Genetics

Question 1

what is karyotype

Answer 1

display of individuals set of chromosomes, arranged in numerical order

Question 2

what is karyotype used for

Answer 2

identifying large abnormalities in chromosome structure or number (trisomy 21)

Question 3

what is genotype

Answer 3

compostion of genes, carries genetic information, expressed in alleles (BB, Bb, bb) or actual DNA sequence

Question 4

what is phenotype

Answer 4

observable traits/the way a gene is expressed (high, eye colour)

Question 5

what is an autosome

Answer 5

chromosome that is the same in males an females

Question 6

what is an autosomal dominant gene

Answer 6

affected gene is dominant over non affected - if heterozygous, affected allele will produce phenotype

Question 7

what is autosomal recessive gene

Answer 7

affected gene is recessive, if heterozygous person is carrier but unaffected

Question 8

what is x-linked inheritance

Answer 8

x chromosome gene isn’t working properly, more commonly affects males as they only have one x chromosome

Question 9

what is polygenic inheritance

Answer 9

traits in variation caused by combined effects of multiple genes

Question 10

what is multifactorial inheritance`

Answer 10

environmental factors cause variation in the trait, influenced by genes as well as stress/exercise etc

Question 11

what is aneuploidy

Answer 11

a condition where a person has an additional or missing chromosomes

Question 12

what is non-disjunction

Answer 12

failure of chromosomes to separate properly during meiosis or mitosis, resulting in daughter cells with an abnormal number of chromosomes

Question 13

what is turner syndrome

Answer 13

sex chromosome aneuploidy - X

characteristics: short, infertal, congenital abnormalities (cardiac/renal), normal intelligence

Question 14

what is klinefelter syndrom

Answer 14

sex chromosome aneuploidy - XXY

characteristics: tall, gynecomastia, hypogonadism, infertility, learning difficulties

Question 15

what is XYY

Answer 15

sex chromosome aneuploidy, learning difficulties, no dysmorphic features, normal fertility, behaviour issues (ADD, hyperactivity, impulsiveness)

Question 16

what are examples of chomosome anomalies

Answer 16

deletion/dupications: large pieces of extra or missing chromosomal material

translocations/inversions: misplaced pieces of chromosome material

Question 17

what is the process from DNA to mRNA

Answer 17

transcription

Question 18

what is the process from mRNA to protein

Answer 18

translation

Question 19

what are examples of autosomal dominant genetic diseases

Answer 19

achondroplasia, marfan syndrom, huntington’s disease, hypertropick cardiomyopathy, hereditary breast/ovarian cancer

Question 20

what are examples of autosomal recessive genetic diseases

Answer 20

cystic fibrosis, sickle cell anemia, tay sachs disease, phenylkenonuria (PKU), heretidary hemochromatosis

Question 21

what are x -linked genetic diseases

Answer 21

duchenne muscular dystrophy, fabry disease, hemophilia, fragile x syndrome, x-linked adrenoleukodystrophy

Question 22

what is variable expressivity

Answer 22

not all family members affected by a genetic disease will have the same signs & symptoms or course of disease

Question 23

what is incomplete penetrance

Answer 23

not all gene carriers will have the disease - ex) BRCA gene mutation means you are at higher risk of getting cancer, but not everybody with that gene gets cancer.

A gene that clinically manifests in everybody is 100% penetrant (although it still may have variable expressivity)

Question 24

what is fluorescence in situ hybridization (FISH) useful for

Answer 24

detecting submicroscopic deletions/duplications or aneuploidy

Question 25

what is karyotyping useful for

Answer 25

large chromosome deletions/duplications, chromosome rearrangements (translocations) or aneuploidy (trisomy)

Question 26

what is chromosomal microarray useful for

Answer 26

the smallest submicroscopic deletions/duplications, aneuploidy

Question 27

what is molecular genetic testing and what is it used for

Answer 27

it is the analysis of human DNA, down to the individual base units, andis used to detect heritable disease-related gene mutations for clinical purposes