NATS 1675 Lecture Notes - Lecture 3: Xx Male Syndrome, Heredity, Fetus
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- CELL DIVISION 2016-02-04 16:25
• MITOSIS—a kind of cell division in which two identical cells are
produced. It is used as one method of reproduction for single celled
microorganisms such as protests and bacteria. It is also the type of
cell division that occurs in multicellular organisms for growth, repair
• MEIOSIS—a process of cell division by which gametes containing
half the normal number of chromosomes are produced. Meiosis is
also called reduction division.
• GAMETES—sex cells, e.g., egg cells, sperm cells, pollen grains.
• CHROMOSOME—a strand of DNA and protein found in the nucleus
of a cell; carries genetic information. In humans there are 46
chromosomes or 23 pairs.
• Chromosomes: String of beads on pearls
• Karyotypes: The chromosomes of a cell,
usually displayed as a
systematized/structured arrangement of chromosome pairs in
descending order of size
• Chromosome Pairs:
o 1-22 = autosomes
o The same for both sexes
• The 23rd chromosome = Sex chromosome
• Female = XX
• Male = XY
• DNA—deoxyribonucleic acid, the chemical molecule that makes up
chromosomes and genes.
• GENE—functional unit of heredity; the part of the chromosome that
transmits a particular hereditary trait. A gene can be likened to a
set of blueprints.