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DAT > Genetics > Flashcards

Genetics Flashcards

1
Q

What does an autosomal recessive pedigree look like?

A

2 unaffected lead to 2 affected

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2
Q

What does an autosomal dominant pedigree look like?

A

2 affected lead to 2 unaffected

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3
Q

What does a sex-linked pedigree look like?

A

affect males only

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4
Q

genetic material on a chromosome for encoding a trait

A

gene

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5
Q

location on chromosome where a gene is located

A

locus

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6
Q

alternative forms of a gene that allow for differences such as different hair or fur colours

A

allele

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7
Q

a pair of chromosomes that contain the same genetic material

A

homologus chromosomes

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8
Q

Law of segregation

A

Mendel’s law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

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9
Q

law of independent assortment

A

Each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random

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10
Q

A cross between individuals that involves one pair of contrasting traits

A

Monohybrid cross

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11
Q

Cross or mating between organisms involving two pairs of contrasting traits

A

Dihybrid cross

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12
Q

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

A

Test cross

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13
Q

How can you determine probabilities of dihybrid crosses without doing the table?

A

Do each gene separately and then multiply the probabilities

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14
Q

incomplete dominance

A

blending of expressions of alelles

Ex. red and white flower make a pink one

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15
Q

Codominance

A

both inherited alleles are completely expressed

Ex. blood type AB has dominant A and dominant B

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16
Q

Multiple alleles

A

three or more forms of a gene that code for a single trait

Ex. blood types

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17
Q

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.

Ex. mice

A

Epistasis

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18
Q

pleiotropy

A

A single gene having multiple effects on an individuals phenotype

Ex. Sickle cell anemia leads to different health conditions, pain, stroke, high BP

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19
Q

What is the difference between polygenic and pleiotropic?

A
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20
Q

the probability an organism with a specific genotype will express a particular phenotype

complete: genes for a trait are expressed in all of the population who have the gene

incomplete: genes for a trait are only expressed in a percentage of the population

A

Penetrance

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21
Q

Variable expressivity

A

individuals with the same genotype have related phenotypes that vary in intensity

Ex. red hair gene could be light red, dark red, or any red in between

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22
Q

What is x-inactivation?

A

during embryonic development one of the two inherited X chromosomes does not uncoil into chromatin and remains as a barr body. barr bodies are not expresed

Ex. calico cats - characteristic of black and orange fur depend on which copy of the x chromosome the cell chooses to leave active

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23
Q

What is an example of a genetic disease that results from X-inactivation?

A
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24
Q

one or more chromosome pairs or chromatids fail to separate during mitosis

A

Nondisjunction

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25
Q

cells undergo nondisjunction have extra or missing chromosomes

A

Mosaicism

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26
Q

Single nucleotide change causing either substitution, insertion, or deletion

A

point mutation

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27
Q

frameshift mutation

A

insertion or deletion because they shift the reading frame

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28
Q

transition mutation

A

purine to purine or pyrimidine to pyrimidine

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29
Q

transversion mutation

A

purine to pyrimidine or vice versa

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30
Q

trisomy 21

A

down syndrome, extra copy of chromosome 21

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31
Q

turner syndrome

A

XO

female is either completely missing or partly missing an X chromosome

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32
Q

klinefelter’s syndrome

A

XXY

male born with extra X chromosome

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33
Q

chromosome segments are rearranged in reverse orientation

A

inversion

34
Q

one segment of a chromosome is moved to another chromosome

A

translocation

35
Q

What are three autosomal recessive conditions?

A

Phenylketonuria (PKU) - can’t produce enzyme for phenylalanine breakdown, causing phenylpyruvic acid to accumulate

Cystic fibrosis - fluid build up in respiratory tracts

Tay-sachs - lysosome defect in which cells can’t breakdown lipids for normal brain function

36
Q

What are three autosomal dominant conditions?

A

Huntington’s - nervous system degeneration

Achondroplasia - drawfism

Hypercholesterolemia - excess blood cholesterol leading to heart disease

37
Q

What are three sex-linked recessive conditions?

A

Hemophilia - abnormal blood clotting

Colour blindness - primarily observed in males

Muscular Dystrophy - muscle loss

38
Q

what are chromosome disorders?

A

down syndrome - trisomy 21
turner’s syndrome - XO
klinefelter’s syndrome - XXY
cri du chat - deletion on chromosome 5

39
Q

Cri du chat

A

deletion on chromosome 5

40
Q

What is extranuclear inheritance?

A

the inheritance of genetic material that is not found within the nucleus (mitochondria and chloroplasts)

41
Q

An organism that has two identical alleles for a trait

A

Homozygous

42
Q

An organism that has two different alleles for a trait

A

Heterozygous

43
Q

single copy of a gene is inherited instead of two

Ex. males inherit one X

A

hemizygous

44
Q

Describe RNA

A

A, U, C, G
- single stranded
- ribose

45
Q

DNA replication is (conservative/semiconservative)

A

semiconservative

46
Q

Describe DNA replication

A
  1. DNA copies itself
  2. Helicase unwinds DNA and forms a replication fork
  3. SSBPS (single stranded binding proteins) keep DNA strands separate
  4. Topoisomerase (DNA Gyrase) break and rejoin the DNA double helix, preventing kinks
  5. DNA polymerase moves in 5’ to 3’ direction
    - leading strand: works continuously
    - lagging strand: has to keep going back to replication fork and work away from it which produces Okazaki fragments
    - RNA primase creates small strip of RNA which DNA can work off of
  6. DNA ligase joins okazaki fragments
47
Q

catalyzes the lengthening of telomeres in germ cells

A

Telomerase

48
Q

What are the three stop codons?

