1. Cells

2. Levels of Organization
Chemical (Least complex)
Cellular
Tissue
Organ
Organ System
Organism (Most complex)

3. History
1600’s Anton Van Leeuwenhoek - first to view nature w/microscope
1665 Robert Hooke - Coined term ‘cells’
1838 Matthias Schleiden - ‘All plants are made of cells’
1839 Theodor Schwann - ‘All animals are made of cells’
1855 Rudolf Virchow - ‘All cells come from pre-existing cells’

4. Cell Theory Schleiden and Schwann 1840.
All living things are made of cells.
New cells are produced from existing cells.
Cells are the basic units of structure and function of all living things.

5. Two types of cells. Prokaryotic cells make up prokaryotes.
Eukaryotic cells make up eukaryotes.
Prokaryotes: No nucleus, genetic material in cytoplasm, only organelle = ribosomes, smaller, simpler, unicellular evolutionarily more ancient
Eukaryotes: Have nucleus, larger, more complex, more organelles, evolutionarily more modern.

6. Basic Cell Structures
Most prokaryotes (bacteria) difficult to see with light microscope
All cells have cell membrane, cytoplasm, genetic material and ribosomes
Presence of other cells structures (organelles) varies

7. Describing Cell Structures
Include:
Structure: describes the shape and smaller component parts of the organelle
Location: Nucleus, cytoplasm or cell membrane, sometimes more specific
Function: what does it do and how does it do it

9. Cell Membrane
Is a phospholipid bilayer with some proteins & carbohydrates associated with it.
Integral proteins form channels & pumps to pass substances across the membrane.
Represented by the “Fluid Mosaic Model”.

10. Cell Membrane Picture

11. Cell Membrane Functions
Controls what goes in and out of the cell.
Proteins are unique within species and individuals and therefore serves as a form of cellular identification.
Encloses cell contents and separates from the extracellular space.
Support & Protection?

12. Cytoplasm A watery gel in which all the organelles reside
The site of multiple enzyme controlled chemical reactions.
Polar compounds go into solution while non-polar compound remain suspended

13. Enzymatic Regulation of Cells
Enzymes are biological catalysts.
Enzymes are proteins
Speed up the rate of chemical reactions
Enzyme Action Effected By: pH
Temperature
concentration

14. Cell Wall When present is exterior to the cell membrane.
Made primarily of cellulose and provides significant support and protection to the cell.
Not present in animal cells.

15. Cell Wall Picture

16. Nucleus
Spherical shape which can be seen with an ordinary light microscope.
Contains nucleolus & chromatin
Controls all cell functions by controlling protein synthesis and hereditary blue-print.
Surrounded by a nuclear envelope - a double membrane layer with pores.

17. Nucleus Nucleolus - a dense area where ribosome production begins.
Contains DNA bound to histone proteins. The complex is called both chromatin and chromosomes depending on the stage of the cell cycle and the function it is performing.

18. Nucleus Picture

19. Organelles “Little organs” including: Ribosomes Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Vacuoles
Chloroplasts
Mitochondria
Centrioles
Cytoskeleton
(Microfilaments & Microtubules)

20. Ribosome Picture

21. Ribosomes
Structure: “B” shape, smallest organelle, made of RNA & protein
Location: Cytoplasm (Free) or surface of rough endoplasmic reticulum (Fixed)
Function: AA joined on surface = site of protein synthesis

22. Ribosome S.L.F. Consisting of a large and small subunit.
Made of rRNA and protein
The smallest organelle.
Can be attached to R.E.R or free.
Site of protein assembly, AA chemically bonded together here (10 Structure)

23. Endoplasmic Reticulum (R.E.R. & S.E.R.) Pictures

24. Rough Endoplasmic Reticulum
A flat & folded internal membrane maze
In the cytoplasm usually close to the nucleus.
Modifies & transports proteins.
Assembles & transports cell membrane parts.

25. Smooth Endoplasmic Reticulum
Does not have ribosomes attached.

26. Golgi Apparatus Picture

27. Golgi Apparatus S.L.F.
Stacks of individual enclosed membranes wider than E.R.
Located in the cytoplasm
Assembles & packages lipoproteins
Binds carbohydrates to proteins

28. Lysosomes Picture

29. Lysosomes S.L.F. Found in the cytoplasm Contains digestive enzymes
Digests food particles
Catabolism of waste & worn out cell parts

30. Vacuoles S.L.F. Various sac-like shapes in cytoplasm
Large in plant cells
Stores water, proteins, carbos, salts
The term ‘vesicle’ is used for a vacuole with a transport function.

31. Vacuoles Picture

32. Chloroplast Picture

33. Chloroplast S.L.F.
Contains maternal DNA, remnants of photosynthetic prokaryotic ancestors
Found in plants of course but also in some protists.
Captures the energy from sunlight to transform carbon dioxide and water into sugars and oxygen.

34. Mitochondrion Picture

35. Mitochondria
Structure: Contains maternal DNA, Kidney shape, double folded inner membrane
Location: Cytoplasm
Function: Aerobic Cellular Respiration = Converts food energy into a form of energy (ATP) the cell can use.
Special: Are remnants of aerobic prokaryotes as explained by the endosymbiotic theory

37. Centrisome Picture

38. Centrisome S.L.F.
Term centrisome refers to a set of two centrioles in a cell.
2 centrioles arranged at 900 angles to each other, made of microtubules in a cylindrical shape grouped in 9 bunches of 3.
Aids in cell division as part of the mitotic spindle.
Only present in animal cells.

