Chapter 12 DNA (deoxyribonucleic acid)

Published a model of the DNA double helix structure based on Franklin’s work

Watson & Crick

Discovered the amounts of thymine and adenine are almost always equal as the amounts of cytosine and guanine

Chargaff

Discovered bacteria contain a molecule that can transfer genetic info from cell to cell

Griffith

Showed the substance that Griffith discovered in DNA

Avery (wl MacLeod & McCarty)

Confirmed the genetic material of viruses is DNA not protein

Hershey & Chase

Recorded an x-ray diffraction pattern showing DNA is in the pattern of a helix

Rosalind Franklin

Showed characteristics are passed along in a predictable way; starting the study of genetics

Mendel

Transformation

The process in which one type of bacteria is permanently changed into another

Who experimented with R strain (harmless) and S strain (harmful) on mice (& discovered the transforming factor had to be a gene)

Griffith

Who conducted an experiment to find which chemical in heat-killed bacteria caused transformation (& found out transformation can’t happen w/out DNA)

Avery

Who conducted experiments w/ radioactively labeled viruses that infect bacteria & determined DNA is genetic material (only the DNA entered the material)

Hershey & Chase

What is DNA made up of?

Nucleotides

3 parts of Nucleotides

Deoxyribose sugar, phosphate group, nitrogenous base

What are the sides/backbone of DNA composed of?

Sugar & phosphates

What are the rungs in the middle made up of?

Nitrogenous bases (connected with hydrogen bond)

This unzips the DNA strand by breaking the hydrogen bonds between base pairs: creates 2 new ”template” strands

helicase

Adds an RNA primer to start replication

Primase

Inserts new complementary based and builds the backbone

DNA polymerase 3

What proofreads the sequence; fixes errors (& replaces RNA primer)

DNA polymerase 1

What strand goes in the opposite way of the leading strand (continuous) & why?

Lagging strand, DNA is made from Okazaki fragments

This enzyme seals DNA

DNA ligase

These protects the ends of chromosomes so that genetic info isn’t damaged

Telomeres

This strand goes in the same direction of helicase

Leading strand

DNA moves in this direction

5’(phosphate) to 3’(sugar)