Presentation on theme: "C & C P. 229 Explain why neither cyclins nor kinases alone can cause a cell to progress through the cell cycle. Interaction of cyclins and kinases is."— Presentation transcript:
2 C & C P. 229Explain why neither cyclins nor kinases alone can cause a cell to progress through the cell cycle.Interaction of cyclins and kinases is required for regulation2. How do controls on the cell cycle protect multicellular organisms from accumulating large numbers of damaged or defective cells?The cycle can be paused (cell-cycle arrest) so that damaged DNA can be repaired.What is the difference between a cancerous tumor and metastasisMetastasis involves the breaking off and movement of cells from the primary tumor to another location in the organism.4. What are the functions of tumor-suppressor genes and proto-oncogenes in noncancerous cells?They serve key roles in regulating many cellular processes, including cell division, where proto-oncogenes promote cell division and tumor-suppressor genes inhibit cell division.
3 DNA: The genetic material A few questions to ponder today:What is DNA?How did we figure out the structure of this important biomolecule?How is it replicated for the cell cycle?
4 Steps to the discovery of DNA: 1869- Freidrich Miesherpurified DNA from pus cells obtained from discarded surgical bandages1923- Robert Feulgendeveloped a procedure that stained this material in the nucleusThis enabled him to measure the amount of “stuff” in the nucleusHe concluded that virtually every cell nucleus in any plant or animal has the same amount of this “stuff”What was this “stuff” found in the nucleus and did it have anything to do with why offspring look like their parents?Was it DNA or a protein that carried the hereditary instructions from generation to generation?Early scientists saw the structure of the DNA molecule as too simple to possibly contain the complex genetic information of an organism
5 In other words, he discovered what was called transformation 1828- Fred Griffith was working on a project that enabled others to point out that DNA was the molecule of inheritance.He was trying to prepare a vaccine against a pneumonia-causing bacterium.He discovered that harmless bacteria could turn virulent when mixed with bacteria that caused disease.In other words, he discovered what was called transformationa change in phenotype caused when bacteria cells take up foreign genetic material.animation
6 1952- Alfred Hershey and Martha Chase settled the controversy. 1944- Oswald Averycontinued with Griffith’s experiment to see what the inheritance molecule was. In his experiment he destroyed the lipids, ribonucleic acids, carbohydrates, and proteins of the virulent pneumonia. Transformation still occurred after this. Next he destroyed the deoxyribonucleic acid. Transformation did not occur. Avery had found the inheritance molecule, DNA!1952- Alfred Hershey and Martha Chase settled the controversy.DNA is the molecule that store genetic info in living cellsanimation
7 1951- Roseland Franklin fired x-rays through DNA crystals, trying to learn how the atoms of the DNA molecule were arranged1953- James Watson and Francis Crick were shown Franklin’s photo and immediately determined the double helical structure of DNA.
8 Deoxyribonucleic Acid Phosphate moleculeSugar moleculeNitrogen Base moleculeHydrogen bondsGuanineAdenineCytosineThymine
9 DNA Structure Nucleotides are the subunits: a phosphate group a 5-carbon sugar moleculeDeoxyribose5’ end3’ enda nitrogen –containing basePurines- made up of 2 rings of carbon and nitrogen atomsAdenine (A)Guanine (G)Pyrimadines- made up of a single ring of carbon and nitrogen atomsThyamine (T)Cytosine (C)
10 Chargaff’s Rule- (1947)-Erwin Chargaff, a chemist who worded at Columbia found that:for each organism studied, the amount of adenine always equaled the amount of thymineand cytosine always equaled guanine.This became known as the Base-Pairing Rules
11 Why does this complementarity exist? □ The two chains of nucleotides are held together by 2 or 3 weak hydrogen bonds that form between the nitrogenous bases:Cytosine and guanine have three hydrogen bondsThymine and adenine have two hydrogen bonds□ Each rung of the DNA ladder needs to have a total of three rings Also, One of the strands of DNA runs in the 3’ to 5’ direction and the other runs in the 5’ to 3’ direction.This is called _______________antiparallel
12 DNA cont. DNA is the molecular “blueprint”— This “instruction manual” makes up an organisms genes.Encoded in the precise order of its nucleotidesThe genetic alphabet only contains 4 letters (ACTG).Human DNA contains more than 3 billion base pairs!
13 COMPARING PROKARYOTIC AND EUKARYOTIC DNA: PROKARYOTESEUKARYOTESConfiguration of DNACircularlinearLength1000 micrometers1.8 metersDNA housed in nucleus?NoYesAssociated proteinsTransient proteinsHistones# of Chromosomes perCell12- 1,262
14 HOW DO ALL THESE BASE PAIRS FIT IN THE NUCLEUS? a NUCLEOSOME consists of 2 loops of DNA wrapped around a central cluster of 8 histone molecules.This shortens the length of DNA by 1/6.This is shortened even further by its coiling into thicker fibers
15 Complete the Concept Map in your packet Begin “Journey into DNA”Finish crossword puzzle and any of the above for homework
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