Genetics - topic 3 (pg 20-28) paper 1

Question 1

meiosis

Answer 1

produces four daughter cells each with half the number of chromosomes
only in gamete producing cells, producing genetically different haploid gametes

Question 2

haploid

Answer 2

one set of chromosomes (me-1-osis)

Question 3

stages of meiosis

Answer 3

the parent cell is a diplod cell (two pairs of chromosomes –> parent cell dividesin two then two again

• before the parent cell divides, each chromosome is copied
• each daughter cell gets a copy of one chromosome form each pair
• each daughter cell has one different haploid set of chromosomes

Question 4

DNA

Answer 4

Deoxyribonucleic acid - genetic material found in the chromosomes in the nucleus of cells

Question 5

gene

Answer 5

short piece of DNA that codes for a specific protein, codes for a characteristic

Question 6

structure of DNA

Answer 6

molecule formed from two strands twisted together in a double helix

Question 7

DNA bases

Answer 7

A(adenine) T(thymine)

C(cytosine) G(guanine)

Question 8

what hols DNA strand together

Answer 8

weak hydrogen bonds

Question 9

DNA structure

Answer 9

DNA is a polymer made of monomers called nucleotides joined together

Phosphate (circle)
        deoxyribose sugar (pentagon)       Base (square)

Question 10

when gametes fuse they form a

Answer 10

diploid zygote

Question 11

allele

Answer 11

different versions of the same gene

Question 12

chromosomes of the same pair have

Answer 12

the same genes in the same order

Question 13

heterozygous

Answer 13

different alleles of the same gene

Question 14

homozygous

Answer 14

same alleles on both chromosomes

Question 15

genotype

Answer 15

shows the alleles in each individual - punnet squares

Question 16

phenotype

Answer 16

the characteristics that are produced - punnet squares

Question 17

dominant

Answer 17

will show when one allele is present in the genotype

Question 18

recessive

Answer 18

will only show when two alleles are present in the genotype

Question 19

pedigree analysis

Answer 19

used to study inheritance of dominant and recessive alleles

predict the chance of someone inheriting a specific allele

Question 20

carriers

Answer 20

have one copy of a faulty allele

Question 21

genotype XX

Answer 21

female chromosomes

Question 22

genotype XY

Answer 22

male chromosomes

Question 23

at fertilisation there is an equal chance of

Answer 23

producing a male or a female

Question 24

variation factors can be

Answer 24

genetic and environmental

Question 25

phenotypic features

Answer 25

hair colour, eye colour

caused by many genes

Question 26

genetic variation

Answer 26

hair colour

eye colour

Question 27

environmental variation

Answer 27

scars

ability to ride a bike

Question 28

genetic and environmental variation

Answer 28

weight

skin colour

Question 29

mutation is created

Answer 29

when subsequent bases in a gene is changed

Question 30

mutations however

Answer 30

• most genetic mutations have no effect on phenotype
• some have a small effect
• a single mutation rarely, significantly affects the phenotype

Question 31

a mutation may cause

Answer 31

• a large change in protein produced
• a small change
• no change

Question 32

mutation in non coding DNA can

Answer 32

increase or decrease ability of RNA polymerase to bind to DNA

Question 33

The Human Genome Project

Answer 33

collaboration between scientists to decode the human genome (order of bases on all human chromosomes)

• completed quickly due to number of scientists working at the same time
• published in 2003
• used for new medicines

Question 34

advantages of the human genome project

Answer 34

• alerting people they are at risk of particular diseases
• distinguishing between differences in diseases like leukaemia, some drugs are beneficial for different forms
• allowing doctor to ‘tailor treatments’ for some diseases to the individual

Question 35

disadvantages of the human genome project

Answer 35

people who were at risk of certain disease like cancer could have claimed more life insurance
- may not be useful to tell someone the risk of a condition with no cure currently