39. Cytoskeleton Microtubules Microfilaments
Long hollow structures found at the base of cilia & flagella and acts as a rigid lever like bone aiding cilia & flagella movement. Serves to maintain cell shape as well as be a track for transport of organelles.
Found in the cytoplasm and made of actin & myosin proteins.Contractile ability. Part of cleavage furrow. When attached to microtubules causes movement of cilia & flagella.

40. Cytoskeleton Microtubules & Microfilaments Pictures

41. Microtubules
Structure: long, slender, made of tubulin proteins with 2 in the middle surrounded by 9.
Location: throughout cytoplasm, also at base of cilia and flagella
Function: part of mitotic spindle,involved in movement of cilia & flagella, transport track

42. Microfilaments
Structure: long, slender, made of actin and myosin proteins
Location: cytoplasm & base of cilia & flagella
Function: contracts like muscle so aids in the movement of cilia, flagella and cell division by forming a cleavage furrow, structure and support of the cell

43. Other Flagella - in humans only found in sperm
Barr body - the second X chromosome in females only which is inactivated

44. Cilia
Cilia Picture

45. Flagella Picture
Flagella

46. Cilia & Flagella Structure

47. Eukaryotic Cilia S.L.F.
Structure - 2 to 20um long, 9 double microtubules around 2, usually many in one cell, .25um diameter
Location – protruding from cell, but covered by plasma membrane
Function – locomotion or movement of liquids or particles in fixed cells, signal antenna

48. Eukaryotic Flagella S.L.F.
Structure – same as cilia except only 1 or 2 per cell if present, but longer (10 to 200um)
Location – protruding from cell, but covered by plasma membrane
Function – locomotion

49. The Cell as a Factory Cell Membrane - gate security
Nucleus - C.E.O. office
Chromosomes = secret recipe
Cytoskeleton - building supports
Vacuoles (Vesicles) - raw material storage and distribution
Ribosomes - assembly line machinery
Lysosomes - waste removal system & cleanup
Mitochondrion - main power source
Chloroplasts - power source in ‘green’ plants
ER - product modification and transport
Golgi - product packaging

50. Part 2

51. Movement Across the Cell Membrane
The cell membrane is a selectively - permeable (semi-permeable) membrane.
Many large molecules cannot cross.
Many charged molecules cannot cross.
Some non-lipid soluble molecules cannot cross.

52. Movement Across the Cell Membrane
Active Transport Mechanisms
Require energy (A.T.P.)
Move against a concentration gradient
Passive Transport Mechanisms
Do not require energy
Moving with a concentration gradient

53. Movement Across the Cell Membrane
Active Transport Mechanisms
Endocytosis
Phagocytosis - cell eating or engulfing solids
Pinocytosis - cell drinking or engulfing liquid
Exocytosis
Protein Pumps
Passive Transport Mechanisms
Diffusion
Osmosis
Facilitated Diffusion

54. Movement Across the Cell Membrane
Diffusion - driven by the movement of particles in a gas or liquid state from an area of higher concentration to an area of lower concentration
Osmosis - diffusion of water across a semi-permeable membrane
Facilitated Diffusion - movement of particles down the concentration gradient with the help of integral proteins in the cell membrane

55. Tonicity
Isotonic - an equal concentration of solutes both in and outside a cell
Hypertonic - a solution with a greater concentration of solutes in relation to another
Hypotonic - a solution with a lower concentration of solutes in relation to another

56. Tonicity in Cells
Hypertonic - term used when the extracellular solute concentration is greater than the cell resulting in movement of water out of the cell causing cell shrinkage or crenation
Hypotonic - term used when the extracellular solute concentration is less than the cell resulting in movement of water into the cell causing cell swelling

57. Fluid Balance - Homeostasis
All living things function best in a narrow range of conditions.
Living things have mechanisms to maintain a stable internal environment
Examples: temperature, pH, water content
All living things need water

58. Water Balance
In plants, water balance is often controlled by: stoma, waxy cuticle, shape, size
In complex organisms like humans water balance is primarily influenced by water intake versus water loss but, there are several regulating mechanisms that control this balance.

59. Water Regulation Sweating, respiration, excretion = loss
Hypothalamus detects [H2O] in the blood.
Antidiuretic hormone (ADH) released and kidneys decrease water removal from the blood & loss in urine.
Thirst mechanism
Increased [H2O] in blood decreases [ADH] and water removal from blood by kidneys increases again. (Negative Feedback Loop)

60. Specialized Cell Types
Differentiated cells contribute to the function of the organism as a whole.
Unicellular organisms must perform all the activities associated with life
Multicellular organisms are more complex & interdependent because individual cells perform only specific functions for the good of the whole organism.

61. Examples of Specialized Cells
Nerve Cells (Neurons) - carry messages in the form of an electrochemical signal
Pancreas Cells - some secrete insulin and some secrete peptidase, amylase or lipase
RBC - have hemoglobin to carry oxygen