Year 12 Biology
2012
Ms Hodgins
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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
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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
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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)
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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
 DifferencesDNA
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
 We
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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
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ACTIVITY 2: Making proteins made simple
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Amino acids have the same basic structureAn amino group (NH4)
 A carboxyl group (COOH)
 A side chain (makes the amino acids different)
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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
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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
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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.
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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 / 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 4.1
ACTIVITY 2: Transcription and Translation Roleplay
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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
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Transcription
Translation
mRNA
tRNA
Locations where events occur
Proteases
Codons
Everyone in the group MUST have a role
HAVE FUN!