1. Cell Size is Limited Surface to Volume Ratio limits upper size
Larger cells have less surface area relative to volume

2. A Generic Animal Cell

3. An idealized plant cell

4. Cell Membrane

5. Function Separates cytoplasm from external environment
Regulates what enters and leaves cell
Cell identification
Cell-cell communication

6. Plasma membrane regulates movement of materials due to its chemical composition: Phospholipids Cholesterol Proteins

7. Phospholipids Phospholipids Bilayer Phospholipids have:
Hydrophilic head
Nonpolar hydrophobic tail
Phospholipids Bilayer

8. Hydrophilic "heads" faces the watery environment inside and outside cell
Hydrophobic tail forced to face inward – away from water.

9. The phospholipids are not bound together – gives the membrane a fluid nature

10. CHOLESTEROL Function: Stabilizes membrane (structural support)
Cell communication (cell-cell and cell- hormone)

11. Some interesting facts
Most common molecule in membrane (>50%)
Due small size and weight – only 20% of membrane mass
Is an amphipathic molecule Homework – find out what this means

12. Proteins
Are embedded in membrane
Serve different functions

13. Functions
1. Channel Proteins - small openings for molecules to diffuse through
2. Carrier Proteins- binding site on protein "grabs” molecules, pulls them into cell
3. Receptor Proteins – act as triggers that set off cell responses (such as release of hormones or opening of channel proteins)
4. Cell Recognition Proteins - ID tags, identify cell to immune system
5. Enzymatic Proteins - carry out metabolic reactions

14. LABEL YOUR DIAGRAM WITH THE FOLLOWING DETAILS

15. Task: Due Tuesday Oct. 4, 2011 Read pages 47 -49 in your text
Answer questions 1 – 5 in practice section
Explain the structure and function of glycoproteins.
How are liposomes used in cancer treatment and gene therapy?
What role might receptor proteins have in medical disorders such as Hypertension?

16. Structure and Function of the Nucleus
Occurs only in eukaryotic cells
Surrounded by a double membrane called the nuclear envelope
It contains
chromatin -a DNA-protein structure
a nucleolus - which produces ribosomal parts
Nucleoplasm

17. Animation of nuclear membrane system
Animation of nuclear membrane system

19. Nuclear Pore Complex
Allows movement of material into and out of nucleus

20. Ribosomes Ribosomes build all the cell’s proteins
Are not membrane bound

21. How DNA Controls the Cell
DNA controls the cell by transferring its coded information into RNA
DNA 1
Synthesis of
mRNA in the
nucleus
mRNA
The information in the RNA is used to make proteins
Nucleus
Cytoplasm 2
Movement of
mRNA into
cytoplasm via
nuclear pore
mRNA
Ribosome 3
Synthesis of
protein in the
cytoplasm
Protein

22. THE ENDOMEMBRANE SYSTEM: MANUFACTURING AND DISTRIBUTING CELLULAR PRODUCTS
Many of the membranous organelles in the cell belong to the endomembrane system
Endoplasmic reticulum - rough and smooth
Golgi Apparatus
Lysosomes
Vacuoles

23. The Endoplasmic Reticulum
The endoplasmic reticulum (ER)
Nuclear
envelope
Greek for ‘network within a cell’
Produces an enormous variety of molecules
Is composed of smooth and rough ER
Ribosomes
Rough ER
Smooth ER

24. Rough ER
The “roughness” of the rough ER is due to ribosomes that stud the outside of the ER membrane

25. The functions of the rough ER include
Producing proteins
Producing new membrane

26. After the rough ER synthesizes a molecule it packages the molecule into transport vesicles1

27. Smooth ER The smooth ER lacks the surface ribosomes of ER
Produces lipids, including steroids and sex hormones
Regulates sugar
Detoxifies drugs
Stores calcium

28. The Golgi Apparatus The Golgi apparatus
Works in partnership with the ER
Refines, stores, and distributes the products of cells
Transport
vesicle
from ER
“Receiving” side of
Golgi apparatus
Golgi apparatus
New vesicle forming
Transport vesicle
from the Golgi
“Shipping” side of
Golgi apparatus
Plasma membrane

