Evolution Flashcards
Variation
Differences in characteristics of individuals in a population
3 causes of variation in any population
-Inheriting different alleles from parents like hair colour
-Environment changes like colours of flower due to soil
-Combo of environment + genetics like height
What causes the genetic variation in species?
Mutations or random changes in DNA
Types of mutations
-No effect on the phenotype
-Influence the phenotype under certain circumstances
-Completely determine the phenotype (rarely)
How do mutations effect a population?
If the environment changes
A mutation could help them survive or resistant to change
Thus the surviving organisms will have a different phenotype
And will be inherited by all other organisms
Which is the baseline for evolution
How have different species come to be on earth?
All have evolved over very long period of time from simple single cells
Through evolution by natural selection
Stages of natural selection aka evolution
Species have a lot of genetic variation for diff phenotypes
If the environment changes, those with alleles to adapt to this change more likely to survive
Thus more likely to reproduce
And their offspring could inherit this allele then reproduce
Thus over time the whole population will have this phenotype
Evolution
The change in inherited characteristics of a population over time through natural selection
How does an animal differentiate into 2 different species?
If 2 populations of species become so different in phenotype over a period of time
Due to evolution
That they can no longer interbreed and produce a fertile offspring
= 2 separate species
Selective breeding
When humans decide which animals/ plants with a specific phenotype to breed in order to get an offspring with a desired phenotype
Pretty much speeding up the process of evolution but so they’re more useful to us
Examples of selective breeding
Dogs = more gentle nature
Crops = disease resistance
Cattle = more milk/ meat
Plants = large flowers
Stages of selective breeding (cows for meat)
Take mixed population of cows and select largest male + female
Breed them
Sexual reproduction = variation so some offsprings don’t have desired characteristic
So select the largest male and female offspring from that
Breed them
Repeat for many generations until all offsprings are large
Big problem with selective breeding
Breeding closely related animals/plants = inbreeding
Which cause being prone to disease or inherited defects
Genetic engineering
When a gene from one organism with a specific characteristic
Is taken from an organism
And transferred to another when in development so it has that characteristic
Using genetic engineering for type 1 diabetes
Putting the insulin producing gene in bacteria from a human
Then purified
So it produces insulin
Thus can help treat type 1 diabetes
Genetically modified
When you transfer a human gene to an organism to make it carry out a specific function/ have a specific characteristic
Why would we genetically modify crops?
Produce a greater yield
Resistant to disease/ insects
Produce bigger fruits
Resistant to herbicides so farmers can kill weeds but not harm the crops
Disadvantages of genetically modified crops?
Possibly harm insects
Or wild flowers
Health effects if humans eat it needs more research
Gene therapy
Using genetic modification to cure inherited disorders in humans
Disadvantages of gene therapy
We don’t know long term effects
Don’t know if it has effects on other genes
Steps of genetic engineering
Identify gene we want to transfer (from animal/human/plant)
Use enzymes to isolate it
Transfer gene into a circle of dna called plasmid from bacteria, or into a virus
Desired gene is transferred into target organism
Vector
The plasmid or virus that transfers the DNA from one organism to another
In genetic engineering Why do we transfer gene at an early stage in the target organisms development?
Make sure all cells receive the transferred gene
So the organism develops with this characteristic
Clone
Organism genetically identical to its parent
Advantages of cloning plants
Because it’s genetically identical to parent we know what it’s characteristics will be
Cloning plants using cuttings
Take small cutting of plant
Dip the end in rooting powder
Thus the plant develops roots
And is genetically identical
What method to get hundreds of clones of a plant?
Tissue culture
Tissue culture stages
Take parent plant
Divide into many small pieces
Containing small number of cells
Incubate with plant hormones
So the plant is stimulated to grow and develop fully grown clones
Conditions for tissue culture
Sterile
So we don’t have any microorganisms like bacteria or fungi
Adv of tissue culture
Thousands of genetically identical plants quick and cheap (commercially)
We can be certain of characteristics
Preserves rare species