D3.2 Inheritance

Question 1

Define Gamete

Answer 1

Haploid cells that fuse together at fertilization to produce a single cell zygote

Question 2

Define Zygote

Answer 2

Diploid cell produced at fertilization when gametes fuse. Contain two chromosomes of each type.

Question 3

Define P, F1 and F2

Answer 3

P: parent
F1: first filial
F2: second filial

Question 4

Process of experimentally performing a genetic cross in flowering plants using cross pollination and self pollination

Answer 4

Cross pollination: One plant fertilizing with ovules of another plant of the same species. Promotes genetic diversity.

Self pollination: One plant fertilizing with ovule of the same plant. Creates genetically similar offspring.

Select parent plants. Remove anther from female parent’s plant to prevent self pollination. Enclose flower to prevent external pollination. Use a small brush to transfer pollen from one plant to other.

Question 5

Difference between gene and allele

Answer 5

Gene is a sequence of DNA that codes for a RNA or protein product. Located on chromosomes.

Alleles are different versions of the same gene. may be difference of one or multiple base in sequence

Question 6

Define Phenotype

Answer 6

Observable trait or characteristic of an individual

Question 7

Phenotype determined by genotype only

Answer 7

ABO blood group

Question 8

Phenotype determined by environment only

Answer 8

Scars

Question 9

Phenotype determined by both genotype and environment

Answer 9

Height

Question 10

Define Dominant allele

Answer 10

Gene producing a certain phenotype even if individual only has one copy. Capital letter.

Question 11

Define Recessive allele

Answer 11

Variation of a gene that must be homozygous when inherited in order to be expressed in phenotype. Lowercase letter.

Question 12

Cause of a allele being dominant

Answer 12

Only one copy of allele needed to make enough of protein coded for by the gene.

Question 13

Define Phenotypic plasticity

Answer 13

Ability of organisms responding to their environment to vary their gene expression and therefore traits.

E.g. melanin production when sunlight hits skin.

Question 14

Why do genetic diseases usually appear unexpectedly

Answer 14

Genetic disease usually caused by recessive allele of a gene. If both parents are carriers, they may not have the disease if heterozygous, but offspring may have it (25% chance)

E.g. Phenylketonuria PKU

Question 15

Consequences of Phenylketonuria

Answer 15

Normal allele codes for an enzyme that converts the amino acid phenylalanine to tyrosine.

PKU causes tyrosine deficiency and excessive amount of phenylalanine.
Nerve cells in developing brain sensitive to phenylalanine levels; can cause brain damage.

Question 16

Treatment for PKU

Answer 16

Diet containing little to no phenylalanine.

Question 17

Define Single nucleotide polymorphism (SNP)

Answer 17

Variation at a single position in DNA sequence among individuals.

Question 18

Define Gene pool

Answer 18

Collection of all genes and alleles of those genes within a population.

Question 19

Explain why any number of alleles of a gene can exist in the gene pool but an individual only inherits two alleles.

Answer 19

They inherit one from the father and another from the mother.

Question 20

Describe ABO blood groups as an example of complete dominance and codominance.

Answer 20

Alleles I^A and I^B show complete dominance over i

Alleles I^A and I^B show codominance

Question 21

Define Sex Linkage

Answer 21

Gene located on a sex chromosome.

Most likely from X chromosome since more genes on X than Y.

Question 22

Consequence of Hemophilia

Answer 22

Normal hemophilia alleles provide instructions for proteins that work together in blood clotting process.

Mutated hemophilia does not allow for blood clotting, leading to continuous bleeding that can be difficult to control.

Question 23

Outcome of allele segregation during meiosis

Answer 23

Two alleles of a single present in a diploid parent will separate from each other and be distributed to each haploid gamete.

Question 24

Describe random orientation of chromosomes and the resulting independent assortment of unlinked genes during meiosis I.

Answer 24

Each homologous pair of chromosomes forms a bivalent on the equator of the cell during metaphase I of meiosis.

Each of the chromosomes of the bivalents move to different pole of the cell during anaphase I. Pole attachment is random.

Question 25

Define Gene Locus

Answer 25

Specific position of gene on one of the 22 types of autosome