1. Chapter 3 Cell Anatomy Cell = Chamber/Compartment
4/22/2017
Chapter 3
Cell Anatomy
Cell = Chamber/Compartment

2. 4/22/2017

3. 4/22/2017

4. Basic Structure of the Cell
4/22/2017
Basic Structure of the Cell
Plasma membrane
Cytoplasm containing organelles (little organs)
Nucleus
Functions of the Cell
Basic unit of life
Protection and support through production and secretion of various kinds of molecules
Movement. Various kinds occur because of specialized proteins produced in the cell (Flagella and Cilla)
Communication. Cells produce and receive electrical and chemical signals
Cell metabolism and energy release
Inheritance. Each cell contains DNA. Some cells are specialized to gametes for exchange during sexual intercourse

5. Plasma Membrane (phospholipid bilayer)
4/22/2017

6. Plasma Membranes Fluid-mosaic model
4/22/2017
Plasma Membranes
Fluid-mosaic model
theory explaining how cell membranes are constructed
Molecules of the cell membrane are arranged in a sheet
The mosaic of molecules is fluid; that is, the molecules are able to float around slowly
Chemical attraction is the force that holds membranes together

7. Membrane Lipids
4/22/2017
Primary structure of a cell membrane is a double layer of phospholipid molecules
Heads are hydrophilic (water-loving)
Tails are hydrophobic (water-fearing)
Molecules arrange themselves in bilayers in water
Cholesterol molecules are scattered among the phospholipids to allow the membrane to function properly at body temperature
Most of the bilayer is hydrophobic; therefore water or water-soluble molecules do not pass through easily

8. Membrane Lipids (cont)
4/22/2017
Membrane Lipids (cont)
What is it composed of?
Phospholipids and cholesterol predominate
Phospholipids: bilayer. Polar heads facing water in the interior and exterior of the cell (hydrophilic); nonpolar tails facing each other on the interior of the membrane (hydrophobic)
Cholesterol: interspersed among phospholipids. Amount determines fluid nature of the membrane

9. Membrane Proteins TYPES of Membrane Proteins Integral / intrinsic
4/22/2017
Membrane Proteins
TYPES of Membrane Proteins
Integral / intrinsic
Extend deeply into membrane, often extending from one surface to the other
Can form channels through the membrane
Peripheral / extrinsic
Attached to integral proteins at either the inner or outer surfaces of the lipid bilayer
Functioning depends on 3-D shape and chemical characteristics. Markers, attachment sites, channels, receptors, enzymes, or carriers.

10. 1) Marker Molecules: Glycoproteins
4/22/2017
1) Marker Molecules: Glycoproteins
Carbohydrates attach to proteins
Allow cells to identify one another or other molecules
Immunity
Intercellular communication

11. 4/22/2017
2) Attachment Sites
Attachment sites to other cells or to extra/intracellular molecules.

12. 4/22/2017
3) Channel Proteins (Integral): hydrophilic region faces inward; charge determines molecules that can pass through
Nongated ion channels: always open
Responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest
Gated ion channels can be open or closed
Ligand gated ion channel: open in response to small molecules that bind to proteins or glycoproteins
Voltage-gated ion channel: open when there is a change in charge across the plasma membrane

13. 4/22/2017
4) Receptor Molecules
Proteins in membranes with an exposed receptor site
Can attach to specific ligand molecules and act as an intercellular communication system
Ligand can attach only to cells with that specific receptor

14. 5) Enzymes and Carrier Protein
4/22/2017
5) Enzymes and Carrier Protein
Enzymes: some act to catalyze reactions at outer/inner surface of plasma membrane.
Carrier proteins: integral proteins move ions from one side of membrane to the other
Have specific binding sites
Protein change shape to transport ions or molecules

15. 4/22/2017
Cytoplasm
Cytoplasm: gel-like internal substance of cells that includes many organelles suspended in watery intracellular fluid called cytosol
Cellular material outside nucleus but inside plasma membrane
Two major groups of organelles (Table 3-3)
Membranous organelles are sacs or canals made of cell membranes
Nonmembranous organelles are made of microscopic filaments or other nonmembranous materials

16. Endoplasmic Reticulum
4/22/2017
Endoplasmic Reticulum
2 Types
Smooth ER
Rough ER

17. Endoplasmic Reticulum
4/22/2017
Endoplasmic Reticulum
Smooth (SER):
No ribosomes attached
Synthesizes lipids and carbohydrates:
phospholipids and cholesterol (membranes)
steroid hormones (reproductive system)
glycerides (storage in liver and fat cells)
Storage of Ca++
Fat metabolism and drug detoxification (liver)
Rough (RER)
Has attached ribosomes
- Proteins produced and modified here

