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Bio 115 exam 4
Terms in this set (39)
DNA -> RNA -> Protein
in what direction is RNA created
which strand of DNA is the coding strand
3'-->5' strand and therefore produces RNA 5'-->3'
what is a codon
the sequence of three bases (triplet) on mRNA that codes for a single amino acid.
what are the four characteristics of the genetic code
1) redundant- all but 2 amino acids are coded for by more than one codon.
2) unambiguous- one codon will only code for one amino acid
3) nearly universal- w/ only a few exceptions, the same codons code for the same amino acids in all organisms
4) conservative- when multiple codons code for the same amino acids, the first two bases are usually the same.
What is the wobble position of a codon
The wobble position refers to the third nucleotide in a codon. Codons can vary in this third position and still use identical tRNAs.
what is a silent mutation
Mutatuion with no effect. Does not effect protein
what is a missense mutation
Point mutation in which a single nucleotide is changed, resulting in a codon that codes for a different amino acid.
what is a nonsense mutation
change resulting in early stop codon
what must happen to a DNA sequence in order for a frame-shift mutation to occur
occur with the insertions or deletion of a single nucleotide
what are the possible results of a frame shift mutation
deletion, inversion, duplication or translocation of genes
where does transcription occur in prokaryotes?
where does translation occur in prokaryotes?
where does transcription occur in eukaryotes?
where does translation occur in eukaryotes?
what are the 3 parts of a gene
middle- transcribed region
end- termination sequence
what is the name of the enzyme that creates mRNA from DNA
what are the stages of bacterial transcription?
What are the differences in prokaryotic and eukaryotic transcription
1) eukaryotic promoter
no -35 or -10 box
has tata box
2) eukaryotic RNA polymerase
3) eukaryotic RNA must be altered after transcription before translation
what are introns
Sequences that are not translated into part of the protein, and must be removed.
what are exons
Coding sections of DNA
what makes up a spliceosome
snRNPs, snRNA and the primary mRNA transcript---splicosome then cuts out introns.
what is mRNA
what is tRNA
Transfer RNA, or tRNA for short, translates the language of nucleotides into the language of amino acids. It carries amino acids and places them in a protein that is being produced according to the instructions of mRNA.
what is rRNA
makes up ribosomes, allows protein synthesis to occur
what is an anti codon
a set of 3 ribonucleotides that forms base pairs with the mRNA codon
what is lactose made up of
glucose + galactose
which two proteins are needed for an E.coli to use lactose and from which genes are these produced?
B galactosidase- lacZ
what is the product of the lacI gene
prevents transcription of lacZ and lacY when lactose is absent in environment
when lactose is absent...
repressor binds to DNA and transcription is blocked
when lactose is present
lactose binds to repressor and transcription occurs
when lactose is present but repressor isnt
What is CAP
regulatory protein of lac operon
glucose high =
glucose low =
what does the addition of acetyl groups do
neutralizes histones and loosens chromatin
places acetyl groups on histone
removes acetyl groups
methylation does what
reduces transcription/silences gene expression.
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