Honor Biology
Ch. 8
Cellular Transport
and the Cell Cycle
I. Cellular Transport
- molecules constantly
enter and leave the cell
A. Diffusion
- movement of molecules
from high concentration
to low conc.
- until dynamic equilibrium
reached
- requires no cell energy
(passive)
B. Osmosis:
- diffusion of water through a
selectively permeable membrane
C. Effects of Osmosis
1.Isotonic Solution
- concentration of solutes
the same on inside and
outside of cell
2. Hypotonic Solution
- solution outside of cell
contains a lower conc. of
solutes than the cell
(more water)
a) Turgor pressure:
- pressure inside plant cells
a) Turgor pressure:
Leaves
and
Onion
Epidermis
a) Turgor pressure:
Plant
Movements
from
Osmosis
b) Cytolysis:
- bursting of cells due to
increased osmotic pressure
c) Contractile Vacuoles:
- “pump” water out of cells of
paramecium, ameba, etc.
living in a
hypotonic
solution
Paramecium
3. Hypertonic Solution
- solution outside of cell
contains a higher conc. of
solutes than the cell
(less water)
a) Plasmolysis:
- loss of cytoplasm
(shrinking of the cell)
b) Wilting:
- loss of turgor in plant cells
D.Passive vs. Active
Transport
1. Passive Transport:
- requires no energy
a) Diffusion and Osmosis
b) Facilitated Diffusion:
- transport proteins in
membrane move sugar,
amino acids, etc.
- follows concentration
gradient
b) Facilitated Diffusion:
2. Active Transport:
- requires cell energy
a) Carrier proteins
transport molecules
from low. conc. to high
conc. using cell energy
Active Transport:
b) Endocytosis:
b) Endocytosis:
- movement of large amounts
of material into a cell by
engulfing and enclosing
within a membrane
- forms a vacuole within cell
b) Endocytosis:
Ameba
c) Exocytosis:
c) Exocytosis:
- expelling large amounts of
material from the cell
c) Exocytosis:
Paramecium
II. Cell Size Limitations
- most cells are very small
-most cells are very small
II. Cell Size Limitations
- most cells are very small
- size of most cells is limited
by several factors:
A.DNA Control
- cannot make protein fast
enough to support cell if
cell is too large
B. Diffusion Rate
- slow and inefficient as
distance increases
C. Surface Area to
Volume Ratio
- large cells don’t have
enough surface area (cell
membrane) to support the
cell with food and oxygen
by diffusion
Surface Area to Volume Ratio
III. Cell Reproduction:
- 1 cell divides into 2
identical cells
- occurs millions of times
each day throughout life
- each new cell requires a
full, exact copy of all
chromosomes
Binary Fission in Bacteria
DNA replicated
Membrane added
Binary Fission in Bacteria
constriction
fission
Functions
of Mitosis
Fertilized
egg
(zygote)
Organs
Multicell
stage
Mitotic cell
division &
Differentiation
Mitotic cell division
Tissues
Asexual Reproduction by Mitosis
Paramecium
New Individuals
Asexual Reproduction by Mitosis
Yeast
Budding
Nucleus divides
by mitosis
Bud forms on
cell
A.Chromosomes:
- made of DNA and protein
- stores genetic information
(genes)
- prokaryotes don’t have
chromosomes
1. Chromatin:
DNA
double helix
Chromatin
Chromosome
1. Chromatin:
- active form of chromosomes
- long, thin strands of DNA and
protein
Chromatin
2. Chromatid:
- one of 2 replicated
halves of
chromosomes
- Centromere:
point of attachment
of 2 sister
chromatids
Human Chromosomes
B.The Cell Cycle:
- 3 parts
1.Interphase
2.Mitosis
overlap
3.Cytokinesis
The
Cell
Cycle
G1: Growth
G0:
nondividing
S:
Synthesis
of DNA
interphase
G2: Growth
C. Interphase:
- period of time between cell
division
- takes up 80 - 90% of a cell's life
- normal cell activity and growth
Nucleus
Nuclear
Membrane
Chromatin
C. Interphase:
- period of time between cell
division
- takes up 80 - 90% of a cell's life
- normal cell activity and growth
1. Cell growth
2. DNA replication
3. Synthesis of
organelles and
centrioles
D.Mitosis:
- 4 stages (P, M, A, T)
Prophase
Anaphase
Metaphase
Telophase
1. Prophase
- first and longest stage
a. Chromatin condenses to form
chromosomes
b. Centrioles move to
opposite ends of
the cell
- animal cells
only
c. Spindle fibers form
- protein fibers that aid in
movement of chromosomes
d. Nuclear membrane and
nucleolus disappear
2. Metaphase
- second and shortest stage
- chromosomes line up along the
middle of the cell
3. Anaphase
- centromeres split and
chromosomes
move apart to
opposite
sides of
the cell
4. Telophase
- last stage
- "reverse" of prophase
a. Chromosomes revert
to chromatin
b. Spindle fibers
disappear
c. Nuclear membrane
and nucleolus
reform
E. Cytokinesis:
1. Animal Cells
- Cell membrane
pinches in
forming 2
daughter cells
2.Plant Cells
- Cell plate forms between 2
daughter cells
Cell plate
Which stage of mitosis?
Anaphase
Which stage of mitosis?
Interphase
Which stage of mitosis?
Metaphase
Which stage of mitosis?
Prophase
Which stage of mitosis?
Telophase
Which stage of mitosis?
Prophase
Interphase
Which stage of mitosis?
Early Anaphase
Which stage of mitosis?
Metaphase
Which stage of mitosis?
Prophase
Which stage of mitosis?
Telophase
IV. Cancer:
- disease in which cells
have lost the ability to
control their own growth
Cervical Cancer Cell Dividing
A. Characteristics of
Cancer Cells:
1. Rapid cell division
2. Undifferentiated cells
3. Metastasis:
- cells don't stick together
and can move elsewhere
B. Causes of Cancer:
- genes controlling cell division have
mutated (changed)
1. Carcinogens:
- cancer causing agents
- nicotine, asbestos, PCB's, etc.
2. Radiation:
- UV (sunlight), X-rays, radon, etc.
3. Viruses
4. Hereditary factor
The End
- in humans:
- skin cell reproduce quickly
- nerve cells reproduce very slowly
Human kidney cells dividing