Edited Invalid date
10.1 Overview of Meiosis
Explain the process of reducing the number of chromosomes.
Meiosis is in sexually reproducing organisms.
The act or process of nuclear division reduces the number of chromosomes from the diploid number.
Meiosis reduces the diploid number of 46 chromosomes to the haploid number of 23.
In plants and animals, the embryo undergoes development to become an adult.
In order to produce diploid offspring, the diploid number of chromosomes has to be reduced by half in each of the parents.
The number of chromosomes would double with each new generation.
In five generations, the number of chromosomes would increase to 1,472 in humans with a diploid number of 46.
In ten generations, the number would increase to 47,104 chromosomes.
The chromosomes are in pairs in diploid body cells.
The members of each pair are called chromosomes.
They have the same length and centromere position.
The genes for the same traits in the same order in the same locations on both chromosomes are found in the homologue.
The genes for long and short fingers can be found on the same chromosomes, but there is a difference in the sequence of the genes for them.
There are alternative forms of a gene for long fingers and short fingers.
Long or short fingers are possible because of the differences in the DNA sequence of alleles.
There are pairs of chromosomes in diploid body cells.
There are two pairs in this micrograph of stained chromosomes from a human cell.
The XX pair includes the sex chromosomes and helps determine human gender, whereas the 1-22 are autosomes.
Each of the chromosomes in the homologous pair is composed of two chromatids.
The sister chromatids have the same genes, but the non sister chromatids have genes that are different for hair and eyes.
The results of the process are depicted.
The sister chromatids are composed of one DNA double helix molecule.
When the haploid sperm and egg fused together, one Page 168 member was inherited from the male parent and the other from the female parent.
The paternal and maternal chromosomes are blue and red, respectively, in this chapter.
This is a method of tracking the chromosomes in diagrams.
Since chromosomes don't have color, geneticists use chromosomes length and centromere location to identify them.
Meiosis reduces the number of chromosomes.
The gametes have only one of the different types of chromosomes, which are derived from either the paternal or the maternal genes.
The goal of meiosis is to reduce the number of chromosomes from 2n to n. The process begins with replicating the chromosomes, then splitting them into two parts during the first division.
The amount of DNA in the n chromosomes is reduced by the second division.
Once the chromosomes become a pair, they may exchange genes, creating a genetic mixture different from the parent.
A second nuclear division is needed because each daughter cell still has a sister chromatid.
Four gametes have n chromosomes.
The two nuclear divisions are indicated in Figure 10.2.
Each of the chromosomes has two sister chromatids.
There is something new that does not happen during meiosis.
This is a process.
Two chromosomes that stay in close association during the first two phases of meiosis I may recombine or exchange genetic information.
The sister chromatids of each duplicated chromosome were present during meiosis II.
There are four haploid daughter cells.
Each daughter cell has a different type of chromosomes.
After synapsis, the members of each pair separate.
It is important for each daughter nucleus to have a member from each pair of chromosomes, because only in that way can there be a copy of each kind.
There are two possible combinations of chromosomes in the daughter cells shown.
The chromosomes are already duplicated and there is no need for DNA replication between meiosis I and II.
Page 169 becomes daughter chromosomes that move to opposite poles.
The haploid chromosomes in each of the four daughter cells contain only one double helix molecule.
The number of centromeres can be used to confirm that the parent cell has a diploid number of chromosomes.
The number of chromosomes has been reduced because there are half as many centromeres.
Each daughter cell has a different number of chromosomes.
Each daughter cell that forms still contains the haploid number of chromosomes, each consisting of a single chromatid, at the end of meiosis II.
The daughter cells become haploid in the plant life cycle.
View flashcards and assignments made for the note
Getting your flashcards
Privacy & Terms