e x a m III Flashcards
which RNAs are functional?
tRNA & rRNA
how many amino acids make up a codon?
three
what is the sequence of the start codon?
AUG
what are the three stop codons?
UGA UAG UAA
what does is mean that the genetic code is degenerate?
some amino acids are encoded by more than one codon
how many combinations are there of amino acids?
64
what is the function of tRNAs
translate the genetic code into amino acid sequence
which RNAs make up the majority of RNAs?
functional RNAs
what is the function of tRNA
serves as the adapter to amino acids
carries amino acids to the proper codon
tRNA synthetases
add charge to amino acid
IF3
binds the large ribosomal subunit to the smaller one
allows mRNA to bind to smaller subunit
shine-delgarno
for correct positioning for initiation
IF2
binds GTP & Met-tRNA
brings them to the P site
what happens when the large ribosomal subunit & small ribosomal subunit are bound?
IF2 & IF3 are released
elongation factor EF-Tu
escorts tRNA into the A site
EF-Ts
catalyzes release of EF-Tu and GDP from ribosome
peptidyl transferase
catalyzes the formation of a peptide zone between amino acids at the A & P sites
EF-G
catalyzes the release of uncharged tRNA
moves the amino acid sequence over in the mRNA
termination
polypeptide is discharged
ribosome is dissociated
how many amino acids are there?
20
primary structure of amino acids
specific amino acid sequence
secondary structure of amino acids
alpha helicies
beta sheets
tertiary structure of an amino acid
spatial arrangement of amino acids
from alpha helix & beta sheets
quaternary structure of an amino acid
spatial relationship of a polypeptide
how they associate into a multi-subunit molecule
one gene codes for…
one protein
anti-codon
complimentary tRNA to strand of mRNA
the genetic code is…
evolutionary conserved
zinc finger motifs
changes the three amino acids in a hormone receptor
i.e. - glucocorticoid –> estrogen receptor
how does a Zn-motif protein work?
amino acid sequence is held together by zinc atom
alters interaction of dna
gene mutations alter protein function how?
the Zn finger domain would not exist
it would unravel and not bind to DNA
what is the consequence of protein mutations
reduced protein function
cystic fibrosis
x-ray crystallography
protein fragments are crystallized
x-rays are scattered through the crystal
atoms diffract the crystal
mathematical analysis determines the structure of the protein
recombinant DNA
engineered DNA from different sources
making recombinant DNA
isolate target DNA
cut DNA
insert name vectors
clone
identical copy of dna
vector
carrier molecule of gene of interest
insert
DNA molecule of interest
restriction endonucleases
enzymes that cut DNA
produce sticky or blunt ends
sticky ends of the same size are…
complimentary
dna library construction
recombinant dna is cut (enzymes or mechanically)
introduced into bacteria
bacterial colonies are grown to amplify dna
what does an antibiotic do in the case of recombinant dna?
the antibiotic will kill bacteria WITHOUT the plasmid
cDNA libraries are used for…
the ENTIRE genome
how to make cDNA library
- isolate RNA
- obtain cDNA from RNA through reverse transcriptase
- transform DNA into vector
difference between cDNA library and PCR
cDNA = entire genome PCR = specific gene
PCR steps:
- heat DNA to separate strands
- lower temp for hybridization of primers
- primers synthesize complimentary DNA
- repeat until there are TONS of copies of the same gene
sanger DNA sequencing
dna sequencing through dedioxynucleotides and RNA polymerase
reverse genetics
START with gene of interest
use recombinant DNA to mutate gene
examine effects of mutated gene on protein
forward genetics
select phenotype of interest
randomly introduce mutations
identify the gene responsible for the mutation
site-directed mutagenesis
methylated dna is digested by enzymes
only newly created dna is left
deletion mutagenesis
necessary domain is deleted
gene is non functional
if successful, florescence isn’t produced
gene knockouts
substitute a non functional allele for a normal allele
structural genomics
molecular organization of genome
