Topic 6 - Inheritance, Variation and Evolution Flashcards
1
Q
DNA is found in the ….. in really long structures called ….. which usually come in ….
A
Nucleus of animals and plant cells
Chromosomes
Pairs
2
Q
DNA is a …. - made of …… in the shape of a ….
A
Polymer
Two strands coiled together
Double helix
3
Q
A gene is a …… - it codes for ….
A
Small section of DNA found on a chromosome
A particular sequence of amino acids which are out together to make a specific protein
4
Q
Only …. Amino acids are used but they make up ….. of different proteins
A
20
Thousands
5
Q
Genes tell the cells ….. together
A
What order to our the amino acids together
6
Q
DNA also determines …. So determines ….
A
What protein the cell produces
What type of cell it is
7
Q
A genome is ….
A
The entire set of genetic material in an organism
8
Q
The human genome allows scientists to ….. to help us develop ….
A
Identify genes that are linked to different types of diseases (eg inherited)
Effective treatments for inherited diseases
9
Q
Scientists can look at genomes to trace the …. - all modern humans are descended from a ….
A
Migration of certain populations of people around the world
Common ancestor who lived in Africa
10
Q
DNA strands are polymers made up of lots of repeating units of … - each consists of a ….., a …. And one ….
A
Nucleotides
Sugar
Phosphate group
Base
11
Q
The sugar and phosphate groups in the nucleotides forms a …. To the DNA strands
Sugar and phosphate groups …..
A
‘Backbone’
Alternate
12
Q
The four bases are …… - one joins to each …
A
A,T,C,G
sugar
13
Q
Each bases links to base on the opposite strand in the helix - pairs are ……
Pairs called ….
A
A with T
C with G
Complementary base pairing
14
Q
It is the order of ……. That decides the order of amino acids in protein
A
Bases in a gene
15
Q
Each amino acid is coded for by a sequence of ….. in the gene
A
Three bases
16
Q
Some parts of the DNA that don’t code for proteins …… so they control whether or not a gene is ….. (….)
A
Switch genes on and off
Expressed
Used to make a protein
17
Q
Proteins are made in the cell …. on ….
A
Cytoplasm
Ribosomes
18
Q
DNA cannot move out of the …… so the cell uses a molecule called …. which is made by ….. and acts as a …. between the DNA and the ribosome
A
Cell nucleus
mRNA
copying the code from DNA
Messenger
19
Q
Protein examples x3
A
Enzymes - biological catalysts
Hormones - carry messages around body
Structural proteins - physically strong eg collagen for connective tissue
20
Q
A mutation is a ….
A
Random change in an organism’s DNA - they can be inherited
21
Q
Mutations occur …. And they can occur ….
Chance of mutation is increased by ….
A
Continuously
Spontaneously (when a chromosome isn’t replicated properly)
Exposure to certain substances or some types of radiation
22
Q
Mutations change the …… in a gene which produces a … which can sometimes lead to ….
A
Sequence of the DNA bases
Genetic variant
Changes in the protein it codes for
23
Q
Most mutations have ….. effect on the protein but some will …..
A
Very little or no
Change it to such a small extent that its function or appearance is unaffected
24
Q
Some mutations can ….. a protein, sometimes the mutation will code for an …. - which could affect its ability to …..
A
Seriously affect
Altered protein with a change in its shape
Perform its function
25
If there is a mutation in non-coding DNA, it can …
Alter how genes are expressed
26
Insertion mutation is when ……
It changes the way the groups of 3 bases are ….. which can change the …..
Can have a …..
A new base is inserted into the DNA base sequence where it shouldn’t be
‘Read’
Amino acid that they code for
Knock-on effect on the bases further on in the sequence
27
Deletion mutations are when ….
Like insertions they change ….. and can have ….
A random base is deleted from the DNA base sequence
The way the base sequence is ‘read’
Knock-on effects further down the sequence
28
Substitution mutations are …..
These change ….
When a random base in the DNA base sequence is changed to a different base
One amino-acid in the sequence
29
Sexual reproduction produces offspring which is ….
Genetically different
30
In sexual reproduction the mother and father produce ….. by …..
Gametes
Meiosis
31
In humans each gamete has …..
23 chromosomes
32
Female gamete =
Egg
33
Male gamete =
Sperm
34
Fertilisation = the ….. of an egg and sperm to form …..
Fusing together
A cell with the full number of chromosomes - half from mother, half from father
35
Flowering plants reproduce …… as they have …. But they have ….
