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Cell Growth and Reproduction. What do all cells have in common?. 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
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What do all cells have in common? • 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
Basic Cell Types • 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
Genetic Material • 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.
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 • Cells grow and reproduce just like every other living thing. • The cell cycle represents the life cycle of a typical eukaryotic cell.
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
Interphase • 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.
Mitosis • Mitosis is when the cell divides the contents of the nucleus • Mitosis occurs in stages: • Prophase • Metaphase • Anaphase • Telophase
Cytokinesis • 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.
Cell Reproduction in Bacteria Cells • Prokaryotes (bacteria cells) reproduce by a process known as Binary Fission. • DNA is circular (no chromosomes) • DNA copies itself • Cell divides…simple
Meiosis • 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.
Fertilization • 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