Download CELL GROWTH

CELL GROWTH
How big are cells?
• Cells are microscopic,
too small to be seen by
the naked eye.
• Most human cells are
0.01-0.03mm.
• But small is still
relative!
QUESTIONS ?????
• When a living thing
grows, what happens to
its cells?
• Does it get larger
because:
a. each cell increases in
size?
b. It produces more cells?
QUESTIONS
• When a living thing
grows, what happens to
its cells?
• Does it get larger
because:
a. each cell increases in
size?
b. It produces more cells!
Fertilization
• When a male sex
cell (sperm) and a
female egg cell
(ovum) fused, it
became one cell
(zygote).
• So we started off
as one cell.
How many
• On average the human adult
has about
100 trillion (100, 000, 000, 000,
000) cells.
A new born baby? About
430 billion (430, 000, 000, 000)
cells.
Questions
• Why do we have so many small cells?
• What can’t we be just one big cell?
• Is there an advantage to having many small cells?
• Is there a disadvantage to having large cells?
CELL SIZE LAB (procedure)
1.
2.
3.
4.
Cut 3 cubes 3*3, 2*2, 1*1 and place in cup.
Add vinegar until completely submerged.
Complete Table 1.
After 10 minutes, remove agar cubes and blot dry
with tissue paper.
5. Cut all 3 cubes in half and measure the distance in
centimeters that the vinegar diffused into each
cube.
6. Complete Table 2.
CELL CYCLE (con’t)
7. In Table 3 estimate the percent of diffusion
into each cube.
8. Calculate the volume of the portion of each
cube that has not changed color. Record your
results in Data Table 3.
9. Calculate the extent of actual diffusion into
each cube as a percent of the total volume.
Answer on back of Lab Sheet.
1. What did the different size cubes represent?
2. Which nutrients does the vinegar represent?
3. Look at Data Table 2. Make a statement about the
relationship between cell size and the rate of
diffusion.
4. Look at Data Table 1. Describe what happens to
the surface area, the volume and the ratio as a
cell grows larger?
5. Why is it more advantageous for cells to be
smaller rather than larger?
6. Make a statement about the surface area/volume
ratio (table 1.) and the extent of diffusion (table
3.).
Points to Remember
• Small cells have a larger surface area to
volume ratio.
• Smaller cells are more efficient than larger
cells.
• Rate of diffusion does not change.
• Smaller cells have a better extent of diffusion
CELL GROWTH AND DIVISON
(Vocabulary)
Mitosis – division of nucleus
•
• Cytokinesis – division of cytoplasm
• Centromere – area where chromatids of chromosomes are attached
• Interphase – period of cell cycle between cell divisions
– G1 – reproduction of organelles
– S - chromosomes
– G2 – reproduction of centrioles
• Cell Cycle – series of events as a cell grows and divides
• Prophase – chromosomes become visible, centrioles separate, move towards
poles of cell
•
•
•
•
•
Metaphase – chromosomes line up along the center of the cell
Anaphase – chromosomes separate and move towards opposite poles
Telophase – chromosomes disperse into a tangle of dense material
Centriole – tiny structures that produce spindle fibers
Spindle – help separate the chromosomes during cell division
Cell Division
• Cell Division solves
the problem of a
cell growing to
large.
• (Cell Division – the
process by which a
cell divides into
two new daughter
cells)
Cell Cycle
• Interphase:
– G1 Phase
– S Phase
– G2 Phase
• Mitosis (division of the
nucleus)
• Cytokinesis (division of
the cytoplasm)
G1 Phase
• G1 Phase is a period of
activity in which cells
do most of their
growing.
• During this phase cells
increase in size and
synthesize new
proteins and
organelles.
S Phase
• Chromosomes are
replicated and the
synthesis of DNA
molecules takes
place.
• Histones are also
synthesized.
G2 Phase
• G2 phase is
normally the
shortest of the three
stages of interphase.
• Centrioles copy
themselves.
Mitosis
• A type of cell division
where the nucleus
divides
• Mitosis has 4 stages
– Prophase
– Metaphase
– Anaphase
– Telophase
Prophase
•
•
•
•
Chromatin coils up into chromosomes
Nuclear membrane disappears
Nucleolus disappears
Centrioles begin to move towards the poles
Metaphase
• Chromosomes line up at the center of the cell.
