Question

1.What do we mean when we say the triplet code is universal?

2.If a mutation causes a permanent change in the DNA sequence, how is it that most mutations are “silent” mutations

3.Suppose a young woman is exposed to a chemical mutagen and some permanent changes arise in the DNA (mutations) of some of her germ line cells. Will those mutations be passed down to her children? Why or why not

4. humans, attached earlobes (A) are dominant to free earlobes (a). Suppose a couple who are both heterozygous for this trait have a child. Tell me
⦁   the phenotype of the parents:
⦁   the genotype of the parents:
⦁   the likelihood (or chance) that their child will have free earlobes:

Which of the following can be seen from the karyotype at the right?
Mark all that apply. (2 points)
⦁   This individual has Downs syndrome.
⦁   This individual is female.
⦁   This individual is male.
⦁   This individual is a carrier for sickle-cell anemia.
⦁   None of these can be seen in this karyotype

Hey please number answer all the question and number them

Answer 1

1) genetic coding are said be universal means , genetic codon code for similar amino acid in all the species. For example if a take an example AUG , this code of methionine in human so this will also code for methionine in all species. Dye to this property we are able to carry out recombinant DNA technology experiment. We use our desires gene, and Express it using e coli machinery. Means e coli translation machinery adding similar amino acid sequence like our machinery.

2) mutation cause heritable change in DNA . But if a mutaion occurs at 3' end of the codon that it will code for same amino acid so although mutaion is present but it is in silent form. It is due to the wobellibg of bases. According to this during recognition between codon and anticodon only inital two base pair are considered, 3 base of codon us not considered. So all the codon which has similar inital two bases but differe in third bases will code for similar amino acid. For example ACU, ACC, ACG,ACA all contain similar initial two base , and differ in third base but code for a single amino acid threonine. In this way if a mutation occurs at 3 base if codon it will be silent.

3) yes mutaion occued in germ cell will passed in coming progeny. Somatic mutation, which occurs in somatic cells do not pass in next generation. This is because it is the germ cell which form gametes. These gametes fuse and start new life, somatic cell do not participate in formation of new life. So whatever changes occur in germ cell will pass in next generation.

4) A us attached ear lobe dominant over free ear lobe (a)

Both parents are heterozygous

Female - attached ear lobes

Male - attached ear lobe

Genotype of female- Aa

Genotype of male - Aa

Aa X Aa

AA : Aa : aa

1 : 2 : 1 no of progeny

Child with free earlobe only aa will have free earlobe so probability will be 1/4 . Or 25%

For next question karyotype is required