1. The structure and function of Cell components
M. Amin Tabatabaiefar, Ph.D
Dep. Of Genetics and Molecular Biology
Isfahan University of Medical Sciences

2. Cells
Smallest living unit
Most are microscopic

3. Discovery of Cells Robert Hooke (mid-1600s) Observed sliver of cork
Saw “row of empty boxes”
Coined the term cell

4. Cell theory (1839)Theodor Schwann & Matthias Schleiden
“ all living things are made of cells”
(50 yrs. later) Rudolf Virchow
“all cells come from cells”

5. Principles of Cell Theory
All living things are made of cells
Smallest living unit of structure and function of all organisms is the cell
All cells arise from preexisting cells
(this principle discarded the idea of
spontaneous generation)

6. Cell Size

7. Cells Have Large Surface Area-to-Volume Ratio

8. Characteristics of All Cells
A surrounding membrane
Protoplasm – cell contents in thick fluid
Organelles – structures for cell function
Control center with DNA

9. Cells chemical composition
Chemical composition-by weight
70% water
7% small molecules
salts
Fatty acids
amino acids
nucleotides
23% macromolecules
Proteins
Polysaccharides
Lipids
DNA,RNA

10. Cells chemical composition
Chemical composition-by weight
70% water
7% small molecules
salts
Fatty acids
amino acids
nucleotides
23% macromolecules
Proteins
Polysaccharides
Lipids
DNA,RNA

11. Prokaryotes and Eukaryotes, continued
Single cell
Single or multi cell
No nucleus
Nucleus
No organelles
Organelles
One piece of circular DNA
Chromosomes
No mRNA post transcriptional modification
Exons/Introns splicing

12. Prokaryotic and Eukaryotic Cells Chromosomal differences
Prokaryotes
The genome of E.coli contains amount of 4X106 base pairs
> 90% of DNA encode protein
Lacks a membrane-bound nucleus.
Circular DNA and supercoiled
domain
Histones are unknown
Eukaryotes
The genome of yeast cells contains
1.35x107 base pairs
A small fraction of the total DNA encodes protein.
Many repeats of non-coding sequences
All chromosomes are contained in a membrane bound nucleus
DNA is divided between two or more chromosomes
A set of five histones
DNA packaging and gene expression regulation
Chromosomal diffecernces
Two labelled columns
Succinct in descriptioon
>90% encodes proteins Many repeats of noncoding sequences
Delete weights

13. Figure 7-5 Plant and Animal Cells Animal Cell
Section 7-2
Cytoplasm
Nucleolus
Ribosomes
Nucleus
Cell Membrane
Smooth Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Golgi Complex
Nickname: The shippers
Function: packages, modifies, and transports materials to different location inside/outside of the cell
Appearance: stack of pancakes
Golgi Bodies
Go to Section:

14. Representative Animal Cell

15. Now let’s talk about structures only found in PLANT Cells!!

16. Representative Plant Cell

17. Plant Cell
Figure 7-5 Plant and Animal Cells
Section 7-2
Vacuole
Cell Membrane
Go to Section:

18. Plant Cell
Cytoplasm
Vacuole
Smooth ER
Ribosomes
Chloroplasts
Cell Membrane
Cell Wall
Nucleolus
Golgi Bodies
Nucleus
Mitochondria
Rough ER

19. Organelles Cellular machinery Two general kinds Derived from membranes
Bacteria-like organelles

21. Cytoplasm
Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures (organelles).
Fluid around the organelles called cytosol.
Most of the cells metabolic reactions occur in the cytoplasm.

22. Cytoplasm Viscous fluid containing organelles components of cytoplasm
Interconnected filaments & fibers
Fluid = cytosol
Organelles (not nucleus)
storage substances

23. Cytoskeleton

24. Cytoskeleton structural support motility regulation Function
maintains shape of cell
provides anchorage for organelles
motility
cell locomotion
cilia, flagella, etc.
regulation
organizes structures & activities of cell

25. Cytoskeleton Made of three types of filaments
Acts as skeleton and muscle
Provides shape and structure
Helps move organelles around the cell
Actin, also found in muscle cells, mainly help maintain cell shape in their cytoskeletal role. Microtubules mostly move organelles around the cell. Intermediate filaments also provide structural support.

26. Cytoskeleton Give the cell its shape
Supports the organelles inside the cell
Provides “tracks” for movement inside the cell
Is involved in cell division

28. Function
Cytoskeletons maintain cell shape, protects the cell, enables cellular motion (using flagella), and plays important roles in both intercellular transport and cellular division.

