Genetics

Question 1

what are genes? what are they made of?

Answer 1

They code all the characteristics of an individual.

They are made of DNA.

Question 2

Where is DNA located in a cell? and in bacteria?

Answer 2

Located in the nucleus of a cell

In the cytoplasm of bacteria as they do not have nucleus.

Question 3

what are chromosomes?

Answer 3

long threads in the nucleus

Question 4

how many chromosomes are in each cell in a human?

Answer 4

46 =, 23 from each parent.

Question 5

what are different versions of the same gene called?

Answer 5

alleles

e.g. eye colour

Question 6

what is a genotype?

Answer 6

The type of alleles present for a particular gene or genes, e.g. Bb

Question 7

what is a phenotype?

Answer 7

The way a gene works or expresses itself, e.g. eye colour

Question 8

what is a dominant gene?

Answer 8

An allele that always expresses itself when if it is present

Question 9

what is a recessive gene?

Answer 9

An allele which ONLY expresses itself when there is no dominant gene present

Question 10

what is a homozygous gene?

Answer 10

Both the alleles for a gene are the same e.g. BB bb

Question 11

what is a heterozygous gene?

Answer 11

Both the alleles for a gene are different

Question 12

what is codominance?

Answer 12

This happens when both allele are expressed, e.g. pink flowers may be the result of codominance between red and white flowers.

Question 13

how are genetic diseases caused?

Answer 13

by a faulty allele.

Question 14

How is cystic fibrosis caused? and What is it?

Answer 14

Caused by a faulty recessive allele involved in making mucus.
The mucus is thick and sticky - increases risk of chest infections. Makes it difficult to create and digest food.

Question 15

which human blood groups are co dominant?

Answer 15

A and B

Question 16

which human blood group is recessive?

Answer 16

O

Question 17

what is polygenic inheritance?

Answer 17

causes a range of phenotypes

Question 18

How is gender inherited?

Answer 18

Gender is determines by the sex chromosomes.

in humans there are 23 pairs or chromosomes, 22 matching pairs and the sex chromosomes x and y

Question 19

what is cell division?

Answer 19

cells divide to make new cells which allows growth and repair.

Question 20

what are the two types of cell division? and what are they for?

Answer 20

Mitosis - growth and repair

Meiosis - making gametes

Question 21

what does mitosis produce? what are the cells?

Answer 21

Produces genetically identical cells.

Diploid because they contain a full set of chromosomes in pairs.

Question 22

what occurs in meiosis?

Answer 22

cells divide twice to produce 4 cells.

Question 23

what is random fertilisation?

Answer 23

The process of fertilisation is random. It depends on which sperm fertilises an egg cell. This causes genetic variation.

Question 24

what is selective breeding?

Answer 24

Involves humans selecting parent organisms with desired characteristics.

Question 25

why does selective breeding have to occur over many generations?

Answer 25

It takes years not to inbreed which can result in harmful recessive alleles being passed on to offspring.

Question 26

how is selective breeding different to natural breeding?

Answer 26

When things are selectively bred a specific outcome is desired, the breeding is monitored while in natural breeding it just happens.

Question 27

what is genetic variation?

Answer 27

They have different combinations of alleles inherited from their parents.

Question 28

give an example of a bacteria that is resistant to antibiotics

Answer 28

MRSA

Question 29

what is a mutation?

Answer 29

a random change to the DNA

Question 30

what is another name for genetic modification?

Answer 30

Genetic engineering

Question 31

what does genetic engineering involve?

Answer 31

cutting a gene out of the DNA of one organism and sticking it into the DNA of another organism.

Question 32

what is a restriction enzyme?

Answer 32

cuts DNA in a specific place

Question 33

what is transgenic?

Answer 33

an organism containing a gene from another species

Question 34

what is a vector?

Answer 34

something that transfers the gene

Question 35

give some examples of vectors

Answer 35

virus | plasmid

Question 36

what is a ligase enzyme?

Answer 36

sticks pieces of DNA together.

Question 37

how is genetically modified bacteria grown?

Answer 37

in large fermenters

Question 38

what is a fermenter?

Answer 38

a larger tank that provides ideal conditions for the growth of bacteria.

Question 39

what are the ideal conditions for bacteria growth?

Answer 39

warmth oxygen glucose amino acids

Question 40

why does a fermenter need a water cooled jacket?

Answer 40

to remove excess heat

Question 41

why does the temperature and pH of a fermenter need to be carefully maintained?

Answer 41

so the enzymes don't denature because then the bacteria would die.

Question 42

why is the fermenter sterilised with steam?

Answer 42

- steam will kill all bacteria | - no chemicals in it so no chemical residue which could affect the fermenter

Question 43

what are the benefits of genetically modified plants?

Answer 43

- solving global hunger, feed more people and can tolerate extreme weather and conditions - environmentally friendly , resistant to insect and weeds etc so less use of pesticides - consumer benefits, better flavour + keeping

Question 44

what is DNA made up of?

Answer 44

a - adenine t - thymine c - cytosine g - guanine

Question 45

what does a match with

Answer 45

a - t

Question 46

what does c match with

Answer 46

c - g

Question 47

how many bases are on a DNA code

Answer 47

3

Question 48

what is transcription?

Answer 48

gene is copied from DNA to mRNA

Question 49

when does a mutation occur?

Answer 49

when the base sequence of DNA is changed

Question 50

what do mutations affect?

Answer 50

the phenotype of an organism

Question 51

what are the causes of mutations?

Answer 51

ionising radiation | chemical mutagens

Question 52

what are stem cells?

Answer 52

undifferentiated ( not specialised ) cells that are capable of developing into many different types of cell.

Question 53

how do cells differentiate (become specialised)

Answer 53

switch some genes on and some genes off.

Question 54

how many types of stem cell are there?

Answer 54

2

Question 55

where do embryonic stem cells come from?

Answer 55

come from a 4 or 5 day old embryo

Question 56

where do adult stem cells come from?

Answer 56

exist throughout the body in different types of tissue

Question 57

what is therapeutic cloning and why is it used?

Answer 57

- copying the patient's own stem cells | - their body will not reject a stem cell implant

Question 58

what are the advantages of stem cells in medicine?

Answer 58

treat a wide range of diseases from cancer to damages tissues - skin cells for burn victims - bone marrow cells for blood cancer - pancreas cells for diabetes

Question 59

what are the disadvantages of Sten cells in medicine?

Answer 59

- infection - organ damage - infertility - stem cell failure

Question 60

why do some people believe that using embryonic stem cells is unethical?

Answer 60

the embryo could develop into a human being

Question 61

what is a clone?

Answer 61

an organism that is genetically identical to another organism

Question 62

why are transgenic animals cloned?

Answer 62

can be given genes to make human proteins to treat diseases.