Slide 1

DNA This is a chromosome? nope it is two chromosomes. This is 2 identical chromosomes joined together A single chromosome looks like

Once a chromosome replicates then it forms the sausage (chromatid) structure attached to its replicated copy.Stuff that any respectful Bio student really should know

Deoxyribonucleic Acid- (learn how to spell it)

The number of chromosomes a species has does not indicate higher order.Human 46Kangaroo 12Pea 6Shrimp -92

DNA StructureDNA strands are made up of Nucleotides.

There are only 4 different nucleotides

DNA StructurePurines (A, G) 2 ringsPyrimadines (C, T) 1 ring

For the Chemists (not examinable)

When labeling the C atoms on the sugar they are given numbers (why? Because chemists get a kick out of it)

Hydrogen bondsChromatidTo form a chromatid the DNA strand winds around protiens (histomes) that package the strand into a lovely organised bundle

Why because the strand is incredibly long On the average, a single human chromosome consists of DNA molecule that is about 5 centimetres longThe World Book Encyclopedia

KaryotypesThis slide is revision from L2 but lets make sure we have it right!

Karyotypes are images of an organisms replicated chromosomes taken of a cell as it prepares to divide (metaphase)

What does this image represent? Is it a..ChromosomeReplicated chromosomeHomologous pair Diploid chromosomeBiozone Pg 60 Q1-6GenomeThis slide is revision from L2 but lets make sure we have it right!

Karyotypes are images of an organisms replicated chromosomes taken of a cell as it prepares to divide (metaphase)

What does this image represent? Is it a..ChromosomeReplicated chromosomeHomologous pair Diploid chromosomeBiozone Pg 60 Q1-6RNA StructureRNA is similar to DNA. The difference is: RNA is single strandedRNA has the base Uracil instead of ThymidineThe sugar in the nucleotide is different.

Donald and Ronald - DNA and RNADouble strand - single strand

Biozone Pg 66 Q1-5Differences between DNA and RNA

Also: mRNA is shorter and mRNA can travel into cytoplasmAnti-parallel structure (DNA)Both these images show the same idea

11Anti-parallel structure (DNA)This diagram shows a lot of stuff not yet discussed.What you need to understand at this point

When an enzyme (DNA polymerase) travels along a strand of DNA it travels in the 3 to 5 direction of the original strand

DNA Polymerase travels 3 to 5 on original strandREVIEW QUESTIONS ONDNA STRUCTURE!

Review Question 3Name three key differences between RNA and DNA.

(Click for answer)