L2: Mendelian Genetics I

Question 1

Genome organisation in humans

Answer 1

2 matching homologous sets of chromosomes, 2 copies of each gene

Question 2

Genome organisation in bacteria

Answer 2

1 set of chromosome, 1 copy of every gene

Question 3

Define gene

Answer 3

Section of DNA that codes for a protein

Question 4

Define alleles

Answer 4

Different forms of the same gene

Question 5

Define genotype

Answer 5

genetic composition of an organism

Question 6

Define homozygous/homozygote

Answer 6

Same alleles

Question 7

Define heterozygous/heterozygote

Answer 7

Different alleles

Question 8

Define phenotype

Answer 8

Observable properties of an organism produced by a combination of genotype & environment

Question 9

Define wild type

Answer 9

(“Normal”) Genotype/phenotype that is most commonly found in nature

Question 10

What can different alleles generate?

Answer 10

Different types of proteins

Question 11

Why are some alleles dominant?

Answer 11

They encode a disruptive protein that can block the activity of the normal protein

Question 12

Why are some alleles recessive?

Answer 12

They encode a non-functional protein which can be covered by a functional protein made from a wild-type allele

Question 13

Cell division in mitosis

Answer 13

1 diploid cell to 2 diploid cells

Question 14

Cell division in meiosis

Answer 14

1 diploid cell to 4 haploid cell

Question 15

Stages of mitosis

Answer 15

1) interphase
2) prophase
3) prometaphase
4) metaphase
5) anaphase
6) telophase

Question 16

Describe interphase

Answer 16

Chromosomes uncoiled, forming chromatin

Question 17

Describe prophase

Answer 17

Chromosomes coil up & condense, centrioles divide & move apart

Question 18

Describe prometaphase

Answer 18

Doubled chromosomes, centrioles in opposite poles, spindle fibres form

Question 19

Describe metaphase

Answer 19

Centromeres align

Question 20

Describe anaphase

Answer 20

Centromeres split & daughter chromosomes migrate to opposite poles

Question 21

Describe telophase

Answer 21

Daughter chromosomes arrive at poles, cytokinesis starts

Question 22

Describe cytokinesis

Answer 22

Cell division

Question 23

Meiosis

What gametes does a homozygous parent generate?

Answer 23

4 haploid gamete, all the same type

Question 24

Meiosis

What gametes does a heterozygous parent generate?

Answer 24

4 haploid gametes, 2 different types

Question 25

Define monohybrid cross

Answer 25

Both parents are homozygous resulting in zygote receiving 1 allele from each parent

Question 26

Importance of using a punnett square

Answer 26

Organise gametes to produce all possible combinations

Question 27

Define dihybrid cross

Answer 27

2 genes where each controls 1 phenotype

e.g
Gene 1 affects smoothness
Gene 2 affects colour

SSYY x ssyy

S: smooth
Y: yellow

s: wrinkled
y: green

Question 28

Features of the F1 x F1 dihybrid cross

Answer 28

Equal chances of getting each gamete but differences in phenotypic ratios

Question 29

Usual ratio for dihybrid cross

Answer 29

9:3:3:1

Question 30

Usual ratio for monohybrid cross

Answer 30

3:1

Question 31

What does random alignment of chromosomes in meiosis I mean for maternal & paternal copies of genes?

Answer 31

Assigned to gametes in random combinations