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Title: Chromosomes and meiosis
Description: Check out my other sales: https://www.stuvia.com/user/emjaymoth This document provides a thorough overview of Chromosomes and meiosis. It covers the definitions of Meiosis and chromosomes, along with the significance of meiosis and its location. The stages of meiosis I and meiosis II are described, and there are accompanying diagrams. The document also explains abnormalities in meiosis. I hope this summary proves helpful.
Description: Check out my other sales: https://www.stuvia.com/user/emjaymoth This document provides a thorough overview of Chromosomes and meiosis. It covers the definitions of Meiosis and chromosomes, along with the significance of meiosis and its location. The stages of meiosis I and meiosis II are described, and there are accompanying diagrams. The document also explains abnormalities in meiosis. I hope this summary proves helpful.
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Chromosomes
Chromosomes and
and meiosis
meiosis
Chromosomes and Meiosis
Meiosis
Meiosis is a process that cells go through to create gametes for sexual reproduction
...
The daughter cells have half as many
chromosomes as their parent cells because they are haploid, whereas the parent cell is
diploid
...
Chromosomes form a part of the
chromatin network
...
Cells in organisms contain 46 chromosomes, with the paternal chromosome coming from the
father and the maternal chromosome coming from the mother, making them diploid cells(2n) ,
with 23 pairs of homologous chromosomes
...
However, human X and Y chromosomes pair with
one another
...
Note:
2 chromatids= 1 chromosome
two matching chromosomes make up a homologous pair
...
haploid=cells that have ONE set of chromosomes
diploid=cells that have TWO sets of chromosomes (2n)
Chromosomes
Chromatid
Chromatid
Homologous chromosomes
Bivalent
Chromosomes and Meiosis
What is meiosis?
Meiosis is a process that cells (cell division) go through to create gametes in humans and
spores in plants for sexual reproduction
...
The number of
chromosomes is reduced from two sets to one in each of the daughter cells (it’s halved)
...
Where does meiosis take place?
Meiosis happens in the reproductive organs in mammals
The process by which sperm cells develop in the testes is known as spermatogenesis
...
Meiosis also occurs in plants when spores are formed in sporangia
...
Megasporangia are the name for the ovules seen in the ovaries of females
...
While this
happens genetic variation is achieved through cross over
...
The two can be confusing sometimes
...
It has 5 stages
...
Meiosis also has the same
stages but there are two divisions
...
Prophase I
spindle fiber
Meiosis I
Homologous
Chromosome pair
(tetrad)
centrioles moving
to opposite poles
membrane
dissolves
Early prophase I: Chromatids are joined together by the centromere
...
Centrosomes begin to move to opposite poles
...
Homologous chromosome
pairs align at the
equator of the cell
...
Homologous chromosome pairs align at the equator of the cell
...
The pairs line up in a randomly selected order
...
This contributes to genetic variation as it is impossible to tell which
chromosome will move to which side of the cell
...
Anaphase I
Daughter chromosomes
separate
Sister chromatids stay
together
Paired chromosomes are separated by the spindles
...
Meiosis I
Telophase I
Cytoplasm divides
Nuclear membrane forms
The chromosomes have reached the opposing poles of the cell
...
Each set of chromosomes is surrounded by a membrane that
develops in order to create two new nuclei
...
Contraction of the cell
membrane causes cytokinesis
...
Crossing over and it’s importance
Diploid cells produce haploid gametes through meiosis, where non-sister chromatids
exchange genetic material, resulting in new allelic combinations in daughter cells
...
Daughter cells that cross over inherit a different set of genetic material, with the exception
of identical twins
...
This increases variance, which might
have an impact on evolution
...
Centrioles duplicate and Spindle fibers
reappear again
...
Spindle fibers connect to chromatid sisters
...
Anaphase II
Separation of
daughter
chromosomes
Spindles
pull
sister
chromatids apart to opposite
poles
...
Meiosis II
Telophase II
Cytoplasm divides
Cytoplasm divides
The chromosomes have reached the opposing poles of the cell
...
Cytokinesis
four haploid cells
that contain a
single copy of each
chromosome
...
Abnormal meiosis
Abnormal gametes in X and Y sex chromosomes cause chromosome anomalies, a term
referring to abnormal meiosis
...
These are
called syndromes
...
This happens during
oogenesis, when the two number 21 chromosomes do not separate correctly
...
The zygote therefore will have a total number of chromosomes
in each cell of 47 instead of 46
...
This is caused when the egg (or, in rare cases, the sperm)
divide unevenly)
...
Abnormal meiosis
Karyotype
The image is a Karyotype
...
It
depicts the number, size, and structure of chromosomes during metaphase of mitosis
...
22 autosomes and one pair of sex
chromosomes
...
Note:
XX= female
XY=male
Title: Chromosomes and meiosis
Description: Check out my other sales: https://www.stuvia.com/user/emjaymoth This document provides a thorough overview of Chromosomes and meiosis. It covers the definitions of Meiosis and chromosomes, along with the significance of meiosis and its location. The stages of meiosis I and meiosis II are described, and there are accompanying diagrams. The document also explains abnormalities in meiosis. I hope this summary proves helpful.
Description: Check out my other sales: https://www.stuvia.com/user/emjaymoth This document provides a thorough overview of Chromosomes and meiosis. It covers the definitions of Meiosis and chromosomes, along with the significance of meiosis and its location. The stages of meiosis I and meiosis II are described, and there are accompanying diagrams. The document also explains abnormalities in meiosis. I hope this summary proves helpful.