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Egg and Sperm Formations in Animals Animation

By: HWC, Views: 1965

Inside the ovaries of a female animal are diploid germ cells called oogonia. An oogonium grows to become a primary oocyte. This large cell is still diploid. Meiosis I followed by unequal cytoplasmic division produces one large secondary oocyte and a smaller polar body. Both are haploid. ...

Sperm Formation

By: HWC, Views: 5721

Spermatogenesis takes place inside the seminiferous tubules. Diploid spermatogonia located near the outer edge of the tubule divide mitotically to form primary spermatocytes. The first meiotic division produces secondary spermatocytes with a haploid number of duplicated chromosomes. T...

Generalized life cycles for plants and animals Animation

By: HWC, Views: 1782

But the life cycles of plants and animals differ in their details. In animals, a multicelled diploid stage gives rise to single-celled haploid gametes, the eggs and sperm. These gametes combine at fertilization to form a diploid zygote, which grows and develops into a new multicelled animal...

Genetic terms Animation

By: HWC, Views: 2101

Diploid organisms have pairs of genes, on pairs of homologous chromosomes. Each gene has a specific location on the chromosome. We call this the gene's locus. In this species, the locus for gene B is always between the loci for genes A and C. Most genes come in two or more slightly differen...

Red alga life cycle Animation

By: HWC, Views: 1919

Life cycle of Porphyra. The most conspicuous part of this algal life cycle is the haploid gametophyte. This sheetlike form is collected and dried for use as nori, the wrapping for sushi. Gametes form in packets interspersed between vegetative cells near the sheet margins. The gamet...

Ciliate conjugation Animation

By: HWC, Views: 2110

Protozoan conjugation is an unusual form of sexual reproduction Prospective partners join together, usually at the surface of their oral depressions. The cells undergo cytoplasmic fusion. Meiosis II produces four haploid micronuclei. Now the macronucleus of each cell begins to bre...

Green alga life cycle Animation

By: HWC, Views: 2345

Chlamydomonas zoospores are haploid flagellated cells. As long as conditions are favorable, these cells reproduce asexually. As many as sixteen cells may form by mitosis within a parent cell. Daughter cells escape when the cell wall ruptures. When conditions become less favorable, the...

Rh blood type and complications during pregnancy & Fertilization

By: HWC, Views: 5079

Complications can arise if an Rh- woman is impregnated by an Rh+ man. The fetus maybe Rh+. During childbirth, some of the fetal Rh+ cells may leak into the maternal bloodstream. The woman's immune system views the Rh+ as foreign and makes antibodies against it. If the woman becomes pr...

SNP Polymorphysim Microarray Chip - How to Test a Person's DNA

By: HWC, Views: 7025

To test a person's DNA, a researcher first needs a source of tissue. Most of the cells in a blood sample are red blood cells, which lack nuclei, but there are also a number of white blood cells, which do contain nuclei and chromosomal DNA. If we could see a particular DNA sequence in these cel...