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5/21/2008

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Revision Guide | Hope Raybould

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Reproduction
There are 2 types of reproduction-

Asexual-

Only 1 parent/ individual needed
no gametes involved
clones formed/ mitosis
genetic variation only occurs due to mutation

Sexual reproduction-

Involves gametes
2 parents/ individuals needed
meiosis
genetic variation due to meiosis and random fission of gametes




Cell cycle

Meiosis
General-

Meiosis…

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o 2nd division- separates chromatids




Homologous chromosomes-

One from mom and one from dad
Each member of the pair-
o are exactly the same length
o have centromere in the same place
o contain the same number of genes
o genes are arranged in the same linear order

Meiosis 1-…

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Nucleoli disappear, centrioles migrate, nuclear envelope breaks down, spindle formation
occurs.

Metaphase I ­

Paired chromosomes, bivalents, line up along the equator of a cell and attach to the spindle

Anaphase I ­

Homologous chromosomes separate to opposite poles of the cell.

Telophase I ­

Doesn't always occur.
Spindle fibres…

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Metaphase I




Anaphase I




Telophase I




Metaphase II



Anaphase II




Telophase II

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Reproductive Systems
Male




Testes

Found in the scrotum
Produce male gametes (sperm)
Leydig cells produce and secrete testosterone
Controlled by anterior pituitary gland

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Ducts

Epididymus and vas deferens collect and store spermatazoa from testes.
Ejaculatory ducts converge on urethra, spermatazoa expelled from urethra.

Exocrine glands

Include seminal vesicles and prostate glands.
They secrete a nutritive and lubricating fluid called seminal fluid.
Semen consists of sperm, seminal fluid, mucus and cells lost from duct…

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Carry ovum from ovary to uterus
Fertilisation of the oviduct usually takes place in an oviduct

Uterus-

Hollow, pear shaped muscular organ
Lining of the uterus (endometrium) undergoes cyclical changes due to changes in the levels
of oestrogen and progesterone.
The cervix is part of the uterus

Vagina-

Muscular tube…

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