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biology 1001 > cycle 4 > Flashcards

cycle 4 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

exogenous DNA damage

A

from outside the organism; UV light, chemicals, ionizing radiation

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2
Q

endogenous DNA damage

A

from inside the organism; DNA replication errors, ROS

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3
Q

DNA damage

A

single stranded change (becomes mutation after replication)

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4
Q

mutation

A

double stranded change (location determines impact)

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5
Q

repair mechanisms for mismatch errors

A

proofreading, mismatch repair

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6
Q

proofreading

A

DNA polymerase detects (detects distortion in backbone) an error when it makes it and it fixes it itself immediately (uses 3’ to 5’ exonuclease activity to remove error)

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7
Q

mismatch repair

A

error is detected by mismatch repair enzymes and is fixed by DNA polymerase (excises damaged DNA and replaces it), DNA ligase then seals the gap

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8
Q

thymine dimers

A

distort the backbone of DNA and halts DNA polymerase, caused by UV light

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9
Q

how do thymine dimers get repaired?

A

photolyase + white light (lost ability in humans, excision repair

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10
Q

photolyase and white light

A

links 2 side by side T nucleotides together

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11
Q

excision repair

A

nuclease cuts the damaged DNA and removes it, DNA polymerase fills in gap, DNA ligase seals gap

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12
Q

reactive oxygen species (ROS)

A

ionizing radiation splits water molecules in cells apart to create ROS (highly electronegative and thermodynamically unstable), ROS will damage DNA to reach stability (steal electrons from DNA)

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13
Q

oxidative stress

A

caused by ionizing radiation, smoking, stress (in aged cells)

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14
Q

what gets rid of ROS?

A

antioxidants

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15
Q

double-stranded breaks

A

caused by radiation that damaged DNA and breaks both strands (repaired by non-homologous end joining)

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16
Q

non-homologous end joining (NHEJ)

A

pieces DNA back together but can be very sloppy (can result in deletions, insertions, or inversions), but it can also put the DNA back together properly

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17
Q

what makes up the DNA sequence?

A

25% unknown (likely junk), 10% essential (2% coding), 10% introns (junk), 55% transposons, viruses, dead genes (junk)

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18
Q

point mutations (substitutions)

A

change in one base pair

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19
Q

spontaneous mutations

A

inherent consequence of DNA replication/repair

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20
Q

induced mutations

A

caused by mutagens

21
Q

types of point mutations

A

silent (doesn’t affect structure/function, codes for the same amino acid), nonsense (changes code to a stop codon), missense (codes for a different amino acid, vary in effect based on location in protein)

22
Q

types of mutations

A

substitution, deletion, insertion, inversion

23
Q

deletion

A

lose base pairs (most of diseases are caused by this)

24
Q

insertion

A

base pairs are added

25
Q

inversion

A

sequence is inverted

26
Q

frameshift mutations

A

single base pair insertion or deletion (alters reading frame of resulting mRNA, resulting polypeptide is not functional)

27
Q

insertional mutagens

A

introduce mutations into organisms

28
Q

SNPs

A

single base pair difference in a DNA sequence, most common type of genetic variation, occur normally

29
Q

SNPs functions

A

associated with health and disease, predict an individual’s response to certain drugs, predict susceptibility to environment factors such as toxins, predict risk of developing particular diseases

30
Q

indel mutations

A

one or two nucleotide pairs inserted or deleted (due to DNA polymerase slippage)

31
Q

backward slippage

A

slips back and forms loop, insertion mutation

32
Q

forward slippage

A

slips forward, deletion mutation

33
Q

tautomeric shifts (spontaneous)

A

change base pairing partners (T* with G, A* with C, G* with T, C* with A), can revert back to normal form after rounds of replication

34
Q

is tautomerization a mismatch error?

A

no, base spontaneously changes

35
Q

tautomerization over rounds of replication

A

parent DNA undergoes a tautomeric shift, during replication one daughter DNA is damaged with tautomeric base, one is normal (WT), in next round damaged DNA undergoes tautomerization back (still damaged), when it replicates again one daughter DNA will be mutated and the other will be normal (WT)

36
Q

5BU

A

mutagen that is a tautomerically unstable base “analogue”, DNA polymerase reads 5BU as T (added instead of T, preferentially pairs with G)

37
Q

transition mutations

A

purine to purine, pyrimidine to pyrimidine

38
Q

transition mutations

A

purine to pyrimidine, pyrimidine to purine

39
Q

transposable elements

A

insertion sequence that codes for its own mobility, can insert itself and excise itself around the entire genome

40
Q

transposable elements and corn pigments

A

if it inserted itself in the pigment gene, no pigment is produced (disrupted, white/yellow kernels), when it exited the gene, pigment is produced (purple kernels)

41
Q

what is responsible for genome size?

A

transposable elements (genome size is not indicative of # of genes)

42
Q

impacts of transposable elements

A

50% of human genome is TE’s, effects vary from negligible to disease (in 70-80% of genes), most are dead due to inactivating mutations, active TE’s have evolved to insert into safe havens (places in genome that don’t interfere with functioning), host silences (inactivates) most active TE’s

43
Q

what do transposable elements do?

A
  • if it lands in a non-coding region: generally silent
  • if it lands in a coding region: can lead to disease causing mutations (hemophilia), can lead to gene shuffling (excision of TE takes gene sequence along with it) (different promoters are paired with different gene’s expressions)
44
Q

what is the most common type of TE?

A

alu elements (over 1 million copies in humans)

45
Q

heart disease

A

associated with SNPs (lifestyle, diet, exercise also play large role)

46
Q

diseases are…

A

multifactorial (majority)

47
Q

cystic fibrosis

A

caused by 1 mutation in CTFR gene coding for a transporter protein in the plasma membrane (2 nucleotide deletion, deletion of phenylalanine), cystic fibrosis is not multifactorial (good lifestyle can’t prevent it)

48
Q

mechanisms that generate genomic variation

A

DNA polymerase base pairing errors, NHEJ, DNA polymerase slippage, tautomeric shifts, transposable elements

49
Q

effects of UV vs gamma on genome

A

gamma radiation is distributed randomly, while UV radiation targets specific regions of the genome

biology 1001 (11 decks)

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