ribozymes are catalytic RNA molecules that function as enzymes and can splice RNA
what are introns?
most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that lie between coding regions called introns
what is RNA splicing?
RNA splicing removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence
what are splicosomes? what are they used for?
splicosomes consist of a variety of proteins and several small nuclear ribonucleoproteins (snRNPs) that recongnize the splice sites in mRNA. In some cases, RNA splicing is carried out by spliceosomes
true or false? all biological catalysts are proteins.
false, ribozomes are catalytic molecules as well
what are the three properties of RNA that enable it to function as an enzyme?
1. it can form a three-dimensional structure because of its ability to base pair with itself
2. Some bases in RNA contain functional groups
3. RNA may hydrogen-bond with other nucleic acid molecules
what is the functional and evolutionary importance of introns?
some genes can encode more than one kind of polypeptide, depending on which segments are treated as exons during RNA splicing--such variations are called alternative RNA splicing. Because of alternative splicing, the number of different proteins an organism can produce is much greater than its number of genes.
Proteins often have a modular architechture consisting of discrete regions called domains. In many cases, different exons code for the different domains of a protein. Exon shuffling may result in the evolution of new proteins
in what two ways are tRNA molecules not identical
1. each carries a specific amino acid on one end
2. Each has an anticodon on the other end; the anticodon basepairs with a complementary codon on mRNA
tRNA's two dimensional structure resembles what? what about its three-dimensional structure?
clover leaf; L-shaped
accurate translation requires that the tRNA has two properties:
1. a correct match between a tRNA and an amino acid, done by the enzyme aminoacyl-tRNAsynthetase
2. a correct match between the tRNA anticodon and an mRNA codon
what is the enzyme that matches each tRNA with its corresponding amino acid?
aminoacyl-tRNA synthetase
what is wobble?
flexible pairing at the third base of a codon is called wobble and allows some tRNAs to bind more than one codon
the two ribosomal subunits (large and small) are made of what?
proteins and rRNA
what are the three binding sites for tRNA on the ribosome?
P site, A site, and E site
describe the P site
it holds the tRNA that carries the growing polypeptide chain
describe the A site
it holds the tRNAthat carries the next amino acid to be added to the chain
describe the E site
it is the exit site, where discharged tRNAs leave the ribosome
what are the three stages of translation?
initiation, elongation, and termination
all three stages require ___ ____ that aid in the translation process
protein factors
During the elongation of the polypeptide chain in ribosomes, each addition of an amino acid involves proteins called ________ ____ and occurs in what three steps?
elongation factors; the three steps are: codon recognition, peptide bond formation, and translocation
termination occurs when a ____ ____ in the mRNA reaches the __ _____ of the ribosome
stop codon; A site
Author
mikepl103
ID
290620
Card Set
biochem 012 DNA and protein synthesis part 4 (watson crick griffith chargoff's rule translation
Description
biochem 012 DNA and protein synthesis part 4 (watson, crick, griffith, chargoff's rule, translation, ribosomes, mRNA) #26
