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33 Cards in this Set
- Front
- Back
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base pair H bonding rules for DNA?
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GC3, AT2
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DNA pol adds bases to what end of the elongating DNA strand?
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5' end
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which DNA pol has both 3'-5' and 5'-3' exonuclease activity? Which DNA pol does most of the work during DNA replication?
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DNA pol I. pol III
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describe lagging strand DNA synthesis.
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RNA primers are made to compliment various parts of the lagging strand template. DNA pol III elongates these RNA primers with DNA. DNA pol I removes the primers and fills in the gaps with DNA then DNA ligase joins them
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RNA pol of E. coli contains what two subunits to make up the holoenzyme?
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sigma factor and core enzyme. note sigma aids the enzyme in the recognition of promoters
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describe Rho independent txn termination.
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a hairpin loop in the RNA forms then a string of U's which have weak H bonds thus termination
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what are the differences between proks and euks concerning txn?
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euks have 3 RNA pols, long lived mRNA, modifications at both ends of mRNA (5' MGcap and 3' poly A tail), monocistronic mRNA's, and uncoupled txn and tsln
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what molecule ensures that the correct tRNA is paired to the correct AA?
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AA tRNA synthetases make sure the correct AA-AMP is charged to the correct tRNA
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briefly describe the process of tsn.
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Initiation from three factors of Fmet tRNA into P spot on 30s ribosome. Elongation by adding new tRNA+AA to A sight then peptide bond formed via peptidyl transferase, then whole complex translocates to P spot in ribosome. Termination when elongation is finished.
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At what level does gene regulation take place.
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Primarily at txn but tsln control can operate
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in terms of gene regulation define negative and positive control.
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neg is when the reg protein bound to DNA turns the gene off. Pos is when reg protein bound to DNA turns gene on.
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describe how the lac operon uses both negative and positive control of induction.
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neg: lactose binds to the reg protein which is bound to the operon causing it to dissociate and turn the operon on. In the presence of cAMP, cAMP binds to a differnt reg protein which thus binds to a differnt site on the operon resulting in more rapid txn and thus more protein. Note that neg. control of induction will over-ride the pos control
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what kind of gene regulation does the TRP operon do?
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negative control of repression (substance must bind the repressor protein so it can bind the operon and turn it off). It also does attenuation. The gene has four seperate sequences, when trp is a plenty, tsln will occur with txn causing a hairpin loop to form bw sequences 3 and 4 before the ribosomes can finish #2 thus txn terminates. When there is no trp, tsln stalls on sequence 1 thus allowing a hairpin loop bw 2 and 3 that does not interfere with txn thus the entire gene is transcribed and translated.
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examples of mutagens?
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base analogs, intercalating agents, chemicals that react with DNA like alkylating agents, radiation including UV that can cause thymine dimers
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what is a missense mutation?
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a pt. mutation that causes substitution of a single AA
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what is a nonsense mutation?
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a mutation that puts in a premature stop codon
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what is direct DNA repair? excision repair?
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removal of dimers. excision of a DNA segment containing the damaged DNA followed by the synthesis of a new strand.
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what are the last two responses of a cell to mutation before it dies?
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SOS response and error prone repair
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distinguish between conjugative and non-conjugative plasmids.
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conjugative are usually large and can initiate conjugation on their own (F plasmids). Non-conjugative are usually small and have to tack on to a conjugative plasmid to be transferred (ex is R plasmid which contains genes for antibiotic resistance).
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what are the phenotypic effects of plasmids?
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code for bacterial toxins, enzymes that metabolize unusual substrates, antibiotic resistance (R plasmids have 2 parts, the RTF which enables resistance to be transferred and the R determinant itself, and the F plasmid can integrate into the bacterial chromosome to form an Hfr strain
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define prophage and lysogen.
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prophage is the genetic material of the phage incorporated into the bac chromosome while lysogen is the name of the bacterial cell that contains a prophage
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why can't bacteria already infected with phage be infected again or superinfected?
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the prophage contains genes that prevent further infection from that phage or related phages
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what is the genetic material of a phage?
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DNA or RNA
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describe generalized and specialized transduction.
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generalized occurs during the lytic phase when the phage is packaged with bacterial DNA instead of viral DNA. Specialized occurs during the transition from lysogenic to lytic phase; a piece of bac DNA attached to the viral
DNA is packaged into the phage. |
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the most frequent form of gene transfer between bac species is?
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conjugation
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define prophage and lysogen.
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prophage is the genetic material of the phage incorporated into the bac chromosome while lysogen is the name of the bacterial cell that contains a prophage
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why can't bacteria already infected with phage be infected again or superinfected?
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the prophage contains genes that prevent further infection from that phage or related phages
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what is the genetic material of a phage?
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DNA or RNA
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describe generalized and specialized transduction.
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generalized occurs during the lytic phase when the phage is packaged with bacterial DNA instead of viral DNA. Specialized occurs during the transition from lysogenic to lytic phase; a piece of bac DNA attached to the viral
DNA is packaged into the phage. |
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the most frequent form of gene transfer between bac species is?
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conjugation
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describe bacterial transposons.
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antibiotic resistant strands of DNA flanked by IS elements (inverted repeats) that have transposase so it can become a mobile DNA element
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what are some important results of recombinant DNA technology and medicine?
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understanding gene function, production of medically important proteins, development and study of virulence factors, diagnosis of genetic disorders, and gene therapy for genetic disorders and cancers
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WHAT DO MICROARRAYS TELL US?
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shows an increase or decrease in expression of a large number of genes in order to identify what genes are causing some sort of change
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