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43 Cards in this Set

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  • Back
What are the 4 characteristics of genetic Material?
1) storage of information 2)expression of information 3)variation by mutation 4)ability for replication of information
What did Fredrich Meischer accomplish?
He separated nuclei from cytoplasm and isolated an acidic substance called nuclein. Nuclein contained large amounts of phosphorous but little sulphur.
Why did people think proteins were genetic material and not nucleic acids?
Proteins are very abundant and varied. They contain 20 amino acids whereas nucleic acids are composed of only 4 nucleotides (A, C, T and G)
What did Rosalind Franklin discover/accomplish?
She studied DNA crystals using X-rays and recognized A and B forms of DNA
In which phase is DNA replicated?
S phase
What did Arthur Kornberg do?
-He purified DNA replication factors from E Coli
-He reconstituted DNA synthesis reaction in vitro
He won Nobel Prize with S. Ochoi in 1959 for work on the biochemistry of DNA synthesis
What are 3 causes of cancer?
1) Bad luck (Mistake is made during DNA replication and not repaired) 2)Bad genes 3)Environmental factors like a)carcinogens b)viruses
What are carcinogens?
Chemicals that promote cancer
What are 3 things that carcinogens do?
1) React with DNA [ex: nitrogen mustards adn UV light] 2)Form a new molecule in the body that reacts with DNA [ex: Benzopyrene] 3) Increase risk of cancer w/o affecting DNA [ex: phorbol esters]
What are 3 common types of DNA damage?
1) Depunination 2)Deamination 3)Thymine Dimer Formation
What does UV light do that causes skin cancer?
It causes adjacent T's and C's to become connected with covalent bonds
What is Xeroderma pigmentosum?
-Rare, recessive mutations
-High incidence of skin cancer
-Very sensitive to sunlight
-Defects in proteins prevents repair of UV damage
-Limited treatment
How do phorbol esters increase the risk of cancer?
They activate a signaling protein called PKC. PKC regulates many cellular processes. The activation of PKC leads to uncontrolled cell growth, which leads to cancer.
What are 3 ways cancer can be treated?
1) Surgery 2) Radiation 3)Chemotherapy
What are 3 challenges to chemotherapy?
1) Cancer cells mutate quickly 2)Chemotherapies often require correct functioning of cell system control proteins, which may be mutated in cancer cells 3)Only one surviving cell can cause cancer to recur
What is the difference between non selective and selective chemotherapy?
Selective has fewer side effects. However, both types are not always effective, and there can be resistance.
What are 2 examples of non selective chemotherapy?
Nitrogen mustards and 5-fluorouracil
What are 2 examples of selective chemotherapy?
Tamoxifen and Gleevec
What is the goal of non-selective chemotherapy? What are side effects?
The goal is to prevent cell divison. Side effects: Kill healthy dividing cells (Hair, stomach lining, immune cells)
What are 2 ways to prevent cell division?
1) Damage DNA-prevent DNA replication 2) Prevent synthesis of key components of cell division-ie, DNA nucleotides
How does Nitrogen Mustard Stop Cell Divison?
Cell senses modified DNA and cannot repair. Triggers cell suicide (apoptosis). If this sensing mechanism fails-it can lead to cancer.
What is the mechanism of 5-Fluorouracil?
It inhibits an enzyme called thymidylate synthase.
5 Fluorouridine monophosphate binds to thymidilate synthase 1000 fold better than uridine monophosphate. A covalent bond is formed with 5-FU which can't be broken-enzyme is destroyed. No more Ts are made for DNA synthesis-signals cell suicide.
What does thymidylate synthase do?
It makes Ts for DNA synthesis.
What is the goal of selective inhibitors in breast cancer?
To treat tumors by inhibiting the action of estrogen. To prevent the synthesis of estrogen.
How do SERMS interact with estrogen receptors?
-Binding of SERM results in a different structure.
-This structure may or may not be recognized by coactivator proteins.
What is the mechanism of Gleevec action?
It inhibits a tyrosine kinase oncogene?
What is the function of some tyrosine kinases?
-growth factors signals receptor in cell membrane to dimerize
-receptor dimer is activated, becoming phosphorylated
-activation signal gets transferred down a cascade of enzymes
-in nucleus genes get turned on (become transcribed) that cause cell to divide
Why is there resistance to chemotherapies?
1) Cancer cells are prone to mutations 2) If one cell is resistance and survives, the cancer will return 3) The cellular processes that enable chemotherapies to work are the ones most likely to be mutated in cancer 4) The cell can develop proteins that can pump out all small molecule drugs
What are some ways the plague can be transmitted?
-Bite from rodent flea carrying plague bacterium
-Handling infected animal (black house rat)
-Plague enters human body through lesions of skin or through mucous membranes of nose of throat
What is The Lethal Factor?
A protease that destroys cellular kinsaes. This activity can lead to cell death.
What does The Edema Factor do?
It causes levels of cAMP to rise in the cell. This leads to fluid outpour into extracellular spaces, resulting in edema, or swelling.
What are the 4 basic concepts Ehrlich introduced?
1) Screen many compounds for killing bacteria 2) Quantitate therapeutic vs. toxic dose 3) Similar compounds act similarly 4) A prodrug is a drug metabolized to active form in body
What were 3 treatments for victims of the Coconut Grove Fire?
1) Blood plasmid-prevent dehydration 2) Sulfa drugs-prevent blood poisoning 3) Penicillin
What is the mechanism of Penicillin?
It prevents cell wall biosynthesis.
How does penicillin inhibit transpeptidase?
A covalent bond is formed between penicillin and transpeptidase. Thus, transpeptidase is no longer able to catalyze other reactions.
What did William Roberts observe?
Cultures of the mold Penicillin glaucum did not exhibit bacterial contamination.
What did Pasteur and Joubert observe?
Growth of the anthrax bacilli was inhibited when the cultures became contaminated with mold.
What did Lister observe?
Samples of urine contaminated with mold did not allow the growth of bacteria.
What does erythromycin do?
It binds to RNA and blocks the exit of protein from ribosome.
What are some uses of antibiotics in the modern world?
-Treatment of many diseases of domestiated animals
-Preservation of food
-Preservation of certain wines, beers, and cheeses
-Preservation and purification of virus preparations and other biologial materials
-Treatment of certain plant diseases
What are some examples of the misuse of antibiotics?
-Often the wrong antibiotic is prescribed
-Unneccessary distribution
What are the 3 biochemical basis of resistance?
1) Production of enzymes that destroy or inactivate the antibiotic
2) Prevention of access for the antibiotics (efflux pumps)
3) Modification of target site or enzyme
What are 3 methods of genetic transfer?
Transformation, Conjugation, and Transduction