Chapter 4- DNA, Proteins and Proteomes

1. Chapter 4- DNA, Proteins and Proteomes Year 12 Biology 2012 Ms Hodgins

2. Lesson 1- Why is DNA so important? • 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

3. WHAT IS DNA? • 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)

4. What is rna? • A copy of DNA • Made in the nucleus, passes into cytoplasm • Differences-

5. What is the end product? • 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

6. Protein formation • Amino acids have the same basic structure- • An amino group (NH4) • 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 H2O) • Dipeptide = 2 amino acids joined together • Tripeptide = 3 amino acids joined together • Polypeptide = many amino acids joined together in a chain • PROTEINS are polypeptides

7. PROTEIN STRUCTURE • 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

8. Lesson 1 Quiz • 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.

9. Lesson 2- How DNA makes proteins 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?

10. Transcription and translation

11. 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

12. 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!