1 / 16

DNA and Protein Synthesis

DNA and Protein Synthesis. Chromosomes are the molecules that contain our genetic code. Every human being has 23 pairs of chromosomes or 46 total chromosomes.

howard-walton
Télécharger la présentation

DNA and Protein Synthesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DNA and Protein Synthesis

  2. Chromosomes are the molecules that contain our genetic code. • Every human being has 23 pairs of chromosomes or 46 total chromosomes.

  3. The word “chromosome” comes from the Greek chroma meaning colour and soma meaning body due to their property of being very strongly stained by particular dyes. • Chromosomes are made up of a material called chromatin • Chromatin is actually composed of a DNA strand and protein. • Each individual DNA strand is actually 10,000 times the length of the chromosome it makes up.

  4. In order to fit all this DNA into the shape of a chromosome, the DNA strands coil around special proteins called histones. • The bead-like structures formed when DNA wraps around histones are called nucleosomes

  5. DNA coils around histones to form nucleosomes • Nucleosomes coil around themselves • The nucleosome coils then coil around themselves again and again forming supercoils • These supercoils eventually make the X shape of the chromosome

  6. At the base of the chromosome structure is the DNA molecule…

  7. Part 1: DNA Structure • DNA or deoxyribonucleic acid is the molecule that stores and transmits the genetic information from one generation of an organism to the next. • i.e. DNA carries the genetic code • The structure of DNA was discovered by Watson and Crick in 1953 • http://www.youtube.com/watch?v=sf0YXnAFBs8

  8. DNA is a polymer formed from units called nucleotides • There are 4 different nitrogenous bases: • Adenine • Guanine • Thymine • Cytosine Purines Pyrimidines

  9. Individual nucleotides are joined together to form a long chain • The deoxyribose sugars and phosphate groups form the backbone of the chain • The nitrogenous bases stick out from the backbone

  10. The nitrogenous bases are held together by weak hydrogen bonds • Thymine and Adenine always pair together • Cytosine and Guanine always pair together. • This phenomenon called “base pairing” is what holds the two strands of DNA together. • DNA is actually composed of 2 chains

  11. DNA does not exist as a flat ladder • The 2 strands of connected DNA actually form a right-handed twist around each other forming a shape called a double helix

  12. Let’s take a closer look at the purines and pyrimidines… • Purines have a double ring structure while pyrimidines have a single ring structure

  13. Why will a purine always pair with a pyrimidine? • Purines are bigger than pyrimidines • In order for all the rungs of the DNA ladder to be the same size, a small molecule must pair with a large molecule • If 2 purines would pair, pyrimidines next to them wouldn't be able to bind with each other, and if two pyrimidines would bond, there wouldn't be enough space for 2 puries next to them to fit. • By having them pair with each other, the spacing along the length of DNA is kept uniform.

  14. Why will A always pair with T and C with G? • Thymine has 2 hydrogen bonding sites and the Cytosine has 3 • Adenine has 2 hydrogen bonding sites while Guanine has 3 • Because they have matching H-bond sites, A must always pair with T and C must always pair with G

  15. This complimentary base pairing results in the final very important piece of information about DNA… • The 2 strands that make up 1 DNA molecule act as templates for each other!

  16. DNA Replication

More Related