Cell Cycle & Mitosis

Cell Division All cells are derived from pre-existing cells New cells are produced for growth and to replace damaged or old cells

Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules

DNA Replication DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands

Identical Daughter Cells Two identical daughter cells Parent Cell

Prokaryotic Chromosome The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane

Eukaryotic Chromosomes Each chromosome is composed of a single, tightly coiled DNA molecule Chromosomes can’t be seen when cells aren‘t dividing and are called chromatin

Eukaryotic Chromosomes All eukaryotic cells store genetic information in chromosomes Most eukaryotes have between 10 and 50 chromosomes in their body cells Human body cells have 46 chromosomes or 23 identical pairs

Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids

Karyotype A picture of the chromosomes from a human cell arranged in pairs by size First 22 pairs are called autosomes Last pair are the sex chromosomes XX female or XY male

The Y Chromosome Decides Boy or Girl? The Y Chromosome Decides Y - Chromosome X - Chromosome

The Cell Cycle

Interphase = between phases Chromatin DNA Duplicates

G1 First growth phase - Cell grows in size Creates mRNA and proteins Ends when the cell enters into the S phase

S PHASE DNA is Replicated S phase occurs between G1 and G2

G2 Cell continues to grow and create mRNA and proteins Cell will duplicate organelles getting ready for the Mitosis phase

Mitosis Division of the nucleus Only occurs in eukaryotes Has four stages Doesn’t occur in some cells such as brain cells

Mitosis = New Cells Results in 2 identical daughter cells 4 chromosomes  4 chromosomes Daughter Daughter

Onion Root Tip Mitosis Pictures Interphase

Prophase Latin = "For" Chromosomes (and copies) condense Chromatid = copy Nuclear Membrane dissappears Centriole spindles form

Prophase

Chromosomes (with copies) line up Metaphase Greek = "Adjacent" Nuclear Membrane gone Centrioles Move Spindles grow Chromosomes (with copies) line up

Chromosomes (with copies) line up Metaphase Nuclear Membrane gone Centrioles Move Spindles grow Chromosomes (with copies) line up

Metaphase

Anaphase Latin = "Away" Spindles contract Copies pulled apart

Anaphase Spindles contract Copies pulled apart

Anaphase

Nuclear Membranes form Early Telophase Latin = "Distant, End" Spindles gone Nuclear Membranes form

Early Telophase

Nuclear Membranes are complete Late Telophase Nuclear Membranes are complete Mitosis is complete.

Late Telophase

Cytokinesis Cell splits

Cytokinesis

Quiz

Metaphase

Interphase = between phases Chromatin DNA Duplicates

Metaphase

Prophase

Anaphase

Telophase

Nuclear Membranes are complete Late Telophase Nuclear Membranes are complete Mitosis is complete.

Mitosis = New Cells Results in 2 identical daughter cells 4 chromosomes  4 chromosomes