Genetics

Question 1

two ways of reproducing

Answer 1

asexually and sexually

Question 2

traits of asexual repoduction

Answer 2

• division is by mitosis
• onne parent
• no genetic variation- all are identical
• divides once to make two cells

Question 3

where is asexual rerproduction common

Answer 3

• small organisms like fungi, small plants and bacteria
• large plants like daffodils
  -body cells

Question 4

traits of sexual reproduction

Answer 4

• involvlves 2 parent sex cells- gametes- fusig together to form a zygote
• offspring will have variation

Question 5

what are gametes and how are they formed

Answer 5

• gamete are sex cells
• formed by meiosis
• examples are sperm and egg cells

Question 6

what does meiosis form

Answer 6

sex cells

Question 7

where does meiosis take place

Answer 7

reproductive organs
- eg ovaries and testes

Question 8

what happens in meiosis

Answer 8

1. all chromasomes in the cell are copied/doubled so there are four of each chromasome
2. the cell dviides in two
3. cell dviides a secod time to make four gametes- all of these cells will have one set of chroasomes rather than pairs

Question 9

what happens at fertilisation

Answer 9

• two gametes join together
• both have 23 chromasome rather than 46 so join to make 23 pairs
• the combination of genes in the chromasomes is uique
• the new cell then begins to divide by mitosis to form an embryo

Question 10

what are chromasomes made up of

Answer 10

long molecules of DNA

Question 11

what are genes

Answer 11

small sections of dna
- this is where genetic info is stored

Question 12

what is DNA

Answer 12

• inside chromasomes
• long two strands of polymer molecules that twist
• forms a double helix structure

Question 13

what do genes do

Answer 13

• stores genetic info
• each gene codes for a particular sequence of amino acids to make a specific protien
• these protiens control the make of enzymes and specialised cells and tissues which form organs

Question 14

whats a genome

Answer 14

the entire genetic material of an organism

Question 15

explain the mitochondria and dna

Answer 15

• the mitochondria has its own DNA
• you inherit it always from your mother
• it comes from the egg

Question 16

what can understandig the human genome do

Answer 16

• helps uderstand iherited disorders eg cystic fybrosis
• undertsand ad identify genes that cause certain diseases
• helps choose optimal treatment
• trace human migration patterns through similarities in dna

Question 17

what are alleles

Answer 17

different variants of genes you inherit

Question 18

homozygote

Answer 18

someone with two of the same alleles for a characteristic
eg BB/ two blue eye genes

Question 19

heterozygote

Answer 19

someoe with dif alleles for a charcateristic
eg. Bb two dif eye colours

Question 20

genotype

Answer 20

genetic makeup of a person in a particular characteristic/ the alleles they have in a gene
- eg Bb or bb

Question 21

phenotype

Answer 21

the phsyical appearance of an individual regarding a characteristic
eg. someone visably has blue eyes

Question 22

whats a dominent allele

Answer 22

an allele that will always be expressed in the phenotype when present

Question 23

whats a recessive allele

Answer 23

can only be expressed on the penotype/ control the protiens made if it is the only allele present

Question 24

whats a genetic cross

Answer 24

considering the offspring from two parent cells
- often modelled using a punnet square

Question 25

what does a punnet square show

Answer 25

- alleles carried by each parent - all possible gametes to be formed by these - how these may combine to form gentotypes and phenotypes

Question 26

female sex chromasomes

Answer 26

XX

Question 27

male sex chromasomes

Answer 27

XY

Question 28

WHAT IS POLYDACTYLY

Answer 28

- extra fingers and toes - caused by a dominent allele from a parent

Question 29

what is cystic fibrosis

Answer 29

-affects organs such as lungs, digestion and reproduction - cell membranes dont allow substances to pass resultung in thick mucus build up particually in the lungs and in the area where the pancrease would release enzymes - infertility

Question 30

is cystic fibrosis recessive

Answer 30

- yes it comes from a recessive allele - if two w the allele have a child theres a 25% chance the child has it but a 75% chance they would carry -

Question 31

how to treat cystic fibrosis

Answer 31

- antibiotics to clear lungs of mucus - enzymes to replace the ones that cant be secreted by the pancreas

Question 32

what does genetic screening do

Answer 32

helps people see whether they carry a faulty allele can help see if foetuses carry an inherited disorder can be screened during ivf before implantation

Question 33

ways to screen a foetus

Answer 33

- amniocentesis - chorioic villus sampling - screen during ivf before foetus is implanted

Question 34

process of amniocentesis

Answer 34

- around 15 weeks of pregnacy - takes fluid from fetus - screens fetal cells in the fluid

Question 35

process of chorioic villus sampling

Answer 35

- earlier than amniocentesis at 10 weeks - takes small sample of tissue - provides fetal cells

Question 36

concerns of genetic screening

Answer 36

- increases risk of miscarriage - can give false positives or egatives - difficult descision if to terminate a pregnancy, can be distressing - expnsive - concerns it increases a need for 'designer babies' and the abolition of disabilities/appearance/geder - no way to cure the disorder

Question 37

which cells fuse in sexual reproduction in plants

Answer 37

pollen and egg

Question 38

what is bacterias reproductive process called

Answer 38

binary fission

Question 39

what is haploid

Answer 39

a cell has half the normal genetic material eg a gamete

Question 40

positive aspects of embryo/genetic screening

Answer 40

- reduces suffering of children - saves people money of treating inherited disorders

Question 41

what is IVF

Answer 41

fertiliisng and growing an egg in a lab before reincerting into the womb