29. Cytoskeleton Filaments & fibers Made of 3 fiber types 3 functions:
Microfilaments
Microtubules
Intermediate filaments
3 functions:
mechanical support
anchor organelles
help move substances

30. Components of cytoskeleton: 1) Microfilaments
Solid rods of globular proteins.
Important component of cytoskeleton which offers support to cell structure.

31. Components of cytoskeleton: 2) Microtubules
Centrosomes and Centrioles
The centrosome
Is considered to be a “microtubule-organizing center”
Contains a pair of centrioles

32. Components of cytoskeleton: 2) Microtubules Centrioles
Found only in animal cells.
Self-replicating
Made of bundles of microtubules.
Help in organizing cell division.

33. Components of cytoskeleton: 2) Microtubules
Shape the cell
Guide movement of organelles
Help separate the chromosome copies in dividing cells

34. Cilia and Flagella
External appendages from the cell membrane that aid in locomotion of the cell.
Cilia also help to move substance past the membrane.

35. An overview of cytoskeleton
Three major cytoskeletal systems and their general properties
a) Intermediate Filaments - a system of elastic fibers - used to strengthen cells and to transmit mechanical strain across cells in a tissue. These filaments are purely skeletal in nature.
b) Microtubules - rigid protein tubules. These are involved in generation of cell shape and provide substrate for two different types of motor systems, dyneins and kinesins. The mitotic spindle is a variant form of the microtubular cytoskeleton.
c) Microfilaments (actin filaments) - this is the most complex system. Occurs in many forms, bundles of fibers or networks. Interacts with many types of molecules including its own class of motor proteins, the myosins. Its most elaborate form occurs in striated muscle. Microfilaments are responsible for cytoplasmic streaming and amoeboid motion.

36. A = actin, IF = intermediate filament, MT = microtubule

37. cilia are thread-like projections of certain cells that beat in a regular fashion to create currents that sweep materials along;                                          

38. Flagella may extend to the rear of a cell and push it forward by snakelike wriggling, or stick out in front and draw it along.

39. Cilia & Flagella Structure
Bundles of microtubules
With plasma membrane

40. Centrioles Pairs of microtubular structures
Play a role in cell division

41. Intercellular junctions
Plant cells
plasmodesmata
channels allowing cytosol to pass between cells
plasmodesmata

42. Cell membrane Found in ALL Cells Structure double layer of fat
phosphate “head”
Found in ALL Cells
Structure
double layer of fat
phospholipid bilayer
receptor molecules
proteins that receive signals
lipid “tail”

43. Cell membrane Function separates cell from outside
phosphate “head”
Function
separates cell from outside
controls what enters or leaves cell
O2, CO2, H2O, nutrients, waste
recognizes signals from other cells
allows communication between cells
lipid “tail”

44. Phospholipids Phosphate heads: Hydrophilic (love water)
Lipid tails: Hydrophobic (fear water)
lipid “tail”
Water Outside the cell
Water Inside the cell

45. Animal cell surface Extracellular matrix
collagen fibers in network of glycoproteins
support
adhesion
movement
regulation

46. Intercellular junctions in animals

47. Intercellular junctions in animal cells
tight junctions
membranes of adjacent cells fused forming barrier between cells
forces material through cell membrane
gap junctions
communicating junctions
allow cytoplasmic movement between adjacent cells
desmosomes
anchoring junctions
fasten cells together in strong sheets

48. Cell Wall Differences
Plants – mostly cellulose
Fungi – contain chitin

49. Functions of the Cell Wall
Maintaining and determining cell shape
Physical barrier to many things like pathogens
Prevents the membrane from bursting in a hypotonic medium
It can control rate and direction of cell growth
Metabolic role- the wall has some enzymes for moving and secretion

50. Membranous Organelles
Functional components within cytoplasm
Bound by membranes

51. Endoplasmic Reticulum
Helps move substances within cells
Network of interconnected membranes
Two types
Rough endoplasmic reticulum
Smooth endoplasmic reticulum

52. Rough Endoplasmic Reticulum
Network of continuous sacs, studded with ribosomes.
Manufactures, pro-cesses, and transports proteins for export from cell (vesicles)
Continuous with nuclear envelope.

53. Rough Endoplasmic Reticulum
Ribosomes attached to surface
Manufacture protiens
Not all ribosomes attached to rough ER
May modify proteins from ribosomes

54. Ribosomes Are the sites of protein synthesis.
Found attached to the Rough endoplasmic reticulum or free in the cytoplasm.
60% RNA and 40% protein.
Protein released from the ER are not mature, need further processing in Golgi complex before they are able to perform their function within or outside the cell.