Sexually
Egg cells
Pollen not sperm
36
Asexual reproduction produces ……. there is …. Parent
Genetically identical
One
37
Asexual reproduction happens by ….. - an ordinary cell makes a new cell by …. - has the ……. As the parent cell (……)
Mitosis
Dividing in two
Exact same genetic information
Clone
38
In asexual reproduction there’s no ….
Genetic variation
39
Asexual reproduction happens in ….
Bacteria, some plants + some animals
40
Meiosis involves …. - only happens in the …..
Two cell divisions
Reproductive organs
41
After two gametes have ….. during fertilisation, the resulting new cell divides by …… many tunes to produce …..
Fused
Mitosis
An embryo
42
As the embryo develops, cells start to ….. into ….. that make up a ….
Differentiate
Different types of specialised cells
Whole organism
43
Advantages of sexual over asexual reproduction x4
- mixture of 2 sets of chromosomes - has variation in offspring
- increases chance of survival in changing environment due to variation
- better adaptations + better chance of survival = more likely to breed successfully + pass genes on - natural selection
- selective breeding speeds up natural selection - producing animals with desirable characteristics - eg increase food production = animals with lots of meat
44
Advantages of asexual over sexual reproduction 4x
- only needs one parent
- uses less energy than sexual reproduction because no need to find a mate
- faster than sexual reproduction because no need to find a mate
- many identical offspring produced in favourable conditions
45
Malarial parasites use both asexual and sexual reproduction
Sexual when …
Asexual when ….
In mosquito
In the human host
46
Fungi use both asexual and sexual reproduction
Asexually-formed spores =
Sexually-formed spores =
Form fungi genetically identical to parent fungus
Introduce variation, are often produced in response to an unfavourable change in environment - to increase the chance of population surviving change
47
Plants use both asexual and sexual reproduction
Sexually =
Asexually =
Produce seeds
Plants producing ‘runners’ - stems growing horizontally on surface of soil to form new plant identical to first plant or bulb plants - new bulbs can form from main bulb and divide off to form identical plant
48
In every human body cell there are ….. of chromosomes
….. are ….. of chromosomes that control ……
The last pair are labelled ….
This decides your ….
23 pairs
22
Matched pairs
Characteristics
XX or XY
Sex
49
Males have genotype …..
XY
50
Females have genotype ….
XX
51
When making sperm the ….. chromosomes are drawn apart in first division in …… - so there is a …… and a ……
X and Y
Meiosis
50% chance of the sperm cell having an X chromosome
50% chance of a Y chromosome
52
The original cell that eggs come from has ….. so all eggs have one …
Two X chromosomes
X chromosome
53
Punnet squares show …..
Probability of genetics
54
What genes you inherit control what ….
Characteristics you develop
55
Most characteristics are controlled by …
Several genes interacting
(Exception eg red-green colour blindness)
56
All genes existing in different versions of are called ……
Alleles
57
You have ….. of every gene in your body - ……
Two versions
One on each chromosome in a pair
58
If two alleles are the same for a particular gene, it is ….. for that trait
If they are different, it is …. For that trait
Homozygous
Heterozygous
59
If the dominant allele is present, …..
It will be expressed eg Cc or CC
60
For the recessive allele to be expressed, …..
You need both to alleles to be homozygous recessive eg ff
61
Your genotype is the …… - your alleles work to determine your …. (…..)
Combination of alleles you have
Phenotype (characteristics)
62
Types of allele pairings + example using F and f
Homozygous dominant = FF
Homozygous recessive = ff
Heterozygous = Ff
63
Cystic fibrosis is a genetic disorder of the ….. - it results in the body producing ….
Allele is …. Shown with……
People with one copy of this allele are known as …..
Cell membranes
Lots of thick sticky mucus in the air passages and pancreas
Recessive
f
Carriers
64
Polydactyly is a genetic disorder where …..
This allele is ….. shown with ….
So if one parent has the defective allele, ……
A baby is born with extra fingers or toes - generally isn’t life-threatening
Dominant
D
The child will also have polydactyly
65
In IVF embryos can be ….. - it is possible to …… and …….
Genetically screened
Remove a cell from each embryo
Analyse its genes
66
Argument for embryonic screening x3
- help stop people suffering
- treating disorders costs the government + tax payers a lot of money
- there are laws to stop it going too far (parents cannot select sex of baby unless for health reasons)
67
Argument against embryonic screening x3
- implies that people with genetic problems are ‘undesirable’ - increase in prejudice
- may come a point that everyone wants to screen their embryos to pick the most ‘desirable’ one
- screening is expensive
68
Mendel was an ….. who during the ….. century had a garden plot at the monastery - he noted how …..
