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Cell Growth and Reproduction
All cells have a plasma membrane.◦ Controls what gets in and out.◦ Made of phospholipid molecules
All cells have cytoplasm◦ Gel-like substance
All cells have genetic material◦ Either DNA or RNA
All cells have ribosomes◦ For making proteins
What do all cells have in common?
Prokaryotic cells◦ Smallest cells◦ No nucleus or membrane-bound organelles◦ Examples: Bacteria
Eukaryotic cells◦ Complex cells◦ Have a nucleus and membrane-bound organelles◦ Examples: Plant cells and Animal Cells
Basic Cell Types
Most cells reproduce by dividing in two. Before they can do this, they must copy all
their genetic information, so that each new daughter cell has a full set of genetic material
The genetic material in eukaryotic cells is in the form of chromosomes.
Genetic Material
Humans have 46 chromosomes in the nucleus of every cell ◦ Two are the sex chromosomes (X and Y)
XX = female XY = male
◦ The other 44 are called autosomes◦ They occur in matching pairs
Called homologous chromosome pairs One chromosome in each pair comes from mom and
the other comes from dad
Cells grow and reproduce just like every other living thing.
The cell cycle represents the life cycle of a typical eukaryotic cell.
Cells Grow and Reproduce
G1 phase: Cell grows S phase: (synthesis) Cell copies its DNA G2 phase: Cell continues to grow and get
ready to divide Mitosis: The cell divides the content of the
nucleus Cytokinesis: The cell divides its cytoplasm
The G1, S, and G2 phase make up a stage called interphase. The cell spends most of its time in interphase.
The cell grows and copies DNA during interphase.
Interphase
Mitosis is when the cell divides the contents of the nucleus
Mitosis occurs in stages:◦ Prophase◦ Metaphase◦ Anaphase◦ Telophase
Mitosis
Cytokinesis occurs when the rest of the cell divides. ◦ For animal cells---the cell membrane pinches in
and the cell splits in two.◦ For plant cells---an new cell plate forms to create
a cell wall between the dividing cells.
Cytokinesis
Prokaryotes (bacteria cells) reproduce by a process known as Binary Fission.◦ DNA is circular (no
chromosomes)◦ DNA copies itself◦ Cell divides…
simple
Cell Reproduction in Bacteria Cells
The reproductive cells divide by a different method….Meiosis.
The cell divides twice. The result is four gamete cells (sperm and
egg cells) with half the number of chromosomes.
Meiosis
Fertilization—union of sperm and egg cell.
Sexual reproduction, involving the production of sperm and egg cells by meiosis followed by fertilization, ensures genetic variation in all offspring
Fertilization
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