Two nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) Monomers: ‘Nucleotide’ – 5-carbon sugar (ribose or deoxyribose) – Phosphate group – Nitrogen base (cytosine, guanine, thymine, cytosine)

Phosphorus covalently bonded to deoxyribose sugar which is bonded to the nitrogen base Sugar-Phosphate backbone Nitrogen base pairs with the complementary base on the other (complementary strand of DNA) Base pairing rules: – G pairs with C – T with A

Same structure except: – 5-carbon sugar is ribose – Uracil replaces thymine – Single stranded, not double stranded

Segments of DNA contain genes Genes contain the information to code for the production of polypeptides on the surface of the ribosome.

Before a proteins can be built: – DNA must undergo replication – Helicase separates the strands of DNA – DNA polymerase assembles the nucleotides Occurs during Interphase DNA copied for the new cells Replicate this strand of DNA – AAGCCGTTA – Animation Animation

Information from DNA must be transported to the ribosomes DNA unwinds and is copied by RNA – mRNA mRNA moves out of the nucleus (pores) and attaches to the ribosomes Transcribe this stretch of DNA – AAA TGC Animation Animation II

Pre-mRNA will lose non- coding sequences called introns – Formally know as junk DNA The important information in a gene will be preserved – Exon

Amino acids are assembled on the surface of a ribosome and a polypeptide is formed. Amino acids are brought the surface of the ribosomes by tRNA Bond with sequences in the mRNA called codons – Anticodon on tRNA bonds with codon on mRNA

The codon sequences of mRNA may be translated into amino acids using the genetic code Always read from the mRNA! UCA = Ser Animation

A single stand of mRNA can produce hundreds of the same polypeptide in a short period of time.