Austrian monk
Mid 19th
Characteristics in plants were passed on from one generation to the next
69
Mendel results were published in …. And became the …… - based off of …..
1866
Foundation of modern genetics
Crosses of height in pea plants
70
Mendel showed that the height characteristic in pea plants was ……
Tall plants = ….. - …..
Dwarf plants = …… - …..
Determined by separately inherited ‘hereditary units’ passed on from each parent
T - dominant
t - recessive
71
Mendels 3 conclusions
- characteristics in plants determined by ‘hereditary units’
- hereditary units passed on to offspring unchanged from both parents - one unit from each parent
- hereditary units can be dominant or recessive - if individual has both, the dominant characteristic will be expressed
72
Mendels work was not ….. -it was …… and people didn’t have the …..
Understood by people
Cutting edge and new to the scientists of the day
The background knowledge of genes, DNA and chromosomes
73
Mendels work was the starting point for …..
Eg x3
Understanding of genes that we have today
- in late 180s - scientists familiar with chromosomes + cell division
- early 20th century - similarities between ways chromosomes and Mendels units acted - proposed that units were found on chromosomes (genes)
- 1953 - structure of DNA was determined - understand how genes worked
74
Two types of variation
Environmental and genetic
75
Genetic variation of characterises is determined by the ….. - passed on in the …
Genes inherited from parents
Sex cells (gametes)
76
Characteristics that are only determined by genes x3
- eye colour
- blood group
- inherited disorders
77
How does environmental variation happen
The conditions that the organisms live and grow causes differences between members of the same species
78
Examples of just environmental variation
Losing toes to a piranha
Getting a sunburn
Having yellow leaves
79
Most characteristics are due to …..
Eg ….
Genes and the environmental factors
Body weight, height, condition of teeth, academic or athletic ability
80
Mutations are ….. - most have …… effect on the protein the gene codes for so …..
Changes to the sequences of bases in DNA
No
Have no effect on the organism’s phenotype
81
Theory of evolution =
All of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago
82
Charles Darwin suggested the theory of ……
He knew that organisms in a species showed …. And that they have to ….
Evolution by natural selection
A wide variation in their characteristics (phenotype)
Compete for limited resources in an ecosystem
83
Darwin concluded that the organisms with the ……. would be …. And would be ……- aka ….
Most suitable characteristics for the environment
More successful competitors
More likely to survive
Survival of the fittest
84
The successful organisms that survive are ….
More likely to reproduce and pass on genes for characteristics that made them successful to their offspring
85
Organisms that are less well adapted would be …. And so are ….
Less likely to survive and reproduce
Less likely to pass on their genes to the next generation
86
Over time, ….. become more common in the population and the species …. - it ….
Beneficial characteristics
Changes
Evolves
87
We now know that phenotype is controlled by …. - new phenotypic variations arise because of …. - beneficial variations are …..
Genes
Genetic variants produced by mutations
Passed on to future generations in genes in gametes
88
If the phenotype of an organism changed so much because of natural selection, ….. - called ….
A completely new species is formed
Speciation
89
Speciation happens when populations ….
Change enough to become reproductively isolated - meaning they cannot interbreed to produce fertile offspring
90
Extinction reasons x5
- environment changes too quickly
- new predator kills them all
- a new disease kills them all
- can’t compete with another (new) species for food
- a catastrophic event happens that kills them all (eg volcanic eruption or asteroid collision)
91
Reasons dodos are extinct x3
- humans hunted them
- humans introduced other animals that ate all their eggs
- humans destroyed the forest where they lived
92
Darwin’s book …. In …. Was very ….
‘On the Origin of Species’
1859
Controversial
93
Reasons Darwin’s book was controversial x3
- against common religious beliefs about how Earth developed - first plausible explanation of life without god/creator
- Darwin couldn’t explain why new characteristics appeared or how they were passed on to offspring
- wasn’t enough evidence to convince scientists
94
Lamarck’s hypotheses- argued that changes that an organism acquires during its life will be …
So if a characteristic was used alot by an organism, it would be …. And …
Passed on to its offspring
Become more developed during its lifetime
The organisms’s offspring would inherit the acquired characteristic
95
In the end, Lamark’s hypothesis was …. Because ….. - eg…..
Darwin’s hypothesis were ….because …., also helped by ….
