In transparency 19a how does the protein labeled point mutation differ from the normal protein

When a point mutation occurs, the protein may differ from a normal protein by two characteristics:

Explanation:

Point mutation is the change in a single nucleotide in the chain. Guanine can be paired with Timine, Adenine with Cytosine and vice versa. This type of mutation is usually due to errors in DNA replication. Its consequences can be silent (the generated mRNA, although it also contains the altered information, results in the formation of the same protein), non-silent or “missense” (the mutation in the DNA ended up leading to the alteration of the amino acid sequence that constitutes the protein , being able to change its structure and function) or meaningless, also called “nonsense” mutation (when changing base pairs generated information for “stop code”, used to signal the end of protein synthesis and, thus, the protein runs out of amino acids in its chain and thus no function).

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.