DNA: made up of nucleotides; nitrongenous bases - Adenine. Thymine, Guanine, Cytosine; carries genetic code for protein synthesis.

Nuclear DNA: DNA found in nucelus.

Extra-Nuclear DNA: DNA found outside of nucelus, montrichondria & chloroplast DNA

Double helix: Shape of DNA molecule consisting of two strands joined together & twisted spririally.

Hereditary: genetic information passed from parent to offspring.

Roaslind Franklin & Maurice Wilkins researched the structure of DNA - used X-ray diffraction images - 1952

Watson & Crick created a 3-D model of the double helix DNA - 1953

Mainly in nucleus - nuclear DNA.

Small amount outside nucelus - extra-nuclear DNA (Chloroplast DNA & Mitochondrial DNA)

Chromatin in nuclei = nuceloproteins; combination of proteins & nucelic acid (in this case, DNA). Very different molecules.

Proteins:

Nulceic acids:

Has a double helix, consisting of monomers that link to form long chains. Sugar is deoxyribose, is attached to nitrongenous base. Phosphate & sugar molecules are attached to one another by strong bonds alternately to form the lomg chains. There are 4 types of nitrongenous bases in DNA - Adenine(A), Thymine(T), Guanine(G), Cytosine(C).

Nitrongenous bases are complimentary & always join in a specific order, A to T & G to C. the sequence can vary, but these difference account for differnt genes. This pairing of the bases means that two strands of DNA are joined together, forming a long ladder-like structure.

The bases are held together by weak hydrogen bonds The ladder-like structure becomes coiled & is known as a double helix structure. DNA strand winds around proteins which are know as histones.

DNa carries hereditary information in the form of genes. Genes are short sections of DNA which code for a specific trait & determine physical characteristics & behaviour of an organism. Most of DNA strands do not code for anything & are known as non-coding DNA.

Main functions of DNA include:

Cytoplasm: the bas substance in which the organelles of the cell are suspended. A watery substance & allows for metabolic reactions to take place.

Ribosome: small, round organelles which are mainly found attached to endoplasmic reticulum / free-floating in cytoplasm. Can als be found inside the chlorplast & mitochondria (but smaller amount). The site of protein synthesis & consist of RNA & protein.

Nucelus: controls all the activities of the cell.

Nucelus has 4 main parts:

All eukaryotic cells have nuclei. Eukaryotic: a DNA enclosed by a membrane & has a true nucleus