The repressor protein blocks the genes from making mRNA.
1. The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called a tRNA.
tRNA are molecules involved in protein synthesis (translation) and those molecules connect codons from mRNA with the amino acids they encode.tRNA has anticodone that binds to mRNA codone.
2. The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called translation.
Translation is a process of gene expression in which proteins are synthesized (translated from the codons on mRNA).
3. Initiation of translation always happens at the start codon of the mRNA.
Translation process can be divided into three stages: initiation (starting off), elongation (adding amino acids to peptide chain that is going to become protein) and termination (finishing up).
4. Amino acids are attached to tRNA by enzymes called aminoacyl-tRNA synthetase.
These enzymes are part of the elongation stage of translation and they catalyze the adding of amino acids.
5. Termination of translation happens when the ribosome hits a stop codon on the mRNA.
Termination is the stage in which the finished polypeptide chain (future protein) is released from the ribosome.
Answer:
a. True, b. False, c.True, d. True
Explanation:
a. Base excision repair is started by a DNA glycosylase that recognizes the changes and removes the altered base by cleavage of the glycosidic bond binding the base and the deoxyribose sugar together.
b. Nucleotide excision repair works by a cut-and patch mechanism that removes their heavy lesions, including pyrimidine dimers and nucleotides . Endonucleases are responsible for the lesion of the damaged strand.
c. Nucleotide excision repair is initiated by the proteins namely UvrA, UvrC, and UvrB in Escherichia coli.
-UvrD (helicase II) later removes the damaged strand
-DNA polymerase I (PolI) fills in the resulting gap.
d. DNA glycolases removes the damaged nitrogenous base.
-It leaves the sugar-phosphate backbone intact and thus creating an apurinic/apyrimidinic site, which is commonly referred to as an AP site.
e. Xeroderma pigmentosum complementation group A(XPA)
-This is an essential protein in the nucleotide excision repair pathway.
- It helps to make a pre-incision complex along with other proteins.
