Questions

Goitre is characterized by the swelling of the neck region. This is due to the enlargement of the thyroid gland which secretes hormone thyroxine. Thyroxine has iodine as an integral part of it. If there is not sufficient iodine in one's  diet, the thyroid gland swells up.

Random mutations are the ultimate source of genetic variation. Mutations are likely to be rare and most mutations are neutral or deleterious, but in some instances, the new alleles can be favored by natural selection. Polyploidy is an example of chromosomal mutation.

Mutations are changes in the DNA. A single mutation can have a large effect.

1) mutation - an alteration in DNA sequence, various types

2) intragenic recombination - results in entirely new associations of genes not present in either parental genome.

Two forms of intragenic recombination:

a) crossing over
b) independent assortment
3) reticulation – acquisition of genetic material from unrelated or relatively unrelated sources (e.g., hybrid species, horizontal gene transfer).

Amino acids are a crucial, yet basic unit of protein, and they contain an amino group and a carboxylic group. They play an extensive role in gene expression processes.

Amino acids become proteins when 50 or more are bonded together in a chain. All the millions of different proteins in living things are formed by the bonding of only 20 amino acids.

Eight of these amino acids are essential and cannot be produced by the body.

They are:

• Leucine

• Isoleucine

• Lysine

• Threonine

• Methionine

• Phenylalanine

• Valine

• Tryptophan

•  Histidine is an amino acid that is categorized as semi-essential since the human body doesn't always need it to properly function

Nonessential amino acids are produced by the human body either from essential amino acids or from normal protein breakdowns. Nonessential amino acids include:

• Asparagine

• Alanine

• Arginine

• Aspartic acid

• Cysteine

• Glutamic acid

• Glutamine

• Proline

• Glycine

• Tyrosine

• Serine.