Question

24. Name and explain three categories of gene mutations.

25. Albinism is lethal in plants, but many plants produce albino offspring. If albino plants always die before reproducing, how does albinism persist?

Answer 1

The changing structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of Single base units in DNA is called Mutation. Types of mutations include ; substitution, insertion and deletion.

Substitution mutation or point mutation is a genetic mutation where a single nucleotide base is changed , inserted or deleted from a sequence of DNA. It occurs when specific bases (A,T,C or G) in a gene are substituted for different bases Substitution mutations have a variety of effects on the down stream of Protein product ,- consequences that area moderately predictable based upon the specifics of the mutations. it has three different effects on an organism' s protein.

Insertion mutation is the addition of one or more nucleotide base pairs into a DNA sequence.Usually it occurs in microsatellite regions due to DNA polymerase slipping. By adding a piece of DNA the number of DNA bases changes during insertion . As a result the protein made by the gene may not function properly. A insertion mutation occurs when an extra nucleotiide is added to the DNA strand during DNA replication.

Deletion or gene deletion is a mutation in which sequence of DNA or part of chromosome is left out during DNA replication. From a single base any number of nucleotides can be deleted. The insertion or deletion that result in a frame shift that changes the reading of subsequent codons.

In plants albinism is characterized by partial or complete loss of chlorophyll pigments and incomplete differentiation of chloroplast membrane. So Albinism in plants interferes with photosynthesis, which can reduce survivability. Albinism in plants is caused by genetic mutations that either causes the plant to start growing without producing any chlorophyll at all or forces the switching on ànd off of certain gene that cause parts of a plant to grow without pigmentation or chlorophyll.

Albinism in plants is caused by genetic mùtations. Albinism is inherited as a recessive gene and thus only plants which have two recessive genes have the ability to express albinism phenotypically.Albino plants lacking chlorophyll , they need to manufacture food, typically for as seedlings after the energy stored in seed is used up. In rare cases Albino plants are able to survive.