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Biology > B6 Inheritance, Variation And Evolution > Flashcards

B6 Inheritance, Variation And Evolution Flashcards

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
Examples of things that asexually reproduce
Bacteria, some plants and animals (like octopus)
26
Two structures of a DNA molecule
Backbone and rungs
27
What does the backbone contain in DNA
Sugar - phosphate. S-p-s-p-s etc. Sugar is a hexagon and phosphate is a golden strand. Sugar in DNA is deoxyribase
28
Structure of the rungs in DNA
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
29
What is meiosis
Type of cell division in which gametes are formed
30
Stages of meiosis
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
31
What’s happens after two gametes fuse
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
32
What chromosomes are male
XY - Y causes male
33
Female chromosomes
XX - x causes female
34
What happens to x and Y chromosomes when making sperm
The x and Y chromosomes are drawn apart in first meiosis division
35
What do Punnett squares show
Show the possible outcome of genotypes (show the phenotype)
36
What’s a genotype
List of alleles you have
37
What’s a phenotype
Outcome of genotype
38
What’s an allele
Form/type of one gene
39
Example of homozygous dominant Homozygous recessive Heterozygous
Homozygous dominant - AA homozygous recessive - aa Heterozygous Aa
40
What do different genes control
Control different characteristics
41
What do genes exist as
Different versions of alleles.
42
How many versions of each gene is in your body
Two, one on each chromosome
43
What happens if two alleles are different (heterozygous)
Allele for the characteristic shown is the dominant one. E.g Aa (A is the characteristic) or AA
44
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
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
What’s the 1:1 Ratio of genetic diagrams mean
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
What is cystic fibrosis
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
What is polydactyl
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
What does it mean when IVF embryos can have their genes analysed
It’s possible to detect genetic disorders and remove cells.
49
What does womb screening mean
Screen genes in womb and find genetic disorders
50
Why are people again screening
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
Why are people for screening
Stops suffering Treating disorders is expensive There are laws to stop screening going too far. E.g can’t choose gender
52
What is variation
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
What are mutations
Mutations are changes to the genome. Mutation is a rare, random change in an organisms DNA
54
What does mutation do
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
Example of little mutation
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
Example of drastic mutation
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
What is evolution
Gradual change in characteristics of a species over time
58
Why did Charles Darwin know about natural selection
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
What is the development of a new species called
Speciation.
60
How does speciation occur
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
What is extinction
When no individuals of a species re,Ian.
62
Why do species become extinct
Quick environment change (habitat destruction) New predator kills them all(humans) Can’t compete for food with new species Catastrophic event kills all
63
What is artificial selection
Humans choose a certain organism(s) as they have useful characteristics
64
What is selective breeding
Humans artificially select the plants or animals with specific characteristics to breed so only particular characteristics remain.
65
What features do farmers selectively breed for
Cow with more meat or milk Crops with disease resistance Dogs with gentle temperament Plants with big flowers
66
Process of selective breeding
Breed stock with wanted characteristics Select offspring with best characteristics and breed Continue process and eventually all offspring with have desired characteristics
67
Risks of selective breeding
``` 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
What is genetic engineering
Transfer a gene responsibility,e for desirable characteristic from one organisms genome into another organism so it has the desired characteristic.
69
Method of genetic engineering
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
Why is genetic engineering used
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
What is gene therapy
Genetically modified treatments for inherited diseases. E.g inserting working genes to replace faulty genes
72
Pros of GM crops
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
Cons of GM crops
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
What are fossils
Fossils are the remains of plants and animals
75
Where are fossils found and what do they provide
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
Fossil formation: gradual replacement by minerals
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
Fossil formation: cast and impressions
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
Fossil formation: preservation in places with no decay
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
Why can’t hypotheses of how life started be supported
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
What is classification
Classification is organising living organisms into groups
81
What’s was the Linnaean system 1700s
Grouped organisms according to characteristics and structures. Organised into kingdoms: phylum, class, order, family, genes and species
82
Why did the classification system change over time
Biochemical processes taking place inside organisms developed and so did microscopes (see more internal structures) so scientists put forward new classification
83
About 1990 Carl woese three Domain system
Archaea , bacteria and eukaryota | Subdivided again into kingdom, phylum, class, order, Family, Genus and species
84
About archaea
Organisms are primitive bacteria. Found in extreme places like hot springs and salt lakes. They have no nucleus and unused sections of DNA
85
About eukaryota
Broad range of organisms including fungi, plants,animals and protists. Has nucleus and unused sections of DNA
86
About bacteria
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
What are ligase
If two sticky ends Match, they are joined with the ligase enzyme
88
What are sticky ends
Unpaired bases on one strand cut in two
89
Process of natural selection
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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