student goals explain the purpose of cell division identify the steps and events of each cell phase
TRANSCRIPT
Student Goals
• Explain the purpose of cell division
• Identify the steps and events of each cell phase.
Which nucleus is bigger?
Cell Size
• Cell size is constrained by cellular needs for raw materials and the chemical properties of molecules.– too big = can’t get enough
matter and energy or get rid of chemical wastes
– too big = too many demands on DNA – things get out of control
• Sometimes, smaller is better
They are exactly the same size.
Life of a Cell
• Cells lining the esophagus live for 2-3 days
• Cells lining the small intestine live 1-2 days
• White blood cells may live for only 10 hrs, or for decades
• Red blood cells live less than 120 days
• Muscle cells live for years• Nerve cells live for many
years
Cell Life
• Most of the time that a cell is alive, it is busy growing, making molecules and using them.
• This is called Interphase (the time between mitotic divisions)
• The DNA is strung out in the nucleus, invisible. (chromatin)
• When the cell reaches its size limit, it gets ready to divide in two in a process called mitosis.
• Before that can happen, the DNA and all the cellular organelles are replicated during interphase.
Life Cycle of a Cell
• Interphase – growth, increase in size, and synthesis of organelles and molecules – G1
– S
– G2
• Mitosis - Cell division– Prophase
– Metaphase
– Anaphase
– Telophase
– Cytokinesis
The Big Picture- 2
• Before PROPHASE the chromatin is replicated (copied).
• During PROPHASE it condenses into chromosomes.
• Each chromosome has a replicated twin = sister chromatids.
• These are the 46 chromosomes in a human cell as mitosis begins.
Chromatin > Chromosome > Chromatids
• Chromatin, Chromosomes, and Chromatids are all the same– named differently depending on the stage.
Chromatin
Chromosome
Chromatids
Differences between Chromatin/Chromosomes/Chromatidshttp://www.youtube.com/watch?v=s9HPNwXd9fk
1. Prophase Pro = pre (before)
2. Metaphase Meta = middle
3. Anaphase Ana = apart
4. Telophase Telo = two
5. Cytokinesis Cyto = cell, kine = move
Examine Allium root tips under the
microscope and identify the parts.
Mitosis: What does it look like?