Year 12 Biology 2012 Ms Hodgins

 We’ve all heard that DNA is important because it holds the instructions for life, but what does it actually do?  DNA holds all of the information needed to make PROTEINS. The information helps to ‘pull’ amino acids together to make polypeptides.  So why are PROTEINS so important?  PROTEINS  Play fundamental roles in cell functioning  Are enzymes  Provide structure  Provide support  Transport materials into and out of cells  Assist in cell recognition and signalling  Act as hormones  Support in bones and muscles  Transport molecules around the body  Provide defence mechanisms  PROTEINS ARE REALLY IMPORTANT FOR LIFE

 Deoxyribonucleic Acid  Found in the NUCLEUS of eukaryote cells  Made up of chemical building blocks called NUCLEOTIDES  Each NUCLEOTIDE has  A phosphate group  A 5-Carbon sugar (deoxyribose) (where the carbons are numbered 1’ – 5’)  A nitrogen containing base  Adenine A, guanine G, thymine T, cytosine C)  DNA double stranded helix due to COMPLIMENTARY BASE PAIRING : A-T, G-C ACTIVITY 1: Making nucleotides (Cut and Paste)

 A copy of DNA  Made in the nucleus, passes into cytoplasm  Differences- DNARNA Deoxyribonucleic AcidRibonucleic Acid Sugar is DeoxyriboseSugar is Ribose Bases are A, T, G CBases are A, G, C, U Double StrandedSingle Stranded NucleusCytoplasm

 We now know-  What DNA is.  What RNA is  Why DNA is important  Why PROTEINS are important  Let’s look at the final products.  PROTEINS- How are they made- made simple ACTIVITY 2: Making proteins made simple

 Amino acids have the same basic structure-  An amino group (NH 4 )  A carboxyl group (COOH)  A side chain (makes the amino acids different)  Refer to Fig 4.10 page 80  Amino acids link together with peptide bonds (removing a molecule of H 2 O)  Dipeptide = 2 amino acids joined together  Tripeptide = 3 amino acids joined together  Polypeptide = many amino acids joined together in a chain  PROTEINS are polypeptides

 PRIMARY STRUCTURE- linear sequence of the amino acids  SECONDARY STRUCTURE- pleating or coiling of the amino acid chains caused by Hydrogen bonds forming  TERTIARY STRUCTURE- folding to create 3D shape determined by the number and sequence of amino acids. (Critical for its function e.g. enzymes)  QUATERNARY STRUCTURE- four polypeptide chains combining ACTIVITY 3:Draw an interpretation of each structure

 1. What does DNA stand for?  2. What does RNA stand for?  3. What are the 3 substances required to make a nucleotide?  4. What is the name of the sugar in DNA?  5. What is the name of the sugar in RNA?  6. Name the bases in DNA  7. Name the bases in RNA  8. How many strands does DNA have?  9. How many strands does RNA have?  10. In DNA, state which bases pair up to form complementary base pairing.

ACTIVITY 1: Making Proteins Role-play  The “raw materials” (amino acids) are converted into a “product” (polypeptides)  11 out of the 20 amino acids are able to be made in human cells. The other 9 are essential amino acids and needs to be consumed as a part of the diet.  Amino acids are found in the cytosol of the cell.  HOW ARE THE CORRECT AMINO ACIDS SELECTED?

Organelle / SubstanceAnalogy DNA of gene in the nucleusMasterplan with the complete set of instructions mRNAWorking copy of one instruction RibosomesConstruction site tRNACarriers of raw materials Amino acidsRaw products Protein chain (polypeptide)End product

 TRANSCRIPTION- copying of a nucleotide sequence of DNA into the nucleotide sequence of RNA  TRANSLATION- assembly of a polypeptide according to the nucleotide sequence if RNA using the genetic code.  The genetic code – refer to page 76 Table 4.1 ACTIVITY 2: Transcription and Translation Role- play

 Numbered 1 or 2- all 1’s together, all 2’s together  Read pages 73, 74, 75  Create a short role play to show how genetic information in the nucleus undergoes transcription and translation to create polypeptides  Include an explanation of  Transcription  Translation  mRNA  tRNA  Locations where events occur  Proteases  Codons  Everyone in the group MUST have a role  HAVE FUN!