• 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

• 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.