Lecture 5

Question 1

Mutant Allele

Answer 1

Rare variant of a gene present in less than 1% of the population

Question 2

Polymorphic Allele

Answer 2

Common variant of a gene present in at least 1% of the population

Question 3

Forward mutation

Answer 3

Mutation from wild-type to mutant

Question 4

Reverse mutation

Answer 4

Mutation from mutant to wild-type

Question 5

Transition

Answer 5

Mutation to the same type of base (purine to purine or pyrimidine to pyrimidine)

Question 6

Transversion

Answer 6

Mutation to the opposite type of base (purine to pyrimidine or pyrimidine to purin)

Question 7

Insertions

Answer 7

Adding of nucleotide(s) in the DNA sequence

Question 8

Deletions

Answer 8

Removal of nucleotide(s) in the DNA sequence

Question 9

Inversion

Answer 9

Flip of a part of the DNA sequence (top to bottom AND left to right)

Question 10

Translocation

Answer 10

Some sequence of DNA are swapped between non-homologous chromosomes

Question 11

Somatic mutation

Answer 11

Mutation non-transmitted to the progeny

Question 12

Germline mutation

Answer 12

Mutation that can be passed to the progeny

Question 13

Type of phenotypic effect of mutation

Answer 13

Viable vs non-viable

Question 14

Type of environment interaction mutation

Answer 14

Conditional vs non-conditional

Question 15

Functional classifications of mutations

Answer 15

Phenotypic effect, inheritance and environmental interaction

Question 16

Mutation threshold effect

Answer 16

Mutated genome percentage needed to trigger the mutant phenotype (because of heteroplasmy)

Question 17

Mutation caused by Intercalator

Answer 17

Small molecule intercalates between nucleotides and provokes an insertion of a random base pair or a deletion

Question 18

Mutation caused by slipped mispairing

Answer 18

DNA polymerase can skip some codon if in repeats region causing the DNA to have a contraction (removal of repeat codons) or extension (addition of repeat codons)

Question 19

Deamination

Answer 19

Process of removing the amine group (-NH2) which is replaced by an Oxygen atom. The nucleotide U pairs with A, modifying the base pair to T-A instead of C-G

Question 20

Mitochondrial DNA mutation threshold effect

Answer 20

A percentage of mitochondria needs to have the mutation to show the phenotype (heteroplasmy)

Question 21

Human per base mutation rate

Answer 21

1/30,000,000

Question 22

Human mitochondrion per base mutation rate

Answer 22

1/30,000

Question 23

Fluctuation test

Answer 23

Experiment to test that mutations arise spontaneously and not in contact of the pathogen

Question 24

Replica plating

Answer 24

Experiment to test that antibiotic resistance is pre-existing. Use a velvet to transfer bacteria over multiple plates => Bacteria that survive are all at the same location

Question 25

Depurination

Answer 25

Removal of a purine, result in a random nucleotide inserted

Question 26

X-ray mutation effect

Answer 26

Double strand break => Deletion

Question 27

UV light mutation effect

Answer 27

Pyrimidine dimer => C-C resulting in deamination effect

Question 28

Base oxydation

Answer 28

G will bind to A

Question 29

Unequal crossing over consequences

Answer 29

Lead to deletion on one chromosome and duplication on the other

Question 30

Replication slippage model

Answer 30

When repeats, DNA polymerase can slip and it results in deletion or addition of DNA (creation of more repeats)

Question 31

Mutagens doing base damage

Answer 31

1. Hydroxylating agent => C binds to A
2. Alkylating agent => G binds to T
3. Deaminating agent => C to A or A to C

Question 32

Consequence of intercalating agent

Answer 32

Indel

Question 33

Types of DNA Repair

Answer 33

1. DNA Polymerase Proofreading
2. Photo repair (Photolyase repairs Pyrimidine dimer)
3. Base Excision Repair
4. Nucleotide Excision Repair
5. Mismatch Repair
6. Homologous Recombination
7. Non-Homologous End Joining

Question 34

Base excision repair mechanism

Answer 34

1. Removal of the wrong base (Glycosylase)
2. Endonuclease cuts the DNA where the base is missing
3. Reconstruction of the DNA through the template

Question 35

Nucleotide Excision repair mechanism and why

Answer 35

Glycosylase not recognizing the damage (pyrimidine dimer).

1. Nick protein cuts whole nucleotide sequence with dimer
2. DNA recontruction + ligase

Question 36

How mismatch repair during dna replication is working

Answer 36

Methyl strand marked, reuse it as template

Question 37

Homologous recombination

Answer 37

Usually happen after replication, so a sister chromatid is available. Otherwise, use an homologous but might include errors or now have recessive phenotype

Question 38

Non-Homologous End Joining

Answer 38

When HR is not available, cleaning the region and end-join the two parts of the DNA. Loss of information

Question 39

Type of DNA mutation

Answer 39

1. Silent mutation
2. Missense mutation
3. Nonsense mutation
4. Frameshift mutation

Question 40

Effect of loss of function mutation

Answer 40

Hypomorphic: Function reduced
Null: Function lost
Dominant negative: Function lost and prevents wild-type allele from functioning

Question 41

Effect of gain of function mutation

Answer 41

Hypermorphic: Function enhanced
Neomorphic: New function

Question 42

Haploinsufficiency

Answer 42

Gene with only one wild-type version is not enough to have the function

Question 43

Ames test

Answer 43

Mutagen chemicals turn His- to His+ to check their mutagenic effects