Exam 2

Question 1

dna replication

Answer 1

producing two identical replicas of DNA from one original DNA molecule

Question 2

transcription

Answer 2

synthesis of an RNA molecule from a strand of DNA

Question 3

translation

Answer 3

the assembly of amino acids into peptide chains read from the RNA molecule

Question 4

exons

Answer 4

expressed portions of genes, includes the protein coding sections

Question 5

introns

Answer 5

intervening sequences of the gene not translated into proteins

Question 6

polymorphisms

Answer 6

common genetic differences (allele frequencies >1%)

Question 7

single nucleotide polymoprhisms (SNPs)

Answer 7

structural genetic variant, most common variant, change in just one nucleotide in the sequence that may or may not change the function of the gene

Question 8

synonymous/neutral/silent mutation

Answer 8

point mutation that does not cause a change in amino acid

Question 9

non-synonymous/missense mutation

Answer 9

point mutation causing a change in the amino acid and as a result a change in function

Question 10

nonsense mutation

Answer 10

substitution resulting in a stop codon prematurely in the sequence

Question 11

variable number of tandem repeats (VNTR)

Answer 11

sequence is repeated a variable number of times in tandem

Question 12

premutation

Answer 12

a change in sequence that is not a problem but predisposes offspring to the disorder

Question 13

genetic anticipation

Answer 13

symptoms appear at an earlier age and with more severity across generations

Question 14

frameshift mutation

Answer 14

type of point mutation that causes a shift in the frame the codon sequence is read, changing the coding for amino acids

Question 15

copy number variants (CNVs)

Answer 15

a large number of DNA bases that have either been deleted or inserted

Question 16

aneuploidy

Answer 16

an abnormal number of chromosomes (either too many or too little)

Question 17

nondisjunction

Answer 17

uneven splitting of chormosome pairs during meiosis

Question 18

incomplete dominance

Answer 18

heterozygote shows an intermediate phenotype

Question 19

co-dominance

Answer 19

both alleles at a locus are expressed in the phenotype

Question 20

pleiotropy

Answer 20

single gene has multiple phenotypic effects

Question 21

epistasis

Answer 21

single trait depends on the interaction between two genes

Question 22

penetrance

Answer 22

% frequency that an allele/genotype expresses itself in the phenotype

Question 23

incomplete penetrance

Answer 23

when penetrance is less than 1, meaning not everyone with the genotype will express the phenotype

Question 24

expressivity

Answer 24

degree to which a penetrant allele expresses

Question 25

heterozygous advantage

Answer 25

when an individual who is heterozygous for a gene has a higher fitness than someone who is homozygous

Question 26

genomic imprinting

Answer 26

expression of the gene is dependent on if it is inherited from the mother or father

Question 27

transcription factors

Answer 27

proteins that help determine which genes are active in each cell in your body

Question 28

epigenetics

Answer 28

stable changes in gene expression that are not due to differences in the DNA sequence (histone modification and DNA methylation)

Question 29

histone modifications

Answer 29

change the way DNA is packaged which changes the likelihood of gene expression

Question 30

DNA methylation

Answer 30

methyl groups or acetyl groups interrupt expression by blocking transcription or translation

Question 31

x-inactivation

Answer 31

an epigenetic effect that turns off one x chromosome at random within a cell, impacting which genes are expressed

Question 32

reprogramming

Answer 32

erasing or remodeling epigenetic marks during mammalian development or in cell culture, meaning epigenetic effects can be passed down through the generations

Question 33

selection study

Answer 33

Breeding for a phenotype over several generations by selecting parents with high or low scores on the phenotype, mating them, and assessing their offspring to determine the response to selection

Question 34

inbred strain studies

Answer 34

Inbreeding related animals (brother-sister, parents-offspring) for at least 20 generations, makes animals within a strain virtual clones
traits that differ across strains= genetic
traits that differ within strains= environmental

Question 35

targeted mutation

Answer 35

process by which a gene is changed in a specific way to alter its function

Question 36

knockout

Answer 36

deleting a DNA sequence (or changing it to make it inoperable)

Question 37

knock-in

Answer 37

substituting a different DNA sequence or implementing more subtle changes that affect regulation in order to increase or decrease expression

Question 38

transgenics

Answer 38

mutated gene transferred to embryos between organisms

Question 39

gene silencing

Answer 39

knocks down gene expression that shares sequence, does not alter DNA so it is NOT heritable

Question 40

synteny homology

Answer 40

when parts of chromosomes in one species has same genes in same order as in another species

Question 41

candidate gene study

Answer 41

a gene-hunting technique which looks at specific genes of interest and tests
whether there is an association between a variant of the gene and the disease state or trait of interest

Question 42

common disease common variant hypothesis (CDCVH)

Answer 42

if a disease that is heritable is common in the population (a prevalence greater than 1–5%), then the genetic contributors will also be common in the population

Question 43

minor allele frequency (MAF)

Answer 43

the frequency at which the second most common allele occurs in a given population (fairly common is > 1%)

Question 44

gene x environment interaction

Answer 44

A genetic variant may only have an effect (or have a different effect) within a certain environmental context

Question 45

population stratification

Answer 45

Systematic difference in allele frequencies between subpopulations, usually due to different ancestry

Question 46

publication bias

Answer 46

only significant results are published or even written up

Question 47

power

Answer 47

the likelihood you will detect a true effect (low power increases the chance that anything you will find will be a false positive)

Question 48

genome wide association studies (GWAS)

Answer 48

a gene hunting technique that tests effects of variants across the entire genome

Question 49

linkage disequilibrium (LD)

Answer 49

when the allele for one SNP tends to occur with the allele of another SNP in a population

Question 50

linkage

Answer 50

when genes segregate together, if the loci of two genes are close on a chromosome, they are more likely to segregate together

Question 51

haplotype

Answer 51

a set of variants that tend to be inherited together (large sections of the chromosome that have high linkage disequilibrium)

Question 52

common disease common variant hypothesis (CDCV)

Answer 52

common disorders are likely influenced by alleles common in the population

Question 53

polygenic scores

Answer 53

the sum of alleles an individual has in their genome that increase the “risk” of having a phenotype