1 / 16

Chapter 10 DNA, RNA, & Protein Synthesis

Chapter 10 DNA, RNA, & Protein Synthesis. Watson & Crick. During the 1950’s James Watson – American Biologist Francis Crick – British Graduate Student tried to determine the structure of DNA. 1953: they came up with the structure - DNA is made up of 2 strands - double helix shape

devlin
Télécharger la présentation

Chapter 10 DNA, RNA, & 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. Chapter 10DNA, RNA, & Protein Synthesis

  2. Watson & Crick • During the 1950’s • James Watson – American Biologist • Francis Crick – British Graduate Student • tried to determine the structure of DNA 1953: they came up with the structure - DNA is made up of 2 strands - double helix shape - they relied on other scientists to develop their DNA model

  3. Wilkins & Franklin Maurice Wilkins – English physicist and molecular biologist Rosalind Franklin - British biophysicist, physicist, chemist, biologist and X-ray crystallographer - took X-ray diffraction photographers of DNA crystals

  4. Chargaff In 1949 Erwin Chargaff – American Chemist • discovered the key that lead to the understanding of DNA structure • same amount of A as T • same amount of G as C • was key because it means that there is base pairing Pyrimidine = contains single ring (T & C) Purine = contains double ring (A & G)

  5. Nobel Prize Winners IN 1962 James Watson Francis Crick Maurice Wilkins Why not Rosalind Franklin? Franklin died in 1958 and could not receive the award, only the living can get a Nobel Prize

  6. Replication • Complimentary base pairs allow for: • hydrogen bonds that help hold the 2 strands of DNA molecule together • helps explain how DNA replicates before a cell divides (one strand can serve as a template for making a new complimentary strand)

  7. What is DNA replication? DNA replication = process by which DNA is copied in a cell before a cell divides by mitosis, meiosis, or binary fission

  8. What basically occurs? • The two nucleotide strands of the original double helix separate along the strands. • Each strand serves as a template to make new complimentary strands. • After replication • -2 identical double stranded DNA molecules separate and move to new cells formed during cell division.

  9. Steps of Replication helicases = enzymes that separate the DNA strands - Helicases move along DNA molecule, breaking hydrogen bonds, allowing the 2 strands of DNA helix to split

  10. Steps of Replication 2. DNA polymerase = enzymes that add complimentary nucleotides to each of the original strands - they are free floating in nucleus - hydrogen bonds are formed

  11. Steps of Replication 3. DNA polymerases finish replicating the DNA and fall off, resulting in 2 separate and identical DNA molecules that are ready to move to new cells during cell division

  12. Semi-Conserative Replication • - 1 strand is new and 1 strand is the original • - each (combination) kept (conserved) one of the 2 original strands • Replication occurs in many locations otherwise it would take 53 days to replicate • DNA ligase = enzyme that joins the gaps

  13. What about errors? • only about 1 error occurs for every billion of paired nucleotides added • DNA polymerases have repair enzymes that “proof read” DNA • example: a friend might check your term paper for spelling errors • DNA example: if A pairs with a C instead of T, the repair enzymes would fix error by removing C

  14. What happens if error is not corrected? Mutation = a change in the nucleotide sequence of a DNA molecule = can have serious effects on the function of an important gene and disrupt an important cell function • some DNA can be damaged from chemicals and UV radiation from the sun • some mutations can lead to cancer • explains how mutations can arise and lead to altered cells and organisms • changes allow individuals to survive and reproduce better, so these variations increase in the population over many generations

More Related