Topic 1: Genetics

Genetics

Describe a DNA molecule

A DNA molecule is made up of two strands coiled to form a double helix. The strands are linked by a series of paired bases (adenine with thymine and cytosine with guanine.) DNA carries the genetic code, which tells the cell to make proteins. The DNA strand that can do this is called the coding strand. A group of three bases is caled a triplet. Each of these is the code for one amino acid in the protein.

What is a gene?

A gene is a section of a long chain of DNA molecule. It is the unit of inheritance.

What does asexual reproduction lead to?

Asexual reproduction leads to genetically identical individuals called clones. An example for this would be the chlorophytum (spider plant.)

How does sexual reproduction, involving fertilisation, lead to variation in the new generation?

Because the offpring do not contain an identical mixture of genes from each parent, you will find variation. 

How does sexual reproduction work?

The oaveries and testies produce the egg and sperm cells. When fertilization occurs, the sperm join the egg and begins to form a zygote. The nuclei…