Download Cell Transport and the Cell cycle

Cellular Transport And the
Cell Cycle
Diffusion
 Diffusion
is the movement of particles from
a region of high concentration to an area of
lower concentration

At all temperatures above absolute zero, the
individual atoms that constitute any substance
are always in movement. The amount of this
movement is what constitutes temperature itself.
Diffusion Cont.

Particles of a
substance will move
from a region of high
concentration to a
region of lower
concentration.
 The difference in
concentration of
atoms is know as a
concentration
gradient

As particles move in
a given area, an
equilibrium is
reached where the
space between the
particles becomes
fairly uniform.
 This equal
distribution of atoms
is called dynamic
equilibrium
Selective Permeability
 Membranes
are selectively permeable,
or semi-permeable which means that
only some substances can pass
through, but not others.
 It’s kind of like a screen door..
Membrane Structure and
Function
Membrane Function
 Membranes
organize the chemical
activities of cells.
 The outer plasma membrane
 forms
a boundary between a living cell and
its surroundings
 Exhibits selective permeability

Controls traffic of molecules in and out
Membrane Function
 Internal
membranes provide structural
order for metabolism
Form the cell's organelles
 Compartmentalize chemical reactions

Fluid Mosaic Model of the PM
A
membrane is a mosaic
 Proteins
and other molecules are
embedded in a framework of phospholipids
A
membrane is fluid
 Most
protein and phospholipid molecules
can move laterally
Membrane Structure
Phospholipid
Phospholipids are
the major structural
component of
membranes.
Membrane Structure
All membranes are phospholipid bilayers
with embedded proteins.
Phospholipid Bilayer
Label the:
Hydrophilic heads
Hydrophobic tails
Plasma Membrane
 Made
up of two
layers of
phospholipids
 Controls what
moves into and out
of the cell
 Selectively
permeable
 Embedded
in the bilayer are proteins
 Most
of the membrane’s functions are
accomplished by the embedded
proteins.
Integral proteins span the membrane
 Peripheral proteins are on one side or the other of
the membrane

Passive Transport
 Transport
(diffusion) of particles across
the membrane without the use of
energy by the cell
 Particles move from a region of high
concentration to a region of low
concentration across the concentration
gradient
Passive transport by proteins
Facilitated Diffusion - Transport of materials
across the plasma membrane with the aid of
channel proteins

Common method for
moving sugars and
amino acids across
membranes
 Driven by a
concentration gradient
(substances on both
sides of the membrane
are trying to reach
equal concentration)
Passive Transport
 Video
What is Osmosis?
– Diffusion of water
across a selectively permeable
membrane
 Osmosis

The plasma membrane does not limit the
diffusion of water
 Water moves freely through proteins called
aquaporins
 In a cell, water always tries to reach an equal
concentration on both sides of the membrane
What Controls Osmosis?
 Concentration
gradient - Unequal
distribution of particles
Cells in an Isotonic Solution
Isotonic Solution – when
the concentration of
dissolved substances in
the solution is the same
as the concentration of
dissolved substances
inside of the cell
 Equal movement of
water into and out of the
cell, cell stays the same
size

Cells in a hypotonic solution
Hypotonic solution – when
the concentration of
dissolved substances is
lower in the solution
outside the cell than the
concentration inside the
cell
 Water is pulled into the
cell, the cell swells and
the internal pressure
increases

Cells in a hypertonic solution
Hypertonic Solution –
where the concentration
of dissolved substances
outside the cell is higher
than the concentration
inside the cell.
 Water moves out of the
cell, the cell shrinks, and
internal pressure
decreases

