1. Cell Structure & Function
Chapter 3

2. The Diversity of Cells in the Human Body
There are over 200 different kinds of cells in the body
Figure 3-1

3. Anatomy of a representative cell

4. Parts of a “representative” cell
Plasma (Cell) Membrane
barrier between outside environment (extracellular fluid (ECF) and inside environment
Cytoplasm
Cytosol (intracellular fluid (ICF))
Organelles

5. Plasma (cell) membrane
Comprised primarily of:
Phospholipids
Proteins
Carbohydrates
Cholesterol

6. Plasma (cell) membrane
Phospholipids
Arranged as bilayer
Hydrophilic phosphate “heads”
Hydrophobic fatty acid “tails”
acts as a selective physical barrier between extracellular fluid (interstitial fluid) and intracellular fluid (cytosol)

7. Plasma (cell) membrane
Proteins

8. Plasma (cell) membrane
Functions of Membrane Proteins include:
Receptors
Channels
Carriers
Enzymes
Anchors
Identifiers

9. Plasma (cell) membrane
Carbohydrates
act as receptors & identity markers

10. Plasma (cell) membrane
Cholesterol
helps keeps membrane fluid (flexible)
Blood type based on glycoproteins (CHO) on RBC membrane

11. Functions of The Cell Membrane
Functions of the plasma membrane include:
Physical isolation
Regulation of exchange with the environment (“selective permeability”)
Sensitivity to surrounding environment
Help maintain shape and structural support between cells
Cell identification
Communication (signaling)
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12. Cytoplasm Cytoplasm All the “stuff” inside a cell The “stuff”:
Cytosol (a.k.a. intracellular fluid ICF)
Organelles
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13. Cytosol
Cytosol
Intracellular fluid that usually has a __________ consistency
Contains water, dissolved nutrients (including amino acids, sugars (glucose/glycogen) & lipids), ions, proteins (enzymes), and wastes
Surrounds and suspends organelles; site of some chemical reactions; transportation medium
ICF not the only place we have fluids in body
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

14. Fluid compartments of the body
Intracellular fluid (ICF) – a.k.a. cytosol
Extracellular fluid (ECF)
interstitial fluid
plasma
lymph
ISF
Blood vessel (plasma)
Cell
(ICF)
Cell
ISF
Lymphatic vessel (lymph)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

15. Transport Processes between/within fluid compartments
Two types of processes of transport (movement):
Passive –
Active –

16. Passive processes of transport
No energy required for movement
Movement occurs with (“down”) the concentration gradient
Includes:
Diffusion (simple & channel-mediated)
Facilitated diffusion (carrier-mediated transport)
Osmosis
Filtration
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

17. Movement continues until “equilibrium” is reached
Diffusion
Random movement down a concentration gradient (from higher to lower concentration)
Simple diffusion: Random movement of molecules from high to low concentration; occurs within interstitial fluid and within/though cytosol
Movement continues until “equilibrium” is reached

18. Diffusion Across Cell Membranes
(simple diffusion)
(channel mediated diffusion)

19. Facilitated Diffusion (passive carrier-mediated transport)
No ATP required but requires a carrier protein (transporter)
(GLUT-1)

20. Osmosis
Movement of water across a selectively permeable membrane, down a water concentration gradient (from higher H2O concentration to lower), due to osmotic pressure
Osmotic pressure – relates to the concentration of solutes. The higher the concentration of solutes, the higher the osmotic pressure.
Water will always move from _______ to _______ osmotic pressure

21. Osmotic Effects of Solutions on cells
Isotonic solution- same concentration solutes (equal osmotic pressure)
Cells maintain normal size and shape
Hypertonic solution- more solutes in surrounding solution (higher osmotic pressure) therefore less H2O
Cells lose water osmotically and shrink and shrivel
Hypotonic solution- less solutes in surrounding solution (lower osmotic pressure) therefore more H2O
Cells gain water osmotically and swell and may burst.
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22. Filtration
Hydrostatic pressure ( _____ pressure in the body) pushes on water
Water crosses membrane (across capillary endothelium in the body)
If membrane is permeable to solutes, solutes follow water movement
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

23. Active processes of transport
- Cell must generate energy (ATP – adenosine triphosphate) for movement
- Movement can occur against (“up”) the concentration gradient - Larger substances can move in/out of the cell
Includes:
Active transport
Vesicular transport
endocytosis
exocytosis

24. Active transport Carrier-Mediated
Energy from ATP consumed by carrier protein
Molecular movement is independent of concentration gradients (low  high concentration)
Ion pumps (e.g. Na-K exchange pump)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

