Genetic Variation

Question 1

locus

Answer 1

the location of the gene (DNA sequence) on a chromosome

Question 2

allele

Answer 2

a version of a gene. They are always present on the same locus

Question 3

homozygous

Answer 3

2 identical alleles

Question 4

heteroyzgous

Answer 4

2 different alleles

Question 5

wild type

Answer 5

the most common verson of a gene. does not mean that it is the most normal

Question 6

variant / mutant

Answer 6

a change from the wild type

Question 7

does a mutant gene mean that it is bad

Answer 7

no! it says nothing about the fitness or funcition. It just indicates that it is different from the wild type

Question 8

polymorphism

Answer 8

there are many forms ie variants within a population

Question 9

what are the criteria for something to be considered polymorphic

Answer 9

2 or more common allele at the same locus in more than 1% of the population

the gene basically has many forms

Question 10

what is a private allele

Answer 10

an allele that is present only in a single family

Question 11

an amish populaiton has certain genes that are found within this population. what is this called

Answer 11

private alleles

Question 12

what are the 3 main causes of genetic variaion

Answer 12

1. mutation: can create an entirely new allele in a population
2. random mating / fertilization-during meiosis: there is a mixing of alleles between 2 different populations
3. recombination b/n homologous chromosomes: crossing over where maternal and paternal exchange their genetic material

Question 13

what has to happen for something to be considrered a mutation.

Answer 13

a change occurs and it is sustained and passed down to future offspring

can be anything from a single nucleotide to an entire chromosome

Question 14

what do we compare things to tell if something is a a mutant

Answer 14

we use the most common allele as the reference sequence

Question 15

what are the 3 sizes of DNA mutations

Answer 15

1. Chromosomal:
   chromosomes are intact but the NUMBER of chromosomes in a cell changes
2. Regional:
   only a PORTION of the chromosome changes
3. Gene or DNA mutations : DNA SEQUENCE change due to substitution, deletion or insertion

Question 16

what are the 4 forms of polymorphisms

Answer 16

1. single nucleotide polymorphism (SNP)- change in a single nucleotide
2. insertion or deletion of bases AKA indel = insertion or deletion , occur in mircostellites or transposons
3. copy number variant= duplication
4. inversion = self explanatory

Question 17

where are the 2 places that changes can occur

Answer 17

somatic- occurs all the time, not usually detectable unless (b/c in junk) it is in a population of cancer cells. Can also lead to somatic mosaicism

-Not passed on

germline - passed to offspring

Question 18

what is an extragentic sequence

Answer 18

happening outside of a gene. Many SNPS and indels here, but since located outside of the gene it doesn’t matter

Question 19

a mutation occurs in an extragenic region, what will occur

Answer 19

nothing, bc the extragenic region is not transcribed

Question 20

a mutation occurs in the regulatory sequence, what does this mean

Answer 20

it will affect the quantity of the protein!

Question 21

do UTR sequences get translated

Answer 21

no , but they are essential because regulatory proteins bind here, they make sure that there are no errors and DNA is copied into RNA

Question 22

What is found in introns

Answer 22

SNP’s and indels (insertions & deletions)

Question 23

what happens if a mutation occurs in an intron

Answer 23

often it does nothing although, it can affect the splicing

Question 24

what are exons

Answer 24

the coding region of the genes

Question 25

what is a silent mutaiton

Answer 25

a change occurs but it doesnt affect anything

Question 26

what is a missence mutaiton

Answer 26

a change occurs which creates a new protein

Question 27

what is a nonsense mutation

Answer 27

coding codon is replaced by a stop codon

Question 28

what are the consequences of mutations

Answer 28

1. Gain of function:
   - amplification of gene
   - alter regulation
   - amino acid changes
2. altered function
   - interfere with normal protein
   - polymerize and resist degradation
3. Loss of function
   - protein absent
   - protein non functional

Question 29

where do gain of function mutations occur

Answer 29

in the dominant allele

Question 30

where do altered function mutations occur

Answer 30

in dominant allele

Question 31

where do loss of function mutations occur

Answer 31

in recessive allele

Question 32

what 2 conditions are associated with dwarfism in humans

Answer 32

osteogenesis imperfect

achondroplasia