Water moves into a cell placed in a
___________________ solution.
A. Osmotic
B. Hypertonic
C. Isotonic
D. Hypotonic
Water moves out of a cell if it is
placed in a
_______________ solution
A. Hypotonic
B. Hypertonic
C. Isotonic
D. Passive
A cell moves particles from a region of lesser
concentration to a region of greater
concentration by _________________.
A. Facilitated Diffusion
B. Passive Transport
C. Osmosis
D. Active Transport
If a cell is placed in salt water, water
leaves the cell by
_____________.
A. Osmosis
B. Diffusion
C. Active transport
D. Phagocytosis
Pickles and Osmosis????
• View the recipe for making pickles.
Dill Pickles
• 15 pickling cucumbers or Kirbies
• Pickling Liquid:
3 cups water
2 cups white vinegar
1/4 cup coarse salt
2 tablespoons granulated sugar
8 garlic cloves, peeled
1 bunch dill
1 sprig thyme
• Bring a large stockpot water to a boil. Add cucumbers, immediately remove from
heat, and drain in a colander. Rinse with cold water and reserve.
• Combine pickling liquid ingredients in a medium saucepan and bring to a boil. Place
cucumbers in a large container with remaining vegetables and herbs.. Pour hot
pickling liquid over cucumber mixture and let cool. Tap down solids until liquid
rises to top. Cover with plastic wrap and let stand at room temperature 1 day.
Transfer to a sealed container
After viewing the recipe above, explain the role of osmosis in
making pickles. Be ready to share your answers!
Active Transport
 Cells
can move particles from a region
of low concentration to a region of high
concentration, but it takes
!
Transport – movement of
materials through a membrane against
the concentration gradient
 Active
Active Transport Cont.
 Proteins
in the cell membrane (Carrier
proteins) bind with particles of the substance.
When the right molecule binds to the right
carrier protein, ATP allows the carrier protein
to change shape so that the particle can be
moved to the other side of the membrane
Examples of Active
transport
Transport of Large Particles

Some cells can take in large molecules,
groups of molecules, or even whole cells
 Endocytosis – process by which a cell engulfs
a material and forms a vacuole inside of the
cell
 Exocytosis – expulsion or secretion of
materials from the cell


Used to get rid of waste, secrete hormones
Both endocytosis and exocytosis require
cellular energy (Active transport)
Endocytosis and Exotytosis
 Use
the play dough to model the
processes of endocytosis and
exocytosis. Be able to explain the
process. When you have finished, wait
for Mrs. Johnson to come and check
your work and hear your explanation.
Active Transport
 Video
Release of waste or large cell products
from inside to outside of cell
_____________________.
A. Endocytosis
B. Exocytosis
C. Osmosis
D. Facilitated Diffusion
Type of cell transport which requires energy
from the cell.
A. Osmosis
B. Facilitated Diffusion
C. Active Transport
D. Passive Transport
Active Transport is to carrier protein as
_____________ is to channel protein.
A. Osmosis
B. Endocytosis
C. Exocytosis
D. Facilitated Diffusion
When cell engulfs a large particle
and forms a vacuole inside the cell
_____________________.
A. Endocytosis
B. Exocytosis
C. Osmosis
D. Facilitated Diffusion
Term for “cell eating”
A. Osmosis
B. Exocytosis
C. Pinocytosis
D. Phagocytosis
Cells come in different sizes
Red blood Cells = 8 µm
 Some nerve cells can be up to 1mm in
length
 The yolk of an Ostrich egg measures 8cm
 Most living cells are between 2 and 200
µm
 Given the wide range of cell sizes, why
can’t most organisms be just one giant
cell?

What limits cell size?
 Diffusion
 Diffusion
is fast and efficient over short
distances but slow and inefficient over
larger distances
a
mitochondrion at the center of a
hypothetical cell with a diameter of 20 cm
would have to wait months before receiving
molecules entering the cell
What limits cell size? cont.
 DNA

The nucleus contains blueprints for the cell’s proteins
(proteins are used throughout the cell by the
organelles)
 There
is a limit as to how quickly the DNA
(blueprints) can be copied
 The cell can’t survive unless there is
enough DNA to support the protein needs
of the cell
 Some large single celled organisms have
developed more than 1 nucleus
What limits cell size? Cont.
 Surface
area to volume ratio
 As
cell size increases, its volume increases
faster than its surface area

