Cell Biology
Structure of Animal Cells
Cell Organelles
What is ATP?
Cell Organelles
Cell Organelles
Organic molecules of Cells
Types of Proteins
Nucleic Acids
Water Molecule
Water Molecule
Cell Membrane
Cell Membrane Composition
Cell Membrane Composition
Lipid Molecules
Osmotic Properties of Cells
Hydrostatic pressure
Donnan Equilibrium
Donnan Equilibrium
Ionic Steady State
Donnan equilibrium
Erythrocyte cell equilibrium
Cell Lysis
Molecules Related to Cell Permeability
Cell Permeability
Crossing the membrane
Modes of Transport
Carrier-Mediated Transport
Channel Mediated Transport
Coupled Transport
Active transport
Active transport
Na+/K+ Pump
Na+/K+ Pump
Na+/K+ Pump
Endo and Exocytosis
Receptor Mediated Endocytosis
The End
Category: biologybiology

Cell Biology. Lecture 2

1. Cell Biology

Lecture 2
Cell Biology
Advanced Physiology of Animals
ANSC 3405
Chapters 3 to 4, Beginning 5

2. Outline

• Cell Structure and Organelles
• Cell Molecular Components
• Water and Chemical properties
• Cell Membrane
• Osmotic Properties of cells
• Cell molecule transportation

3. Structure of Animal Cells

Cell Video

4. Cell Organelles

• Nucleus
– 1 Nuclear envelope
– Chromatin and DNA
– Nucleolus
• Mitochondria
– Double membrane
– Mitochondrial (maternal) DNA
– “Power House” of the cell
• Food converted into energy
– Adenosine triphosphate (ATP)
• Consumes Oxygen, produces CO2

5. What is ATP?

• Nucleotides
– “Carry” chemical
energy from easily
• Combine to form coenzymes (coenzyme A (CoA)
• Used as signaling molecules (cyclic AMP)

6. Cell Organelles

• Endoplasmic Reticulum
– Site where cell membrane and
exported material is made
– Ribosomes (rough)
• Make protiens
• Smooth ER- lipids
• Golgi Apparatus
– Recieves and modifies
– Directs new materials
• Lysosomes
– Intracellular digestion
– Releases nutrients
– Breakdown of waste

7. Cell Organelles

• Peroxisomes
– Hydrogen Peroxide generated and degraded
• Cytosol
– Water based gel
– Chemical reactions
• Cytoskeleton
– Filaments (actin, intermediate and microtubules)
– Movement of organelles and cell
– Structure/strengthen cell
• Vessicles
– Material transport
– Membrane, ER, Golgi derived vessicles

8. Organic molecules of Cells

• Proteins
• Carbohydrates
• Lipids
• Nucleic acids

9. Proteins

• Most diverse and complex macromolecules
in the cell
• Used for structure, function and information
• Made of linearly arranged amino acid
– “folded” up with “active” regions

10. Types of Proteins

1) Enzymes – catalyzes covalent bond breakage or
2) Structural – collagen, elastin, keratin, etc.
3) Motility – actin, myosin, tubulin, etc.
4) Regulatory – bind to DNA to switch genes on or off
5) Storage – ovalbumin, casein, etc.
6) Hormonal – insulin, nerve growth factor (NGF), etc.
7) Receptors – hormone and neurotransmitter receptors
8) Transport – carries small molecules or irons
9) Special purpose proteins – green fluorescent protein, etc.

11. Lipids

• Hydrophobic molecules
– Energy storage, membrane components,
signal molecules
– Triglycerides (fat), phospholipids, waxes,
• Sugars, storage (glycogen, starch), Structural
polymers (cellulose and chitin)
• Major substrates of energy metabolism

12. Nucleic Acids

acid) and RNA
encode genetic
information for
synthesis of all
• Building blocks of


14. Water Molecule

• Polarity of H20 allows H bonding
• Water disassociates into H+ and
OH• Imbalance of H+ and OH- give
rise to “acids and bases”
- Measured by the pH
• pH influence charges of amino
acid groups on protein, causing a
specific activity
• Buffering systems maintain
intracelluar and extracellular pH
(Figure 3-6, pg 46)

15. Water Molecule

• Hydrophobic “Water-fearing”
– Molecule is not polar, cannot form H bonds
and is “repelled” from water
– Insoluble
• Hydrophillic “Water-loving”
– Molecule is polar, forms H bonds with water
– Soluble

