Inheritance, Variation and Evoloution (Paper 2) Flashcards
2 main ways that organisms can reproduce
Sexual and asexual reproduction
True or false, some organisms can reproduce through both types of reproduction
True
E.g plants
What is fertilisation
Fusion of male and female gametes
Name for fusion of male and female gametes
Fertilisation
Why are the offspring of sexual reproduction genetically different to the parent
They contain a mixture of both parents genes, not just one
During sexual reproduction in plants which 2 gametes fuse together
Pollen and egg
3 examples of gametes
Sperm, egg, pollen
True or false, gametes only have half the genetic material of a normal cell
True
True or false, sexual reproduction always has to involve sex/ sexual Intercourse
False, as long as it involves the fusion of male and female gametes
E.g when plants reproduce through combination of pollen and egg cells
Which type of reproduction involves gametes
Only sexual
Does asexual reproduction involve any gametes
No
(Only sexual reproduction does)
In asexual reproduction is there any mixing of genetic material
No (as there’s only 1 parent)
In which type of reproduction are all the offspring identical clones
Asexual
Which type of reproduction is achieved by mitosis
Asexual
E.g in eukaryotic organisms, fungi and plants
Which process is used to create gametes
Meiosis
What does DNA stand for
Deoxyribonucleic acid
What is the chemical that all our genetic material is made of
DNA (Deoxyribonucleic acid)
True or false, DNA is a polymer
True
It’s made up of lots of similar units stuck together
What is special about the 23rd pair of chromosomes
They are the sex chromosomes- there is an X chromosome and a Y chromosome
(Women have 2 X, men have 1 X and 1 Y)
Name for small section of DNA that codes for a particular type of protein
Gene
What is a gene
A small section of DNA that codes for a particular type of protein
How many different types of amino acid are there
20
Name for entire set of genetic material in an organism
Genome
What is meant by genome
Entire set of genetic material in an organism
What type of structure does DNA have
Double helix structure
The DNA in typical human cells is found in tight coils known as what
Chromosomes
The chromosomes in the 23rd pair are known as what
Sex chromosomes
DNA can code for proteins by coding for the sequence in which what are joined together
Amino acids
Name for specific diseases that genes can cause
Inherited disease
3 things scientists have found by studying the whole human genome
Genes linked to different diseases
Understand and treat inherited disorders
Trace human migration patterns from past
Name for different versions of a particular gene
Alleles
What is meant by alleles
Different versions of a particular gene
How many versions of each gene do we have and why
2
1 from each parent (each different version is a different allele as the height gene from one parent might be really tall but the height gene from the other might be really small so even though they’re both height genes they’re different versions)
Alleles can be either dominant or what
Recessive
In order to be expressed, how many recessive alleles need to be present
2
Phenotype meaning
Characteristics expressed by an organism as a result of their genotype
Homozygous vs heterozygous
Homozygous= an individual carries 2 copies of the same allele for a trait (e.g 2 brown eye)
Heterozygous= an individual carries 2 different alleles for a trait (e.g 1 brown eye, 1 blue eye)
Genotype
Combination of alleles an individual has
E.g 1 blue eye and 1 brown eye
Term used to describe combination of alleles an individual has
Genotype
2 Advantages of sexual reproduction
Variation in offspring
If the environment changes, the offspring may have a survival advantage by natural selection due to their genetic variation
3 Disadvantages of sexual reproduction
Much slower than asexual reproduction
(Finding a mate and reproducing) is time consuming + requires lots of energy
6 Advantages of asexual reproduction
Only 1 parent needed
Time efficient (don’t need to find mate)
Energy efficient (don’t need to find mate)
Faster than sexual reproduction
Successful traits passed on as offspring are identical
Many identical offspring can be produced when conditions are favourable
2 disadvantages of asexual reproduction
Reduced genetic variation- offspring may have survival disadvantage if environment changes
Harmful mutations in parent are passed down to all offspring
Name for each monomer in DNA polymer
Nucleotide
What 3 parts is a nucleotide made up of
Phosphate
Sugar
Base
A phosphate, sugar and base make up what
A nucleotide (the monomer in DNA)
True or false, every nucleiotide has exactly the same phosphate and sugar
True (it’s just the base that can be different)
Out of the phosphate, sugar and base which is the one that can vary across different nucleotides
Base
(Phosphate and sugar are always the same)
4 different bases
T A C G
The phosphate of one nucleotide bonds to the what in the next nucleotide to form a polymer
Sugar
What is a sugar- phosphate backbone
Name for one long chain formed between a sugar and phosphate of different nucleotides bonding together (outside part of double helix)
Name for long chain formed by alternating phosphate and sugars from different nucleotides bonded together (outside part of double helix)
Sugar- phosphate backbone
What holds the 2 strands of DNA together
Bases (they each pair up with one from the other strand)
To form the double helix from 2 strands of DNA only complimentary bases can pair together.
