QUARTER 1 Week 6 [School-based] Flashcards
(34 cards)
What is Meiosis?
Meiosis is a cell cycle that happens in gametes or sex cells, which involve sperm and egg cell. It divides
2 TIMES to produce 4 DAUGHTER CELLS containing half of the information of the genetic material.
This is the complete display of human chromosomes …46 chromosomes in total, 23 pairs
Human Karyotype
Pair 1 - 22 of chromosomes
called “Autosomes”, or BODY CHROMOSOMES which are responsible for the manifestation of physical and emotional characteristics…such as your eye color, height, etc.
any chromosome that is not a sex chromosome
Autosomes are also called _____________
Body chromosomes
2 types of sex chromosome
XX Female
XY Male
the Y in the male chromosome is a BAR CHROMOSOME…in humans, the presence of a bar chromosome automatically means they’re MALE.
control the sex of an organism, if it has XX chromosome, then it will develop female reproductive organs and vice versa
sex chromosomes
is used to distinguish sections or divisions in a chromosome
CHROMATIDS
A chromosome has 2 centers
Kinetochore
Centromere
before Meiosis, there are _________ chromosomes
46
after Meiosis 1, there are ________ chromosomes in one cell
23 chromosomes for each daughter cell
after Meiosis 2, there are __________ chromosomes
23 chromosomes for each daughter cell
responsible for dividing the chromosome into two (meiosis 1 yung isa, sa meiosis 2 yung isa)
it is where the spindle fibers attach
KInetochore and Centromere
2 Stages of Meiosis
Meiosis 1 - Reduction Stage
Meiosis 2 - Division Stage
What happens in Meiosis 1?
- The first purpose of Meiosis 1 is to divide the cell
- Second purpose is to reduce the chromosomes from diploid to haploid
diploid is the complete set of chromosomes
haploid has ONLY ONE SET OF 23 CHROMOSOMES
What happens in Meiosis 2 - Division Stage
The 2 cells futher divide into 4 daughter cells (2 for each)
it is an exact copy of Mitosis
What is the difference of Mitosis and Meiosis
their difference lies in the presence of reduction stage (Meiosis 1) in Meiosis
What happens in Meiosis 1? (6 events)
- Interphase
- Prophase 1
- Metaphase 1
- Anaphase 1
- Telophase 1
- Cytokinesis
Under Prophase 1 we have:
Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
What happens in Leptotene
The chromosomes thicken to the point that it is visible under electron microscope (but STILL AS THIN THREADS)
What happens in Zygotene
The 46 choromosomes find their pair at a process called “Synapsis”. The pair now will be held by a protein ribbon and will be called “Synaptonemal Complex”
What happens in Pachytene
The chromosomes become condensed because the protein ribbon tightens, thus, allowing recombination or “exchange of parts” to happen…there will be a crossing over
What happens in Diplotene
The protein ribbon disintegrates and the synaptonemal complex becomes slighly separated but still attached at a point called “Chiasmata”
What happens in Diakinesis
the chromosome is still attached at a point called “chiasmata” but is now ready for division
What happens in Metaphase 1
the homologous pair line up in the equator
the spindle fiber attaches to the homologous pair at a point called “kinetochore” (1:1)
