GCSE Biology - B1 Summary (OCR 21st century)

The 

Things that cause variation:

Genes - Inherited from the parents, controls how an organism develops and functions.
Environment - Things that an organism comes into contact with. 

Some feautures are a resullt of either genes (e.g. blood group) or environment (e.g. scars) 
Most features are a result of both genes and the environment (e.g. weight and height) 


Where are they found?


Nucleus' control a cell because it contains the instructions for making every protein in an organism.


Within the nucleus' are the genetic material


This includes the chromosones


Genes are in bands around the chromosones


Chromosones are long threads of DNA (deoxyribonucleic acid)

DNA within a chromosone within a nucleus
within a cell

Proteins

They have many functions: 

• Building cells 
• Moving muscles 
• Fighting bacteria and viruses 
• Carrying oxygen in the blood 
• Sending chemical messages round the body
• Enzymes are made of proteins and are used to speed up chemical reactions in teh body.

These functions can be divided into two categories

Structural: They 'build' the body. e.g. Callagen which is a protein found in tendons

Functional: Take part in chemical reactions oft he body. e.g. Enzymes