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How We Store Genetic Information
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How We Store Genetic Information
Chromosomes
- Consist of 2 arms (chromatids) joined by a specialised structure at the centre called a centromere.
- Karyotype - the array of human chromosomes.
- 22 homologous pairs of chromosomes.
- Sex chromosomes - Female XX, male XY. Autosomes - all other chromosomes.
- Each chromosome contains a single molecule of DNA.
Genes
- Allele - known variations of a particular gene.
- DNA: a. carries genetic information that is used to synthesise proteins; b. it's structure can be easily duplicated/replicated; c. is relatively stable.
- DNA is a double-stranded molecule, the strands are made up of nucleotides (sugar, base and phosphate). Base pairings - A:T (U in RNA), C:G.
- Dominant disorders - requires only one defective copy (allele) of the gene.
- Recessive disorders - requres two defective copies (alleles) of the gene.
Each cell contains 23 pairs of chromosomes (46 total).
- Each of the 24 (22 of the same, 23 (X) and 24 (Y)) different types of chromosomes contain different genes.
- Each homologous pair of chromosomes (22 autosomes, and X chromosomes in females) contain the same genes in the same order - so each gene is present twice in the nucleus of every cell.
- Each of the 24 (22 of the same, 23 (X) and 24 (Y)) different types of chromosomes contain different genes.
