Mod 5: Critical Q4

Question 1

What are genotypes?

Answer 1

Set of alleles in DNA of an individual organism

Question 2

What are alleles?

Answer 2

Alternative form of a gene

Question 3

How many alleles are inherited by an individual?

Answer 3

2 - one from their father and one from their mother

Question 4

How does variation in a population occur?

Answer 4

One gene having many alleles

Question 5

What are phenotypes?

Answer 5

Observable traits

Question 6

How are phenotypes determined?

Answer 6

Inheritance + effects of an organism’s environment

Question 7

What is an example of a phenotype?

Answer 7

Skin colour -> depends on how much skin pigment (melanin) is produced. Also dependent on exposure to sun. Greater exposure -> More melanin produced

Question 8

How are dominant phenotypes expressed?

Answer 8

If an individual carries at least 1 allele for dominant trait

Question 9

How are recessive phenotypes expressed?

Answer 9

If an individual carries 2 alleles for recessive trait

Question 10

What are heterozygous alleles

Answer 10

One allele dominant (Always EXPRESSED) and one allele recessive

Question 11

What are homozygous alleles

Answer 11

Identical alleles of a gene (2 recessive allele or 2 dominant allele)

Question 12

What is a monohybrid cross?

Answer 12

Hybrid of 2 individuals with homozygous genotypes which results in the opposite phenotype for a certain genetic trait

Question 13

How many chromosomes do humans have?

Answer 13

23 homologous pairs, 46 in total

Question 14

What are sex chromosomes?

Answer 14

• Code for sexual characteristics
• Determine sex of organism (XX - Female, XY - Male)

Question 15

What are autosomes?

Answer 15

Don’t code for any sexual characteristics

Question 16

What is autosomal inheritance?

Answer 16

Patterns in the expression of characteristics which are found on autosomes

Question 17

What are the 3 types of autosomal inheritance?

Answer 17

Dominant/ Recessive
Co - dominant
Incomplete

Question 18

What is sexual inheritance?

Answer 18

Patterns in the expression of characteristics which are found on sex chromosomes

Question 19

What is an example of sexual inheritance?

Answer 19

Y chromosomes have fewer genes than X chromosomes. If male inherits faulty allele on X chromosome, will always be expressed

Question 20

What is X-linked inheritance?

Answer 20

Transmission of genes found on x chromosome

Question 21

How does X-linked inheritance affect male & females differently?

Answer 21

Dominant: Affect gender equally
Recessive: Affect men more. Higher chance of a man inheriting faulty x chromosome

Question 22

What is Y-linked inheritance?

Answer 22

Transmission of genes found on Y chromosome (Only passed from father to son)

Question 23

What is Co-dominance?

Answer 23

When both alleles are expressed in the phenotype

Question 24

What is Incomplete dominance?

Answer 24

Dominant allele is only partially expressed -> Doesn’t completely control phenotype of heterozygous organism

Question 25

What is a pedigree?

Answer 25

Diagram -> shows how traits are passed on over generations

Question 26

What are the applications of pedigrees?

Answer 26

- Identify inheritance patterns of traits - Determine genotype + predict phenotype

Question 27

What are the 4 common inheritance patterns?

Answer 27

- Autosomal dominant - Autosomal recessive - Sex-linked dominant - Sex-linked recessive

Question 28

How do we determine whether a trait is autosomal or sex-linked?

Answer 28

- Sex Autosomal: No. of females affected is similar to affected males Sex-linked: All affected individuals are males

Question 29

How do we determine whether a trait is dominant or recessive?

Answer 29

- Generations Dominant: Appears in every generation Recessive: If parents are affected, all children are affected

Question 30

What is allele frequency?

Answer 30

Relative proportion of a particular allele in a pop.

Question 31

How can we calculate allele frequency?

Answer 31

No. of an allele in a pop./ Total no. of allele in the pop.

Question 32

What is the Hardy-Weinberg model?

Answer 32

Describes & predicts frequencies in a non-evolving pop.

Question 33

What is the Hardy-Weinberg equilibrium?

Answer 33

Allele frequencies will stay the same across generations (when no evolutionary progresses occur)

Question 34

What is the Hardy-Weinberg equation?

Answer 34

Calculates genotype frequencies in a pop. based on given allele frequencies - P^2 + 2pq + q^2 = 1