Genetics flash

Question 1

Questions

Answer 1

Answers

Question 2

Restriction fragment lengthpolymorphism (RFLP)

Answer 2

Use restriction enzyme that cuts at specific sequences and measure sequence lengths

Question 3

Short tandem repeats (STRP)

Answer 3

microsatelite repeats.

Question 4

Variable number tandem repeats (VNTR)

Answer 4

Minisatelite repeats. Can be detected via MW

Question 5

Copy number variation (CNV)

Answer 5

Used to detect DNA polymorphisms. All people have same genes, some have extra copies

Question 6

Single nucleotides polymorphism (SNP)

Answer 6

Single base change. Most common

Question 7

Automated sequencing

Answer 7

Allows us to build whole genome databases for individuals to provide personalized medicine

Question 8

Microarray

Answer 8

Oligo nucleotide probes on microarray that bind fluorescently labeled DNA from subject that is complementary. Used to profile gene expression.

Question 9

Genetic drift

Answer 9

Shift in observed allele frequency from expected from generation to generation due to small population

Question 10

Founders effect

Answer 10

Subset of genetic drift (small founding population) and some sort of natural selection/ heterozygote advantage

Question 11

Gene flow

Answer 11

Change of allele frequency due to admixture and migration

Question 12

Proband

Answer 12

Person from whom the pedigree is initiated

Question 13

Consanguinity

Answer 13

Mating between related persons

Question 14

Penetrance

Answer 14

% of individuals that have a certain genotype and express the expected phenotype. (# people with pheno)/(# people with geno.)

Question 15

Expressivity

Answer 15

Degree to which a genotype is expressed. Variation of severity

Question 16

Genetic anticipation

Answer 16

Genetic trait is more strongly expressed and earlier in life expressed with each subsequent generation due to increase of triplet nucleotide expansion

Question 17

Haplotype

Answer 17

Multiple components or loci (ex. A1B1 and A2B2), exhibt linkage

Question 18

Linkage Disequilibrium

Answer 18

Certain haplotype is more dominant than others, possibly linked to disease while lesser ones are linked

Question 19

Bad disease marker

Answer 19

Marker segregates randomly, meitotic crossing over

Question 20

LOD score

Answer 20

Logarithm of odds score. Measures recombination between marker and genetic disease. Lod 3 = 1000:1, significant. Lod -2 is exclusion of marker.

Question 21

Physical genetic mapping

Answer 21

Use genomic library and genome sequence from human genome project and preform “chromosome walking”

Question 22

Genetic linkage

Answer 22

Shared within families. Different families have different segments.

Question 23

Genetic Association

Answer 23

Same variation shared across all families

Question 24

Epigenetics

Answer 24

Heretible changes in gene expression due to mechanisms other than underlining DNA sequence. Epigenetic marks are erased during gametogenesis/ embryogenesis or linger for 2-3 generations

Question 25

What nucleotide is methylated

Answer 25

Cytosine

Question 26

DNA methylation

Answer 26

Transcriptional silencing, protect genome from transposition, genomic imprinting, X inactivation, tissue specific gene expression. Established new every generation

Question 27

Histone modification

Answer 27

Acetylation, methylation, phosphorylation, ubiquitilation, different histone combinations

Question 28

Eurchromatin

Answer 28

DNA is unmethylated, histone is acetylated. Transcription on

Question 29

Heterochromatin

Answer 29

DNA is methylated, histones are deacetylated. Transcription off

Question 30

HAT

Answer 30

histone acetylase, acetylated histones to make them active

Question 31

HDAC

Answer 31

histone de-acetylase, deacetylated histones to pack them tightly together

Question 32

Genomic imprinting

Answer 32

Parent derived chromosomes are epigenetically marked (imprinted = turned off)

Question 33

Prader-Willi syndrome

Answer 33

Microdeletion of paternal chromosome, maternal chromosome has genomic imprinting. Paternal deletion results in no active genes. Sym: short, mental retardation, hypogonadism, emotional lability, unregulated appetite

Question 34

Angelman Syndrome

Answer 34

Microdeletion of chromosome that is maternally imprinted. Sym: Microcephaly, seizures, emotional exuberance, attnetion problems, motor problems

Question 35

Multifactorial disorders

Answer 35

Phenotype is affected by genotype and enviromental factors. Ex: obesity, Diabetes type 2, atherosclerotic heart disease

Question 36

Threshold model

Answer 36

Underlying genetic liability distribution in population which must be reached for phenotype to be seen

Question 37

Concordance study in twins

Answer 37

Measure hereitability of disease (1= one twin has it the other twin has 100% chance of having it)

Question 38

Monozygotic twin

Answer 38

genetically identical

Question 39

Dizygotic twin

Answer 39

share 50% of chromosome (like siblings)

Question 40

Enviromental factors

Answer 40

outdoor, indoor, occupational, consumption

Question 41

Barker hypothesis

Answer 41

Adverse events in fetal life and early childhood establish increased risk of disease in adult life

Question 42

Sensitivity

Answer 42

Proportion of true positives accurately detected = true positive/ (true pos. + false neg.)

Question 43

Specificity

Answer 43

Proportion of true negatives accurately detected = true neg./ (false pos. + true neg)

Question 44

Positive predictive value

Answer 44

Portion of those that are actually positive who test positive = true pos./ (true + false positive)

Question 45

Negative predictive value

Answer 45

Portion of those who are actually negative that test negative = true neg. / (true + false negative)

Question 46

Loss of heterozygosity

Answer 46

2nd mutation (often gross event) leading to both alleles being mutated (1st is often inherited or somatic)

Question 47

Knudsen's 2 hit hypothesis

Answer 47

1) 1st is inherited, 2nd is gross chromosomal change 2) normal --> very rare 1st event, frequent 2nd event