Which bases are complimentary
A and T
C and G
Each set of how many bases codes for a single amino acid
3
(Type of amino acid depends on order of bases)
2 steps that make up protein synthesis
Transcription
Translation
Why can’t the whole DNA leave the nucleus
It’s too big
What is mRNA
A copy of a single gene
In simple terms what is transcription
The copying of a single gene of DNA to mRNA
Where does transcription take place
Nucleus
Why does a gene of DNA have to be copied to mRNA before protein synthesis to occur
DNA is too large to leave the nucleus and get to the ribosomes
(mRNA is shorter than DNA so can leave the nucleus as it’s only a single gene long)
3 ways mRNA is different to DNA
mRNA is shorter (only 1 gene long)
mRNA is a single strand but DNA is a double strand
mRNA doesn’t have a T base, instead it has a U base
Which base is different in mRNA compared to DNA
DNA has T, mRNA has U instead (all other bases are the same)
True or false, mRNA is only a single strand of DNA
True
True or false, mRNA is shorter than DNA
True
As it’s only one gene long- unlike DNA this allows it to leave the nucleus to get to the ribosomes
Where does the mRNA go to once it’s left the nucleus
Ribosome
Name for chain of amino acids
Polypeptide
What is a polypeptide
Chain of amino acids
What is meant by a mutation
Change in the DNA base sequence
Name for change in DNA base sequence
Mutation
2 things that increase risk of mutations
Carcinogens
Certain types of radiation
True or false, carcinogens and certain types of radiation e.g X-rays and gamma rays always cause mutations
False, they just increase the risk of it occurring
Name for each set of 3 bases that codes for 1 of the 20 different amino acids
Triplet/ codon
True or false, mutations always have a significant effect
False,
Mostly mutations don’t have a significant effect (it only effects the protein very slightly so can still work in the same way)
Most mutations occur in what type of DNA
Non- coding DNA
(This part of DNA doesn’t code for a protein so the mutation won’t have an effect)
3 types of mutations
Substitutions
Insertions
Deletions
What happens to a base in a substitution mutation
It is changed for another random base (therefore changes codon and the amino acid being coded for)
What happens in an insertion mutation
An extra base is inserted into the sequence somewhere so that all the bases are shifted along one and are all out of sync by 1 meaning that all the codons are completely different and therefore all the amino acids coded for are completely different
What happens in a deletion mutation
One base is delete (removed) from the sequence so all the bases have to shift along one and are all out of sync by 1 therefore the codons are all different and the amino acids coded for are completely different
True or false, mutations can occur spontaneously in our cells
True
(Although certain factors e.g carcinogens and some types of radiation increase the risk of them occurring)
What is meant by a gene being expressed
It’s turned on, so the protein it codes for will be produced
Describe how a change to one base in a gene (e.g through a substitution mutation) for an enzyme could affect the functioning of that enzyme
Change in base changes the triplet/ codon
This changes the amino acid it codes for
Therefore there will be a different sequence of amino acids
So the polypeptide will fold into a different shaped protein (enzyme)
Shape of active sites may change
Can no longer bind to substrate to form enzyme- substrate complex (as isn’t complementary)
So can’t catalyse reaction as well
What experiment did Mendel do with pea plants
He took one pea plant with green pods and one with yellow pods
He then crossed the plants together and all the offspring were yellow pea plants
He then crossed the 2 yellow pea plant together and 1/4 of the offspring were green , 3/4 were yellow
(He then did the same thing with different height plants and different colour flower plants)
Which 3 traits did Mendel study in his experiments to see inheritance of different characteristics
Pea colour
Flower colour
Plant height
Technical name for when everyone in our population is different
Variation
2 factors that effect our phenotype (characteristics that are expressed)
Genes
Environment
Who came up with the phase ‘survival of the fittest’ and then called it natural selection
Charles Darwin
Name for process of some animals being adapted to survive better than other so they pass on their genes
Natural selection
(This then droves evolution)
Who proposed the theory of evolution
Charles Darwin
2 things that provide evidence for the theory of evolution
Fossil evidence
Antibiotic resistance
What is speciation
The evolutionary process by which populations evolve to become distinct species
Classification order of living organisms
Katie Pye can out fast Great speeds
Kingdom
Phylum
Class
Order
Family
Genus
Species
Describe the process of natural selection
In any species there is variation between individuals
There is competition for food, water, land etc
Organisms with useful characteristics are more likely to survive and pass them on to the next generation
Their offspring has a beneficial variation which makes them a better competitor whilst other competitors die out
What is variation
The differences in characteristics between individual organisms of the same species
What process drives evolution
Natural selection
Survival of the fittest meaning
Organisms most suited to the environment survive and reproduce
What is selective breeding
Process by which humans breed plants/ animals for particular genetic characteristics
Selective breeding is the process where by humans breed plants and animals for what
Particular genetic characteristics
Describe process of selective breeding (process of humans breeding plants and animals for particular genetic characteristics)
