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Prokaryotic cell division VS eukaryotic cell division (pg 119)

1 Prokaryotic cells (bacteria) reproduce using binary fission – a process in which the parent organism makes exact copies of itself

2 Eukaryotic cells may be part of a larger Multicellular organism but also make duplicate copies of themselves in a process called mitosis

Chromosomes (pg 119)

1 Chromosomes are a structure made of DNA on which the genes are located (genetic material takes this form just before and during cell division)

1 DNA - (deoxyribonucleic acid) - a double sided nucleic acid that stores genetic information (carries the traits passed down from the parents)

2 gene - a section of a chromosome containing specific trait information

3 chromatids - 2 exact copies of DNA that make up a single chromosome

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Chromosome number & structure (pgs 120-121)

1 The number of chromosomes present varies by species; the number of chromosomes does not determine the complexity of the organism

2 Homologous Chromosomes - pairs of chromosomes

1 homologue - single chromosome in a pair, contains similar size, shape and information as its partner; the information on one homologue comes from the mother the other from the father of the organism

2 diploid - cell with both homologues present (pairs of chromosomes, like body cells)

3 haploid - cell with only one of each homologue (like gametes or spores)

4 zygote - diploid cell formed from the fusion of two haploid gametes

5 autosomes – chromosomes not directly involved in determining gender

6 sex chromosomes – determine the gender of the organism (in humans a pair with 2 X homologues is female, 1 X and 1 Y homologue is male)

Testing chromosome number and structure

1 Karyotype - (pg 122) - photo of a set of chromosomes arranged in homologous pairs by size; used for predicting potential problems in development of the embryo; abnormalities in chromosome number can lead to developmental problems

1 amniocentesis - (p 123) a small amount of amniotic fluid (fluid surrounding the fetus in the uterus) is removed to obtain genetic information from the fetus

2 chorionic villi sampling (CVS) - tissue is collected from the extensions of the placenta that connect with the uterus called chorionic villi

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2 Abnormalities in chromosome structure can also lead to developmental problems (pg 124)

1 Deletion - a piece of the chromosome is missing due to a problem during DNA replication (making a copy)

2 Duplication - one or more pieces of the chromosome appears twice

3 Inversion - one or more pieces of the chromosome is switched with an adjoining piece

4 Translocation - one or more pieces of the chromosome have been moved to an incorrect location

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The Cell Cycle (pg 125)

1 The cell cycle is a repeating sequence of cellular growth and division

1 The cell spends 90% of it’s time in Interphase which contains three phases…

1 First Growth (G1) phase - cell grows rapidly and carries out routine functions, cells not preparing to divide stay in this phase

2 Synthesis (S) phase - Cell’s DNA is replicated (copied), at the end of this phase each chromosome consists of two chromatids attached at the centromere

3 Second Growth (G2) phase - preparations are made for the nucleus to divide

2 The last two phases deal directly with cell division

1 Mitosis - process of cell division in which the nucleus is divided into two identical nuclei

2 Cytokinesis - process of cell division in which the cytoplasm is divided to form two identical cells

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Mitosis (forms two identical diploid cells - pgs 130-1)

1 Prophase

1 chromosomes become visible

2 nuclear envelope dissolves

3 spindle forms (the spindle is made of the centrioles and microfibers that move the chromosomes during mitosis)

2 Metaphase

1 chromosomes line up along the equator

3 Anaphase

1 centromeres divide (duplicate copies of chromosomes are separated)

2 chromatids (now called chromosomes) move toward opposite sides of the cell

4 Telophase

1 Nuclear envelope forms around each set of chromosomes

2 chromosomes uncoil

3 spindle dissolves

4 cytokinesis begins

Cytokinesis

1 Cytoplasm is divided into equal halves

2 In animal cells the cell membrane pinches in toward the center

3 In plant cells a plate is formed in between the two halves of cytoplasm, from this plate the new cell walls are formed

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Meiosis (forms 4 haploid cells - pgs 142-3)

1 Prophase I

2 Metaphase I

3 Anaphase I

4 Telophase I & Cytokinesis

5 Prophase II

1 new spindle forms in both cells

6 Metaphase II

1 chromosomes line up at the equator of both cells

7 Anaphase II

1 centromeres divide

2 chromosomes are pulled apart

8 Telophase II

1 nuclear envelopes develop

2 cytoplasm divides

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Meiosis in male vs. female animals (pg 146)

1 Male meiosis (spermatogenesis) produces 4 functional haploid sperm

2 Female meiosis (oogenesis) produces 1 viable egg and 3 non-functional polar bodies

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