Quiz – Page 381. Give 3 examples of a structural protein.

2. What class of protein in ferretin?

3. What does kinesin do?

4. What protein carries iron?

5. What class of protein is rhodopsin.

collagen, elastin, tubulin, keratin,a ctin

storage

it interacts with microtubules to move organelles

transferrin

receptor

Proteins Homework due today!

Lesson 6 – Nucleic Acids

Nucleic AcidsOn your desks draw out the structure of a nucleic acid as you remember it.

Nucleotide StructureAll nucleotides are made up of a pentose sugar, a phosphate group and a variable nitrogenous base.

Purines and PyrimidinesThere are 2 types of nitrogenous bases – purines (double ring structures) and pyrimidines (single ring structures).

UracilUracil has one ring so it is a….

pyrimidineIn fact it is structurally VERY similar to Thymine.

Nucleotide Structure Up Close

The Phosphodiester Bond

A bond forms between the phosphate group (C5) of one nucleotide and the hydroxyl group (C3) on the sugar of another.

The nucleotide monomers are joined by a dehyration synthesis reaction.

Phosphodiester bond

Base PairingOn your desks write how the bases pair up. Indicate which are purines and which are pyrimidines.

Purines always pair with pyrimidines. They are held together by hydrogen bonds.

3 bonds between C andG and 2 bonds between T and A (or U and A).

The Double HelixThe 2 strands of the double helix are in an anti-parallel arrangement.

3’ and 5’3’ is read “three prime” and refers to the third carbon on the sugar. Five prime refers to the 5th.

Antiparallel Arrangement showing 3’ and 5’

Double Helix (again)Features of the DNA double helix:

1. One complete turn has a length of 3.4 nm.

2. The diameter of the molecule is 2.0 nm.

3. There is a major groove and a minor groove.

4. The helix is described as right handed.

RNA vs DNAList ways that DNA and RNA differ.

Polymerase EnzymesDNA polymerase is an enzyme that catalyses the formation of the phosphodiester bond between bases.The formation of new strands of DNA occurs from 5’ to 3’ only. This presents a problem during DNA replication as one strand (called the leading strand) can be replicated as the molecule unzips but the other strand (the 3’ to 5’ side, called the lagging strand) needs to be replicated in sections then joined together later by an enzyme called DNA ligase.

Your Task- Nucleic Acids1. Past Paper QuestionsYou will need to access these in the department. Please DO NOT TAKE past papers home – we have limited numbers.

2004 MC Q82005 MC Q 112006 MC Q 4

2007 MC Q 7,92008 MC Q 6

2009 MC Q 3,42. Complete Scholar activities on nucleic acids.3. Read and make notes on pages 39-42.4. Make sure your glossary is up to date.

DUE Monday(December 3rd)