Transcript Topic: Types of Cells and Membranes

All Organisms Are Made of Cells
 The Cell Theory
 All living things are
composed of cells
 Cells are the basic unit of
structure and function in
living things
 All cells come from preexisting cells
Overview Of Animal & Plants
 Organelle
 Plasma membrane
 “Mini-organ”
 Most are membrane
bound & perform
specific functions
 Outer covering that
defines the boundary
 Regulates things
going in and out
 Crucial for
homeostasis
Overview of Plant & Animal Cells
 Nucleus
 Cytoplasm
 Membrane bound
structure that houses
the DNA
 Fluid that fills entire
cell and suspends the
organelles
Two Major Classes of Cells
 Prokaryotic Cells
 Lack a nucleus and
other membrane
bound organelles
Cell wall
Bacteria
Archaea
Earliest cells in Earth’s
fossil record
Two Major Classes of Cells
 Eukaryotic Cells
 True nucleus
 Membrane bound
organelles
 Much bigger in size
Is It Alive?
 Viruses ?
Cell Size
 Some characteristics of
life
 Smallest infectious
agents
 Composed of mostly
protein and genetic
material
 Coat called capsid
 Some have envelope
similar to cell membrane
Structure of Cell Membrane
 Membrane Structure
Polar Group
Hydrophilic
head (polar)
Phosphate
fatty acid chain
fatty acid chain
Glycerol
 Phospholipid
molecule
 Phosphate head
Hydrophilic
Contains arrangement
of atoms attached to
glycerol including
phosphate group
 Lipid tail
Hydrophobic
Two fatty acid chains
Hydrophobic
tail (non-polar)
Structure of Cell Membrane
 Organization of phospholipids
 Bilayer (2 layers)
 Hydrophobic tails make up
inside layer
 Hydrophilic heads face extracellular space and intra-cellular
space
Structure of Cell Membrane
 Proteins within the membrane
 Enzymes- carry out reactions
 Facilitate communication
between cells and allows for
recognition between cells
 Assists in the transport of
molecules across the
membrane (like water &
sugars)
Membranes Regulate the Traffic of
Molecules
 2 ways materials such
as water, salts, sugar,
and nutrients move
across the cell
membrane, in order to
maintain homeostasis
 PASSIVE TRANSPORT


1. Passive transport
2. Active transport
 Molecules move from an area
of high concentration to an
area of low concentration
 No energy required
Equilibrium
Movement of molecules continues, across
the membrane, but at the same rate in
both directions
Molecules are equally dispersed 
BALANCE
 Types of Passive
Transport
 Simple diffusion:
Small molecules (oxygen &
carbon dioxide) pass through the
membrane from an area of high
concentration to an area of low
concentration
 Facilitated diffusion:
Larger molecules use protein
channels to move across the
membrane from an area of high
concentration to an area of low
concentration
http://www.biology.com/
Moving Molecules against a Gradient
ACTIVE
TRANSPORT
When molecules are moved
from an area of lower
concentration to area of
higher concentration
Cell expends energy
Usually performed to prevent
equilibrium from occurring
Example: Neuron
Passive Transport Continued
 Osmosis
 Solutions
 Passive transport of water across
a selectively permeable membrane
 Water moves from an area of high
concentration to an area of low
concentration
A solution is made up of
two things : Solute and
Solvent
Solute: Substance in a solution that is
dissolved & present in a lesser amount
Solvent: Substance in a solution that
dissolves the other substance & is
present in a greater amount
Types of solutions
 Hypertonic solution
 Hypotonic solution
 Isotonic solution
 Hyper = over
Hypertonic solution is a
solution that has a high
concentration of solutes
• Hypo= under
Hypotonic solution is a solution
that has a low concentration
of solutes
• Iso= same
Isotonic solutions are ones
that have an equal
concentration of solutes and
water in and outside of the
cell
Osmosis in Different Cells
Turgor Pressure:
The pressure produced inside
the cell from a hypotonic
solution
Plasmolysis:
When the cell membrane shrinks
away from the cell wall.
Organs of the Urinary system-
 Kidneys
 Ureters
 Urinary bladder
 Urethra
Chapter 32.2
Urinary System
4 Organs
 Kidneys
2 Bean shaped structures
Excrete waste products & regulate
water and salt balance
Filter the blood
 Produce urine = Liquid composed of water,
urea, and other nitrogen containing waste
products
 Ureters (2)
Tubes that extend from each kidney
carrying urine to the urinary bladder
Urinary System
4 Organs
 Urinary Bladder
Collapsible sac that temporarily holds
urine until it is eliminated from the body
 Urethra
Urine leaves the bladder through
another tube called the urethra
Urinary System
Primary Goal of the
Kidney
 Excrete waste products and
regulate water and salt balance
 Two Roles
 Clean out toxins from blood
 Restore water
4 Steps Involved when Blood is Processed
& Urine is Excreted
 Step #1 = Filtration
Blood pressure forces water and small solutes,
including urea, into the Bowman’s Capsule
 Step #2 = Reabsorption
Active Transport reabsorbs
 Glucose, amino acids, and other ions from the filtrate back
into the blood
Water solution left behind is hypotonic causing
osmosis to move water back into the blood
4 Steps Involved when Blood is Processed
& Urine is Excreted
Step #3: Secretion
The following substances are transported from
the blood back into the filtrate
Nitrogenous waste products
• Urea
• Uric Acid
• Toxins
Excess Water
4 Steps Involved when Blood is Processed
& Urine is Excreted
Step #4: Excretion
Remaining filtrate is transported to the bladder
to leave the body
Regulating Water Balance
Mechanisms of homeostasis regulate the
amount of water reabsorbed by the kidney
Example: Negative Feedback Loop
 How the body responds to a stimulus, in order to create a
balance again…
Regulating Water Balance
Decrease water level in your body
Increase concentration of solutes in your blood
Thirst center in your brain is activated
Motivates you to drink
ADH (anti-diuretic hormone) is released
ADH travels in the blood to the kidneys 
stimulates the nephrons to reabsorb more water
Result:
Decrease in solute concentration in the blood to
within the normal range
Water content of urine decreases  Yellow;
concentrated
Regulating Water Balance
Drink too much water
Solute concentration in blood drops below the
normal range
Less ADH is released from the brain
Lower level of ADH, decreases the amount of
water reabsorbed in the nephrons
Result:
Urine contains more water  lighter in color
Transporting Large Molecules
 Endocytosis
 Moving large molecules into
the cell within vesicles
 Vesicles: Small membrane
bound sacs specialized in
moving materials in and out of
cell
 Exocytosis
o Moving large molecules out of
the cell within vesicles