Cellular Reproduction

Biology I Factoids

Factoid 100Section 8

Diagram of a Chromosome:

Sister chromatids

centromere

Factoid 101

• The Cell Cycle is made up of the G1 phase, the S phase, the G2 phase, and the M phase.

Factoid 102

• The cell grows during the G1 phase.

Factoid 103

• DNA replication occurs during the S phase.

Factoid 104

• The organelles duplication and the cell prepares for mitosis during the G2 phase.

Factoid 105

• The M phase (M for Mitosis) is divided into prophase, metaphase, anaphase, and telophase.

Factoid 106

• During prophase– The chromosomes become visible– The nuclear membrane disappears– The spindle forms

Factoid 107

• During Metaphase– Chrmosomes line up along the equator of the

cell

Factoid 108

• During Anaphase– spindle fibers pull the sister chromatids apart

to opposite poles.

Factoid 109

• During telophase– Everything done during prophase is “undone”

Factoid 110

• During cytokinesis the cell splits.

Factoid 111

• Cytokinesis forms by a cleavage furrow in animal cells and by a cell plate in plant cells.

Factoid 112

• Organisms have two basic types of cells: somatic cells are body cells and gametes are sex cells

Factoid 113

• Sex cells (gametes) are produced by meiosis. Somatic cells are produced by mitosis.

Factoid 114

• Male sex cells are called sperm and female sex cells are called eggs.

Factoid 115

• Somatic cells are diploid (2n). Sex cells are haploid (n). Meiosis divides the chromosome number in half.

• Diploid cells meiosis haploid cells fertilization diploid cells again.

Factoid 116

• Humans have 46 chromosomes. Sperm have 23 chromosomes and eggs have 23 chromosomes. Sperm (23) + egg (23) = baby (46).

Factoid 117

• Meiosis adds genetic variation. This means that it allows for different shapes, colors, and forms of organisms.

Factoid 118

• Meiosis is divided into two parts: meiosis I and meiosis II.

Factoid 119

• Each part of meiosis has 4 parts: Meiosis I has Prophase I, Metaphase I, Anaphase I, and Telophase I. Meiosis II has Prophase II, Metaphase II, Anaphase II, and Telophase II.

Factoid 120

• An organism is only successful if it successfully spreads its genes to the next generation. This is the driving force behind most evolution.

Factoid 121

• External fertilization occurs outside the body (frogs and fish). Internal fertilization occurs inside the body (higher animals and humans).

Factoid 122

• Asexual reproduction is the production of an offspring involving only 1 parent, produces genetically identical clones, and without splitting the chromosomes.

Factoid 123

• Three types of asexual reproduction– Binary fission – a single cells splits in half.

Common in bacteria and some protists.– Budding – small area of cells grow into a new

organism. Used by fungi and simple animals.– Vegetative propagation – plants send out

runners that grow into a new plant or a cutting can be made.