DNA
Inheritance of genetic information (to each generation).
Traits: inherited characteristics between parents (that sexually reproduce) and offspring.
Traits can be acquired from the environment.
DNA; deoxyribonucleicacid
DNA is organized into genes;
Gene is a unit of inherited material.
Components
Composed of a long chain of subunits called nucleotides.
T & C (thymine and cytosine) are pyrimidines (single rings).
A & G (adenine and guanine) are purines (double ring).
Can combine in various sequences.
Nucleotide is made up of three parts; A ring-shaped sugar (deoxyribose), a phosphate group, and a nitrogen base.
Chromatin: DNA exists as this; Long, invisible, tangled fibres.
Eukaryotic cells store DNA in the nucleus.
Histones: Bead-shaped proteins; DNA tightly coiled around this.
Nucleosomes: Resemble beads; DNA & histone packages form this structure.
Chromosomes: Chromatin thickens and shorten to become this; Happens when the cell is preparing to divide.
Human somatic (body) cells have 46 chromosomes.
Chromosomes are paired based on similarity.
22 of the pairs are autosomes (non-sex chromosomes).
1 pair is the sex chromosome (XX = female, XY = male).
Karyotype: a photograph / chart of chromosome make-up.
Replication
DNA unwinds and "unzips".
Genetic mutation
When DNA replication does not occur perfectly.
Can alter the structure of the protein it produces.
Ex. sickle cell anaemia, albinism, melanoma (skin cancer), and DNA-resistant bacteria.
Causation
Mutation: a change in the DNA of an organism.
Mutagen: a factor or substance that can cause a mutation.
Ex. radiation (UV/X-rays), mercury, cigarette tar.
Cell Cycle
Interphase: the growing stage.
Mitotic phase: Mitosis & cytokinesis.
Mitosis: nucleus and genetic material distributed equally between 2 daughter cells.
Cytokinesis: cell's cytoplasm divides into 2; typically starts before mitosis ends.