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biology > inheritance, variation and genetics - b6 > Flashcards

inheritance, variation and genetics - b6 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the structure of dna

A

a double helix structure with two strands

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2
Q

what is a chromosome

A

a tightly coiled piece of dna

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3
Q

how many chromosomes does a cell have

A

46, 23 pairs

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4
Q

what is a gene

A

a section of the dna that codes for specific protein

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5
Q

what is the genome

A

the entire genetic material in an organism

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6
Q

what are the benefits of knowing the entire genetic material

A

we can know what genes cause diseases and trace the paths of our ancestors

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7
Q

what is an allele

A

the different versions of a particular gene

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8
Q

what does a homozygous allele mean

A

both alleles from both parents are the same

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9
Q

what does a heterozygous allele mean

A

both alleles are different

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10
Q

what is a genotype

A

the two alleles someone has for a gene

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11
Q

what is a phenotype

A

the characteristics expressed by a genotype

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12
Q

what is the structure of dna

A

a sugar phosphate backbone with bases attached

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13
Q

why is dna considered a polymer

A

because it is made up of the same monomers called nucleotides

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14
Q

what is trasncription

A

copying a single gene of dna into mrna

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15
Q

what is special bout mrna compared to dna

A

its shorter and its only a single strand

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16
Q

what is translation

A

the formation of a sequence of amino acids from a triplet code

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17
Q

what is a chain of amino acids called

A

a polypeptide

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18
Q

what is a mutation?

A

a change to the base codes of dna

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19
Q

what usually increases the risk or a mutation

A

carcinogens and ionising radiation

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20
Q

what are the three types of mutation

A

substitution, insertion and deletion

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21
Q

what is a substitution mutation

A

when a particular base on the dna is replaced

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22
Q

what is a insertion mutation

A

when a base is added to a gene

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23
Q

what is deletion mutation ?

A

when a base is deleted from a gene

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24
Q

where do mutations ususally occur

A

in the non-coding part of the dna

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25
Q

what is sexual reproduction

A

when a male gamete and a female gamete fuse = fertilisation

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26
Q

what does sexual reproduction produce

A

genetically different offspring

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27
Q

how many chromosomes to human gametes have and what cause this

A

23 - meiosis

28
Q

what is asexual reproduction

A

when only one parent is involved and the offspring are gentically identical

29
Q

what the pros of asexual reproduction

A

its quicker as it only involves one parent
- so a species can populate an entire area quickly

30
Q

what are the cons of asexual reproduction

A

there is no genetic variation so a disease could quickly wipe out a whole population
they would struggle to adapt to changing environment

31
Q

what are the pros of sexual reproduction

A

there is genetic variation so a disease will not wipe out a whole population
they can adapt to changing environments and evolve

32
Q

what are the cons of sexual reproduction

A

it is time consuming as a lot of time and energy has to go into finding a mate
the characteristics they have are most likely for attraction and not survival

33
Q

is cystic fibrosis an recessive or dominant condition

A

recessive

34
Q

what is cystic fibrosis

A

a condition that causes thick, sticky mucus to build up in the lungs and the digestive system

35
Q

what is polydactyly

A

a condition that causes someone to be born with extra fingers or toes

36
Q

is polydactyly causes by a recessive or dominant allele

A

dominant

37
Q

what is embryo screening

A

looking at the cells of an embryo (usually during IVF) to check for any genetic disorders
if there is a genetic diorder they might decide to disregard the embryo

38
Q

what are the pros of embryo screening

A

it reduces the total amount of suffering
saves money

39
Q

what are the cons of embryo screening

A

its unethical because you are throwing away a life that could have been a human
it also presents the idea that people with genetic disorders are less desirable

40
Q

who was gregor mendel

A

a scientist that discovered the laws of inheritance

41
Q

what plants did he use and what did he measure

A

pea plants
measured colour of pods, height and colour of flowers

42
Q

what did he find about inheritance

A

he found that different characteristics were being expressed in different generations
he called this hereditary units and they could be dominant or recessive