• Spindle Fibers connect to centromeres of
Chromosomes
• Centrioles move the poles of the cell
Anaphase
• Sister chromatids separate and move apart
Telophase
• Chromosomes uncoil and disperse
• Nuclear Envelope begins to reform
• Cytoplasm begins to pinch in half
Cytokinesis
• Cytoplasm pinches in half and the two cells
separate.
• Mitosis Video.
• Different Organisms and their
chromosome count.
Assessment
• Turn to questions 1-7 on page 257.
• Answer them on a blank sheet of paper.
Arrange the 7 steps in Order
•
•
•
•
•
•
•
Anaphase
Metaphase
Cytokinesis
Interphase
Telophase
Late Prophase
Early Prophase
QUESTION 1
• The number of chromosomes in a human cell is
_______.
A.
B.
C.
D.
2
4
23
46
QUESTION 2
• Genetic information is transferred from parent
to daughter cells through the _______.
A.
B.
C.
D.
endoplasmic reticulum
mitochondria
nucleus
centrioles
QUESTION 3
• The resting stage of the cell is known as the
_______.
A.
B.
C.
D.
anaphase
prophase
telophase
interphase
QUESTION 4
• During which stage of mitosis do nucleoli
reappear?
A.
B.
C.
D.
Anaphase
Early Prophase
Late Prophase
Telophase
QUESTION 5
• During which stage of mitosis do chromatids
separate?
A.
B.
C.
D.
Anaphase
Prophase
Interphase
Telophase
QUESTION 6
• Which of the following is NOT correct?
A.
B.
C.
D.
Mitosis is produces genetically identical cells.
Cytokinesis is a part of mitosis
Metaphase occurs before anaphase.
All somatic cells are produced by mitosis.
CELL CYCLE REGULATION
• Not all cells move through the cell cycle at the same
rate:
– Muscle and nerve cells do not divide at all once they
have developed.
– Skin, digestive tract and bone marrow cells grow and
divide rapidly (every few hours).
– Cells in a petri dish (page 250).
Cell Cycle Regulators
• Hunt and Kirschner discovered cyclin, a protein
what when injected into a nondividing cell made it
divide (page 251).
• Cell growth is regulated carefully. Uncontrolled cell
growth is severe. Cancer is a disorder in which
some of the body’s cells lose the ability to control
growth.
• Masses of cells called tumors develop.
MEIOSIS
(pages 275-277)
MEIOSIS Vocabulary
• Meiosis - process by which the number of chromosomes is cut in half
through the separation of homologous chromosomes.
• Homologous chromosomes – chromosomes that each have a
corresponding chromosome from each parent.
• Diploid (2N) – a cell that contains both sets of homologous chromosomes.
• Haploid (N) – a cell that contains only a single set of chromosomes.
• Tetrad – structure containing 4 chromosomes that forms during meiosis.
• Crossing Over – process by which homologous chromosomes exchange
portions of their chromatids during meiosis.
• Gamete – specialized cell involved in reproduction (female gamete =
egg/ovum, plural ova//male gamete = sperm)
• Somatic cells – body cells.
• Sexual Reproduction – process by which cells from two different parents
unite to produce the first cell of a new organism.
• Asexual Reproduction – process by which a single parent reproduces by
itself.
Questions
• How many chromosomes do human being have?
• Can reproduction work by mitosis work? (draw
diagram)
• What do you think has to happen for every human
being to maintain that number of chromosomes?
• Chromosome number has to halved!
Meiosis Overview
•
•
•
•
•
•
•
Cells produced are haploid
Two divisions (Meiosis I & II)
8 Stages (P1, M1, A1, T1, P2, M2, A2, T2)
Prophase 1: Tetrads (4 chromatids) form
Prophase 1: Crossing over occurs
Four daughter cells (gametes) produced
Interphase does NOT occur between M1 and M2
• MEIOSIS VIDEO
What do you notice?
• Down’s Syndrome
or Trisomy 21.
Down’s Syndrome
Question 1
• Which cells are not formed during meiosis?
A.
B.
C.
D.
somatic cells
Gametes
Sex cells
Sperm cells
Question 2
• Which is part of meiosis but not mitosis?
A.
B.
C.
D.
Cell division
Duplication of chromosomes
Reduction of chromosome number
Production of new cells
Meiosis
•
•
•
•
Meiosis, 8 stages you can tell,
Meiosis, produce 4 daughter cells,
Meiosis, just before the cell splits,
Meiosis, half the chromosomes is
what it gets.
(Repeat twice)
Verse
If we want to grow or cells need repair,
Don’t fear, MITOSIS will be there,
But when we need reproductive cells,
MEIOSIS is the process that does it well.