Genetics

Question 1

Abiotic Factor

Answer 1

Non-living environmental factor, such as temperature, pH, humidity, carbon dioxide concentration

Question 2

Acetylation

Answer 2

Addition of an acetyl group COCH3

One of several histone modifications that can control transcription

Question 3

Addition

Answer 3

Type of gene mutation in which a base is added, causing a frame shift in one direction so that many codons are changed

Question 4

Adult stem cell

Answer 4

Multipotent cells found only in specific adult tissues, including bone marrow, that can only nature into limited number of cell types

Question 5

Autosome

Answer 5

Any chronosome that is not a sex-determining chromosome

Question 6

In meiosis, why do X and Y chromosomes pair up differently

Answer 6

Don’t form a typical bivalent
X and Y are different sizes and shapes and lengths
Chromatids are unable to line up and firm bivalent because most of the length is not homologous and short pairing region

Question 7

Gene

Answer 7

A section of DNA that codes for a specific protein

Question 8

Genotype

Answer 8

The genetic constitution of an organism

All the alleles it possesses

Question 9

Genepool

Answer 9

All the alleles within an interbreeding population at a specific time

Question 10

Population

Answer 10

All the individuals of the same species that occupy the same area at the same time

Question 11

Phenotype

Answer 11

The expression of observable characteristics of an organisms genotype and its interaction with its environment

Question 12

Locus

Answer 12

The position of a gene on a chromosome

Different alleles for same gene are found in same loci on homologous chromosomes

Question 13

Homozygous

Answer 13

Most organisms are diploid

Having two copies of the same allele of a gene

Question 14

Heterozygous

Answer 14

Most organisms are diploid
Having two different copies of an allele of a gene
Usually phenotype isn’t a mixture of them both and one is expressed in it only

Question 15

Dominant allele

Answer 15

Always expressed in the phenotype regardless of being homozygous or heterozygous

Question 16

Recessive allele

Answer 16

Only expressed in the phenotype if genotype is homozygous

Question 17

Codominant allele

Answer 17

Equally expressed within the phenotype

Question 18

Diploid

Answer 18

Adult stem cells (somatic) are usually diploid
Two copies of a gene
Can be same of different (homozygous or heterozygous)

Question 19

Genetic cross

Answer 19

Diagrams that show the way in which alleles are inherited from one generation to the next
Allele represented by a letter
Dominant = Uppercase
Recessive = Lowercase

Question 20

Expected phenotype offspring for monohybrid (heterozygous parents)

Answer 20

3:1

Question 21

Expected phenotype offspring for codominance (heterozygous parents)

Answer 21

1:2:1

Question 22

Expected phenotype offspring for dihybrid (heterozygous parents)

Answer 22

9:3:3:1

Question 23

Expected phenotype offspring for epistasis (heterozygous parents)

Answer 23

9:4:3
15:1
9:7
Ratio adds up to 16 but not 9:3:3:1

Question 24

Expected phenotype offspring for autosomal linkage (heterozygous parents)

Answer 24

3:1 if there is no crossing over
4:4:1:1 due to formation of recombinant alleles
4 phenotypes not showing 9:3:3:1

Question 25

Haploid

Answer 25

Only one copy of a gene

Gametes produced from meiosis to prepare for fertilisation in sexual reproduction

Question 26

Hardy Weinberg equations

Answer 26

P+q=1

P2+2Pq+q2=1

Question 27

P+q=1
P?
q?

Answer 27

Frequency of the dominant allele

Frequency of the recessive allele

Question 28

P2+2Pq+q2=1
P2?
2Pq?
q2?

Answer 28

Frequency of the homozygous dominant individuals
Frequency of the heterozygous individuals
Frequency of the homozygous recessive individuals

Question 29

Hardy Weinberg principle predicts…

Answer 29

The allelic frequencies of a particular gene from one generation to the next will remain constant
Providing there is no migration, gene mutations or selection

Question 30

Hardy Weinberg assumes…

Answer 30

No migration (isolated gene pool no gene flow in/out)
No random gene mutations
No selection for or against allele

Population size is large
Mating/fertilisation should be random

Question 31

Monohybrid Inheritance

Answer 31

Inheritance of a single gene that determines a single characteristic

Question 32

Order when working through breeding individuals

Answer 32

Phenotype
Genotype
Gametes circles
Cross
Genotypes
Genotype ratio
Phenotypes
Phenotype ratio

Question 33

Codominance (monohybrid)

Answer 33

No dominant/recessive relationship
Heterozygous individuals produce an intermediate phenotype
C^R and C^W

Question 34

Multiple alleles (monohybrid)

Answer 34

Several alleles in the population like black brown ginger blonde
H^b H^bl H^g etc

Question 35

Sex linked rules for dads and daughters to prove its not sex linked

Answer 35

If a daughter is affected
And father is not
And it is recessive
It is not sex linked

Question 36

Sex linked rules for mothers and sons to prove it is not sex linked

Answer 36

If son is affected
And mother is not
And it is dominant
Then it is not sex linked

Question 37

Crossing over

Answer 37

Prophase 1
Bivalent forms between 2 homologous chromosomes
Chiasmata and equal lengths of non sister chromatids exchanged
New recombinant alleles formed
5 to 10% only

Question 38

Genetic linkage

Answer 38

Tendency of genes located close to each other on the same chromosome to be inherited together during meiosis and appear in the same gamete

Question 39

Epistasis

Answer 39

Interaction between two genes where one allele affects/influences the expression of another
Can lead to graduation of a phenotype
Can occur in metabolic pathways

Question 40

Why isn’t the expected phenotypic ratio always observed

Answer 40

Random fertilisation of gametes
Small sample size
Linked genes, sex linkage
Epistasis
Lethal genotypes