequences on target mRNA to inhibit expression

can either promote endonuclease activation or prevent target mRNA from binding to ribosomes (blocking translation)

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4
Q

endonuclease

A

cleaving the phosphodiesterase bond from the middle

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5
Q

exonuclease

A

cleaving the phosphodiesterase bond from the ends

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6
Q

rRNA

A

ribosomal RNA

pairs with specific proteins to form the ribosome

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7
Q

tRNA

A

transfer RNA

pairs mRNA codons with specific amino acids during translation

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8
Q

snRNA

A

small nuclear RNA
confined to the nucleus
pairs with snRNPs to force the spliceosome

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9
Q

siRNA

A

small interfering RNA
binds complementary mRNA and signals for its degradation
functions as RNA interference

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10
Q

speciation

A

formation of a new species from an existing species

may occur if 2 populations of a single species are separated for an extended period and become so genetically different that individuals are no longer able to reproduce with one another

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11
Q

bottleneck events

A

sudden environment change that rapidly decreases number of individuals in a population

often leads to decreased genetic diversity

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12
Q

natural selection

A

evolutionary process in which beneficial traits that improve a species fitness are more likely to be passed onto the next generation than less favorable traits

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13
Q

starting codon

A

AUG

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14
Q

stop codons

A

UGA, UAA, UAG

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15
Q

noncoding strand of DNA

A

used as a template for translation
read 3’ –> 5’
creates complementary 5’ –> 3’ strand which is identical to coding strand except T –> U

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16
Q

complement probability rule

A

P(A) = 1 - P(A1)

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17
Q

addition rule for mutually exclusive events

A

P (A or B) = P(A) + P(B)

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18
Q

multiplication rule for independent events

A

P (A and B) = P(A) x P(B)

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19
Q

“at least one” Rule

A

P (at least one) = 1 - P(none)

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20
Q

inclusive fitness

A

ability of individual organism to pass on its genes to next generation, taking into account shared genes passed by organism’s close relatives

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21
Q

transcription

A

transcription factors and RNA polymerase 2 bind to TATA box on double stranded DNA

RNA polymerase will move down non-coding (template) strand of DNA in 3’ –> 5’ direction, synthesizing a strand that is identical to the coding strand (minus T –> U) in the direction of 5’ –> 3’

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22
Q

7-methylguanosine

A

5’ cap added after transcription
prevents degradation
recognized by ribosome during translation

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23
Q

poly A tail

A

added after transcription
prevents degradation
helps export mRNA from nucleus –> cytoplasm to be translated

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24
Q

euchromatin

A

high acetylation, low methylation

open so high gene expression

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25
Q

heterochromatin

A

low acetylation, high methylation

without acetyl groups - the histones can tightly bind DNA
methyl groups bind to MBD’s which recruit histone deacetylases

closed so low gene expression

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26
Q

methylation

A

added to DNA will silence the gene expression

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27
Q

interphase

A

cells grow and synthesize DNA

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28
Q

prophase

A

ditch nuclear envelope
sister chromatids held on by kinetochore
mitotic spindle beginst o form

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29
Q

kinetochore

A

the thing that holds chromosomes in the middle

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30
Q

metaphase

A

mitotic spindle fully formed
sister chromatids align in middle
spindle fiber microbubules connect to chromatids by kinetochore

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31
Q

anaphase

A 
pull apart (disjunction)
retract centrioles to opposite poles
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32
Q

telophase

A

nuclear envelope reforms

33
Q

cytokinesis

A

divides cell into 2 identical daughter cells

34
Q

nondisjuction

A

occurs in mitosis and meiosis when sister chromatids fail to separate during anaphase

35
Q

difference between transcription and translation in eukaryotes vs prokaryotes

A

eukaryotic cells are transcribed and modified in the nucleus where they undergo additions that will prevent degradation of the molecule as it moves through the cytoplasm where it will be translated by ribosomes

prokaryotes lack a nucleus and a nuclear envelope so transcription and translation can happen at the same time

36
Q

What size ribosome binds to eukaryotic mRNA

A

80s

60s large subunit + 40s small subunit

37
Q

what size ribosome binds to prokaryotic mRNA

A

70s

50s large subunit + 30s small subunit

38
Q

Where does the ETC take place in prokaryotes?

