Chapter 2
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51 terms
Terms | Definitions |
|---|---|
 It was assumed that genes would be composed of ______? | Amino acids (because at that time they appeared to be the only biomolecules with sufficient complexity). |
| Research on the mold neurospora was done by who? | Beadle and Tatum. |
| Beadle and Tatum supported what hypothesis? | They supported Archibald Garrod's hypothesis that genes work by controlling the synthesis of specific enzymes. |
| Recap: Genes work by _______ the synthesis of ______ _______. | controlling; specific enzymes. |
| The idea of DNA being genetic material emerged from? | Frederick Griffith in 1928 from studies on a pneumonia cuasing bacterium. |
| Pathogenicity reflected the action of what gene? | The capsule gene which coded for a key enzyme involved in the synthesis of the carbohydrate-containing capsule that surrounds most pneumonia casuing bacteria. |
| The capsule gene (s gene) coded for an enzyme involved in? | The synthesis of carbohydrate capsule. |
| What did Frederick Griffith do? | He basically "transformed" the R strain with the S strain. The s cell was heated to kill... The S gene was released and recombined in the R cell (non pathogenic). |
| Griffith's experiment was done with what bacteria? | Streptococcus. |
| In 1944, after 10 years of research ____ showed that transforming agent was ______. | Oswald Avery, Colin MacLeod, and Maclyn McCarthy; DNA. |
| Oswald basically isolated and purified DNA from s strains and added to R cells to tranform them T/F? | True. |
| The transforming ability of purified active fractions was destroyed by addition of? | deoxyribonuclease. |
| Did the addition of either ribonuclease or proteases have an effect on transforming ability? | No it did not. |
| Hershey Chase experiment involved what? | Involved a T2 phage or bacteriophage. |
| What did Hershey and Chase lable radioactively? | 35-S (protein) and 32-P (DNA). |
| What did Hershey and Chase's experiment do? | They took the phage and introduced it to a host cell in which it infected. After agitation, the "ghost" protein coat fell off and the DNA material was inside the host cell which then replicated and formed new phages. |
| What did Hershey and Chase's experiment prove? | It proved that the protein coat only served to protect the genetic material and transport it. After violent agitation it simply fell off. (VIRAL GENES ARE NUCLEIC ACIDS). |
| What are the steps of infection? | 1. Adsorption 2. Penetration 3. Replication 4. Release of virions. |
| In 1938 Astbury first _______. | X-ray diffraction of DNA. |
| 1950s Wilkins and Franklin confirmed? | DNA was helical shaped and composed of more than one polynucleotide chain. |
| 1952 Alexander Todd lab showed? | DNA chains were held together by 3' --> 5' phosphodiester bonds. |
| Erwin Chargaff proved what? | A = T C = G and purines = pryimidines. |
| The new DNA strand grows from _' to _'. | 5' to 3'. |
| The 3' OH is linked to the _' ______. | 5' phosphate. |
| Is the strand anti parallel? | Yes it is antiparallel. |
| The 3' strand has the __ group and the 5' stand has the __ group. | OH; phosphate. |
| What did Meselsohn and Stahl do? | They tested the replication of DNA by doing a CsCl density gradient centrifugation to show the separation of complementary strands during DNA replication. |
| In M and S experiment after one generation of growth the strands are? | A hybrid of one heavy and one light. |
| After two generations of growth what happened? | Half the DNA molecules were light and half hybrid. |
| M and S used what isotopes? | 14 N and 15 N. |
| DNA models: semi, cons, and disp | Semi: each of the two daughter DNAs should be of hybrid density (one original and only newly synthesized strand). Cons: one daughter DNA is heavy (both original strands) and the other daughter DNA is light (both newly synthesized strans). Disp: DNA strands proposed to be broken as frequently as every 10 bp & used to prime synthesis. |
| Protein synthesis in all eukaryotic cells occurs in? | The cytoplasm. |
| DNA cannot be the template that directly orders amino acids during protein synthesis T/F? | True. |
| A typical gene has how many base pairs? | 1000 number of potential genes in that size? 4^1000 much greater than the # of genes in any organism. |
| What did Torbjorn Caspersson & Jean Brachet find? | RNA is in the same cellular compartment where protein synthesis occurs (mostly in cytoplasm). |
| What two things distinguish RNA from DNA? | 1. Sugar (deoxyribose vs ribose). 2. No thymine but uracil. |
| RNA is usually found ___ stranded but _______. | Single stranded; double stranded can form but each strand is the same. |
| Francis Crick called it the _________ which stated DNA -> RNA -> Protein | Central Dogma. DNA ----transcription---- RNA ----translation---- Protein. |
| Crick proposed that the amino acids were first attached ______. | To specific adapter molecules. |
| Zamecnik and Hoagland proposed _______. | transfer RNA molecule (Crick's adapter molecule). |
| tRNA accounts for __ of all RNA. | 10 percent. |
| About __ of all cellular RNA is found ____. | 85 percent in ribosomes. |
| The amino acid attaches to which end on the tRNA? | The 3' end on the tRNA. |
| About __ of total cellular RNA is mRNA. | 4 percent. |
| Because only a small segment of mRNA is attached at a given moment to a ribosome, a single mRNA molecule can simultaneously be read by several ribosomes. T/F? | True this is called polyribosomes in this case. |
| What enzyme actually transcribed RNA from DNA templates? | RNA Polymerases. |
| These RNA Polymerases were found by? | Jerard Hurwitz and Sam B. Weiss. |
| These RNA Polymerases required what substrates (4)? | ATP, GTP, CTP, & UTP. |
| The new RNA strand from the DNA template grew from _' to _'. | 5' to 3'. |
| What is degeneracy? | When more than one codon codes for the same amino acid. |
| What are the initiator codons in prokaryotes and eukaryotes? | AUG, GUG; AUG. |
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