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Genetics > Exam 3: Biochemical Pathways, Mutations and more Genes, Oh My! > Flashcards

Exam 3: Biochemical Pathways, Mutations and more Genes, Oh My! Flashcards

1
Q

What is Neurospora and why is it a good model organism?

A

-red bread mold
- haploid, reproduces quickly

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2
Q

Describe Biochemical pathways

A

Proper flowthrough the pathway is dependent on enzymes and enzymes are encoded by genes

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3
Q

What is an example of biochemical pathways?

A

Eye color
-it affects production of pigment or transport of pigment

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4
Q

Describe Lactose intolerance

A

-Enhancer found in nearby gene
-Controls expression of LCT (lactase) gene
- Gene expression is usually turned off when young mammal is weaned from mother’s milk

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5
Q

Describe PKU- Phenylketonuria

A

-w/o the enzyme PAH
-phenylalanine builds up, crosses w brain
- interferes w/ brain development and function, which causes mental deterioration

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6
Q

What is the Ommochrome Pathway?

A

produces xanthommatin= brown pigment (not fluorescent)

(in wild type flies)

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7
Q

What is the Pteridine pathway?

A

Produces drosopterin= bright red pigment (what we saw in chromatography)

(in wild type flies)

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8
Q

Describe the alcohol digestion pathway

A

Alcohol > ADH> acetaldehyde> ALDH> acetic acid

-acetaldehyde (toxic, hangovers)
- acetic acid (non-toxic)

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9
Q

Describe Alcohol tolerance

A

-Women tend to have lower ADH activity, which gives lower tolerance
- Some people have super hyper efficient ADH, which makes a ton of acetaldehyde
- High tolerance, no buildup of acetaldehyde

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10
Q

What does the medication Disulfiram do?

A

medication that blocks ALDH to give massive buildup of acetaldehyde, have super bad side effects to change Alcohol abuse behavior.

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11
Q

Describe the Beadle and Tatum experiment

A

-Take neurospora, which can grow in minimal media (MM), as it makes most nutrients it needs itself
-Mutate them
- Grow them in MM
-See what grows and what doesn’t

Example: mutated spore grown in Vitamin C broth= grow
same mutant grown w/o vitamin C= die

mutation altered gene needed to synthesize vitamin C

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12
Q

Describe Srb and Horowitz experiment

A

Conclusion: Each gene encodes a separate protein- in this case, an enzyme

different groups were grown in different medias to see what was mutated

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13
Q

What is an Auxotroph?

A

a nutirtional mutant that needs something to grow

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14
Q

What is a Prototroph?

A

an organism that can make everything it needs in minimal media

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15
Q

Describe a complementation test

A

It sorts mutants
First: make diploids
Second: evaluate phenotypic results

example:
1,3,4
2,6
7
These were found from those weird grids, with lining up (-) and these represent 4 different genes

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16
Q

What is the Chi-square test?

A

X^2= E(observed-expected)^2/ expected

Corresponds to accept/reject Mendielian genetic ratio

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17
Q

How do you find the degrees of freedom?

A

d= n-1, where n= # catagories

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18
Q

What is a DNA mutation?

A

The process by which DNA structure changes

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19
Q

What happens when a mutation occurs in a gene?

A

When the mutation occurs in a gene, the gene changes structurally, resulting in alleles (different forms of a gene)

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20
Q

How do you organize the study of mutation?

A

-phenotype
-cause
-scale/type of molecular change

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21
Q

What are some GENERAL types of mutations

A

-visible
-nutritional
-biochemical
-behavioral
-regulatory: altered gene expression
-lethal
- conditional

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22
Q

What is a Spontaneous mutation?

A

mutations from replication error, meiotic/mitotic, chemical nature, natural processes that alter bases

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23
Q

What is an Induced mutation?

A

a mutation from high energy radiation, UV light, and natural/synthetic chemical

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24
Q

What is Depurination?

A

-purines randomly lost from DNA
- 10k purines from mammal genome per cell in 20hr cell cycle
-Produces an apurine site, no purine, DNA backbone still preserved

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25
Q

What is Deamination?

A

-Amine group lost
-which changes base pairing
-cytostine –> uracil
- 5-methyl cytosine –> thymine

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26
Q

What does reactive oxygen do?

A

Mutates!
-DNA fragmentation
-Mitochondrial DNA damage
-Y chromosome microdeletions
-Telomere attrition
- Epigenetic abnormalities

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27
Q

What does UV Light do?

A

It distorts DNA, blocks replication and transcription

but cells can repair

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28
Q

Describe Radiation Damage

A

-rupture DNA strands
- alter bases
-destroy sugars
-crosslink bases to form dimers

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29
Q

What can happen when the cell tries to repair thedamage?

A

it can either be perfect or it can mis-repair and lead to mutation or carcinogenesis

30
Q

What is the Ames test?

A

-Uses different strains of bacteria that are able to reveal presence of specific mutations
- Looks for reverse mutations that allows bacteria to grow

used in cigarette/cigar cancer study

31
Q

List some chromosome mutations

A

-duplications
-translocations
- Inversions
-Loss

32
Q

List some gene mutations

A

-point mutation
-silent
-missense
-nonsense
-frameshift

33
Q

What is a point mutation?

