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Biology > B6 Inheritance, Variation And Evolution > Flashcards

B6 Inheritance, Variation And Evolution Flashcards

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1
Q

What are chromosomes

A

Really long molecules of DNA

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2
Q

What does DNA stand for

A

deoxyribase nucleic acid

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3
Q

What is DNA

A

it’s a chemical that contains all the genetic material that a cell is made up of. Contains coded information.

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4
Q

What does DNA determine

A

Determines what inherited characteristics you have

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5
Q

Chromosomes normally come in

A

Pairs.

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6
Q

What is DNA and what is it made up of

A

DNA is a polymer and is made up of two strand coiled together in the shape of a double helix.

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7
Q

What do genes do

A

Each gene codes for a particular sequence of animal acids which are put together for a specific protein. Only 20 amino acids are used

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8
Q

What is a genome

A

Term for the entire set of genetic material of an organism

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9
Q

What does sexual reproduction provide

A

Produces genetically different cells

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10
Q

What is sexual reproduction

A

Where genetic information from two organism (mother and father) is combined to produce an offspring which are genetically different to either parent.

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11
Q

What do the mother and father produce during sex

A

Produce gametes by Meiosis. Each gamete contains 23 chromosomes. Half the Chromosomes in a normal cell. The egg and sperm cell rise together to form a cell with the full number of chromosomes.

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12
Q

Sexual reproduction involves…

A

The fusion of female and male gametes.

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13
Q

What does the mixture of genetic information produce in sex

A

Produces variation in the offspring

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14
Q

What does asexual reproduction produce

A

Genetically identical cells because there is only one parent. This occurs by mitosis. (Ordinary cell makes a new cell by dividing in two)

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15
Q

In asexual reproduction there’s only…

A

One parent. There’s no fusion of gametes and no genetic variation. The offspring are genetically identical as they’re clones.

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16
Q

What is a genome

A

The entire set of genetic material in an organism

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17
Q

What is important about understanding the human genome

A

Important tool for science and medicine

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18
Q

What does the human genome allow scientists to do

A

Identify genes in the genome linked to different diseases
Knowing which genes are link to inherited diseases could help us understand them
Look at genomes to trace migration of certain populations of people
Human genome was mostly identical, but as different populations migrated from Africa, gradually developed differences in genomes.

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19
Q

What is sexual reproduction

A

Genetic information from two organism (mother and father) is combined to Produce genetically different offspring.

Involves fusion of male and female gametes. This means there’s a mixture of parents genes

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20
Q

What is produced during sexual reproduction and how

A

Gametes through meiosis

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21
Q

What does a gamete contain

A

23 chromosomes, so when the egg and sperm fuse they form 46 chromosomes. This means offspring contain genetic information from both parents and offspring is varied.

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22
Q

What are gametes

A

Sperm and egg

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23
Q

What is asexual reproduction.

A

There’s only one parent, so no fusion of gametes or mixing chromosomes; no genetic variation. The offspring are genetically identical to the parent - a clone

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24
Q

How does asexual reproduction happen

A

Mitosis. Ordinary cell makes a new cell by dividing in two.

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25
Q

Examples of things that asexually reproduce

A

Bacteria, some plants and animals (like octopus)

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26
Q

Two structures of a DNA molecule

A

Backbone and rungs

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27
Q

What does the backbone contain in DNA

A

Sugar - phosphate.
S-p-s-p-s etc.
Sugar is a hexagon and phosphate is a golden strand.
Sugar in DNA is deoxyribase

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28
Q

Structure of the rungs in DNA

A

Four nitrogenous bases
Adenine - thymine (form 2 hydrogen bases)
Cytosine - guanine (form 3 hydrogen bases)
Bases form a sequence along one strand and other strand has the corresponding bases

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29
Q

What is meiosis

A

Type of cell division in which gametes are formed

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30
Q

Stages of meiosis

A
  1. Before division, cell duplicates
  2. First division chromosome pairs line up in middle
  3. Pairs pulled apart so each new cell has one copy of each chromosome
  4. Second division, chromosomes line up in centre. Arms of chromosomes are pulled apart.
    End up with 4 gametes, each with a single set of chromosomes. Each gamete is genetically different as chromosomes shuffle
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31
Q

What’s happens after two gametes fuse

A

New cell divides with mitosis to copy itself. This repeats to make lots of cells in an embryo
Cells start to differentiate into specialised cells that make up a whole organism

