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57 Cards in this Set
- Front
- Back
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what is the basic unit of DNA?
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the nucleotide
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what are nucleotides composed of?
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deoxyribose, phosphate group, nitrogenous base
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what are the two types of bases that compose nucleotides?
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purines, pyrimidines
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what are the purines?
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adenine and guanine
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what are the pyrimidines?
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cytosine and thymine
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how many hydrogen bonds form between T and A?
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2
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how many hydrogen bonds form between G and C?
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3
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what does it mean that DNA replication is semiconservative?
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that each daughter helix is composed of one strand of parental helix and one newly synthesized strand
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what is the "language" of proteins?
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20 amino acids
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the base sequence of mRNA is translated as a series of triplets, known as what?
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codons
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why are most amino acids coded for by more than one codon?
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because there are 64 codons and only 20 AA
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DNA --> DNA
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replication
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DNA --> RNA
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transcription
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RNA --> protein
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translation
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what does the term degeneracy or redundancy of the genetic code imply?
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the fact that different codons represents the same amino acid
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what are the DNA nucleotides?
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guanine, thymine, cytosine, adenine
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what are the RNA nucleotides?
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guanine, uracil, cytosine, adenine
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in RNA, is uracil considered a purine or pyrimidine?
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pyrimidine, because it's replacing thymine
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what is the significance of mRNA?
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mRNA carries the complement of a DNA sequence (a message) from the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs.
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what are the 3 types of RNA involved in protein synthesis?
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mRNA, tRNA, and rRNA
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what is tRNA?
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transfer RNA- carries AA to the to mRNA at the ribosomes.
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what role does rRNA play?
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structural component of the ribosome
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where is rRNA synthesized?
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in the nucleolus
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what is transcription?
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the process whereby information in the code sequence of DNA is transcribed into a strand of mRNA, which leaves the nucleus through nuclear pores.
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what is translation?
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the process whereby mRNA codons are translated into a sequence of amino acids.
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what is AUG?
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start codon
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what are episomes?
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circular rings of DNA (plasmids) that are capable of integrating into the bacterial genome
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how do bacterial cells reproduce?
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binary fission
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how do bacterial cells increase genetic variation?
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1. transformation
2. conjugation 3. transduction |
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what is transformation?
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process by which a plasmid is incorporated into bacterial chromosome via recombination.
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what is conjugation?
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"sexual mating" in bacteria
the transfer of genetic material between 2 bacteria that are temporarily joined. |
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what are plasmids?
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circular rings of DNA found in bacteria
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what are episomes?
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plasmids capable of integrating into bacterial genome
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how do bacterial cells reproduce?
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binary fission
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since bacteria reproduce asexually, how do they increase genetic variation?
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1. transformation
2. conjugation 3. transduction |
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what is transformation?
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plasmid is incorporated into bacterial chromosome via recombination
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what is conjugation?
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"sexual mating" in bacteria
genetic material is transferred between two bacteria that temporarily join. |
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what is the best studied example of conjugation/sex factors?
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the F factor in Ecoli
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what MUST two bacteria contain in order to conjugate?
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sex factors
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what is transduction?
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fragments of bacterial chromosome are accidentally packaged into viral progeny produced during viral infection
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what is the most complex and best understood virus?
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bacteriophage AKA phage virus
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what are the two cycles bacteriophages use to reproduce?
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1. lytic
2. lysogenic |
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what is the lytic cycle
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bacteriophage enters host cell and takes over, replicating itself and then causing cell to burst, releasing all the copies.
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what is the lysogenic cycle?
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bacteriophage enters cell and replicates itself without destroying host cell. the phage virus incorporates itself into site in host DNA and remains dormant, as a "prophage" which is replicated along with host cell, until eventually an environmental trigger causes cell to switch to lytic phase.
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what are retroviruses?
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viruses that contain RNA instead of DNA and use their RNA as a template strand after infecting host cell by the use of reverse transcriptase. usually inserts itself into host genome
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UAA, UAG, UGA are what?
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stop codons
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where does translation occur?
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cytoplasm
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what is PCR used for?
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amplification of genes
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what is southern blot used for?
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detection of a specific DNA sequence in a DNA sample
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besides southern blot, what is another way to amplify genes?
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gene cloning
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what occurs before a preRNA strand is sent into the cytoplasm?
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RNA processing:
1. 5' cap 2. Poly A tail 3. Intron splicing |
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what removes introns in RNA processing?
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snRNPs (snurps)
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what is 5' cap?
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modified guanine nucleotide added to 5' end
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what is poly-a tail?
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string of adenine added to 3' end (prevents degradation by hydrolytic enzymes)
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what is the operon?
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an important model of gene regulation composed of "switches" and genes that control expression.
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what is the difference between the Lac and Tryptophan operons?
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Lac= inducible = off until switched on
Tryptophan = repressible = on until turned off |
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what are prions?
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misfolded versions of protein normally found in the brain. responsible for scrapie, mad cow and CJD diseases
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