DNA structure

stands for deoxyribonucleic acid

  • Contains genetic information that determines the structure of the cell and the way it functions

Location: most DNA molecules found in the nucleus nuclear DNA

  • but some are found in the mitochondria (mitochondrial DNA or mtDNA).

Inside the nucleus, the DNA is arranged in 23 pairs of chromosomes.

Chromosomes

2-3m worth of DNA in every cell

(DNA) coiled around 8 proteins called histones to form a nucleosome

The network of nucleosomes are called chromatin

  • If the cell-dividing chromatin is loosely coiled

  • During cell division chromatin will become super coilded into structures called chromosomes

Nuclear DNA

Mitochondrial DNA

Double helix

circular molecule

DNa bounded to 8 protein molecules (histones)

not bounded by histones

23 a pair

37 genes

Both mother and father

exclusively from mother to offspring

DNA structure

Double helix - twisted ladder

  • The sides of the leader are sugar phosphate backbone

  • and rungs of the ladder are nitrogenous bases

Nucleotide

Each nucleotide is made of a sugar, phosphate and nitrogenous base

Neuclotide bond to the phosphate of another, forming a chain of alternating sugars and phosphates

Dna sugar: Deoxyribose

Rna sugar ribose sugar

Nitrogenous bases - DNA

Purines Adenine (A) and Guanine (G)

Pyrimidies Thymine (T) and Cytosine (C)

During DNA replication and transcription

purines will match with pyrimidines using hydrogen bonding

A and T, C and G

  • In RNA

    • A and U

    • U = Uracil

Gene

Genes - section of DNA that codes for a protein

Each gene has a unique sequence of bases producing a unique protein - combination of proteins give us a unique phenotype

  • Not all DNA codes for protein