Meiosis: Turning Diploid Cells To Haploid Flashcards
First division in meiosis (meiosis I) where diploid cell is reduced to haploid
Reductional division
The second division (meiosis II) where sister chromatids separate, which is a process similar to mitosis
equational division
Are paired chromosomes that came from the parents during fertilization. Sister chromatids make up this.
Homologous chromosomes
Five stages in Prophase I
Leptotene, zygotene, pachytene, diplotene, and diakinesis
In this stage (prophase I) , chromatins condense and chromosomes appear
Leptotene stage
A stage in prophase I where synapsis starts
Zygotene stage
It is the close pairing of the homologous chromosomes
Synapsis
A highly organized protein structure that connects the two homologous chromosomes together. This structure is speculated to mediate the chromosomes’ successful consensation, pairing, and recombination, and may play a role during crossing-over.
Synaptonemal complex
A stage in prophase I where synapsis is complete and where crossing-over can take place.
Pachytene stage
It is where nonsister chromatids in the homologous chromosomes exchange their segments and increases genetic variations of the organisms
Crossing-over
The stage in prophase I where the synaptonemal complex starts to dissolve, and the homologous chromosomes start to separate
Diplotene stage
It is the separation from the centromere towards the ends
Terminalization
Strands of DNA are still connected at the site of exchange, forming an X-shaped structure called
Chiasma (plural: chiasmata)
Stage in prophase I where the homologous chromosomes continue to separate and the chiasmata undergo terminalization. The homologous chromosomes are condesed and shortened and the nucleolus and nuclear membrane disappear.
Diakinesis
Homologous chromosomes move to the metaphase plate or equatorial plate.
Metaphase I
The homologous chromosomes separate where each chromosome still holds the sister chromatids.
Anaphase I
At this stage, homologous chromosomes have reached the poles. The resulting cells have only half the number of chromosomes. Chromosomes still have pairs of attached chromatids. The nuclear membrane starts to reappear. Cytokinesis completes the creation of the two haploid daughter cells
Telophase I
A brief resting period between telophase I and prophase II
Interkinesis
In this process, the chromosomes begin to condense again. The nuclear membrane and nucleolus disappear
Prophase II
The chromosomes align at the equatorial plate. Kinetochores attached to centromere. Sister chromatids prepare to move at opposite poles
Metaphase II
Sister chromatids begin to separate. Each moves to opposite poles
Anaphase II
The failure to separate the homologous chromosomes
Nondisjunction
People with _______ have 3 copies of chromosome 21 instead of just two
Down syndrome
Has XXY as sex chromosomes
Klinefelter syndrome
Has just one X as the sex chromosome
Turner syndrome
2 sex chromosomes syndrome
Klinefelter syndrome
Turner syndrome
The chromosomes uncoil. Nuclear membrane and nucleolus reappear.
Cytokinesis finally splits the cells producing 4 haploid cells
Telophase II
Is the process of producing gametes
Gametogenesis
Also known as sex cells
Gametes
2 types of gametogenesis
Spermatogenesis
Oogenesis
Process of producing sperm cells in male
Spermatogenesis
Process of producing egg cells in females
Oogenesis
In spermatogenesis, the ______ forms into the primary spermatocyte
spermatogonium (plural: spermatogonia)
The primary spermatocyte enters meiosis I to produce
Two secondary spermatocytes
The secondary spermatocyte enter meiosis II to produce
Four haploid spermatids
Spermatids undergo _____, wherein spermatids mature into motile spermatozoa
Spermiogenesis
Sperm cells
Spermatozoa
Each cycle of spermatogenesis produces ______ from one spermatogonium
Four sperm cells
Oogenesis starts with the
Oogonium (plural: oogonia)
The oogonium becomes the primary oocyte which will enter meiosis I. The result is
One secondary oocyte and one polar body
Secondary oocyte will enter meiosis II to produce
One egg cell and one polar body
It cannot be fertilized by a sperm
Polar bodies
Each cycle of oogenesis produces _____ all from one oogonium
One egg cell and three polar bodies
The haploid sperm and egg produced in meiosis will meet during
Fertilization
