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57 Cards in this Set

  • Front
  • Back
what is the basic unit of DNA?
the nucleotide
what are nucleotides composed of?
deoxyribose, phosphate group, nitrogenous base
what are the two types of bases that compose nucleotides?
purines, pyrimidines
what are the purines?
adenine and guanine
what are the pyrimidines?
cytosine and thymine
how many hydrogen bonds form between T and A?
2
how many hydrogen bonds form between G and C?
3
what does it mean that DNA replication is semiconservative?
that each daughter helix is composed of one strand of parental helix and one newly synthesized strand
what is the "language" of proteins?
20 amino acids
the base sequence of mRNA is translated as a series of triplets, known as what?
codons
why are most amino acids coded for by more than one codon?
because there are 64 codons and only 20 AA
DNA --> DNA
replication
DNA --> RNA
transcription
RNA --> protein
translation
what does the term degeneracy or redundancy of the genetic code imply?
the fact that different codons represents the same amino acid
what are the DNA nucleotides?
guanine, thymine, cytosine, adenine
what are the RNA nucleotides?
guanine, uracil, cytosine, adenine
in RNA, is uracil considered a purine or pyrimidine?
pyrimidine, because it's replacing thymine
what is the significance of mRNA?
mRNA carries the complement of a DNA sequence (a message) from the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs.
what are the 3 types of RNA involved in protein synthesis?
mRNA, tRNA, and rRNA
what is tRNA?
transfer RNA- carries AA to the to mRNA at the ribosomes.
what role does rRNA play?
structural component of the ribosome
where is rRNA synthesized?
in the nucleolus
what is transcription?
the process whereby information in the code sequence of DNA is transcribed into a strand of mRNA, which leaves the nucleus through nuclear pores.
what is translation?
the process whereby mRNA codons are translated into a sequence of amino acids.
what is AUG?
start codon
what are episomes?
circular rings of DNA (plasmids) that are capable of integrating into the bacterial genome
how do bacterial cells reproduce?
binary fission
how do bacterial cells increase genetic variation?
1. transformation
2. conjugation
3. transduction
what is transformation?
process by which a plasmid is incorporated into bacterial chromosome via recombination.
what is conjugation?
"sexual mating" in bacteria

the transfer of genetic material between 2 bacteria that are temporarily joined.
what are plasmids?
circular rings of DNA found in bacteria
what are episomes?
plasmids capable of integrating into bacterial genome
how do bacterial cells reproduce?
binary fission
since bacteria reproduce asexually, how do they increase genetic variation?
1. transformation
2. conjugation
3. transduction
what is transformation?
plasmid is incorporated into bacterial chromosome via recombination
what is conjugation?
"sexual mating" in bacteria

genetic material is transferred between two bacteria that temporarily join.
what is the best studied example of conjugation/sex factors?
the F factor in Ecoli
what MUST two bacteria contain in order to conjugate?
sex factors
what is transduction?
fragments of bacterial chromosome are accidentally packaged into viral progeny produced during viral infection
what is the most complex and best understood virus?
bacteriophage AKA phage virus
what are the two cycles bacteriophages use to reproduce?
1. lytic
2. lysogenic
what is the lytic cycle
bacteriophage enters host cell and takes over, replicating itself and then causing cell to burst, releasing all the copies.
what is the lysogenic cycle?
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.
what are retroviruses?
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
UAA, UAG, UGA are what?
stop codons
where does translation occur?
cytoplasm
what is PCR used for?
amplification of genes
what is southern blot used for?
detection of a specific DNA sequence in a DNA sample
besides southern blot, what is another way to amplify genes?
gene cloning
what occurs before a preRNA strand is sent into the cytoplasm?
RNA processing:

1. 5' cap
2. Poly A tail
3. Intron splicing
what removes introns in RNA processing?
snRNPs (snurps)
what is 5' cap?
modified guanine nucleotide added to 5' end
what is poly-a tail?
string of adenine added to 3' end (prevents degradation by hydrolytic enzymes)
what is the operon?
an important model of gene regulation composed of "switches" and genes that control expression.
what is the difference between the Lac and Tryptophan operons?
Lac= inducible = off until switched on

Tryptophan = repressible = on until turned off
what are prions?
misfolded versions of protein normally found in the brain. responsible for scrapie, mad cow and CJD diseases