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32
Q

What chromosomes are male

A

XY - Y causes male

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33
Q

Female chromosomes

A

XX - x causes female

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34
Q

What happens to x and Y chromosomes when making sperm

A

The x and Y chromosomes are drawn apart in first meiosis division

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35
Q

What do Punnett squares show

A

Show the possible outcome of genotypes (show the phenotype)

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36
Q

What’s a genotype

A

List of alleles you have

37
Q

What’s a phenotype

A

Outcome of genotype

38
Q

What’s an allele

A

Form/type of one gene

39
Q

Example of homozygous dominant
Homozygous recessive
Heterozygous

A

Homozygous dominant - AA
homozygous recessive - aa
Heterozygous Aa

40
Q

What do different genes control

A

Control different characteristics

41
Q

What do genes exist as

A

Different versions of alleles.

42
Q

How many versions of each gene is in your body

A

Two, one on each chromosome

43
Q

What happens if two alleles are different (heterozygous)

A

Allele for the characteristic shown is the dominant one. E.g Aa (A is the characteristic) or AA

44
Q

Breeding hamsters with super powers example.
b = superpowers B = normal.
1. What’s the outcome if you Breed a Bb and a bb
2. Outcome if you breed the offspring of 1

A
  1. BB and bb create Bb, Bb, Bb, Bb. All boring, no superpowers because B is dominant characteristic.
  2. Bb and Bb create BB, Bb, Bb and bb. 3 of them are normal as B is dominant. One has superpowers (bb)
45
Q

What’s the 1:1 Ratio of genetic diagrams mean

A

1:1 happens when there’s for example 4 short hair (h) and 4 long hair(H)
You can expect it when you have parent Hh and hh

46
Q

What is cystic fibrosis

A

Genetic disorder of membranes. It produces thick sticky mucus in air passages and pancreas. Recessive ‘f’ causes. ‘ff’ means you have it. ‘Ff’ means you’re a carrier

47
Q

What is polydactyl

A

Genetic disorder where you’re born with extra fingers or toes.
Caused by ‘D’ meaning only one parent needs it as it’s dominant.
‘Dd’ have it as D is dominant
‘dd’ unaffected

48
Q

What does it mean when IVF embryos can have their genes analysed

A

It’s possible to detect genetic disorders and remove cells.

49
Q

What does womb screening mean

A

Screen genes in womb and find genetic disorders

50
Q

Why are people again screening

A

Implying genetic people with disorders are ‘undesirable’
Everyone may want to screen embryos - expensive

Screening leads to decision of abortion
IVF means destruction of bad alleles

51
Q

Why are people for screening

A

Stops suffering
Treating disorders is expensive
There are laws to stop screening going too far. E.g can’t choose gender

52
Q

What is variation

A

Differences in organisms. Differences can be genetic (differences in genotypes) or environmental interaction can influence phenotype e.g sunlight on plant = green. Plant in dark = yellow
Variation determined by mixture of genetic and environmental factors

53
Q

What are mutations

A

Mutations are changes to the genome. Mutation is a rare, random change in an organisms DNA

54
Q

What does mutation do

A

Mutation alters the gene and produces a genetic variant.

Genes code for a sequence of anime acids for a protein -> gene mutations lead to changes in protein

55
Q

Example of little mutation

A

Eye colour is controlled by more than one gene. A mutation in one gene will change the eye colour a bit, but not lots

56
Q

Example of drastic mutation

A

Cystic fibrosis caused by a mutation will large affect on phenotype.
Gene codes for protein to move salt and water in and out cells. Protein mutated, gene stops working and leads to excess mucus production in lungs.

57
Q

What is evolution

A

Gradual change in characteristics of a species over time

58
Q

Why did Charles Darwin know about natural selection

A

Charles Darwin knew about variation in characteristics (phenotypic variation) and knew organisms compete for limited resources. Therefore most suitable characteristics would survive and be passed on, and not good characteristics would be lost.

59
Q

What is the development of a new species called

A

Speciation.

60
Q

How does speciation occur

A

Phenotype of an organism changes so much a new organism is form. Speciation happens when a population of the same species becomes reproductively isolated. (Can’t interbreed)

61
Q

What is extinction

A

When no individuals of a species re,Ian.

62
Q

Why do species become extinct

A

Quick environment change (habitat destruction)
New predator kills them all(humans)
Can’t compete for food with new species
Catastrophic event kills all

63
Q

What is artificial selection

A

Humans choose a certain organism(s) as they have useful characteristics

64
Q

What is selective breeding

A

Humans artificially select the plants or animals with specific characteristics to breed so only particular characteristics remain.

