Breeding + Genetic Engineering + Tissue Culture Flashcards
What is selective breeding?
Plants or animals with desirable characteristics are chosen to breed together, so that the offspring will be produced that inherit these trait.
What are the steps in selective breeding with plants?
1) plants with good features are crossed.
2) plants grown from seeds of these crosses are selected for their good features and crossed with each other.
3) selection + crossing is repeated many times until a high-yielding variety is produced.
What are the reasons for selective breeding?
- disease resistance
- increased yield
- better ability to cope with difficult conditions
- faster growth
- better flavour
Whats a disadvantage of selective breeding?
You breed closely related organisms so they show less genetic diversity and may show genetic defects.
Whats the difference between natural selection and selective breeding?
NS occurs by chance and is survival or organisms with a more advantageous phenotype.
SB is carried out with a specific aim.
Whats one problem of selective breeding in crop plants?
Little genetic variation within population so if there is a disease then it could spread very easily.
What is genetic engineering?
Changing the DNA of an organism, often by introducing genes from another to create genetically modified organisms.
How does genetic engineering work?
1) the gene for a trait is cut out of a chromosome using enzymes.
2) the gene is inserted into a chromosome inside the nucleus of a cell in a different organism.
3) the cell of this organism now produces the characteristic of the gene.
How could a GM crop with herbicide resistance be developed?
The gene for herbicide resistance is put into some plant cells.
- the cells are grown by tissue culture so they develop into new plants.
How does plant tissue culture work?
1) tissue sample cut from parent plant.
2) is put on a agar jelly containing plant hormones and nutrients.
3) samples grow into tiny plants.
4) put plants onto trays of compost.
What are the advantages of using animal cell cultures?
- test the effects of drugs and other chemicals on cells.
- check for cancer cells in a sample from a patient.
- produce important proteins e.g. antibodies.
What are the advantages of plant cell cultures?
- produce lots of identical plants (clones) from just one parent.
- cells can be grown to make plant products.
- produce disease-free plants.
What are the stages in genetic modification?
To make human insulin:
1) DNA from human cell is cut into pieces using restriction enzymes. These make cuts across the DNA, leaving a few unpaired bases at the end, called sticky ends.
2) Bacterial cells contain plasmids and the same enzymes are used to cut plasmids open, leaving sticky ends with matching sets of unpaired bases.
3) The pieces of DNA with the insulin are mixed with the plasmids. The bases in the sticky ends pair up. DNA ligase are added, linking the DNA back into a continuous circle.
4) Plasmids are inserted into bacteria. They grow in huge fermenters, where they make human insulin.
What are vectors?
Anything that carries the new gene into a cell.