29. Lysosomes A lysosome is a membrane-enclosed sac
Greek for ‘breakdown body’
It contains digestive enzymes
Isolated by membrane
The enzymes break down
Macromolecules
Old organelles

30. Lysosomes have several types of digestive functions
They exit the Golgi apparatus

31. They fuse with food vacuoles to digest the food

32. They fuse with old organelles to recycle parts
Digest bacteria in white blood cells

33. Lysosomal diseases Genetic disorders Recipe is messed up
Enzyme doesn’t work
what should get broken down doesn’t
Tay-Sachs
lipids aren’t broken down
build up occurs
death by age 5
Pompe’s disease
glycogen builds up

34. Vacuoles Vacuoles are membranous sacs
Two types are the contractile vacuoles of protists and the central vacuoles of plants
Central
vacuole
Contractile
vacuoles
(a) Contractile vacuoles in a protist
(b) Central vacuole in a plant cell
Figure 4.15

35. A review of the endomembrane system

36. CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION
Cells require a constant energy supply to do all the work of life

37. CHLOROPLASTS
Chloroplasts are the sites of photosynthesis, the conversion of light energy to chemical energy
Inner and outer
membranes of
envelope
Space between
membranes
Granum
Stroma (fluid in
chloroplast)
Figure 4.17

38. Chloroplasts Double membrane Grana Stroma- fluid filling chloroplast
Stacks of thylakoids
Hollow disks
Sunlight energy is coverted to chemical energy
Stroma- fluid filling chloroplast
Contains some DNA

39. Mitochondria
Mitochondria are the sites of cellular respiration, which involves the production of ATP from food molecules
Outer
membrane
Inner
membrane
Cristae
Matrix
Space between
membranes
Figure 4.18

40. Mitochondria Double membrane Matrix -space inside inner bag
Big bag stuffed into smaller bag
Folds of inner bag called cristae
Matrix -space inside inner bag
Contains some DNA

41. THE CYTOSKELETON: CELL SHAPE AND MOVEMENT
The cytoskeleton is an infrastructure of the cell consisting of a network of fibers
Microfilaments - small threads
Intermediate filaments - ropelike
Microtubules - small tubes

42. Maintaining Cell Shape
One function of the cytoskeleton
Provide mechanical support to the cell and maintain its shape

43. Figure4.9x

44. The cytoskeleton can change the shape of a cell
This allows cells like amoebae to move

45. Cilia and Flagella
Cilia and flagella are motile appendages

46. Flagella propel the cell in a whiplike motion
Cilia move in a coordinated back-and-forth motion
Figure 4.20A, B

47. Some cilia or flagella extend from nonmoving cells
The human windpipe is lined with cilia
Smoking damages the cilia

48. Cilia and Flagella Same structure and function
9 + 2 arrangement of microtubules
Wrapped in plasma membrane

49. Mechanism of Movement
Dynein arms use ATP for energy to ‘walk’ up adjoining microtubule, causing them to bend

50. CELL SURFACES: PROTECTION, SUPPORT, AND CELL-CELL INTERACTIONS
Most cells secrete materials that are external to the plasma membrane
This extra cellular matrix
Regulates
Protects
Supports

51. Plant Cell Walls and Cell Junctions
Plant cells are encased by cell walls
These provide support for the plant cells
Walls of two adjacent
plant cells
Vacuole
Plasmodesmata
(channels between cells)
Figure 4.21

52. Animal Cell Surfaces and Cell Junctions
Animal cells lack cell walls
They secrete a sticky covering called the extracellular matrix
This layer helps hold cells together

53. Animal cells connect by various types of junctions
Tight junctions – leakproof – fuses membranes of cells – found in intestinal epithelium (lining of intestine). Made of filaments (type of cytoskeleton material made from glycoprotein)
Anchoring junctions - Desmosomes - hold cells together
Communicating junctions - gap junctions. Provides a channel between cells for passage of small ions and molecules. Gap junctions are found in embryos, cardiac muscles and endocrine glands

54. Extracellular matrix (a) Tight junctions (b) Anchoring junctions
(c) Communicating
junctions
Plasma membranes
of adjacent cells
Extracellular matrix
Figure 4.22