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Biology > Genetics > Flashcards

Genetics Flashcards

1
Q

what are genes? what are they made of?

A

They code all the characteristics of an individual.

They are made of DNA.

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2
Q

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

A

Located in the nucleus of a cell

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

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3
Q

what are chromosomes?

A

long threads in the nucleus

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4
Q

how many chromosomes are in each cell in a human?

A

46 =, 23 from each parent.

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5
Q

what are different versions of the same gene called?

A

alleles

e.g. eye colour

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6
Q

what is a genotype?

A

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

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7
Q

what is a phenotype?

A

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

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8
Q

what is a dominant gene?

A

An allele that always expresses itself when if it is present

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9
Q

what is a recessive gene?

A

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

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10
Q

what is a homozygous gene?

A

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

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11
Q

what is a heterozygous gene?

A

Both the alleles for a gene are different

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12
Q

what is codominance?

A

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

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13
Q

how are genetic diseases caused?

A

by a faulty allele.

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14
Q

How is cystic fibrosis caused? and What is it?

A

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.

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15
Q

which human blood groups are co dominant?

A

A and B

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16
Q

which human blood group is recessive?

A

O

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17
Q

what is polygenic inheritance?

A

causes a range of phenotypes

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18
Q

How is gender inherited?

A

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

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19
Q

what is cell division?

A

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

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20
Q

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

A

Mitosis - growth and repair

Meiosis - making gametes

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21
Q

what does mitosis produce? what are the cells?

A

Produces genetically identical cells.

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

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22
Q

what occurs in meiosis?

A

cells divide twice to produce 4 cells.

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23
Q

what is random fertilisation?

A

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

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24
Q

what is selective breeding?

A

Involves humans selecting parent organisms with desired characteristics.

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25
Q

why does selective breeding have to occur over many generations?

A

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

26
Q

how is selective breeding different to natural breeding?

A

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

27
Q

what is genetic variation?

A

They have different combinations of alleles inherited from their parents.

28
Q

give an example of a bacteria that is resistant to antibiotics

A

MRSA

29
Q

what is a mutation?

A

a random change to the DNA

30
Q

what is another name for genetic modification?

A

Genetic engineering

31
Q

what does genetic engineering involve?

A

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

32
Q

what is a restriction enzyme?

A

cuts DNA in a specific place

33
Q

what is transgenic?

A

an organism containing a gene from another species

34
Q

what is a vector?

A

something that transfers the gene

35
Q

give some examples of vectors

A

virus

plasmid

36
Q

what is a ligase enzyme?

A

sticks pieces of DNA together.

37
Q

how is genetically modified bacteria grown?

A

in large fermenters

38
Q

what is a fermenter?

A

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

39
Q

what are the ideal conditions for bacteria growth?

A

warmth
oxygen
glucose
amino acids

40
Q

why does a fermenter need a water cooled jacket?

A

to remove excess heat

41
Q

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

A

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

42
Q

why is the fermenter sterilised with steam?

A
  • steam will kill all bacteria

- no chemicals in it so no chemical residue which could affect the fermenter

43
Q

what are the benefits of genetically modified plants?

A
  • 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
44
Q

what is DNA made up of?

A

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

45
Q

what does a match with

A

a - t

46
Q

what does c match with

A

c - g

47
Q

how many bases are on a DNA code

A

3

48
Q

what is transcription?

A

gene is copied from DNA to mRNA

49
Q

when does a mutation occur?

A

when the base sequence of DNA is changed

50
Q

what do mutations affect?

A

the phenotype of an organism

51
Q

what are the causes of mutations?

A

ionising radiation

chemical mutagens

52
Q

what are stem cells?

A

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

53
Q

how do cells differentiate (become specialised)

A

switch some genes on and some genes off.

54
Q

how many types of stem cell are there?

A

2

55
Q

where do embryonic stem cells come from?

A

come from a 4 or 5 day old embryo

56
Q

where do adult stem cells come from?

A

exist throughout the body in different types of tissue

57
Q

what is therapeutic cloning and why is it used?

A
  • copying the patient’s own stem cells

- their body will not reject a stem cell implant

58
Q

what are the advantages of stem cells in medicine?

A

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
59
Q

what are the disadvantages of Sten cells in medicine?

A
  • infection
  • organ damage
  • infertility
  • stem cell failure
60
Q

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

A

the embryo could develop into a human being

61
Q

what is a clone?

A

an organism that is genetically identical to another organism

62
Q

why are transgenic animals cloned?

A

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

Biology (20 decks)

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