chapter 9 pt 2 Flashcards
degeneracy
most amino acids have multiple codons
what defines protein identity
primary structure
what is universal
genetic code
trna during translation
use anticodon to interpret the mRNA codons and bring aa
trna enters p site of ribosome and binds to mRNA when?
when it has a complementary anticodne and methionine amino acid
what does stop codon release?
peptides
what will the second tRNA do?
with a complementary anticodon will fill the A site
where does the peptide bond form during translation
between the amino acids on neighboring tRNAs in the ribosome
what codon has no corresponding tRNA?
stop codon
-when it is reached the ribosome just falls off and the tRNA is removed from the polypeptide
prokaryote vs eukaryote
transcription and translation in cytoplasm not nucleus
-eukaryote only does transcription in nucleus snd rna processing
polyribosomal complex
allows simultaneous synthesis of many protein molecules from the same mRNA molecule
-can only form after RNA has left the nucleus
-found in all domains
prokaryotes can
couple translation with transcription
-transcription does not have to be finished for translation to begin
eukaryotic mRNA
monocistronic
genes are only active when?
when their products are required
what coordinates gene regulation in prokaryotes?
operons
-a set of genes that are regulated as a single unit
-have defined functions
inducible
operon is turned on/ expressed by a substrate/ inducer being present
-lac opeon on when lactose is present
catabolic operons
-make enzymes resposible for catbolism
-lac operon is inducible operon and catabolic bc we need it to degrade the substrate/ lactose
repressible
genes in a series are turned off by the products they synthesize
-trp and arg.
anabolic operon
enzymes used to synthesize an amino acid stop being produced when they are not needed
-stops when trp is made
-trp operon
lac operon segments
regulation (gene codes for repressor), control locus (promoter and operator), and structural locus (encode enzymes to catabolize lactose)
bgal transacetylase
unknown function
promoter
recruit RNA pol to transcribe protein
what has to happen before oxidative phosphorylation
lactose must be broken down by enzymes into d galactose and d glucose
what turns on the operon?
lactose
what type of operon is arginine?
repressor: turns off when there is enough arginine
when is the argenine operon on?
when arg is being used by the cell
-turns on bc the repressor will change shape so it cant bind to the dna
-only the presence of a corepressor can bind it to the DNA
what does the presence of argenine do?
bind to the repressor and change it so the operon turns off
-arg is the corepressor
chemical mutations from?
nitrous acid, bisulfite ethidium bromide acridine dyes, nitrogen bases
template strand
non coding strand
-NOT the sense strand
missence
change in a single amino acid
silent
changes base not amino acid
back mutation
mutates gene reverts back to orignal composition
mutations can do what to proteins?
misfolding, truncations (incomplete and nonfunctioning), inactive (cant catalyze rxn or wrong shape), super active (enzyme regulation is disrupted and it is always on constituive)
what looks for mistakes in DNA
polymerase proof reads
mismatch repair
locates and repairs mismatch nitrogen bases that arent fixed by dna pol
-proteins looking for mistakes
excision repair
locates and repairs incorrect sequence by removing a segment of the DNA and adding the correct base
ames test looks for
a chemical capable of mutating bacterial DNA bc then it could maybe mutate mammalian
-test medicines, agriculture things etc
indicator oragnism of Ames?
mutates salmonella typhimurium that is auxotroph for histidine
-succeptable to back mutation
genetic recombination
happens occurs when an organism aquires and expresses genes that originated in a different organism
-horizontal gene transfer
genetic recombination in bacteria
-conjugation
-transformation
-transduction: use of a virus
gram negative
has a fertility plasmid for pilus formation
-transfers fertility
HFr
donors fertility plasmid is integrated into the genome
gram neg transfer
f plasmid copies itself first them goes to donot