year 12 biology 2012 ms hodgins. we’ve all heard that dna is important because it holds the...
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CHAPTER 4- DNA, PROTEINS
AND PROTEOMES
Year 12 Biology
2012
Ms Hodgins
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
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)
WHAT IS RNA? A copy of DNA Made in the nucleus, passes into
cytoplasm Differences-DNA RNA
Deoxyribonucleic Acid Ribonucleic Acid
Sugar is Deoxyribose Sugar is Ribose
Bases are A, T, G C Bases are A, G, C, U
Double Stranded Single Stranded
Nucleus Cytoplasm
WHAT IS THE END PRODUCT? We now know-
What DNA is.What RNA isWhy DNA is importantWhy PROTEINS are important
Let’s look at the final products. PROTEINS- How are they made- made
simple ACTIVITY 2: Making proteins made simple
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
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
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.
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?
TRANSCRIPTION AND TRANSLATIONOrganelle / Substance Analogy
DNA of gene in the nucleus Masterplan with the complete set of instructions
mRNA Working copy of one instruction
Ribosomes Construction site
tRNA Carriers of raw materials
Amino acids Raw 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 4.1ACTIVITY 2: Transcription and Translation Role-play
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!
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