Biology 2

Cell - Basic unit of all organisms.

Nucleus - Controls the cell, contains the chromosomes.

Chromosomes - Tightly coiled molecule DNA.

Gene - A length of DNA that codes for a characteristic, a protein.

DNA - The molecules that genes are made of.

Only 1 parent is involved.

No egg and sperm involved.

Offspring identical to parent - No genetic variation.

Produces large amount of offspring. 

Potato tubers, strawberry runners, cuttings, bacteria.

Problems from parent passed onto offspring - diseases spread.

Two parents involved.

Ovum - Sperm and egg join together in animals.

Gametes - Ovules (eggs) and pollen (sperm) join together in plants.

Genetic variation - Offspring not identical to parents.

Produces variations and new types.

Problematic as egg and sperm have to meet.

Disease not likely to spread through the population.

Small sample - scraped from parent plant.

Samples put in agar plate with nutrients and auxins.

Samples develop into plantlets.

Plantlets planted into compost to grow.

This process produces lots of plantlets at a time, and not much is needed for it.

Sperm taken from best male animal and used to fertilize an egg from the best female animal.

Fertilized egg divides to form an embryo containing several cells. 

Embryo is separated into individual cells.

Cells grow into new embryos in the lab. Each embryo contains identical genes.

The embryos are implanted into surrogate mothers.

The nucleus from an egg cell is removed, leaving an egg cell without a nucleus.

The nucleus from an adult cell is transferred into this egg cell.

A small electric shock is given to the new egg cell which causes the cell to start dividing to form an embryo.

The embryo is placed in a uterus of another animal and the baby sheep develops. It will look identical to the sheep which donated the egg cell.

Enzymes act as a pair of scissors to cut out the DNA either side of the required insulin gene.

Bacterial DNA - plasmid is opened using enzymes.

Human gene is inserted into the bacterial plasmid using enzymes as a 'glue'.

New bacterial plasmid is put back into bacterium.

Bacterium reproduces and produces human insulin on a large scale, which can be harvested.