Topic 1

Question 1

Classical Genetics

Answer 1

inheritance of traits
“Transmission genetics” discovered by Gregor Mendel

Question 2

Molecular Genetics

Answer 2

study of DNA & RNA structure, function, and molecular control of gene expression

Question 3

Evolutionary/Population Genetics

Answer 3

interaction of genes and gene pools and the environment

Question 4

Gene

Answer 4

hereditary unit of information

Question 5

Gene Locus

Answer 5

positon of a gene on the chromosome

Question 6

Allele

Answer 6

one of two (or more) versions of a gene that differs in sequenece and exists at the same loci

Question 7

Genotype

Answer 7

combinations of alleles for any gene

Question 8

Phenotype

Answer 8

observable characteristics, as determined by the genotype

Question 9

Wildtype (phenotype)

Answer 9

most prevalent phenotype in the population under natural conditions

Question 10

Mutant (phenotype)

Answer 10

a deviation to the wild-type phenotype as a result from an allelic change in the DNA sequence

Question 11

Dominant (phenotype)

Answer 11

phenotype observed in heterozygous individuals (ie. genotype includes both allele variants)

Question 12

Recessive (phenotype)

Answer 12

phenotype observed only in individuals that are homozygous for the recessive allele variant

Question 13

A wild-type phenotype is produced when an organism has two copies of the ______________________, or when one copy is sufficient to meet the ____________________________.

Answer 13

wild-type allele; protein requirements

Question 14

Loss of Function

Answer 14

significant decrease or complete loss of functional gene product

Question 15

Gain of Function

Answer 15

gene product acquires a new function or expression increased above wild-type activity

Question 16

Incomplete Dominance is where…

Answer 16

heterozygous individuals display intermediate phenotypes between either homozygous type

Question 17

Codominance results when there is…

Answer 17

detectable expression for both alleles in the heterozygotes

Question 18

Recessiveness is observed in mutations in genes that are….. The mutate allele is the …

Answer 18

functionally haplosufficient (+/m, where m is the mutate allele)

recessive allele

Question 19

Dominance: In genes that are _________________, in a heterozygote (+/M), the single wild-type allele (+) cannot provide enough prouct for normal function. The mutated allele (M) is the ________________.

Answer 19

haploinsufficient
dominant allele

Question 20

Nomenclature: What does upper case denote?

Answer 20

dominant allele

Question 21

Nomenclature: What does lower case denote?

Answer 21

recessive allele

Question 22

Nomenclature: What do slashes indicate?

Answer 22

alleles for genes on homologous chromosomes

Question 23

Nomenclature: What do semicolons indicate?

Answer 23

genes on non-homologous chromosomes

Question 24

What did Gregor Mendel do?

Answer 24

examined seven traits through crossing and selfing

Question 25

What is Mendel’s 1st Law of Equal Segregation?

Answer 25

Half of gametes carry one member of gene pair, half carry the other member

Question 26

What is a test cross?

Answer 26

cross use to determine the genotype of an individual that is expressing a dominant phenotype (the cross to homozygous recessive)

Question 27

What are the parts of a chromosome?

Answer 27

telomere - ends
centromere - point between both arms
P arm - shorter arm
Q arm - longer arm

Question 28

What is a metacentric chromosome?

Answer 28

centromere is in the centre - both arms of equal length

Question 29

What is an acrocentric chromosome?

Answer 29

centromere is off centre - arms of different legnths

Question 30

What is a telocentric chromosome?

Answer 30

centromere is on one end - only one arm

Question 31

What does “n” refer to?

Answer 31

number of sets of chromosomes (not total number)

Question 32

What does homogametic mean?

Answer 32

matching pair of sex chromsomes (ie. XX)

Question 33

What does heterogametic mean?

Answer 33

no matching pair of sex chromosomes (ie. XY)

Question 34

Sex chromosomes are…

Answer 34

non-autosomes

Question 35

What is the test for sex linkage?

Answer 35

a reciprocal cross - parental cross but switches phenotypes between male and females

Question 36

What does a reciprocal cross explain?

Answer 36

It explains the result of crosses if mutant allele was present on the X chromosomes

Question 37

What is a pedigree analysis?

Answer 37

looking back through family trees and medical records as test crosses are not ethical for humans

• allows us to look for patterns suggesting dominance and sex-linkage

Question 38

What is a propositus?

Answer 38

first member of the family who comes to the attention of a geneticist (usually has a disease)

Question 39

What are the characteristics of an autosomal recessive pedigree?

Answer 39

• disease shows up from unaffected parents (heterozygous - hence carriers of the recessive allele)
• if both parents have the trait, all children will have it
• males and females have equal likelihood of showing the trait, although totals might not be equal

Question 40

What are the characteristics of an autosomal dominant pedigree?

Answer 40

• no skipping of generations occurs – each affected individual MUST have at least one affected parent
• both males and females can transmit mutant allele to both sons and daughters with equal probability
• two affected parents CAN produce unaffected children, but two unaffected parents CANNOT have affected children