A

the plasma membrane because they lack mitochondria (bound organelle)

39
Q

epigenetics

A

same DNA with different expression

caused by DNA methylation or histone modification that can alter DNA expression (euchromatin vs heterochromatin)

40
Q

penetrance

A

proportion of individuals with a certain genotype that express the associated phenotype

can either be complete (all individuals show phenotype) or incomplete (only some individuals show phenotype)

41
Q

variable expressivity

A

a single genotype can give rise to a range of phenotypes

42
Q

heteroplasmy

A

presence of more than one type of organellar genome (mtDNA or plastid DNA) within a cell or individual

important for considering severity of mitochondrial diseases because difference in ratio between different DNA leads to range of severity in infection

ex: severity of mitochondrial disease changes depending on ratio of wild type mtDNA and mutant mtDNA

43
Q

PCR

A

for DNA replication

  1. denature with high temperature
  2. anneal through cooling
  3. additional primers will elongate new strand 5’ -> 3’

requires:

  • source DNA template (containing deoxyribonucleotides)
  • primer pairs
  • thermostable DNA polymerase (that won’t denature in high temperatures)
  • buffer solution with positively charged ions (provides optimal environment by neutralized negatively charged phosphates on DNA backbone)

also GC-rich DNA fragments are more stable at high temperature

44
Q

neutral theory of molecular evolution

A

most genetic mutations are neutral and do not affect the fitness of an organism

45
Q

genetic drift

A

variation in relative frequency of different genotypes due to random change

particularly due to death or lack of reproduction

46
Q

gene cloning

A

technique used to generate many copies of a previously identified gene of interest

47
Q

signal sequence

A

located within the un-translated mRNA

once mRNA is bound to ribosome, the sequence will be translated into a signal peptide that induces the transport of the ribosome-mRNA complex to the rough ER

48
Q

elongation factors

A

proteins that facilitate the lengthening of amino acid chain during translation

49
Q

translation

A
  1. initiation
  2. elongation
  3. termination
50
Q

translation initiation step

A

small 40s ribosomal subunit binds the 5’ cap of the mRNA
a tRNA is recruited to the start codon and contains an anti codon that is complementary. The very first tRNA for start codon AUG is a Methionine

the large 60s subunit binds the initator tRNA at the P site to complete the complex

51
Q

translation elongation step

A

the tRNA in the A site is moved to the P site. Enzyme peptidyl transferase transfers the growing polypeptide chain from the tRNA at the P site to the new tRNA at the A site by catalyzing the peptide bond between adjacent amino acids.

as another tRNA is added, tRNA in P site is moved to E site where it is ejected

mRNA is read 5’ -> 3’

52
Q

translation termination step

A

a stop codon is read and everything breaks apart

protein will then move to golgi body to do post translation modifications

53
Q

chemotaxis

A

process by which mobile cells both sense and move toward or away from an increasing concentration of a specific chemical

used by pathogens to find host cells to invade by sensing chemicals that are released

54
Q

mitochondrial DNA

A

genome consists of singular circular DNA similar to prokaryotes
encodes rRNA, tRNA, and other proteins for ETC and ATP synthase
exhibits maternal inheritance

55
Q

signal recognition particle

A

recognizes incomplete polypeptide (didn’t finish translation) and will dock it to the cytoplasmic surface to complete translation

