Where New Alleles and Genes Come From

Question 1

Where do New Alleles Come From?

Answer 1

1. Mutation by Deamination
2. Mutation by Misalignment
3. Point Mutation
4. Spliced-site Mutation
5. InDel/Deletion Mutation

Question 2

a spontaneous mutation that occurs when an amine group is removed from a nitrogenous base in DNA

Answer 2

deamination

Question 3

Steps in mutation by deamination

Answer 3

1. Deamination (ex. C->T)
2. Replication
3. Completed substitution

Question 4

Mutation by misalignment results in duplications and deletions

Answer 4

After replication an insertion will occur and a single base-pair

Question 5

a term used in molecular biology to describe a newly formed DNA molecule, either during its formation or when it is complete

Answer 5

nascent

Question 6

CASES OF SPONTANEOUS CHEMICAL DECAY PER DAY

Answer 6

20,000

Question 7

REPLICATION ERRORS PER DIVISION

Answer 7

100,000

Question 8

polymerase uses _______ to remove incorrect nucleotide

Answer 8

3’ to 5’ exonuclease activity

Question 9

refers to a genetic state in which the number of repeats in a specific DNA sequence is above the normal range but not high enough to cause symptoms of a disorder.

DNA level alteration

Answer 9

Premutation

Question 10

mutations that don’t change the amino acid sequence of the protein

Answer 10

silent mutation

Question 11

DNA methylation - inhibits transcription which affects gene expression

Question 12

can react with water which results in loss of amine group and becomes thymine

Answer 12

5-methylcytosine

Question 13

proofreading enzyme

Answer 13

exonuclease

Question 14

which has a more severe effect, transition or transversion

Answer 14

transversion

Question 15

2 types of missense mutation

Answer 15

Conservative (minor loss in mutation) and Nonconservative (change in structure phenotype)

Question 16

Nonsense mutation

• protein malfunction
• premature stop codon

Question 17

is a protein that connects with actin filaments in the Z line

Answer 17

Alpha-actinin-3

Question 18

no Alpha-actinin-3 = more efficient use of energy

Question 19

where is Alpha-actinin-3 found

Answer 19

only in type II (Fast-Twitch) muscle fibers

Question 20

A band
Myosin
M line

Actin
Z line
I band

Question 21

absence of fingerprints

point mutation and intervening mutation

Answer 21

Adermatoglyphia

Question 22

is a gene that encodes a protein involved in chromatin remodeling.

for skin and fingerprints

Answer 22

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, containing DEAD/H box 1 (SMARCA1)

Question 23

mutation when introns are not spliced - protein nonfunctional

Answer 23

Spliced-site mutation

Question 24

deletion of single base

Answer 24

InDel/ Deletion Mutation

Question 25

Where do new genes come from

Answer 25

1. Gene duplication by unequal crossing over
   - homologous chromosomes align incorrectly - inner chromatids cross over at non-allelic loci - duplication happens and new gene is made
   ex. Charcot-Marie-Tooth disease type I A and Hereditary Neuropathy with Liability to Pressive Palsies (Chromosome 17 misalignment during meiosis)
2. Retroposition or retroduplication
   -a gene duplication mechanism that involves the reverse transcription of a messenger RNA (mRNA) template into a complementary DNA (cDNA) strand
   ex. Chondrodysplasia in dogs (fgf4 gene fibroblast growth factor)
3. New genes from scratch
   -C22orf45, or Chromosome 22 open reading frame 45, is a human-specific protein-coding gene that evolved from noncoding DNA