Chromosomes, Genes and DNA

Key Facts
1. The genetic material- deoxyribonucelic acid- is contained in the Chromosomes
2. Chromosomes occur in functional pairs except in gametes
3. Genes are short sections of Chromosome that control specific characterisitics
4. Genes are therefore short lenghs of DNA
Structure of DNA
1. Backbone
  1. Deoxyribose Sugar
  2. Bases
  3. Phosphate
  4. Nucleotide
2. Bases
  1. Pyrimidines
    1. Thymine
    2. Cytosine
  2. Purines
    1. Adenine
    2. Guanine
  3. Complementary base pairs
3. Double helix structure
Chromosomes
1. Humans have 46 Chromosomes
  1. They are arranged into 23 pairs
2. A chromosome is a tightly coiled length of DNA
  1. A GENE is a short length of DNA that codes for a protien or characteristic
Base triplets
1. Why have three?
  1. "CCA" "CCC" "CCG" and "CCT" code for the same amino acid- this lowers the chance of mutatos
    1. If the change in base results in a different amino acid being formed then it will form a different protein and may not function
      1. Causes: Radiation e.g UV Light
Discovering DNA
1. Watson and Crick
  1. Used modelling to hypothesise the 3 dimensional structure of DNA in the double helix format
2. Franklin and Wilkins
  1. Studied the 3 dimensional structure of DNA using crystallograpgy (X-rays)
3. Chargaff
  1. Discovered that there where equal amounts of guanine and cytosine as well as adenine and thymine

Resource summary

	Created by Mya Mccalmont about 7 years ago