Meiosis and Genetic Variation Flashcards
What is the result of mitosis in terms of the number of daughter cells and chromosome mutation?
Mitosis produces two daughter cells with the same number of chromosomes as the parent cell and as each other
How many daughter cells are produced in mitosis, and how do they compare to the parent cell?
Two daughter cells are produced, each genetically identical to the parent cell with the same number of chromosomes
What is the result of meiosis in terms of the number of daughter cells and chromosome number?
Meiosis usually produces four daughter cells, each with half the number of chromosomes as the parent cell
How does the chromosomes number in daughter cells compare between mitosis and meiosis?
Mitosis results in daughter cells with the same chromosome number as the parent cell, while meiosis results in daughter cells with half the chromosome number
Why is meiosis important in sexual reproduction?
Meiosis halves the number of chromosomes, preventing the chromosome number from doubling at each generation
What is the diploid number of chromosomes in humans, and what is the number of haploid number of chromosomes in humans?
Diploid number of chromosomes in humans is 46 chromosomes, and haploid number of chromosomes in humans are 23 chromosomes
When is the haploid number of chromosomes restored to diploid?
The haploid number is restored to 46 at fertilisation when two gametes fuse
What happens to homologous chromosomes during meiosis?
Homologous pairs separate so that only one chromosomes from each pair enters each daughter cell
In most animals, when does meiosis occur?
During the formation of gametes
What are the two main stages of meiosis called?
Meiosis I and Meiosis II
What happens during Meiosis I?
Homologous chromosomes pair up, and their chromatids wrap around each other. Crossing over may occur. Homologous chromosomes then separate into two daughter cells
What happens during Meiosis II?
The chromatids of each chromosome separate and move into different cells, forming a total of four haploid cells
How many cells are produced at the end of meiosis, and how many chromosomes does each have in humans?
Four cells are produced, each with 23 chromosomes (haploid)
What is crossing over, when does it occur?
Crossing over is the exchange of equivalent portions of chromatids between homologous chromosomes, occurs during meiosis I
What are two main ways meiosis introduces genetic variations?
- Independent segregation of homologous chromosomes
- New combinations of maternal and paternal alleles due to crossing over
Define a gene:
Define locus:
Gene ~ The length of DNA that codes for a polypeptide
Locus ~ The position of a gene on a chromosomes or DNA molecule
Define allele:
Define homologous chromosomes:
Allele ~ One of the different forms of a particular gene
Homologous chromosomes ~ A pair of chromosomes, one maternal and one paternal, that have the same gene loci
