An environmental agent, which triggers transcription from an operon, is a
The inducer is an environmental agent, which triggers transcription from an operon. The inducer or effector molecule are small sized which can bind to a regular protein.
The lac operon is an example of
The lac operon consists of a promotor gene, an operator gene and structural genes. There are three structural genes designated as z, y and a, which code for the enzymes β-galactosidase, lac permease and transacetylase respectively. It is an example of inducible operon.
Anticodon is an unpaired triplet of bases in an exposed position of
tRNA works as an adoptor molecules for carrying amino acid to the mRNA templated during protein synthesis. It bears anticodon and recognizes the specific codon on mRNA.
Okazaki fragments are seen during
Replication of DNA is discontinuous over the lagging strand over which only small stretches of DNA are built due to opposite running of DNA template. The small stretches of DNA are called okazaki fragments.
The translation termination triplet is
Termination codons ( triplet) are the stop signals which when encountered cause termination of polypeptide synthesis. The termination codons are UAA, UAG and UGA.
The basis for DNA fingerprinting is
DNA finger printing is a technique to identify a person on the basis of his DNA which is specific for every individual. This technique for first time was developed by Alec Jeffreys and his colleagues at Leicester University in U.K. DNA of an individual carries specific sequences of nucleotides which are repeated many times throughout the length of DNA. This reveals polymorphism in DNA. These are inherited. Each individual inherits these repeats from his/her parents which are used as gentic markers in personal identity test.
Which step of translation does not consume a high energy phosphate bond ?
During the activation of amino acids, in the presence of Mg2+ and ATP an amino acid gets attached to a specific enzyme aminoacyl t-RNA synthetase. Pyrophosphate is released which breaks up to release energy. During translocation, in the presence of the enzyme translocase and energy from GTP the ribosome moves in such a way that the peptidyl bearing t-RNA of A - site comes to lie on the P-site, exposing a new codon at A - site. In the peptidyl transferase reaction energy is provided by GTP.
Three codons causing chain termination are
Termination codons are the stop signals which when encountered cause termination of polypeptide synthesis. They are UAA (ochre), UAG (amber) and UGA (opal). Codons are determined by the sequence of bases on the DNA. Thymine is not present on RNA.
A mutation at one base of the first codon, of a gene, produces a non-functional protein. Such a mutation is called
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.
If a completely radioactive double stranded DNA molecule undergoes two rounds of replication in a non-radioactive medium, what will be the radioactive status of the four resulting molecules?
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.
Different mutations referrable to the same locus of a chromosome give rise to
Multiple alleles are multiple alternatives or alleles of the same gene which occur in the population of same species . Polygene is a gene, single dominant allele of which express only a unit of trait . Polygenes are the genes controlling quantitative inheritances. Oncogenes are the cancer causing genes.
During development of an organism, the product of one gene is required to activate another gene. Such gene products are called
In eukaryotes separate protein factors take part in recognition and initiation during transcription. They are called transcription factors. Coenzymes are non protein organic cofactors which get loosely attached to apoenzymes during the functioning of holoenzymes.
In eukaryotes, after transcription of mRNA, some of its nucleotides are removed before it is translated into polypeptide. The nucleotides which are removed from mRNA are called
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.
What base is responsible for hot spots for spontaneous point mutations?
The term "hot spots" was used by Benzer for the sites which are more mutable than other sites. Studies in 1978 revealed that 5-methylcytosine residues occur at the position of each hot spot.
The eukar yotic genome differs from the prokaryotic genome because 
DNA is complexed with histones in eukaryotes.
DNA elements which can switch their position are called
Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called transposition. In the process, they can cause mutations and change the amount of DNA in the genome. Transposons are also called “jumping genes” or “mobile genetic elements”. Discovered by Barbara McClintockearly in her career, the topic went on to be a Nobel winning work in 1983. There are a variety of mobile genetic elements, and they can be grouped based on their mechanism of transposition.
Genes that are involved in turning on or off the transcription of a set of structural genes are called
Operator gene allows the functioning of the operon.
In DNA, when AGCT occurs, their association is as per which of the following pairs?
In DNA adenine always pairs with thymine and guanine always pairs with cytosine, this is called complementary base pairing.
The Pneumococcus experiment proves that
Griffith’s experiment with Pneumococcus proves that DNA is the genetic material.
In operon concept , regulator gene functions as
Regulator gene produces a biochemical for suppressing the activity of the operator gene.
How many base pairs (bp) are found in the haploid genome of humans?
The number of base pairs (bp) found in the haploid genome of humans is 2.9 × 109.
Mutation generally produces
Polygene is a gene, single dominant allele of which expresses only a unit of the trait, lethal genes on expression stop producing vital products essential for survival of an individual.
Protein synthesis occurs
Ribosomes are the sites of protein synthesis. Mitochondria being a semi autonomous organelle has its own protein synthesizing machinery.
One function of the telomeres in a chromosome is to
Seal the ends of chromosomes. The telomere is a "ribonucleoprotein complex" composed of a protein component and an RNA primer sequence which acts to protect the terminal ends of chromosomes. This prevents chromosomal disintegration and prevents the ends of the chromosome from being processed as a double strand DNA break, which could lead to chromosome-tochromosome telomere fusions.
In negative operon
In negative (re pressible) operon, the repressor co-repressor complex binds with the operator. The free repressor cannot bind to the operator.