Biology Retake

Brandon Cassens p.3


Meiosis is cell divisions that produce gametes, eggs, and sperm. Contains half the number of parent chromosomes. Meiosis makes mistakes such as karyotype, nondisjunction, trisomy, monosomy, and polyploidy. Four haploid cells are made with one chromosome from a pair. Meiosis phase two is identical to mitosis. It separates sister chromatids into same cells. Involves cell division in two parts: prophase to telophase one and prophase to telophase two.

Mitosis Phases

Telophase 1- The spindle has broke down chromosomes uncoils and plasma divide. One pair per cell.
Metaphase 1- Centromere attached to spindle fibers and pulled to the center. The tetrads line up next to eachother.
Prophase 1- Chromosomes line up at the tetrads and pair bonds to non sister chromatids that exchange genetics. Humans have 2-3 crossovers per chromosome pair.
Anaphase 1- Homologous chromosomes move to opposite ends of cells. Only receive 1 chromosome per pair.
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Male hormones release Luteinizing hormone (LH) and Follicle Stimulating hormone (FSH). LH produces testosterone stimulates sperm production in the testicles. It also produces secondary characteristics like sex organs, sperm, body hair, muscle, voice change, and growth in arms and legs. Females at puberty have FSH and LH hormones. Estrogen causes secondary charactaristics such as
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There are 2 types of fertilization internal and external. Internal prevents scattering of gametes outside its exposure, the gametes are normally short lived. External is the process of gametes fusing outside female body. Mostly can happen to water breeding animals such as fish, frogs and many more.


When formation happens the Acrosome enzymes dissolve the eggs protective shell,it allows enterence to the nucleus. The gametes then join creating the diploid. It restores the number of chromosomes around the egg and sperm. A zygote is a fertilized egg. An embryo is a fetus early developing.
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