Rejected
Experiments didn’t support it
Dye a hamster’s fur bright pink it’s offspring will be born with normal fur colour
Supported
Discovery of genetics provided explanation of how organisms are born with beneficial characteristics that have been passed on via genes
Fossil records - shows organisms developing slowly over time
96
There is so much evidence for Darwin’s idea that it is now an ……
Accepted hypothesis (theory)
97
Selective breeding is the ….
Breeding of selected plants or animals so that the genes fro a particular characteristic remain in the population
98
Used to breed for features that are ….
Eg x4
useful or attractive
Animals producing more meat or milk, dogs with good gentle temperament, crops with disease resistance, decorative plants with big or unusual flowers
99
Process of selective breeding x4
- from existing stock select ones which have characteristics you need
- breed them with each other
- select best of the offspring and breed them together
- continue process for several generations and desirable trait will get stronger untuck all offspring have the characteristic
100
In agriculture, selective breeding used to …..
Eg ….
Improve yields
Meat yields - breed cows and bulls with best characteristics for producing meat like large size for several generations
101
Disadvantage of selective breeding = ….
- can cause ….
- can be deadly if ….
Limited gene pool as inbreeding has to occur
Health problems like genetic defects
New disease appears because there is not much variation in population meaning there is less chance of any resistant allele being present in the population Used to
102
Genetic engineering is to …..
Transfer a gene responsible for a desirable characteristics that have from one organism’s genome into another organism so it also has the desired characteristic
103
Genetic engineering process x2
- useful gene is isolated (cut) from one organism’s genome using enzymes and is inserted into a vector (usually a virus or bacterial plasmid)
- vector introduced to target organism, the useful gene is inserted into its cells
104
Genetic engineering examples x4
- bacteria to produce human insulin to treat diabetes
- GM crops to improve size and quality of fruit + be resistant to disease, insects and herbicides
- sheep to produce substances in their milk to treat human diseases eg drugs
- genetic modification treatments for inherited diseases - gene therapy
105
In genetic engineering, in some cases the transfer of the gene is carried out when … which means the organism …..
Organism receiving gene is at an early stage of development (eg embryo or egg)
Develops with the characteristic coded for by the gene
106
GM crops pros x3
- GM crops can increase yield, making more food
- people living in developing nations often lack nutrients in their diets and GM crops can be engineered to contain missing nutrients eg ‘golden rice’ - has beta-carotene
- GM crops are already being grown often without any problems
107
GM crops cons x3
- some people think growing GM crops will affect number of wild flowers (therefore pop. of insects) that live in and around crops - reducing farmland biodiversity
- not everyone convinced GM crops are safe and some concerned that we don’t understand the effects of eating them on human health
- transplanted genes may get out into natural environment eg herbicide resistance gene picked up by weeds
108
Cloning plants by ….
Tissue culture or cuttings
109
Cloning by cuttings process = ….
Plants can be produced …..
This is an ……. method than tissue culture
Gardeners take cuttings from good parent plants and then plant them to produce genetically identical copies of the parent plant
Quickly and cheaply
Older, simpler
110
Cloning plants by tissue culture process =
These plants can be made ….., in …. And be grown …..
Used by scientists to …… and by plant nurseries to ….
A few plant cells are put in a growth medium with hormones + they grow into new plants - clones of the parent plant
Very quickly
Very little space
All year
Preserve rare plants that are hard to reproduce naturally
Produce lots of stock quickly
111
Animal clones + embryo transplant process - 3x
- sperm cells take from prize bull and egg cells are take from prize cow - artificially fertilised + embryo develops is then split many times to form clones before any cells become specialised
- cloned embryos then implanted into lots of other cows where they grow into baby calves
- hundreds of ideal offspring can be produced every year from best bull and cow
112
Adult cell cloning process x4
- taking unfertilised egg cells + remove nucleus
- nucleus from adult body cell is removed and inserted into the egg cell
- egg cell then stimulated by electric shock to make it divide, just like a normal embryo
- implanted into womb of adult female - grows into a genetically identical copy of original adult body cell as it has same genetic information
113
Famous cloned sheep called ….. created by …..
Dolly
Adult cell cloning
114
Cons to cloning x3
- reduced gene pool - more susceptible to new diseases
- cloned animals could not be as healthy as normal ones
- human cloning could lead to many unsuccessful attempts eg children severely disabled
115
Pros to cloning x2
- study of animal clones could lead to greater understanding of development of embryo, ageing and age-related disorders
- help preserve endangered species