If cell size doubles, the cell would require eight times
more nutrients and would have eight times more
waste to excrete. The surface area would increase
only by a factor of four. The plasma membrane would
not have enough surface area for nutrients, waste and
oxygen to diffuse through
Surface area to volume ratio
1cm
1cm
2cm
Surface area = 6cm2
Volume = 1cm3
4cm
2cm
Surface area = 24cm2
Volume = 8cm3
4cm
Refer to PS lab 8.1
pg 209
Surface area = ??
Volume = ??
Cell Size
 Video
The structure most responsible for
maintaining cell homeostasis is the
___________.
A. Cytoplasm
B. Mitochondria
C. Cell Wall
D. Plasma Membrane
As a cell grows, its ___________
increases more than its ___________.
A. Length, volume
B. Width, surface area
C. Volume, surface area
D. None of these
Which of the following explain why a cell’s
size is limited?
A. Volume increases faster than surface area
B. Surface area increases faster than volume
C. Homeostasis is disrupted by a cell that is
too large
D. Both a and c
Limits to cell Size summary….
-The cell membrane controls what moves in and out of the
cell…homeostasis
-The cell membrane represents the surface area of the cell
-Small cells have a greater surface area to volume ratio than larger
cells…which is good.
-If cells get too large:
- they can’t make enough protein to keep the cell
running
-diffusion is too slow so the cell won’t be able to get what it
needs (food and waste)
-the surface area to volume ratio decreases, which
decreases the ability of the plasma membrane to do its job for
the cell (the cell can’t get in enough food, oxygen… or get rid of
enough waste, CO2)
-Many different types of cells have found ways to become large by
developing adaptations that increase their SA to V ratio and amount
of DNA
Cell Reproduction
Cell Reproduction (video clip)
 The
cell theory states: all cells come from
preexisting cells
 We know that all organisms grow and
change
 Throughout our lives, worn-out tissues are
repaired or replace by new cells
 All of this occurs through Cell Division
The process by which new cells are produced
from one cell
 Results in two cells that are identical to the
parent cell

What are Chromosomes?

Chromosomes – dark staining structures that
contain genetic material (DNA)

Made up of DNA and protein

Chromatin – long strands of DNA wrapped
around protein (resembles a tangled plate of
spaghetti)

Before a cell can divide,
the long strands of chromatin
must be organized into a
chromosome
http://www.sirinet.net/~jgjohnso/modchromosome.jpg
Chromosomes
http://www.uic.edu/classes/bios/bios100/labs/realchromo.jpeg
Video clip
http://lhs.lps.org/staff/sputnam/Biology/U3Cell/chromosome_1.png
The Cell Cycle
 The
sequence of growth and division of
a cell
2
phases:
 Growth
 Division
The Growth Phase:
Interphase
 The
majority of a cell’s life is spent growing
and making more DNA, this period is
called – Interphase
 During
interphase, cell grows in size and the
chromosomes are duplicated
G1 phase - rapid growth
 S phase – DNA synthesis and replication
 G2 phase – Centrioles replicate and cell prepares
for division

The Division Phase:
Mitosis

Cells undergo mitosis as they approach the
maximum cell size at which the nucleus can
provide blue-prints for proteins and the
plasma membrane can efficiently transport
nutrients and waste into and out of the cell

4 phases of Mitosis:
Prophase
Metaphase
Anaphase
Telophase
The Cell Cycle
http://lhs.lps.org/staff/sputnam/Biology/U3Cell/cellcycle_1.png
Cell Cycle Summary
-All cells have a life cycle where they grow carry out their
functions then divide. Cell cycles vary from cell type to cell
type.
-There are two main phases of the cell cycle
Interphase – Growth
Mitosis – Division
-During Interphase, the cell grows (G1), copies DNA (S).
and gets ready to divide (G2)
-As a result of Mitosis, two new cells are formed having
properties like the parent cell because the DNA was
replicated before division
-The cell’s DNA is doubled during the synthesis (S) phase
then reduced back to the original amount after mitosis (M)
Mitosis: Prophase
1st stage of mitosis
(longest stage)
 Chromatin coils up into
visible chromosomes
 Each duplicated
chromosome is made of
2 sister chromatids held
together by a centromere
 The nucleus begins to
disappear
 Centrioles migrate to
opposite ends of cell
 Spindle fibers become
visible

Mitosis: Metaphase
2nd stage of mitosis
(short stage)
 Chromosomes
become attached to
the spindle fibers by
their centromeres
 Chromosomes line
up on the midline

Mitosis: Anaphase
3rd stage of mitosis
 Sister chromatids are
pulled apart
 the spindle fibers
attached to the
centromere and the
centriole begin to shorten
pulling the chromatids
from each other

