Cell Structures and Functions

Presented by: Joevani S. Peñol

1. Plasma MembraneOutermost component of the

cell. Encloses the cytoplasm and

forms the boundary between material inside and materials outside the cell.

Structure of the Plasma Membrane

The plasma membrane is a double layer (bilayer) of proteins and phospholipids and is fluid rather than solid.

This can be interpreted by the fluid mosaic model developed by Jonathan Singer and Garth Nicolson in 1972.

Function of the Plasma Membrane Regulate material moving into and

out of the cell. Separate the internal and external

part of the cell. Provide a large surface area on which

specific chemical reactions can occur.

Functions of the Plasma Membrane

Separate cells from one another.

Site for the receptors containing

specific cell identification markers

that differentiate one cell type

from the other.

2. Cytoplasm

Semifluid enclosed within plasma

membranes and are consist of

organelles, cytosol and other

structures.

Animal Cell

Function of the CytoplasmDissolves substances and

houses organelles and vesicles.

3. NucleusControl center of the cell.Contains nucleolus and DNA.

4. Endoplasmic Reticuluman extensive membranous

network continuous with the outer nuclear membrane.

Contains series of channels and is storage unit for enzymes and other proteins.

Endoplasmic Reticulum

2 Types of ERRough Endoplasmic ReticulumSmooth Endoplasmic

Reticulum

Rough Endoplasmic ReticulumAttached to it is the

ribosomes.

Microscopic view of Rough ER

Smooth Endoplasmic ReticulumSite for lipid production,

detoxification of a wide variety of organic molecules and storage of calcium ions in muscle cells.

Don’t have ribosomes attached on it.

Microscopic View of the Smooth ER

5. Golgi ApparatusCollection of membranes

associated physically and functionally with the ER in the cytoplasm.

Named after Camillio Golgi, 1998.

StructureComposed of flattened stacks of

membrane bound cisternae

Function Sorts, packages, and secretes proteins

and lipids.

Golgi Apparatus/Golgi Bodies

6. Mitochondrion

Double-membrane bound organelles that are spherical to elongate in shape.

Powerhouse of the cell. Contains its own DNA.

7. Lysosomes Membrane bound spherical

organelles that contain enzymes called acid hydrolases, which are capable of digesting organic molecules under acidic conditions.

Microscopic view of the Lysosome

8. Centrioles Located within microtubule-

organizing center. Contains nine triplet microtubules Forms basal body of cilia and flagella. Function in mitotic spindle fiber

formation.

Microscopic view of the Centriole

9. ChloroplastFound only in plant cellsSite of photosynthesis.Contains its own DNA.

Chloroplast

10. RibosomesSite of protein synthesis.

11. Cilia/FlagellaThreadlike processes.Move small particles past

fixed cells and are a major form of locomotion in some cells.

Cilia and Flagella

12. Vacuoles Membrane surrounded, often

large sac in the cytoplasm.Storage site of food and other

compounds, also pump water out of a cell.

13. CytoskeletonInterconnecting microfilament

and microtubules; flexible cellular framework.

Assist in cell movement; provides support; site for binding of specific enzymes.

Cytoskeleton

14. PeroxisomesSmall membrane bound

vesicles containing enzymes that break down fatty acids, amino acids, and hydrogen peroxide (H2O2).

15. Cell WallRigid (up to many

micrometers in thickness) and gives plant cells a very defined shape.

Composed of cellulose fiber, polysaccharides, and proteins.

Function

1. Cell stability2. Determines its shape,3. Influences its development,

protects the cell against pathogens

4. Counterbalances the osmotic pressure.

StructureComposed of primary and secondary cell

walls.

References http://www.phschool.com/science/biolog

y_place/biocoach/cells/intro.html http://people.eku.edu/ritchisong/301not

es1.htm http://www.uic.edu/classes/bios/bios100/

summer2002/lect05.htm