43
Q

what is natural selection

A

when the organisms with the most favourable qualities survive in an environment

44
Q

what is evolution

A

when the inherited characteristics of a species change over time due to natural selection

45
Q

what influences variation

A

genes and environment

46
Q

what cause genes to change

A

mutations

47
Q

what was lamarcks theory of evolution

A

that the characteristics an organism gained during its lifetime changed its dna and these traits were passed onto its offspring

48
Q

what was darwin’s and wallaces’s theory of evolution

A

organisms within a species were varied
the ones with the most desirable characteristics survived and passed these down to their offspring
this keeps happening until the whole species has evolved to have them all have that one desirable trait

49
Q

what is selective breeding

A

it is when the organisms with the best traits are chosen out of a population and bred together to create offspring that has even better traits

50
Q

what are the cons of selective breeding

A

it decreases variation and the gene pool
this means the whole population is at risk of getting a disease
also as the organisms that are bred are closely related they are more likely to get inbreeding = more rare birth defects and diseases

51
Q

what is genetic engineering

A

modifying an organism by taking the desirable trait from one organism and putting it in it

52
Q

give examples of things that have genetically modified

A

sheeps milk - contains drugs that can treat diseases
bacterial plasmids- given them the gene for insulin so when they divide they produce more and we can harvest it
rice- golden rice contains beta carotene which protects people from going blind

53
Q

what is gene therapy

A

treating an inherited disorder by giving somone a healthy copy of faulty gene

54
Q

what are the cons to gene therapy

A

it would be hard as the new gene would have to be put in every cell
to solve do it at an earlier stage of development

55
Q

what are the pros of gm crops

A

better yield = more food for cheaper
better taste
resistance to diseases

56
Q

what are the cons of gm crops

A

we dont know the full side effects of them, they could end up harming us
also there is a chance they could end up in the wild, overtake other plants and change a whole ecosystem

57
Q

how do we genetically engineer

A

first take the desired gene and isolate it from the dna
then put it in a vector like a virus or bacterial plasmids
these can then go into a human, the body cells will absorb the vector and start to produce that gene in dna replication

58
Q

how can we clone an animal

A
  1. take an egg cell from a donor mum and take the nucleus out so its enucleated
  2. take an adult skin cell from the animal you want clone, remove its nucleus and put the nucleus from the egg cell inside
  3. stimulate the egg with a small electric shock so that it multiplies to form an embryo4. place in a surrogate mum and the embryo will develop normally to create a foetus.
59
Q

what is a trasngenic organism

A

an organism that has dna from another species

60
Q

what are the pros of trangenic organisms

A

we can give them the gene to code for helpful proteins and then use it for what we need

61
Q

how do you clone from embryonic transplant

A

1.take a male and female with desirable traits and fuse their egg and sperm cell together
2. let the new zygote multiply into an embryo
3. separate each embryo cell from each other
4. put each one in 1 surrogate mother
5. the embryo will develop normally and all the offspring will be identical

62
Q

what are fossils

A

the remains of animals from millions of years ago that are found in rocks

63
Q

what are the ways that fossils are formes

A
  • gradual replacement by minerals , things like bones and shells take longer to decay and as they do they are replaced my minerals leaving a rock in the same shape as them
  • cast and impressions , if animals are buried in soft materials, as they decay and it hardens they leave an imprint or impressions like a footprint
    -preservations - when they are preserved in a place that does not have the write conditions for decay like amber, tar pits, ice and peat bogs
64
Q

why is the fossil record not complete

A

-some organisms that lived earlier were very soft bodied and so decayed very quickly
-fossils from before have been destroyed

65
Q

why do species go extinct

A

-natural disasters
-disease
new predators
-more competition
-catastrophic event
-loss of habitat
rapid change in temperature

biology (7 decks)

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