a) Give reason .
i) X-linked recessive disease are more common males than in females.
ii) Sex of the child depend on father.
iii) Meiosis is called as reductional division.,
b) Define the following.
i) Karyotype ii) Nucleosome
iii) Genome iv) Chiasma v) Heredity
c) Mention two applications of Mendel’s law.
Answers
Answer:
a) i) X-linked recessive inheritance
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.
ii) Almost everyone has around a 50% chance of having a boy and a 50% chance of having a girl. What we can say is that dad's sperm determines whether a baby will be a boy or a girl. About half of his sperm will make a boy and half a girl. The sex of the baby depends on which sperm gets to the egg first.
iii) The process of meiosis involves two divisions of the genetic material. The first division is called the reduction division – or meiosis I – because it reduces the number of chromosomes from 46 chromosomes or 2n to 23 chromosomes or n (n describes a single chromosome set
b) i) A karyotype is an individual's collection of chromosomes. The term also refers to a laboratory technique that produces an image of an individual's chromosomes. The karyotype is used to look for abnormal numbers or structures of chromosomes
ii) A nucleosome is the basic repeating unit of eukaryotic chromatin. In a human cell, about six feet of DNA must be packaged into a nucleus with a diameter less than a human hair. A single nucleosome consists of about 150 base pairs of DNA sequence wrapped around a core of histone proteins.
iii) A genome is the genetic material of an organism. It consists of DNA (or RNA in RNA viruses). The genome includes both the genes (the coding regions) and the noncoding DNA,[1] as well as mitochondrial DNA[2] and chloroplast DNA. The study of the genome is called genomics.
iv) A chiasma is the point of contact, the physical link, between two (non-sister) chromatids belonging to homologous chromosomes. At a given chiasma, an exchange of genetic material can occur between both chromatids, what is called a chromosomal crossover, but this is much more frequent during meiosis than mitosis. In meiosis, absence of a chiasma generally results in improper chromosomal segregation and aneuploidy.
v) Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics.
c) don't know.........