56
Q

primase

A

synthesizes RNA primers and positions them at the beginning of each DNA strand

57
Q

dNTP

A

deoxyribonucleoside triphosphates
dTTP, dATP, dCTP, and dGTP (correspond to nucleotides)

composed of a base, deoxyribose sugar, and three phosphate groups

58
Q

How is dNTP added during replication

A

the 3’ OH from the last nucleotide of the growing strand will attack the 5’ PO4 group of an incoming dNTP

going to release the other 2 PO4 groups. This reaction will release water and generates energy (exergonic process)

the energy released will be used to form a covalent phosphodiester bond between the last nucleotide of the growing strand and the incoming dNTP (endergonic reaction)

when there is no 3’ OH, then no more replication will occur

59
Q

reverse transcriptase

A

generates a single strand of cDNA from a target mRNA

60
Q

cDNA cloning

A

reverse transcriptase generates a single stranded cDNA from target mRNA sequence

DNA polymerase synthesizes the second complementary DNA strand and amplifies target cDNA sequence

target cDNA can be inserted into a plasmid vector via actions of a restriction enzyme and DNA ligase joins the cDNA to the vector

61
Q

codominance

A

co-expression of alleles as observed in the phenotype of heterozygous individuals

62
Q

penetrance

A

portion of offspring that express a genetic trait

63
Q

expressivity

A

range of symptoms observed in individuals with given genetic condition

64
Q

genetic linkage

A

tendency of alleles in close proximity on the same chromosome to remain on the same chromosome

less likely to get separated during crossover events that occur during meiosis

leads to unequal combination of alleles in haploid cells formed by meiosis

greater number of nonrecombinant cells will be found than recombinant cells

65
Q

promoters

A

regions of DNA that are upstream of the given gene and initiate transcription by binding specific transcription factors that contribute to the binding of RNA polymerase

66
Q

enhancers

A

DNA sequences that are located further away from the gene of interest and work by binding transcription factors that twist DNA into a hairpin loop that helps initiate transcription

67
Q

acetylation

A

high acetylation helps relax histones and DNA so that the euchromatin form can dominate

acetylation binds to lysine to make it less positively charged so that DNA is wrapped less tightly to the histones and that will open up gene transcription

68
Q

telomeres

A

regions at chromosomal ends that are repeatedly truncated with each round of cell division

both telomeres and centromeres are composed of heterochromatin (tightly condensed complex of DNA wrapped around histones)

this means it is transcriptionally inactive - gene poor and contain repetitive DNA

only contain TTAGGG

69
Q

incomplete dominance

A

results in a blended or intermediate phenotype in heterozygous individuals based on the phenotypes of homozygous parents

ex: red flowers x white flowers = pink flowers

70
Q

In a combined population of 15X chromosomes and 5Y chromosomes, which of the following alleles would be most susceptible to loss due to random chance alone?

A

loss of alleles due to random chance occurs due to genetic drift

lower frequency alleles have a higher chance of being eliminated due to probability therefore alleles on the Y chromosome would be most affected

71
Q

alternative splicing

A

produces multiple protein products from the same gene

occurs when different exons are removed so will take one mRNA sequence and can create a bunch of different proteins from it

72
Q

gene duplication

A

chromosomes have gene portions that are more than the original, often caused by unequal crossing over

over time the duplicate genes may undergo mutations, so while they were originally identical genes, now these genes can carry out distinct roles and have become unique

but there is still a high sequence similarity between the genes and they are considered evolutionary related

73
Q

converging evolution

A

two separate species from distinct backgrounds will evolve to share a similar characteristic when in similar environments

74
Q

diverging evolution

A

two similar species will evolve distinct characteristics when in contrasting environments

75
Q

parallel evolution

A

two or more closely related species continue to evolve the same characteristics to adapt to similar environments, but have diverged

will look like fork in the road

76
Q

adaptive radiation

A

process of diversifying species to better fit into an environment

comes from a single species

ex: making a cat with longer claws to be able to better hunt bigger prey

77
Q

fecundity

A

number of offspring you can have (based on your fitness)

78
Q

How are point mutations detected using southern blots?

A

use restriction site polymorphisms (RSPM)

usually cut at palindromic sequences which have the same code forwards and back and are usually 4-6 nucleotides long

79
Q

DNA structure

A

phosphate groups connect different nucleotides

when DNA is cut -> this cuts the bond between the P and the O.

Biology (15 decks)

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