(d) Eukaryote RNAs contain non coding intervening segments called introns.
The process of removal of introns through cutting and joining the essential coding sequences (exons) is called splicing.
(a) In eukaryotes, separate protein factors take part in recognition and initiation during transcription.
They are called transcription factors.
(a) Multiple alleles are multiple alternatives or alleles of the same gene which occur in the population of same species.
(a) mRNA has same sequence as coding strand with T replaced by U.
(a) DNA replication is semiconservative. i.e. at each replication one of the parental strands is retained and a new daughter strand is obtained.
Thus only half of the parental DNA molecule is carried to the next generation.
(b) A mutation bringing about early stoppage of polypeptide formation is called nonsense mutation.
Frame shift mutation is a type of gene mutation where the reading of codons is changed due to insertion or deletion of nucleotides.
(d) Termination codons are the stop signals which when encountered cause termination of polypeptide synthesis.
They are UAA (ochre), UAG (amber) and UGA (opal).
(c) Only the peptidyl transferase reaction does not require energy.
The aminoacyl-tRNA binding to ribosome involves elongation factors and energy (GTP).
Amino acid activation requires energy.
Translocation requires an elongation factors and energy (GTP).
(c) A regulator gene is a gene involved in controlling the expression of one or more other genes.
In prokaryotes, regulator genes often code for repressor proteins.
(d) Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, and the process is called transposition.
They can cause mutations and change the amount of DNA in the genome.
