IMMS genetics

Question 1

genotype

Answer 1

genetic constitution of an individual

Question 2

phenotype

Answer 2

appearance of an individual (physical, biochemical, physiological)
interaction of environment and genotype

Question 3

allele

Answer 3

one or more altenative forms of a gene at a specific locus

Question 4

polymorphism

Answer 4

frequent hereditary variations at a locus

Question 5

homozygous

Answer 5

identical alleles at a given locus (affected)

Question 6

heterozygous

Answer 6

two different alleles at a given locus (unaffected, carriers)

Question 7

hemizygous

Answer 7

only one allele refers to a locus on a X chromosome in a male

Question 8

autosomal dominant inheritance

Answer 8

disease which is manifest in the heterozygous state

Question 9

karyotype

Answer 9

the number and visual appearance of the chromosomes in the nuclei of an organism or species

Question 10

autosomal recessive inheritance

Answer 10

disease which manifests in the homozygous state

Question 11

X linked recessive inheritance

Answer 11

caused by pathogenic variants in genes on the X chromosome

Question 12

Properties of mitochondrial inheritance

Answer 12

maternal

Question 13

what are multifactorial genetic conditions

Answer 13

diseases that are due to a combination of genetic and environmental factors

Question 14

mendelian inheritance

Answer 14

pattern of inheritance following the laws of segregation and independent assortment

Question 15

what is Mendel’s 2nd law

Answer 15

law of independent assortment
- each pair of genes separate independently of each other in production of sex cells.

( gene pairs on separate chromosomes assort independently at meiosis)

Question 16

autosome

Answer 16

any chromosome other than the sex chromsomes, that occurs in pairs in diploid cells

Question 17

recessive

Answer 17

manifest only in homozygotes

Question 18

allelic heterogeneity

Answer 18

lots of different variants in one gene

Question 19

what is mendelian inheritance

Answer 19

autosomal vs sex linked

dominant vs recessive

Question 20

what is non- mendelian inheritance

Answer 20

imprinting
mitochondrial inheritance
multifactorial

Question 21

what are the typical features of autosomal recessive inheritance

Answer 21

• affected individuals only in a single generation
• males and females affected in equal proportions
• parents can be related (consanguineous)

Question 22

consanguinity

Answer 22

reproductive union between 2 relatives (represented as double lines on pedigree)

Question 23

autozygosity

Answer 23

homozygosity by descent

(inheritance of the same altered allele through 2 branches of the same family

Question 24

Autosomal recessive, what is chance of offspring being affected, 2 carrier parents

Answer 24

25%

Question 25

autosomal dominant inheritance

Answer 25

disease manifests in the heterozygous state (only one affected gene needed)

Question 26

what are the typical features of autosomal dominant

Answer 26

- affected individuals in multiple generations - male and females affected in equal proportions - transmission by individuals of both sexes, to both sexes

Question 27

penetrance

Answer 27

the percentage of individuals with a specific genotype showing the expected phenotype

Question 28

expressivity

Answer 28

refers to the range of phenotypes expressed by a specific genotype

Question 29

anticipation

Answer 29

whereby a genetic disorder affects successive generations earlier or more severely (usually due to expansion of unstable triplet repeat)

Question 30

somatic mosaicism

Answer 30

genetic fault present in only some tissues in body

Question 31

gonadal mosaicism

Answer 31

genetic fault present in gonadal tissue

Question 32

late onset

Answer 32

condition not manifest at birth (congenital), classically adult onset

Question 33

sex limited

Answer 33

condition inherited in AD pattern that seems to affect one sex more than another

Question 34

X linked inheritance

Answer 34

genes carried on X chromosome

Question 35

typical features of X linked inheritance

Answer 35

usually only males affects transmitted through unaffected females no male to male transmission

Question 36

lyonization (x- inactivation)

Answer 36

process by which one of the X chromosome can be activated in females

Question 37

X linked inheritance | will an affected male have carrier daughters

Answer 37

yes

Question 38

Autosomal dominant | if both parents are unaffected, can children be carriers or affected

Answer 38

NO good way to spot on pedigrees

Question 39

imprinting

Answer 39

epigenetic phenomenon that causes genes to be expressed in a parent of origin specific manner mother affected allele causes a different disease to a father affected allele

Question 40

homoplasmy

Answer 40

eukaryotic cell whose copies of mitochondrial DNA are all identical

Question 41

heteroplasmy

Answer 41

there are multiple copies of mitrochondria DNA in each cell

Question 42

what causes mitrochondria genetic disease

Answer 42

mutations in the mitrochondiral DNA or in nuclear genes (then imported to mitrochondria)

Question 43

what does a diamond and small circle mean on a pedigree

Answer 43

diamond- sex unknown | small circle- abortion/ still birth

Question 44

do inherited cancers require 1 or 2 mutations to become malignant

Answer 44

1 sporadic cancers = 2

Question 45

variable expression

Answer 45

when one genotype can produce a wide range of different phenotypes

Question 46

sex limitation

Answer 46

genes present in both sexes but only expressed in one, remains turned off in the other

Question 47

what bases form a start codon

Answer 47

AUG

Question 48

what are numerical chromosome abnormalities

Answer 48

trisomy (47, XX +21) monosomy (45 X) polyploidy (more than two paired (homologous) sets of chromosomes)

Question 49

what are structural chromosomal abdnormalities

Answer 49

- translocation (portion of chromsome breaks off and attaches to another chromsome) - inversion - duplication - deletions

Question 50

what is the name for looking at chromsome abnormalities

Answer 50

Cytogenetics

Question 51

genetic polymorphism

Answer 51

occurrence of multiple alleles at a locus

Question 52

how can multiple proteins get made from the same DNA

Answer 52

alternative splicing of the pre-MRNA | exon shuffling

Question 53

what are the types of genetic variant (general)

Answer 53

duplications of genes or part of genes deletions (whole gene or some exons) variants within the regulatory sequence splice site variants

Question 54

what is a non-sense variant

Answer 54

introduce premature stop codon (out of frame deletion produces a stop codon)

Question 55

what is a miss-sense variant

Answer 55

single base substitution and changes the type of amino acid in the protein.

Question 56

difference between out of frame and frame deletion

Answer 56

out of frame- reading frame is completely disrupted (not a multiple of 3 bases are deleted) in frame- multiple of 3 DNA bases are deleted so an entire codon is deleted, frame shift does not occur

Question 57

splice site variant

Answer 57

affects the accurate removal of an intron

Question 58

locus heterogeneity

Answer 58

variants in different genes give the same clinical condition

Question 59

Multifactorial diseases are due to an interaction of genes with environment, what are the embryonic environmental factors

Answer 59

drugs and chemicals maternal infections physical agents maternal illness

Question 60

Multifactorial diseases are due to an interaction of genes with environment, what are the post natal environmental factors

Answer 60

``` type 2 diabetes (obesity) lung cancer (smoking) ```

Question 61

what is the difference between screening test and diagnostic test?

Answer 61

screening test- process of identifying people with an inc chance of condition diagnostic test- confirms whether disease is present or not

Question 62

when does crossing over occur

Answer 62

prophase I

Question 63

what is an example of a super secondary structure

Answer 63

zinc finger