Mitosis: Telophase



4th stage of mitosis
Chromatids reach the
opposite poles of the cell
Chromosomes unwind,
spindle begins to break
down, nucleolus
reappears and nuclear
envelop forms around
each set of new
chromosomes
Mitosis
http://www.sirinet.net%2F%7Ejgjohnso%2Fmodchromosome.jpg&rurl=http%3A%2F%2Fwww.sirinet.net%2F%7Ejgjohnso%2
Freprod.html&size=35.1kB&name=modchromosome.jpg&p=chromosome+structure&type=jpeg&no=85&tt=573&ei=UTF-8
 Mitosis
animation
Division of Cytoplasm
Cytokinesis – division of
cytoplasm between the two
newly formed cells
 Different for plant and animal
cells

Life Cycle of a Cell and Cell
Division
Video clip
Among the following, the term that includes
the others is ___________.
A. Interphase
B. Nuclear division
C. Mitosis
D. Cell Cycle
By the end of prophase, each of the following
has occurred except ______________.
A. Tighter coiling of the chromosomes
B. Breaking down of the nuclear envelope
C. Disappearing of the nucleolus
D. Lining up of chromosomes in the cell
The longest phase of the cell cycle is
________________.
A. Prophase
B. Interphase
C. Metaphase
D. Mitosis
A chromatid is attached to a spindle fiber by
the ________________.
A. Nucleolus
B. Deep furrow
C. Centromere
D. Centriole
The sequence of growth and division of a
cell makes up ______________
A. Mitosis
B. The Cell Cycle
C. Chromosomes
D. Cytoplasmic Division
Identify the stage of mitosis
A. Anaphase
B. Metaphase
C. Prophase
D. Telephase
Identify the stage of mitosis
A. Anaphase
B. Metaphase
C. Prophase
D. Telephase
Results of Mitosis
So what’s the point?
 Mitosis
guarantees that the two new
cells that are produced are genetically
identical. The two new daughter cells
will carry out the same cellular
processes and functions as those of the
parent cell and will grow and divide just
as the parent cell did.
Control of the Cell Cycle
 The
full story of how the cell cycle is
controlled is not fully understood
 Scientist do agree on some aspects of
what causes cells to divide
Enzymes
Enzymes Control the Cell
Cycle
 Different
enzymes control different parts
of the cell cycle
Interphase
growth (G1 phase)
synthesis (S phase)
getting ready (G2 phase)
mitosis (prophase, metaphase,
anaphase, telophase)
Sometimes cells lose control
of the cell cycle
 Can
result from:
 Not
enough enzyme
 Too much enzyme
 Production of enzymes at the wrong time
Enzyme production is controlled by
genes
Cancer cells…

…behave
much differently
than normal cells.
 …spend
very little time in
interphase and go through
mitosis uncontrollably.
 Approx.
1/10,000 of your
cells are cancerous-the good
news-your defense cells
usually kill them fast.
Cancer

Uncontrolled cell
division can result in
cancer
 Cancer is a mistake
in the cell cycle.
Video clip

Cancerous cells
form tumors
 Tumors deprive
normal cells of
nutrients
 Cancer cells can
enter the blood
stream and spread
throughout the body
(metastasis)
Causes of Cancer

Genetic factors (Heredity)
 Viruses that cause damage to genes
 Environmental Factors that damage genes





Cigarette smoke
Air pollution
Water pollution
UV exposure
Radiation
Incidence of Cancer
 People
of different countries develop
different types of cancer
 Ex.
Breast cancer is high in the U.S,
Stomach cancer is high in China
When people move from one country to another,
cancer rates follow the pattern of the country in
which they are currently living
Cancer Prevention

There is a clear link between a health lifestyle
and incidence of cancer
 Diet



Vitamins & Minerals




Low fat, high fiber
Fruits, vegetables, grains
Caratenoids
Vitamins A, C & E
Calcium
Exercise
 No tobacco use
Cell Aging and Cancer
 Video
clip
Growth and Development in
Multicellular Organisms
 Cells
 Tissues
 Organs
 Organ
systems
 Organism
Video clip
No matter how complex the organism, the
cell is still the basic unit of organization