Zusammenfassung der Ressource
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.