16. Cell Membrane

17. Cell Membrane Composition

• Plasma membrane encloses cell and cell
• Made of hydrophobic and hydrophillic
– Semi-permeable and fluid-like
– “lipid bilayer”

18. Cell Membrane Composition

• Integral proteins interact with “lipid bilayer”
– Passive transport pores and channels
– Active transport pumps and carriers
– Membrane-linked enzymes, receptors and
• Sterols stabilize the lipid bilayer
– Cholesterol
(Figure 4-4, pg 81)


(Figure 4-2, pg 80)

20. Lipid Molecules

(Figure 4-3, pg 81)



23. Osmotic Properties of Cells

• Osmosis (Greek, osmos “to push”)
– Movement of water down its concentration
• Hydrostatic pressure
– Movement of water causes fluid mechanical
– Pressure gradient across a semi-permeable

24. Hydrostatic pressure

(Figure 4-9, pg 85)

25. Donnan Equilibrium

Add Ions
(Figure 4-9,
pg 81)
Deionized water
Balanced charges among
both sides

26. Donnan Equilibrium

Add anion
More Cl- leaves I to
balance charges

27. Ionic Steady State

• Potaasium cations
most abundant
inside the cell
• Chloride anions
ions most abundant
outside the cell
• Sodium cations
most abundant
outside the cell

28. Donnan equilibrium

A- Cl-K+
A- ANa+

29. Erythrocyte cell equilibrium

•No osmotic pressure
- cell is in an isotonic solution
- Water does not cross
•Increased [Osmotic] in cytoplasm
- cell is in an hypotonic solution
- Water enters cell, swelling
•Decreased [Osmotic] in cytoplasm
- cell is in an hypotonic solution
- Water leaves cell, shrinking
(Figure 4-14, pg 90)

30. Cell Lysis

• Using hypotonic
• Or interfering with
Na+ equilibrium
causes cells to burst
• This can be used to
advantage when
isolating cells
(Figure 4-16, pg 91)

31. Molecules Related to Cell Permeability

• Depends on
– Molecules size (electrolytes more
– Polarity (hydrophillic)
– Charge (anion vs. cation)
– Water vs. lipid solubility
(Figures 4-18;19, pg 92)

32. Cell Permeability

• Passive transport is carrier mediated
– Facilitated diffusion
– Solute molecule combines with a “carrier” or
– Electrochemical gradients determines the
– Integral membrane proteins form channels

33. Crossing the membrane

• Simple or passive diffusion
• Passive transport
– Channels or pores
• Facilitated transport
– Assisted by membrane-floating proteins
• Active transport pumps & carriers
– ATP is required
– Enzymes and reactions may be required

34. Modes of Transport

(Figure 4-17, pg 91)

35. Carrier-Mediated Transport

• Integral protein binds to the solute and undergo
a conformational change to transport the solute
across the membrane
(Figure 4-21, pg 93)

36. Channel Mediated Transport

• Proteins form aqueous pores allowing specific
solutes to pass across the membrane
• Allow much faster transport than carrier proteins

37. Coupled Transport

• Some solutes “go along for the ride” with a
carrier protien or an ionophore
Can also be a Channel
coupled transport
(Figure 4-22, pg 95)

38. Active transport

• Three main mechanisms:
– coupled carriers: a solute is
driven uphill compensated
by a different solute being
transported downhill
– ATP-driven pump: uphill
transport is powered by ATP
hydrolysis (primary)
– Light-driven pump: uphill
transport is powered by
energy from photons

39. Active transport

• Energy is required

40. Na+/K+ Pump

• Actively transport Na+ out of the cell and K+ into the cell
•Against their
•For every 3 ATP, 3
Na+ out, 2 K+ in
(Figure 4-24, pg 96)

41. Na+/K+ Pump

• Na+ exchange
(symport) is
also used in
epithelial cells
in the gut to
drive the
absorption of
glucose from
the lumen, and
eventually into
(by passive
(Figure 4-35, pg 105)


(Figure 4-26, pg 97)

43. Na+/K+ Pump

• About 1/3 of ATP in an animal cell is used to
power sodium-potassium pumps
• In electrically active nerve
cells, which use Na+ and K+
gradients to propagate
electrical signals, up to 2/3 of
the ATP is used to power
these pumps

44. Endo and Exocytosis

• Exocytosis
- membrane vesicle fuses with cell
membrane, releases enclosed material to
extracellular space.
• Endocytosis
- cell membrane invaginates, pinches in,
creates vesicle enclosing contents

45. Receptor Mediated Endocytosis

(Figure 4-30, pg 102)

46. The End

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