Exam 4

Genes that are present in a cell

the expression of a gene

• deoxyribosenucleic acid
• 4 bases: Adenine-Thymine, Guanine-Cytocine 

• ribosenucleicacid
• 4 bases: Adenine-Uracil, Guanine-Cytocine  

• Coding: 2%
• Non-coding: 98% 

ribosomal RNA

messenger RNA

transfer RNA

Sense strand

Nonsense strand

• Enzyme divides strands of DNA
• DNA polymerase is used to copy continuously from 5'-3'
• Okazaki fragments fill in from 3'-5' 

• DNA being copied to mRNA
• Occurs in nucleus
• requires RNA polymerase 

Ribosome reads mRNA and creates proteins from amino acids coded in mRNA

Coding sequences only in eukaryotic DNA

Non-coding sequences in eukaryotic DNA that are cut out.

structure of a gene

an operon that can be turned on and off

• cells prefer glucose as a fuel
• When glucose is present: cAMP levels are low
• When glucose is absent: cAMP levels are high

• any change in DNA sequence
• can be good, harmful, neutral or deadly 

mutation codes for same amino acid, so organism is unaffected

• codes for different amino acid
• could be good or bad 

• adds a premature stop codon
• usually deadly 

• addition or deletion of a base, changing sequence after
• usually deadly 

1 in 1,000,000 (10^-6)

• 1) Spontaneous mutation
• 2) Mutagens
• 3) Radiation
• 4) Certain Viruses 

• Increases mutation rate by 10-1000x
• asbestos
• benzopyrene (burnt stuff)
• aflatoxin (PB in other contries)
•  

UV and gamma

• sunburn causes thymine dimers. 
• Two T's attach to each other instead of A's
• Excision repair fixes it
•  

HPV

• ex. testing antiobiotic resistance
• Putting bacteria on antibiotic plate. If any growth they are antibiotic resistant.
• Positive selection entails the growing the culture on a medium that will alow for the growth of only the mutant colonies

.If, for example, we want to find mutants that resistant to penicillin, we grow the culture on a medium that contains pencillin. Only those colonies that are resistant to penicillin will grow and we ca identify them directly 

• Negative selection is used to identify mutants that have lost the ability to perform a certain function that their parents had.
• -Auxotrophic mutants, for example, are bacteria that have lost the ability to synthesize an essential nutrient.

• The replica-plating technique is used to identify mutants by negative selection.
•      -the replica-plating technique can be used, for example, to identify mutants that have lost the ability to synthesize the amino acid histidine. Therefore, mutants are His- and require histidine in order to survive.
• `Inoculate a histidine enriched medium with bateria. Incubate so that cells can form colonies. This is the master plate.
• `Press a sterile velvet surface into the colonies of the master plate. Some cells from each of the colonies adhere to the velvet.
• `Prepare two mediums, one with histidine, the other without histidine.
• `Transfer cells from the velvet to each plate.
• `Compare growth on the two plates after incubation. Colonies that grow on the histindine enriched medium but not on the medium lacking histidine are His- mutants.

using sterile velvet to move organisms to different plates

• Good at testing out potential carcinogens. 
• Reverses gene mutations
•  

Uptake of naked DNA

F+ bacterial cell transfering DNA to F- bacterial cell via pili

• Virus takes over cell and makes new viruses inside infected cell
• Sometimes they accidently pick up host DNA and bring it to a new host 

• Jumping genes.
• Segment of DNA that can cut itself out and move to another chromosome
• Indian corn 

Chemicals some bacteria produce to harm other bacteria

• use of microbes for a desired outcome
• ancient-beer, cheese 

• moving genes from one organism to another to get the gene expressed
• new since 1970s
• first time: putting firefly genes in tobacco to make it glow 

identical DNA

Trying to mutate cells to create a better geneotype

• cut DNA at specific sequences
• Can be blunt cut or staggered cut 

a circular vector piece of DNA

viruses that infect bacteria

• amplifies DNA from one strand to billions in 3 hours
• requires heat
• DNA is split, primers are added and DNA polymerase copies DNA 

Proves that you are successful in getting DNA into e. Coli

Bacteria did not take up vector

Vector got ito bacteria, but not DNA

• Successful!
• Both Vector and DNA entered cell 

uptake of DNA

put DNA in test tube and give it an electric shock

• Enzymatically remove cell walls from 2 cells and put it in dense glycerine solution
• causes cells to fuse together into 1 cell 

gun that coats DNA in gold bullets and shoots into cells

• Injectiing DNA into cell
• IVF 

• Holds pieces of DNA and cells
• DNA is cut up, put in vectors, put in e. coli and deep frozen 

• Turns RNA into cDNA
• HIV virus 

complementary DNA

• Subunit vaccines
• gene therapy
• DNA vaccines
• Gene scilencing
• HGH
• Insulin

• proteomics
• reverse genetics
• human genome project
• human microbiome project
• DNA fingerprinting/forensics

• more nutritiotous animals and plants
• dourght resistance
• salt resisntace
• pseudomonas syringae-prevents frost damage
• bacillus thuriengenesis-kills mosquito larvae