55. Courtesy of http://micro.magnet.fsu.edu/55

56. Structure Non-membrane bounded particles in cells
Made in the nucleolus
The number of ribosomes in a cell depends on the cell’s function
Consist of 2 subunits
60S (large)
40S (small)
Each subunit has its own mix of ribosomal RNA (rRNA) and proteins 56

57. Smooth Endoplasmic Reticulum
Similar in appearance to rough ER, but without the ribosomes.
Involved in the production of lipids, carbohydrate metabolism, and detoxification of drugs and poisons.
Stores calcium.

58. Smooth Endoplasmic Reticulum
No attached ribosomes
Has enzymes that help build molecules
Carbohydrates
Lipids

59. Function
The major function is the synthesis of lipids & carbohydrates (such as phospholipids & steriods)
The function is dependent of the cell: testes: produces testosterone liver:helps detox the body off of drugs by producing enzymes muscles: assists in the contraction of muscle cells & in brain cells Works with rough ER to transport molecules to other parts of the cell.

60. Golgi apparatus
Golgi apparatus are found in both animal and plant cells.
Their structure is made up of flat membranes by the name of cisternae as many as 60 have been found in a single cell.
Consists of four sections  cis-Golgi network, medial-Golgi, endo-Golgi, and trans-Golgi all of which carry different ensymes that help them get there job done.
Located next to the cell nuclus most of the time.

61. Golgi Apparatus Involved in synthesis of plant cell wall
Packaging & shipping station of cell

62. Golgi complex- It is organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER. 
Just like our postal packages which should have a correct shipping address, the proteins produced in the ER, should be correctly sent to their respective address. 
In the cell, shipping and sorting done by the Golgi complex. It is a very important step in protein synthesis.
If the Golgi complex makes a mistake in shipping the proteins to the right address, certain functions in the cell may stop. 
                                                                                            

63. Functions
The functions of the Golgi apparatus is to modify proteins, transport lipids through out the cell and create lysosomes( garbage disposal of cell).
The golgi gets everything ready to be sent out to its proper place for the cells survival

64. Courtesy of: http://micro.magnet.fsu.edu

65. Protein modifications in Golgi [Fig. 12-6 from Becker]
Predict the location of enzymes, galactosyl transferase and
sialic acid transferase

66. Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi

68. Lysosomes Contain digestive enzymes Functions Aid in cell renewal
Break down old cell parts
Digests invaders

69. Contain digestive enzymes that break down wastes and old organelles

70. Lysosomes function as the cell's recycling compartment.
Lysosomes receive cellular and endocytosed proteins and lipids that need digesting. The metabolites that result are transported either by vesicles or directly across the membrane.

71. Vacuoles Membrane bound storage sacs
More common in plants than animals
Contents, Store waste or raw materials used in synthesis of proteins
Water
Food
wastes

72. Function
The function and importance of vacuoles vary according to the type of cell, having much greater importance in plant cells than in animal and bacteria cells. In plant cells it is responsible for maintaining the shape and structure of the cell. The pressure applied by the vacuole, called turgor, is what controls the size of the cell not the expanding cytoplasm. In animal cells, vacuoles are generally small.
In general the functions of vacuoles include:
Removing harmful material from the cell
Containing waste products
Maintaining turgor within the cell
Maintaining an internal acidic pH
Store nutrients and metabolites

73. Bacteria-Like Organelles
Release & store energy
Types
Mitochondria
(release energy)
Chloroplasts
(store energy)

74. Mitochondria
Have their own DNA
Bound by double membrane

76. Mitochondria Provides the cell with energy.
Is the site of cellular respiration.

77. Mitochondria
Mitochondria are membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells. Their main function is the conversion of the potential energy of food molecules into ATP.
Every type of cell has a different amount of mitochondria. There are more mitochondria in cells that have to perform lots of work, for example- your leg muscle cells, heart muscle cells etc. Other cells need less energy to do their work and have less mitochondria.

78. Mitochondria Break down fuel molecules (cellular respiration)
Glucose
Fatty acids
Release energy
ATP

79. Electron transport and H+ pumping in mitochondria
14_10_resp_enzy_comp.jpg 4 4 2
14_10_resp_enzy_comp.jpg

80. Chloroplasts Derived form photosynthetic bacteria
Solar energy capturing organelle

82. Photosynthesis Takes place in the chloroplast
Makes cellular food – glucose

83. Review of Eukaryotic Cells

84. Review of Eukaryotic Cells

86. 86

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