18. 4/22/2017
Ribosomes
- Tiny round bodies in the cytoplasm made of a large and small subunit
- Build polypeptides in protein synthesis
Two types:
Free ribosomes in cytoplasm:
manufacture proteins for cell
Fixed ribosomes attached to ER membranes:
manufacture proteins for secretion

19. 4/22/2017
Golgi Apparatus
Flattened membrane sacs stacked on each other (cisternae)
Modification, packaging, distribution of proteins and lipids for secretion or internal use

20. Function of Golgi Apparatus
4/22/2017
Function of Golgi Apparatus
Proteins made in the ER are packaged into tiny vesicles, which pinch off and move towards the golgi apparatus.
Vesicles fuse with the golgi membrane and release the proteins.
Enzymes within the golgi modify the proteins
The processed molecules eventually pinch off and move towards the plasma membrane where they are secreted.

21. Function of Golgi Apparatus
4/22/2017
Function of Golgi Apparatus

22. Lysosomes Powerful enzyme containing vesicles Functions of Lysosomes
4/22/2017
Lysosomes
Powerful enzyme containing vesicles
Functions of Lysosomes
Clean up inside cells:
Break down large molecules
Attack bacteria
Recycle damaged organelles
Eject wastes by exocytosis

23. Proteasomes Hollow protein cylinders found throughout the cytoplasm
4/22/2017
Proteasomes
Hollow protein cylinders found throughout the cytoplasm
Break down abnormal or misfolded proteins and normal proteins no longer needed by the cell (and that may cause disease)
Break down protein molecules one at a time by tagging each one with a chain of ubiquitin molecules, unfolding the protein as it enters the proteasome, and then breaking apart peptide bonds

24. 4/22/2017
Proteasomes

25. Peroxisomes Peroxisomes Smaller than lysosomes
4/22/2017
Peroxisomes
Peroxisomes
Smaller than lysosomes
Detoxify harmful substances in cell
Contain enzymes to break down fatty acids and amino acids
Contain peroxidase and catalase
Hydrogen peroxide is a by-product of breakdown

26. Mitochondria Major site of ATP synthesis Membranes
4/22/2017
Mitochondria
Major site of ATP synthesis
Membranes
Cristae: Infoldings of inner membrane
Matrix: Substance located in space formed by inner membrane
Mitochondria increase in number when cell energy requirements increase.
Mitochondria contain DNA that codes for some of the proteins needed for mitochondria production.

27. 4/22/2017

28. Nucleus - The cell’s control center Contains genetic material (DNA)
4/22/2017
Nucleus
- The cell’s control center
Contains genetic material (DNA)
Three distinct regions:
1. Nuclear Membrane
2. Nucleoli
3. Chromatin

29. Nuclear Structure and Content
4/22/2017
Nuclear Structure and Content
Nuclear Membrane
- double membrane connected by nuclear pores
-encloses nucleoplasm
Nucleoli
- site of ribosome formation
Chromatin
-carries cells DNA
-condenses into Chromosomes during cell division

30. 4/22/2017

31. 4/22/2017

32. 4/22/2017
Cytoskeleton
Supports the cell but has to allow for movements like changes in cell shape and movements of cilia
Cell fibers:
Microfilaments: “cellular mm”
Made of thin, twisted strands of protein molecules that lie parallel to the long axis of the cell
Can slide past each other and cause shortening of the cell
Actin and myosin are subcategories
Microtubules: hollow, made of tubulin.
Internal scaffold, transport, cell division, move things around cell
Intermediate filaments: mechanical strength

33. 4/22/2017
Cell Fibers

34. 4/22/2017
Centrosome
An area of the cytoplasm near the nucleus that coordinates the building and breaking apart of microtubules in the cell
Nonmembranous structure also called the microtubule organizing center
Center of microtubule formation
Before cell division, centrioles divide, move to ends of cell and organize spindle fibers
General location of the centrosome is identified by the centrioles

35. Cell Extensions Cilia Appendages projecting from cell surfaces
4/22/2017
Cell Extensions
Cilia
Appendages projecting from cell surfaces
Capable of movement
Moves materials over the cell surface
Shorter and more numerous than flagella
Coordinated oar like movements
Respiratory tract

36. Flagella Similar to cilia but longer Usually only one per cell
4/22/2017
Flagella
Similar to cilia but longer
Usually only one per cell
Move the cell itself in wave-like fashion
Human Example: sperm cell

37. Microvilli Extension of plasma membrane Line intestines
4/22/2017
Microvilli
Extension of plasma membrane
Line intestines
Increase the cell surface area for absorption
Normally many on each cell
One tenth to one twentieth size of cilia
Do not move

38. Cell Connections Membrane junctions
4/22/2017
Cell Connections
Membrane junctions
1. Tight junctions – Adjacent plasma membranes fused together tightly
2. Desmosomes – Anchoring junctions that prevent cells subjected to mechanical stress
from being pulled apart
3. Gap junctions - Allow communication between cells