I.
Proteins
a.
have a variety
of functions
i.
some will be used
in the membrane of the cell
ii.
remain in the cytoplasm or be transported out of the cell
b.
many copies of a
protein can be made from one mRNA molecule
c. enzymes, hormones are examples of proteins
II.
Protein synthesis
a.
accomplished
through a process called translation
b.
composed of a chain
of polypeptides
c.
after DNA is transcribed into a messenger RNA (mRNA) molecule during transcription, the mRNA must be translated to produce a protein
d.
mRNA along with transfer RNA (tRNA) and
ribosomes work together to produce proteins.
III.
Transfer
RNA
a.
transfer RNA is
shaped like a clover leaf with three loops
b.
contains an amino
acid attachment site on one end and a special section in the middle loop called
the anticodon site
c.
translate the
message within the nucleotide sequence of mRNA to a specific amino acid
sequence
d.
sequences are
joined together to form a growing polypeptide chain
IV.
Ribosomes
a.
consist of two
parts, a large subunit and a small subunit, contain a binding site for mRNA and
two binding sites for tRNA located in the large ribosomal subunit
b.
clusters of
ribosomes that translate a single mRNA sequence are called polyribosomes or
polysomes.
V.
Ribosomes
in Protein Synthesis
a.
initiator tRNA
resides in one binding site of the ribosome called the P site,
leaving the second binding site, the A site, open
b.
when a new tRNA
molecule recognizes the next codon sequence on the mRNA, it attaches to the
open A site
c.
peptide bond forms
connecting the amino acid of the tRNA in the P site to the
amino acid of the tRNA in the A binding site
d.
as the ribosome
moves along the mRNA molecule, the tRNA in the P site is
released and the tRNA in the A site is translocated to
the P site
e.
A binding site
becomes vacant again until another tRNA that recognizes the new mRNA codon
takes the open position.
3 comments:
I would have liked to see a little more detailed information on proteins
this is really good! I agree though that there should be more information on proteins
Great work Lizzy! Proteins are extremely important in the body and play so many different roles---just as you mentioned. I would have liked to have seen more specific examples of proteins, as well as a tRNA model picture that shows where aminoacyl tRNA synthetase attaches the specific amino acid on the 3' end/CCA attachment site. :)
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