Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCB 10 > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

mutational hot spots

A

short repetitive sequences

palindromes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

short repetitive sequences (mutational hot spot)

A

pairing of repeats may interfere with replication of repair enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

palindromes (mutational hot spot)

A

often associated with insertions or deletions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Does DNA symmetry increase or decrease the likelihood of mutation

A

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How are repeated genes prone to mutation?

A

by mispairing during meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Induced mutation

A

Caused by mutages, many are also carcinogens and cause cancer

  • ex: acridine dyes = add or remove base
  • ex: radiation- breaks chromsome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Dimer mutation

A

An example of induced mutations because UV radiation creates thymine dimers, which is the mainc ause of melanoma skin cancers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Ames test

A

An in vitro test of the mutagenicity of a substance
One version uses Salmonella bacteria with mutation in gene for histidine
- Bacteria are exposed to test substance
- Growth on media without histidine is recorded
- Bacteria only grow if mutations have occurred
- Substance can be mixed with mammalian liver tissue prior to testing to mimic toxin processing in humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Mutagen exposure

A 
workplace
industrial accidents - chernobyl
medical treatments
weapons
natural sources (cosmic rays, sunlight, earth's crust)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Point mutations

A

A change of a single nucleotide

  • transition - purine replaces purine or pyrimidine replaces pyrimidine
  • transversion - purine replaces pyrimidine or pyrimidine replaces purine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

consequences of point mutations

A

-missense mutation - replaces one amino acid with another
-nonsense mutation - changes a codon for an amino acid into a stop codon
a stop codon that is changed to a coding codon lengthens the protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

splice site mutations

A

alters a site where an intron is normally removed from mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can splice site mutations affect the phenotype?

A
  1. intron is translated or exon skipped (ex: CF mutation)

2. Exon is skipped (ex: familial dysautomia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Deletions and Insertions

A

Nucleotide changes in multiples of 3:

  • does not cause a frameshift mutation (disrupts the reading frame and alter amino acids after mutation)
  • may alter the phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Can different types of mutation cause the same single-gene disorder?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

pseudogenes

A

a DNA sequence similar to a gene but which is not translated

  • may not even be transcribed into RNA
  • may have evolved form original gene by duplication and acquired mutation
  • crossing over between a psuedogene and function gene can disrupt gene expression
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

expanding repeats

A

insertion of triplet repeats leads to extra amino acids

  • the longer proteins shut down the cells
  • number of repeats correlates with earlier onset and more severe phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Anticipation

A

the expansion of the triplet repeat with an increase in severity of phenotype with subsequent generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

An example of a triplet repeat disease

A

myotonic dystrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

copy number variants (CNV)

A
  • sequences that vary in number from person to person
  • range in size from a few bases to millions
  • account for about 25% of our genome
  • CNVs may have no effect on the phenotype or they can disrupt a gene’s function and harm health
21
Q

silent mutations

A

mutations that do not alter the encoded amino acid

22
Q

synonymous codons

A

a mutation that alters the DNA but the protein sequence remains unchanged. for example CAA and CAG both code for glutamine. and therefore are synonymous codons.

23
Q

Nonsynonymous codon

A

created by a missense mutation which alters the encoded amino acid to another amino acid

24
Q

conditional mutation

A

produces a phenotype under particular condition or environments

ex: glucose 6-phosphate dehydrogenase enzyme, which responsds to oxidants, chemicals that strip electrons form other molecules

25
Q

DNA repair

A

errors in DNA replication or damage to DNA create mutations and may result in cancer
-most errors and damage are repaired

26
Q

The 3 types of DNA repair in many species

A

1) photoreactivation repair
2) excision repair
3) mismatch repair

27
Q

Excision repair

A

pyrimidine dimers and surrounding bases are removed and replaced

1) nucleotide excision repair replaces up to 30 bases and corrects mutations caused by different insults
2) base excision repair replaces 1-5 bases specific to oxidative damage

28
Q

mismatch repair

A

enzymes detect bucleotides that do not base pair in newly replicated DNA
-the incorrect base is excised and replaced

29
Q

proofreading

A

the detection of mismatches

30
Q

what happens if both copies of a repair gene are mutant

A

a disorder can result

31
Q

failture of DNA repair

A

if damage of DNA is too severe, the pp53 protein, which motiors repair of DNA, promotes programmed cell death or apoptosis

32
Q

Repair disorders: inherited colon cancer

A
  • hereditary nonpolyposis colon cancer
  • affects 1/200 individuals
  • defect in mismatch repair
  • HNPCC gene is on chromosome 2
33
Q

statistics of cancer

A

1/3 will be affected

34
Q

cancer

A

genetic, but not usually inhertied. cancer is a group of diseases caused by loss of cell cycle control.

35
Q

carcinogens

A

substances that cause cancer. most are mutagens (damage DNA)

36
Q

tumor

A

growth is formed if a cell escapes normal control over its division rate; tumor can cause cancer

  • a tumor is benign if it does not spear or “invade surrouding tissue
  • a tumor is cancerous or malignant if it infiltrates nearby tissues
37
Q

metastasis

A

the tumor spreads to other parts of the body via the blood or lymph vessels

38
Q

oncogenes (cancer-causing gene)

A

cause cancer if inappropriately activated

39
Q

tumor suppressor genes

A
  • deletion or inactivation causes cancer

- cell cycle control/checkpoints

40
Q

cancer causing genes

A

oncogenes
tumor suppresor genes
changes in gene expression

41
Q

what controls the cell cycle

A

the checkpoints, which ensure that mitotic events occur in the correct sequence

42
Q

what does timing, rate and number of cell divisions depend on

A
  • protein growth factors
  • signaling molecules form outside the cell
  • transcription factors within
43
Q

cancer cells

A
  • result form faulty check points
  • goes down a pathway of unrestricted cell dividion
  • either lose specializations or never specialize
44
Q

telomeres

A

loss of control of telomere length may also contribute to cancer

45
Q

telomerase

A

the enzyme (complex of RNA and protein) that adds telomere sequences to the ends of chromosomes.

  • normal, speciaized cells have telomerase turned off, limits cell division
  • cance cells have to express telomerase to be able to divide indefinitely
46
Q

inherited vs sporadic cancer

A

inherited: germline mutations
sporadic: somatic mutations

47
Q

somatic mutations

A
  • occur sporadically in nonsex cells
  • result from a single dominant mutation or two recessive mutation in the same gene
  • cancer susceptibility not passed on to offspring
48
Q

germline mutations

A
  • cancer susceptibility passed on to offsrping
  • usually requires second somatic mutation
  • rarer but strike earlier than sporadic cancers
49
Q

which cancer (inherited or sporadic) strikes earlier?

A

inherited cancer - germline mutations

MCB 10 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions