Protein synthesis can be divided into two main processes
TRANSCRIPTION and TRANSLATION
TRANSCRIPTION: takes place in the NUCLEUS
the information required to make a protein is carried on a segment of chromatin (DNA) called a GENE. The BASE SEQUENCE on the gene will determine the type of protein made
The following is a sequence of events that takes place in order to transcribe a gene:
1.The site at which the gene is located on the DNA UNCOILS and EXPOSES the base sequence
2.Only ONE SIDE of the DNA is used as a TEMPLATE to copy the information into messenger RNA (mRNA)
3.Free floating RNA in the nucleoplasm will pair up with their complementary base pairs on DNA
4.As the RNA nucleotides are joined together, the mRNA strand is RELEASED from the DNA and the DNA recoils into its double helix
5.Once the gene is completely transcribed it is released and moves into the CYTOPLASM through a nuclear pore
TRANSLATION
1.once the mRNA is in the cytoplasm, the ribosomes will attach to the mRNA strand
2.the ribosome covers six bases on mRNA
3.the code on mRNA is read three bases at a time
4.these three bases are called a CODON
5.each codon codes for one amino acid
6.transfer RNA (tRNA) is the molecule that carries the amino acid to the ribosome and mRNA
7.tRNA has a triplet of bases (anticodon) that is complimentary to the mRNA codon
8.each ribosome can hold two tRNA
9.once the two tRNA anticondon are paired correctly with the mRNA codon, the ribosome will
join the two amino acids together by forming a PEPTIDED BOND
10.the first tRNA is then released from the ribosome and will pick up another amino acid
11.the ribosome will move down one codon and the second tRNA moves into the first position with the growing polypeptide chain
12.a new tRNA move in the open position with its amino acid and the steps are repeated
13.once the ribosome reaches the end of the mRNA strand they are released from each other
14.the polypeptide chain will then fold into its functional shape.
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o Lysosomes are relatively large vesicles formed by the Golgi apparatus and containing a large number of digestive enzymes responsible for the metabolism of various cell products.
o Lysosomes play an important role in the recycling process of cell materials and help eliminate cellular wastes. The process starts by the engulfment of cells by Phagocytosis of a food particle.
o Lysosomes enzymes are made of proteins that are made by the ribosomes on the endoplasmic reticulum.
o The enzymes (proteins) enter the endoplasmic reticulum (ER) and then go out to the cytoplasm in transport through a vacuole before it enters the Golgi apparatus.
o At the Golgi apparatus the enzyme (protein) are modified so they can work. (perform specific tasks)
o The enzymes leave the Golgi apparatus in sacs called vacuoles or lysosomes and will float around in the cytoplasm.
Lysosomes will fuse with food vacuoles that have entered the cell through one of the two forms of endocytosis and must be digested.
OR
Lysosomes fuse with old or damaged organelles that must be digested. These enzymes in both scenarios digest (breakdown) the unwanted particles into their nutrient components. If the lysosomes were not contained in these vacuoles it would be possible for the cell to digest its-self.
o Once digestion has been completed the remaining material becomes a waste vesicle that will be discarded from the cell via exocytosis.
LYSOSOMAL DIGESTION
o Lysosomes are relatively large vesicles formed by the Golgi apparatus and containing a large number of digestive enzymes responsible for the metabolism of various cell products.
o Lysosomes play an important role in the recycling process of cell materials and help eliminate cellular wastes. The process starts by the engulfment of cells by Phagocytosis of a food particle.
o Lysosomes enzymes are made of proteins that are made by the ribosomes on the endoplasmic reticulum.
o The enzymes (proteins) enter the endoplasmic reticulum (ER) and then go out to the cytoplasm in transport through a vacuole before it enters the Golgi apparatus.
o At the Golgi apparatus the enzyme (protein) are modified so they can work. (perform specific tasks)
o The enzymes leave the Golgi apparatus in sacs called vacuoles or lysosomes and will float around in the cytoplasm.
Lysosomes will fuse with food vacuoles that have entered the cell through one of the two forms of endocytosis and must be digested.
OR
Lysosomes fuse with old or damaged organelles that must be digested. These enzymes in both scenarios digest (breakdown) the unwanted particles into their nutrient components. If the lysosomes were not contained in these vacuoles it would be possible for the cell to digest its-self.
o Once digestion has been completed the remaining material becomes a waste vesicle that will be discarded from the cell via exocytosis.
1 comment:
Dear Mr. smith,
Thank you for posting the notes on
protein synthesis and lysosmal digestion, they really help alot
Thank you
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