Download Biology Ch 10 Notes - Cell Division, Growth and

Chapter 10:
Cell Growth, Division & Reproduction
Why do living things get bigger?
Do cells grow in size or do they divide giving you more cells?
How big is too big for a cell and why?
- As cell gets bigger, its volume gets larger, but surface
area gets smaller
- Smaller surface area means less room for substances to
flow in and out of cell. As cells get bigger, it gets harder
for them to get enough nutrients and manage activities.
- Cells grow to a point and before getting too big, they ÷
CELL DIVISION: process by which a cell divides into 2 new
daughter cells.
In plants & animals, cells grow and then ÷ into 2 cells.
These 2 new cells also grow and then ÷ into 2 cells.
(ASEXUAL REPRODUCTION– identical DNA, only 1 parent cell)
CELL CYCLE: time from beginning of one cell division to the
next cell division. Cell’s need to prepare before they divide
and go through 4 phases during a cell cycle- G1, S, G2, & M
phases.
G1 Phase – most of cell Growth & activity
S Phase – chromosome replicate, DNA Synthesis
G2 Phase – final Growth preparations before it divides
M Phase – cell division through Mitosis
S Phase: copy chromosomes (cells DNA – genes)
- Synthesizes DNA (makes another copy, duplicates)
M Phase: MITOSIS – phase where cell actually divides
- happens in eukaryotic cells (cells with a nucleus)
- Process when cells double in size, then
- divide into 2 daughter cells
Interphase: time in-between cell divisions – includes G1, S,
and G2 phases. (Phases in-between Mitosis)
How long does the cell cycle take?
- Embryonic cells – 30 min Average adult – 20 hrs
- Most nerve, heart and muscle cells do not divide, Skin &
digestive cells constantly divide
Stages of Cell Cycle
Interphase: G1, S, and G2 phases (preparation stages)
- Phases that occur between cell division
Chromosomes (DNA) are not visible, DNA is chromatin
and looks like spaghetti, long strands of DNA unfolded
Mitosis: stage where cell divides
- Cell divides into 2 daughter cells
- 4 phases: Prophase, Metaphase, Anaphase, & Telophase
1. Prophase
- Longest phase; Nucleus starts to disappear
- Chromatin coils up into bar-like Chromosomes
- Chromosome has 2 identical strands called sister
chromatids attached by a centromere
- Centrioles (animal cells) organize microtubules spindles
2. Metaphase (meta= middle)
- Shortest phase
- Chromosomes attach to spindles and line up in middle
3. Anaphase
- Centromere splits and chromatids separate
- Chromatids move to opposite poles (sides) of cell
4. Telophase
- Microtubules of spindle start to dismantle
- Nuclear membrane reforms around chromosomes
- Become 2 separate daughter nuclei
Cytokinesis = cytoplasm divides so each daughter cell has
cytoplasm. Happens during anaphase & telophase
All phases of Mitosis:
PLANT CELLS
CELL PLATE: Only in plants! becomes cell wall
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Cell Division in Prokaryotes (cells WITHOUT a Nucleus)
- Bacteria and other organisms
- Process of division is called BINARY FISSION
Cell Specialization & Organization
We all started as a single cell. That cell went thru millions of
cell divisions. Those cells specialized into certain jobs/types.
Cell specialization: cells carry out specific functions / jobs
Ex: Macrophages: WBCs cells that protect against germs
Phagocytosis
Neurons: nerve cells; communicate thru signals, impulses
Tissue: group of similar cells that perform similar function
Organ: Group of tissues that work together for a function
Organ System: Group of organs working together
CELLS – TISSUES – ORGANS – ORGAN SYSTEM – ORGANISM
Controlling Cell Cycle
What controls the cell cycle, cell division, how do cells know
when divide, when to stop growing? What regulates them?
- Proteins called Cyclins
Cyclins: regulate timing of cell cycle
M-phase cyclins build up in cell and trigger Mitosis to occur.
- When mitosis is complete, cell destroys its M-phase cyclins.
Cyclin proteins control cell cycle at 3 points: G1 Phase, S
Phase, G2 Phase
Growth Factors: proteins that stimulate growth and division
of cells
Apoptosis: process of programmed death, cell destroys itself
to make way for new healthy cells.
Cancer: Cancer cells do not respond to signals to stop
growing, so they grow out of control.
- Defect in cell cycle regulation.
- Can lead to growth of a tumor – mass of cells
LAB: Mitosis in Animal & Plant Cells
ANIMAL CELL: Circular Shaped Cell
On one piece of paper, draw for an ANIMAL CELL Interphase,
the 4 phases of Mitosis (Prophase, Metaphase, Anaphase &
Telophase), and 2 identical daughter cells. Use both sides of
the paper to show the 6 phases. Draw and label:
Chromosomes, Centrioles, Spindle fibers, Nuclear
Membrane(if present) & Chromatin (if present).
PLANT CELL: Square Shaped Cell
On another sheet of paper, draw for an PLANT CELL
Interphase, the 4 phases of Mitosis (Prophase, Metaphase,
Anaphase & Telophase), and 2 identical daughter cells. Use
both sides of the paper to show the 6 phases. Draw and
label: Chromosomes, Spindle fibers, Nuclear Membrane (if
present), Chromatin (if present), and Cell Plate.