B13 Flashcards
What is the theory of evolution?
All of todays species have evolved from simple life forme that first started to develop over three billion years ago
Who was charles Darwin and what did he come up with?
He came up with the theory of natural selection
What is the theory of natural selection?
- In a species all individuals are different and show a wide range of variation
- This variation is because of difference in their genes( continuous mutations)
- Individuals with characteristics most suited to the environment have an advantage and are moe likely to survive an reproduce
- The genes/ alleles that allow these individuals to be successful have an advantage are passed to their offspring
What is speciation?
Over a long period of time, the phenotype of organisms can change so much because of natural selection that a completely new species if formed. Happens when populations of the same species changes enough to become reproductively isolated , so it can interbreed to produce fertile offspring
Why do species become extinct?
- environment changes too auickly
- new predator kills them all
- new disease kills them all
- they cant compete with another (new) species for food
- catastrophic event happens that kills them all
What happens two populations of one speciies becomes so different in phenotype what happens.
No longer interbreed to produce fertile offspring they have formed two new species
What is selective breeding?
When humans artificially select the plants or animals that are going to breed so that the genes for a particular characteristics remain in the population. Organisms are selectively bred to develop desirable characteristics.
Example of selective breeding?
- animals that produce more meat or milk
- crops with disease resistance
- dogs with a good, gentle temperament
- decorative plants with big flowers
Process of selective breeding?
1) from existing stock , select ones with characteristics your after
2) breed them together
3) select best offspring and breed them together
4) continue the process for several generations
What are the main problems with selective breeding?
Reduces the gene pool, nujber of different alleles in a population. This is because they use animals that are closely related and could lead to interbreeding
Why interbreeding is bad?
Cause health problems as organisms have more chance of inheriting harmful genetic diseases when the gene pool is limited. Also if a new disease appears , because not much variation , if one dies by a disease th others are likely too
What is genetic engineering?
Transfer a gene responsible for a desirable characteristics from one organism’s genome into another organism.
How have plant crops been modified ?
To be resistant to diseases or to produce bigger better fruits
How has bacteria been genetically modified?
Produce useful substances such as human insulin to treat diabetes
What happens in genetic engineering?
1) useful gene is isolated from one organisms genome using enzymes and is inserted into a vector
2) vector is usually a virus or bacterial plasmid, depending on the type of organism that the gene is being transferred to
3) when the vector is introduced to target organism useful gene is inserted into its cell