A

1 base pair affected at a time

34
Q

What is a silent mutation?

A

no phenotype, can occur between genes, in an intron, 5’/3’ UTR, wobble position of codon

35
Q

What is a missense mutation?

A

Base change in the open reading frame that changes amino acid sequence of protein at that site. May/may not produce protein that is non functional

36
Q

What is a nonsense mutation?

A

Base change in ORF that changes an Animo acid to a stop codon, protein is often nonfunctional.

37
Q

What is a frameshift mutation?

A

shift the codon from that point on

Insertion/deletion

38
Q

What is an Intragenic mutation?

A

another mutation within the same gene.

1) back mutation: back to normal

2) Suppressor 2nd site- deletion can mask frameshift insertion

39
Q

What is intergenic suppression?

A

Mutation at separate gene/location

-mutation on one gene is suppressed by mutation in another gene (suppressor gene)

suppressor genes: tRNAs, interacting proteins

40
Q

What is a gene landmark?

A

sequences that have a specific function and are often conserved, and you find them via bioinformatics

41
Q

What are two medications that can treat cystic fibrosis?

A

Kalydeco and Trikafla

42
Q

What does Kalydeco do?

A

-targets the G441D allele

the mutation introduces a bulky, negatively changed side chain into ATP site 2, abolishing ATP induced opening of CFTR.

Kalydeco binds, bends and restores, opens it back up (like breathe right strips)

43
Q

what is an Intron

A

non coding, gets kicked out

44
Q

what is an exon

A

genetic code

45
Q

what is an operon

A

transcriptional unit that makes everything the cell needs

promoter and additional sequences that control transcription (operator) and structure genes

46
Q

What is a regulator gene

A

DNA sequence encoding products that affect the operon function, but not part of operon

47
Q

What is Positive Control?

A

An activator protein is involved
(car w/ only gas pedal. go=push down, stop=let go)

48
Q

What is Negative control?

A

A Repressor protein is involved
(car w/ only break pedal. go=let go, stop=push down)

49
Q

What is an Inducible operon?

A

Transcription is usually off and needs to be turned on

50
Q

What is a Repressible operon?

A

Transcription is normally on and needs to be turned off.

51
Q

Describe Negative Inducible transcription

A

Normally, repressor is on and transcription is off. Inducer binds of substrate making the repressor inactive, transcription starts

“taking foot off break”

52
Q

Describe Negative Repressible transcription

A

So much product, helps apply the “break” to stop it.

“Applying break to stop it”

53
Q

Describe Positive inducible transcription

A

Starting with transcription off, want it on. Starting material makes substrate activator active, transcription turns on
“push gas pedal”

54
Q

Describe Positive repressible transcription

A

Final product makes activator inactive, transcription is turned off

“take foot off gas”

55
Q

What is a famous operon?

A

The Lac operon

56
Q

How is lactose metabolism in E.coli regulated?

A

By a Negative Inducible system

57
Q

What is the Inducer of lactose metabolism in E.coli?

A

Allolactose (presence of lactose)

58
Q

What is lacl? ( in lactose metabolism in E.coli)

A

the regulator gene (a repressor-encoding gene)

59
Q

what is lacP? ( in lactose metabolism in E.coli)

A

operon promoter

60
Q

what is lacO? ( in lactose metabolism in E.coli)

A

operon operator

61
Q

what is lacZ ( in lactose metabolism in E.coli)?

A

A structural gene, encoding B-galactidases

62
Q

what is lacY ( in lactose metabolism in E.coli)?

A

encoding permease

63
Q

what is lacA( in lactose metabolism in E.coli)?

A

encoding transaceylase

64
Q

Is repression in lac operon completely shut down?

A

No, transcription is not completely shut down

65
Q

what is Lac I ( in lactose metabolism in E.coli)?

A

produces an allosteric repressor protein

66
Q

What happens when there is no lactose present ( in lactose metabolism in E.coli)?

A

Enzymes are not needed, expression of genes encoding enzymes are repressed

67
Q

What happens when there is lactose present( in lactose metabolism in E.coli)?

A

indirectly induces activation of genes by binding to repressor, pulling it away from operon (ONLY IF NO GLUCOSE THERE)

68
Q

What happens when Glucose is present ( in lactose metabolism in E.coli)?

A

Glucose is always first choice (bacteria love glucose!) Glucose is always the first choice to be processed. Lactose is only processed if glucose is low or absent.

When glucose is HIGH, no need use lactose even if it is present (little transcription)

When glucose is LOW, now the cell can use lactose

69
Q

What are the standard conditions ( in lactose metabolism in E.coli)?

A

No transcription, repressor binds to operator

70
Q

What is Global regulation ( in lactose metabolism in E.coli)?

A

don’t need to break down lactose if glucose is around

71
Q

What is the Catabolite-activating protein (CAP)

A

involved in:
-repressing expression of lac operon when glucose is present

-boosting expression when glucose is absent

Genetics (4 decks)

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