A

U Are Annoying (UAA)
U Go Away (UGA)
U Are Gone (UAG)

49
Q

Least abundant RNA and contains codons

A

mRNA

50
Q

the exact base pair of the third nucleotide in the codon is often not required, allowing 45 different tRNA’s to base pair with 61 codons that code for amino acids

A

Wobbles

51
Q

What is directional selection?

A

the favouring of traits at one extreme of the range

52
Q

superior quality of offspring resulting from crosses between two different inbred strains, species, or varities of organisms

A

hybrid vigor (heterosis)

53
Q

when a small group of individuals migrate to a new location, the gene pool of the small group will be less than the original population; after successive generations, the genetic makeup will be unique from the original population

A

founder effect

54
Q

Transporter of anticodons

A

tRNA

55
Q

type of RNA that combines with proteins to form ribosomes

A

rRNA

56
Q

What are the five requirements for hardy weignberg?

A
  1. no mutations
  2. no natural selection
  3. no gene flow
  4. large population
  5. random mating
57
Q

What is the most abundant RNA?

A

rRNA

58
Q

What are the three steps of transcription?

A

INITIATION
- RNA polymerase attaches to promoter (TATA BOX) and unzips DNA

ELONGATION
- assembly of RNA nucleotides using one strand of template DNA

TERMINATION
- RNA reaches AAAAAA sequence

59
Q

What is the “TATA box” of prokaryotes?

A

Pribnow Box

60
Q

What are the modifications mRNA goes through before leaving the nucleus?

A
  1. 5’ cap added for stability and attachment to ribosomes
  2. poly A tail added to 3’ end for stability and movmement
  3. RNA splicing
    - introns removed
    - exons join together
61
Q

What occurs during translation?

A

INITIATION
- small ribosome subunit attaches to 5’ end of mRNA
-tRNA methionine attaches to AUG
- large ribosomal unit attaches to form complex

ELONGATION
- A site: tRNA binds and peptide bond forms
- P site: tRNA moves from A site to P site and the next tRNA joins the A site

TERMINATION
- ribosome encounters a stop codon

POST-TRANSLATION
- free-floating ribosome attaches to endoplasmic reticulum and then will go to the Golgi

62
Q

What is the start codon for prokaryotes??

A

n-formylmethionine

63
Q

When a mutation occurs, but the new codon still codes for the same amino acid, therefore there is no effect

A

silent mutation

64
Q

the new codon codes for a stop codon

A

nonsense mutation

65
Q

mutation where there is no change in protein function

A

neutral mutation

66
Q

a new codon codes for a new amino acid, can be minor or fatal

A

missense mutation

67
Q

What are the repair mechanisms in genomes?

A
  1. Proofreading: DNA polymerase
  2. Mismatch repair: enzymes repair what was missed by DNA polymerase
  3. Excision repair: enzymes remove nucleotides damaged by mutagens
  4. Nucleotide excision repair: can be used to repair issues like thymine dimers (does it in chunks)
  5. Base excision repair: same as nucleotide but only repairs the base itself
68
Q

structure formed when DNA is coiled around bundles of 8-9 histone proteins, kind of like beads on a string

A

nucleosome

69
Q

Compare and contrast euchromatin and heterochromatin

A

Euchromatin - chromatin is loosely bound to nucleosomes; present when DNA is actively being transcribed

Heterochromatin - areas of tightly packed nucleosomes where DNA is inactive and appears darker

70
Q

DNA segments that can move to a new location on either the same or different chromosome

A

transposon

71
Q

DNA that does not code for proteins or RNA

A

psuedogene

72
Q

Not viruses or cells, but are infectious, mis-folded versions of proteins in the brain that cause normal versions of proteins to also become mis-folded. These are fatal and are implicated in diseases such as Mad Cow, kuru, scrapie, and Creutzfeldt-Jakob.

A

prions

73
Q

very small circula RNA molecules that infect plants

A

viroids

74
Q

region of DNA that controls gene transcription

A

operon

75
Q

sequence of DNA where RNA polymerase attaches to begin transcription

A

promoter

76
Q

region that can block action of RNA polymerase if occupied by repressor proteins

A

operator

77
Q

DNA sequences that code for related enzymes

A

structural genes

78
Q

located outside of the operon region and produce repressor proteins

A

regulatory genes

79
Q

What does the Lac operon (e.coli) do?

A

controls the breakdown of lactose

OPTION 1
- lactose available –> binds to repressor –> inactivates it –> RNA polymerase transcribes genes

OPTION 2
- glucose is low, cAMP is high –> binds to a CAP binding site of promoter –> allows RNA polymerase to breakdown lactose

OPTION 3
- lactose and glucose high, operon shuts off because cAMP is low and can’t bind to CAP

80
Q

What does the Trp operon (e.coli) do?

A

produces enzymes for tryptophan synthesis

tryptophan binds inactive repressor –> activates the repressor –> binds to operator –> blocks RNA polymerase

81
Q

How are eukaryotic genes regulated?

A
  1. Regulatory proteins: enhancers/repressors influence RNA attachment to promoter region
  2. Nucleosome packing
    - methylation of histones: tighter packing that prevents transcription
    - acetylation of histones: uncoils chromatin, encourages transcription
    - direct DNA methylation: leads to lower expression
  3. RNA Interference
    - Micro RNA (miRNA): degrades target or blocks translation
    - Short interfering RNA (siRNA): similar to miRNA
82
Q

How much of the human genome is non-coding DNA?

A

97%

DAT (6 decks)

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