review for ch. 12

Griffith..

• Griffith-1st major experiment led to discovery of DNA as genetic material(MOUSE AND BACTERIA) …

• 2 bacteria harmful and harmless.. Heated harmful mixed with harmless and they transform which is what he wanted to find.

His experiment….

Avery

• Identified molecule transformed R strain of bacteria to S strain

• S=deadly and smooth R= rough and harmless

• Concluded when cells were killed when DNA was released.

• R bacteria incorporated this DNA into their cells changed into S cells

Hershey and Chase

• Used radioactive labeling to trace DNA and protein.

• Concluded that the vital DNA was injected into the cell and provided the genetic information needed to produce new viruses.

Their experiment…

Watson and Crick

• Built a model of double helix that confronted others’ research.

• Outside 2 strands made of alternate deoxyribose and phosphate.

• Inside connectors cytosine and guanine base pairs by 3 hydrogen bonds.

• Inside connectors thymine and adenine base pairs to each other by 2 hydrogen bonds.

Their model…

Chargaff

• Analyzed the amount of adenine, guanine, thymine, and cytosine into the DNA of various species.

• Found that C=G and T=A.

DNA replication

• Semiconservative- parental strands of DNA separate, serves as templates, and produces DNA molecules that have one strand of parental DNA and one new strand.

• Simple steps to remember: Unwinds, Base Pairing, Replicates, Rejoins.

Video so you can understand

• http://www.wiley.com/college/pratt/0471393878/student/animations/dna_replication/index.html

Protein Synthesis

• Basic steps: transcription, separates junk and info, translation, goes to cytoplasm, transcription, finds ribosome, copies.

• In transformation

DNA T= A RNA

A=U

G=C

C=G

Video so you understand

• http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP1302

Gene Regulation

• Ability of an organism to control which genes are transcribed in response to the environment.

• In prokaryotes, operon controls the transcription of genes in response to changes in the environment.

• Sections are: Operator, Promoter, Regulatory gene, and genes coding for proteins.

Gene Regulation Cont.

• In eukaryotic regulation, it must control transcription.

• They use transcription factors (next slide) and the complex structure of eukaryotic DNA.

Transcriptions Factors

• They ensure a gene is used at the right time and that the proteins are made in the right amounts.

• https://www.youtube.com/watch?v=vJSmZ3DsntU

• But remember, before it leave nucleus introns are removed.

Operon

• Operon- section of DNA contains the genes for the proteins needed for a specific metabolic pathway.

• Example in class : Lac Operon which is people that are lactose intolerant.

• Link to Video with Lac Operon:

http://www.biostudio.com/d_%20Lac%20Operon.htm

Beadle and Tatum

• Their experiment showed that one gene codes for one enzyme.

• We now know that 1 gene codes for 1 polypeptide.

Hox Genes• Hox genes are responsible for the general

body pattern of most animals.

RNA Interference

• RNA interference can stop the mRNA from translating its message.

• Video link to help you understand: http://www.nature.com/focus/rnai/animations/animation/animation.htm

Mutations

• A permanent change that occurs in a cell’s DNA is called a mutation.

• Types of mutation: Point mutation, Insertion, and Deletion .

• Insertion and Deletion cause frame shift, add or take away one of the codes.

• Point mutation is like substituting one code for another.

Causes of Mutation

• Can occur spontaneously

• Chemical and radiation can also damage DNA.

• High-energy forms of radiation. Such as X Rays and gamma rays, are highly mutagenic.

Protein Folding and Stability

• Substitutions also can lead to genetic disorders.

• Can change both the folding and stability of the protein.

• Video for help (just look at overview): http://www.wiley.com/college/boyer/0470003790/animations/protein_folding/protein_folding.htm