Select organisms with desirable characteristics to breed
Pick offspring that demonstrate these desirable characteristics and breed them again
Continue this over many generations until all offspring show these desirable characteristics
4 key examples of selective breeding
Disease resistant garden plants/ food crops
Animals that produce more meat or milk
Domestic dogs with gentle nature
Large/ unusual/ brightly coloured/ heavily scented flowers
Disadvantages of selective breeding (process where humans breed plants and animals for particular genetic characteristics)
Reduced genetic variation- all species could be susceptible to certain diseases if new pest evolved/ introduced
Inbreeding (offspring produced are very genetically alike due to breeding close relatives)- some breeds particularly prone to inherited diseases or defects (increases chance of disease being passed down to offspring)
Rare disease genes can be unknowingly selected as part of positive trait (e.g lots of Dalmatians are deaf)
3 advantages of selective breeding
Animals can be selected that don’t cause harm e.g cattle without horns
New varieties may be economically important e.g producing more/ better quality meat
Desirable characteristics produced
What is inbreeding
Where close relatives are bred together which makes some breeds more prone to diseases/ inherited defects
(Can occur from selective breeding)
What is genetic engineering
Process that involves changing genome of organism by introducing a gene from another organism to produce a desirable characteristic
Examples of genetic engineering (changing genome of organism by introducing gene from another organism to produce desired characteristic)
Bacteria cells can produce useful substances like insulin to treat diabetes
Plant crops become resistant to diseases/ can produce bigger fruits/ higher yields etc (are genetically modified (GM))
Genetically modified crops have undergone what process
Genetic engineering
(Genome changed by introducing gene from another organism to produce desired characteristics e.g larger fruit size)
2 Advantages of genetic engineering
Bacterial cells can produce insulin to help treat diabetes
Better crops (e.g enhanced nutrition like golden rice, bigger fruit size, higher yield so more profitable, resistant to pests/ diseases/ droughts/ floods)
3 risks of genetic engineering
Genes from GM plants/ animals can spread into wildlife- devastating effect on ecosystems
Ethical concerns- in future genes of children could be manipulated to ensure certain characteristics
Long term health effects of eating GM crops haven’t been fully explored
What is a clone
An individual that has been produced asexually and is genetically identical to their parent
Are clones individuals that have been produced sexually or asexually
Asexually
4 different methods of cloning (producing an individual asexually)
Tissue culture
Cutting
Embryo transplant
Adult cell cloning
Method to produce clone of plants from cuttings (simple but old technique used by gardeners)
Cut off shoot from parent plant and remove lower leaves
Plant stem in damp compost
Add rooting powder (plant hormones encourage nee roots to develop)
Cover cutting in clear plastic bag to keep it moist and warm
Which method of cloning is a simple but old technique used by gardeners
Cuttings (for plants)
Process of cloning using tissue culture
Small tissue sample taken from parent plant
Tissue grown in Agar with plant hormones and nutrients to form big mass of tissue
Identical plantlets (small plants) formed which can then be planted into compost to further grow
When is tissue culture used as a method of cloning
Preserving rare plant species
Growing plants commercially
Process of embryo transplant (method of cloning animals)
1) Get Embryo (cluster of identical cells)
2) Divide each embryo into individual cells
3) Each cell grows into identical embryo in lab
4) Embryo transplanted into host mother
5) Identical cloned animals born (identical to each other but not biologically related to host mother)
Process of animal cell cloning
Take body cell from sheep A and egg cell from sheep B
Remove nucleus from both cells to leave empty egg cell
Insert nucleus from Sheep A body cell into empty egg cell
Fused cell develops into embryo
Cloned embryo implanted into uterus of host mother (random other sheep)
Host mother gives birth to sheep that is a clone of sheep A
Genetic engineering process
Enzyme used to isolate gene
Gene inserted into vector e.g bacteria
Vector used to insert gene into required cell
Genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.
In genetic engineering what is used to insert gene with desired characteristic into single cell of another organism
Vector e.g bacteria, animal, fungi, plant
Describe process of how to produce insulin (think genetic engineering method)
1) identify gene in humans that produces insulin
2) enzymes used to cut out gene from human cells and isolate it
3) Gene inserted into DNA of vector e.g bacteria
4) Bacteria reproduce asexually (mitosis) and all offspring now have insulin gene
5) Bacteria now produce human insulin (insulin can be taken and used to help treat diabetes)
4 steps in speciation
Isolation (populations of same species separated .g some humans live in Africa, some live in Antarctica)
Genetic variation (exists between populations e.g within Africa population everyone has different genes)
Natural selection (operates individually within each population e.g those less prone to the cold may survive in Antarctica)
Speciation (the Africa and Antarctica populations become so different that inbreeding isn’t possible)
Formation of fossils process
Organism dies and buried under rock/ mud
Organism doesn’t completely decay as there is no exposure to oxygen where it’s buried
Minerals replace hard parts of organism creating a fossil
Extinction meaning
Permanent loss of all members of a species
