Cell structure function

1. The Cell
Structure
& Function

2. Learning objectives
• By the end of this presentation the
students have to understand and discuss
the following:
Definition of cell
Cell theory
Cell parts
Function of cell parts

3. Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.

4. Examples of Cells
Amoeba Proteus
Plant Stem
Red Blood Cell
Nerve Cell
Bacteria

5. History of Cell Theory
mid 1600s – Anton van Leeuwenhoek
 Improved microscope, observed many living cells
mid 1665 – Robert Hooke
 Observed many cells including cork cells
1850 – Rudolf Virchow
 Proposed that all cells come from existing
cells

6. Cell Theory
• All living things are made up of cells.
• Cells are the smallest working units of
all living things.
• All cells come from preexisting cells
through cell division.

7. Surrounding the Cell

8. Nucleus
Cell Membrane
Nuclear Membrane
Chromosomes
Cytoplasm
Endoplasmic
Reticulum
Ribosomes Mitochondria
Centrosome
Golgi Bodies
Vacuoles
Lysosome

11. Cell Parts
Organelles

12. Cell Membrane
 Outer layer
 Double layer of phospholipids
with proteins that controls
movement in and out of the cell
structure

14. • Support
• Protection
• Controls movement of materials in/out
of cell (Selectively permeable )
• Barrier between cell and its environment
Function

16. Inside the Cell

17. Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA

18. • Contains the hereditary material
of the cell (DNA) responsible for
providing the cell with its unique
characteristics.

19. • The DNA is similar in every cell of
the body, but depending on the
specific cell type, some genes may be
turned on or off - that's why a liver
cell is different from a muscle cell,
and a muscle cell is different from a
fat cell.

20. Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus

21. Chromosomes
• In nucleus
• Made of DNA
• When a cell is dividing, the
nuclear chromatin (DNA and
surrounding protein) condenses
into chromosomes that are
easily seen by microscopy

22. Nucleolus
• Inside nucleus
• The nucleolus produces
ribosomes, which move out of
the nucleus and take positions
on the rough endoplasmic
reticulum where they are critical
in protein synthesis.
http://library.thinkquest.org/12413/structures.html

23. Cytoplasm
• Clear, thick , and gel-like mixture
• Surrounded by cell membrane
( inside outer plasma membrane and
outside DNA region)
• Organelles found inside cell
membrane
• Supports and protects cell organelles
• Contains :

24. Endomembrane System

25. Structures of the
Endomembrane System
Endoplasmic Reticulum (ER)
Transport vesicles
Golgi apparatus
Ribosomes

27. Endoplasmic Reticulum (ER)
 The ER is continuous with the outer
membrane of the nuclear envelope
 There are 2 types of ER:
• Rough ER – has ribosomes attached
• Smooth ER – no ribosomes attached

29. Endoplasmic Reticulum
 Rough Endoplasmic Reticulum (RER)
• Network of flattened membrane sacs
create a “maze”
 RER contains enzymes that
recognize and modify proteins
• Ribosomes are attached to the
outside of the RER and make it
appear rough

31. Endoplasmic Reticulum
Function RER
•Proteins are modified as they
move through the RER
•Once modified, the proteins are
packaged in transport vesicles for
transport to the Golgi body

32. 1. Endomembrane System
Smooth ER (SER)
 Tubular membrane structure
 Continuous with RER
 No ribosomes attached
 Function SER
 Lipids are made inside the SER
• fatty acids, phospholipids, sterols..
 Lipids are packaged in transport
vesicles and sent to the Golgi

33. Golgi Apparatus
 Golgi Apparatus
 Stack of flattened membrane sacs
 Function Golgi apparatus
 Completes the processing substances
received from the ER
 Sorts, tags and packages fully processed
proteins and lipids in vesicles

34. Golgi Apparatus

35. Transport Vesicles
 Transport Vesicles
 Vesicle = small membrane bound sac
 Transport modified proteins and lipids from
the ER to the Golgi apparatus (and from Golgi
to final destination)

36. Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on
Endoplasmic
Reticulum &
floating
throughout the cell

37. 2.Mitochondria
• Double membrane; Outer
membrane smooth, Inner
membrane folded into
cristae
• Energy house
Produces energy through
chemical reactions –
breaking down fats &
carbohydrates

38. Mitochondria

39. 3.Centrosome
• The centrosome, or Microtubule
Organizing Center (MTOC), play A role
in cell division

40. 4. Lysosome
• contains digestive enzymes
for proteins, fats, and
carbohydrates
• Digests unwanted cell parts
and other wastes
• Transports undigested material to
cell membrane for removal
• Cell breaks down if lysosome
explodes
•

41. 5. Vacuoles
• Membrane-bound
sacs for storage,
digestion, and
waste removal
• Contains water
solution
http://library.thinkquest.org/12413/structures.html

42. Genetic material in the form
of DNA
 Prokaryotes – no membrane
around the DNA
 Eukaryotes – DNA is within a
membrane

43. Prokaryotic Cell

44. CYTOSKELETON
MITOCHONDRION
CENTRIOLES
LYSOSOME
GOLGI BOD
SMOOTH ER
ROUGH ER
RIBOSOMES
NUCLEUS
PLASMA
MEMBRANE
Fig. 4-15b, p.59
VESICLE
CYTOPLASM