PATHOLOGY

PATHOLOGY MCQ

GENETICS AND DISEASE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has-
A
12 chromosomes
B
23 chromosomes
C
46 chromosomes
D
92 chromosomes
Explanation: 

Detailed explanation-1: -Therefore, meiosis results in four haploid genetically unique daughter cells, each with half the DNA of the parent cell (Figure below). In human cells, the parent cell has 46 chromosomes (23 pairs), so the cells produced by meiosis have 23 chromosomes. These cells will become gametes. An overview of meiosis.

Detailed explanation-2: -The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half-from 46 to 23-to form sperm and egg cells.

Detailed explanation-3: -Each daughter cell will have half of the original 46 chromosomes, or 23 chromosomes. Each chromosome consists of 2 sister chromatids. The daughter cells now move in to the third and final phase of meiosis: meiosis II. At the end of meiosis I there are two haploid cells.

Detailed explanation-4: -We can think of meiosis as a way cells very carefully count and divide their chromosomes so that each gamete, each egg or sperm, has exactly 23 chromosomes. Then when an egg with its 23 chromosomes is fertilized by a sperm with its 23 chromosomes, the resulting fertilized egg has exactly 46 chromosomes.

Detailed explanation-5: -Humans have 46 chromosomes in all their somatic cells (body cells: all cells other than sex cells). Thus, the body cells have both the sets of chromosomes i.e. they are diploid. But the sex cells, egg and sperm, are haploid ie. only one set of chromosomes is present in them.

There is 1 question to complete.