25. Vesicular Transport Membranous vesicles requiring energy for movement
Transport in both directions
Endocytosis - movement into cell
Receptor-mediated endocytosis
Pinocytosis
Phagocytosis
Exocytosis - movement out of cell
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26. Receptor-Mediated Endocytosis

27. Pinocytosis Cell membrane folds inward “engulfing” ECF
“_____________”
Cell membrane folds inward “engulfing” ECF
No receptor proteins involved

28. Phagocytosis

29. Exocytosis
Secretory
vesicles
Exocytosis

30. The Organelles Membranous organelles Nonmembranous organelles
- Isolated compartments
Nucleus
Mitochondria
Endoplasmic reticulum (smooth & rough ER)
Golgi apparatus
Lysosomes
Nonmembranous organelles
- In direct contact with cytosol
Cytoskeleton (including microvilli, centrioles, cilia, flagella)
Ribosomes
Nucleolus

31. The Nucleus

32. DNA/Chromosomes/Chromatin/Genes
DNA = deoxyribonucleic acid
Gene
Adenine
Guanine
Cytosine
Uracil (RNA only)
Thymine

33. Nucleoli Nucleoli are non membranous organelles within the nucleus
Synthesize ribosomal RNA (rRNA) – building block that creates ________________
RNA = ribonucleic acid

34. Ribosomes Made of ribsosomal RNA & protein subunits
Found free in cytoplasm (free ribosomes) or attached to rough endoplasmic reticulum (ER) (fixed ribosomes)
Participates in protein synthesis by manufacturing of polypeptides (translation)

35. Protein Synthesis
Two step process:
Transcription –
Translation –

36. Protein Synthesis
Transcription — the production of RNA from a single strand of DNA
Occurs within nucleus with production of messenger RNA (mRNA)
mRNA exits through nuclear pore to go to ribosome

37. Protein Synthesis
Translation — the assembling of a polypeptide (“potential” protein) on ribosomes
Transfer RNAs (tRNA) bring specific amino acids based on transcribed “message” of mRNA
Occurs within cytoplasm

38. The Endoplasmic Reticulum
Network of intracellular membranes primarily for molecular synthesis, storage & intracellular transport
Rough ER (RER)
Contains ribosomes on surface of membrane
Stores, modifies (folds) & transports newly made ________________
Smooth ER (SER)
Lacks ribosomes
Synthesizes, stores & transports ________ & ______

39. Golgi apparatus Receives new proteins from RER & lipids from SER
Modifies proteins by adding carbohydrates and lipids
Packages proteins & lipids in vesicles
Secretory vesicles (for exocytosis)
Membrane renewal vesicle
Synthesizes Lysosomes

40. Overview of Protein Synthesis, Processing, and Packaging

41. Lysosomes Produced by golgi apparatus
Vesicles containing digestive enzymes
Clean-up cellular debris & recycle worn out organelles
Defend against bacteria

42. Mitochondria Site of ___________________ production
Double layered membrane with inner folds (cristae) enclosing metabolic enzymes for cellular respiration (aerobic metabolism)
Figure 3-15

43. The Cytoskeleton
Internal protein framework to provide strength & structural support, movement of cellular structures & materials
Includes:
Microfilaments
Microtubules

44. The Cytoskeleton Microfilaments
microvilli – increase cell surface area

45. The Cytoskeleton Microtubules
centrioles - move chromosomes during mitosis
cilia - move substances across cell surface
flagella - moves cell through fluid (sperm)

46. Cell division
Somatic Cell division - The reproduction of body cells; necessary for growth & repair. Results in the formation of 2 genetically identical “daughter” cells
Mitosis - nuclear (chromosomal) division of somatic cells (after chromosomal replication has occurred).
Cytokinesis - division of cytoplasmic contents
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47. Nucleus Spindle fibers Mitosis begins Chromosome with two
Interphase
Early prophase
Late prophase
Nucleus
Spindle
fibers
Mitosis
begins
Chromosome
with two
sister chromatids
Centrioles
(two pairs)
Centromeres
Metaphase
Anaphase
Telophase
Separation
Daughter
chromosomes
Cytokinesis
Metaphase
plate
Cleavage
furrow
Daughter
cells
Figure 3-22
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

48. Cell Diversity and Differentiation
Somatic (Body) Cells
All have same genes
Some genes inactivate during development
Cells thus become structurally and functionally specialized. This specialization is known as “differentiation” of cells
Specialized (differentiated) cells form distinct tissues in the body