65
Q

What features do farmers selectively breed for

A

Cow with more meat or milk
Crops with disease resistance
Dogs with gentle temperament
Plants with big flowers

66
Q

Process of selective breeding

A

Breed stock with wanted characteristics
Select offspring with best characteristics and breed
Continue process and eventually all offspring with have desired characteristics

67
Q

Risks of selective breeding

A 
Reduces genepool(number of alleles in a population) 
As farmer breeds from best organisms, they’re all closely related causing health issues. 
Likely to inherit harmful genetics from restricted genepool 
If one dies from a new disease, all of them will die as they don’t have varied characteristics as they’re all closely related
68
Q

What is genetic engineering

A

Transfer a gene responsibility,e for desirable characteristic from one organisms genome into another organism so it has the desired characteristic.

69
Q

Method of genetic engineering

A

Useful gene is isolated(cut) with restriction enzymes. The plasmid is then removed from bacterium and cut with restriction enzymes. The use gene is then attached to the open plasmid with lipase and then the plasmid is placed back into the bacterium’s

70
Q

Why is genetic engineering used

A

Bacteria genetically modified to produce insulin
Crops generics,LG modified for different sizes and to make resistant to diseases
Sheep genetically modified to produce substances like drugs in milk to help treat humans.

71
Q

What is gene therapy

A

Genetically modified treatments for inherited diseases. E.g inserting working genes to replace faulty genes

72
Q

Pros of GM crops

A

Increase yield
Lack of nutrients can be fixed with genetic modification e.g golden rice produced to contain beta-carotene for less fortunate countries so blindness is reduced

73
Q

Cons of GM crops

A

Worried it might affect number of wild flowers, therefore affecting insects and reduce biodiversity
Worries of it not being safe for human health
Modified genes may get into the natural environment. E.g herbicide resistances gene may be picked up by weeds creating a super weed variety

74
Q

What are fossils

A

Fossils are the remains of plants and animals

75
Q

Where are fossils found and what do they provide

A

Found in deep rocks (deeper = older) and provide evidence for organism that life ages ago
Fossils provide us with how much/little organisms have evolved.

76
Q

Fossil formation: gradual replacement by minerals

A

Happens with most fossils
Teeth, shells and bones don’t decay easily so they can last long when buried. Eventually replaced by minerals as they decay, forming a rock like substances shaped with the original hard shape. Fossil stays distinct

77
Q

Fossil formation: cast and impressions

A

Sometimes formed when an organism is buried in soft material like clay. The clay, gardens Weih die the organism and organism decays, leaving a cast of itself.
Things like footprints leave an impression

78
Q

Fossil formation: preservation in places with no decay

A

Amber and tarpits have no oxygen or moisture so decay microbes don’t survive.
Glacier it’s too cold for decay microbes to survive.

79
Q

Why can’t hypotheses of how life started be supported

A

Many early life were soft bodies and decayed easily.

Fossils that did form may have been destroyed from geological activity (tectonic rock movement etc)

80
Q

What is classification

A

Classification is organising living organisms into groups

81
Q

What’s was the Linnaean system 1700s

A

Grouped organisms according to characteristics and structures.
Organised into kingdoms: phylum, class, order, family, genes and species

82
Q

Why did the classification system change over time

A

Biochemical processes taking place inside organisms developed and so did microscopes (see more internal structures) so scientists put forward new classification

83
Q

About 1990 Carl woese three Domain system

A

Archaea , bacteria and eukaryota

Subdivided again into kingdom, phylum, class, order, Family, Genus and species

84
Q

About archaea

A

Organisms are primitive bacteria. Found in extreme places like hot springs and salt lakes. They have no nucleus and unused sections of DNA

85
Q

About eukaryota

A

Broad range of organisms including fungi, plants,animals and protists. Has nucleus and unused sections of DNA

86
Q

About bacteria

A

Contains true bacteria like E. coli and staphylococcus. Lots of biochemical differences to archaea even though they look similar. No nucleus and no unused sections of DNA

87
Q

What are ligase

A

If two sticky ends Match, they are joined with the ligase enzyme

88
Q

What are sticky ends

A

Unpaired bases on one strand cut in two

89
Q

Process of natural selection

A
  1. Mutation is alleles
  2. Variation in offspring
  3. Competition for resources
  4. Selection
  5. Successful alleles passes to offspring
  6. Repeat

Biology (7 decks)

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