THE CELL AND ITS PARTS

Herbert M. San PedroLecturer

The Cell

- A cell type which has a complex organization, - In terms of structure, it is somewhat larger and

more complicated than prokaryotic cells

- But, the functions of their respective common parts (organelles) are very much similar.

- Organelles – small parts which are placed inside the cells, which exhibit special functions

The Eukaryotic Cell

Parts of the Eukaryotic Cell:

Cell Membrane:

•Enclosing delicate, semi-permeable membrane, made of CHO, CHON, Lipids•Regulates or controls the movement of materials to and from the cell

CytoplasmOrganelles are small, membrane-bound components of the cell with specialist functions. The fluid of the cell is called the CYTOSOL, and the cytosol plus organelles is called the CYTOPLASM. The cytosol is full of proteins involved in cell function, and is where all of the cell's protein synthesis occurs.The CYTOSKELETON consists of involved in the maintenance of cell shape and in intra-cellular movement. Cytoskeleton elements generally cannot function without associated proteins.

Nucleolus:

•Composed of RNA and protein

•Site of production of RNA

Nucleus: Double membrane with poresOuter membrane continuous with ERNuclear matrix - protein-containing fibrilar networkNucleoplasm - the fluid substance in which the solutes of the nucleus are dissolvedChromosomes - protein and DNA complexesNucleolus - involved in the synthesis and assembly of ribosomes

Ribosomes:RIBOSOMES are complexes of proteins involved in the translation of mRNA into proteins. Ribosomes act in conjunction with tRNA and mRNA as well as other proteins to assemble amino acids into protein sequences. Because the proteins produced are often inserted directly into the ER, ribosomes are often seen on the surface of the ER (thus, RER).

The ENDOPLASMIC RETICULUM (ER) is a labyrinthine membraneous organelle involved in the transport and modification of proteins through the cell. It is closely associated with the nucleus and the membrane of the ER is continuous with the outer membrane of the nucleus. Proteins destined for the ER are made at the ER membrane surface and inserted directly through the membrane.

Three is ROUGH ER (RER, sometimes called RIBOSOMAL ER) and SMOOTH ER (SER), which have different functions but are connected to each other.

Endoplasmic Reticulum (ER)

Rough Endoplasmic Reticulum

•Organelle which contains Ribosomes (site of protein synthesis) on its surface.

•RER provides surface for the synthesis of proteins and carbohydrates.

Smooth Endoplasmic Reticulum

The smooth endoplasmic reticulum is not studded with ribosomes giving it a smooth appearance.  The membranes of the smooth endoplasmic reticulum extend from the rough endoplasmic reticulum in the cytoplasm. 

 The SER has two functions; it synthesizes lipids and detoxifies harmful substances.  

Golgi Apparatus (Body, Complex):

The Golgi apparatus is often considered the distribution and shipping department for the cell's chemical products. It modifies proteins and lipids (fats) that have been built in the endoplasmic reticulum and prepares them for export outside of the cell or for transport to other locations in the cell.

MitochondriaMitochondria are rod-shaped organelles that can be considered the power generators of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy "currency" of the cell that powers the cell's metabolic activities. This process is called aerobic respiration and is the reason animals breathe oxygen. 

Lysosome:These are tiny, spherical, sac-like structures scattered all over the cytoplasm. Their main function is digestion. They contain powerful destructive enzymes capable of digesting all organic material, and hence called “digestive bags”.

Vacuole:  Capture of food - Maintenance of internal water pressure- Containment of waste products- Maintenance of an acidic internal pH- Storage of defense molecules (toxins) and - Enable a cell to elongate rapidly

Centriole or CentrosomeFound only in animal cells, these paired organelles are typically located together near the nucleus in the centrosome, a granular mass that serves as an organizing center for microtubules. Within the centrosome, the centrioles are positioned so that they are at right angles to each other

1. Directly through the Lipid Bilayer

2. Through the membrane channels

3. With carrier molecules in the membrane

4. In vesicles

Membrane Transport Mechanisms

PASSIVE PROCESS (Downhill)

Higher to Lower Conc Requires no energy

- Diffusion (Solute), Osmosis (solvent), Filtration (both), Facilitated Diffusion.

CONT:

ACTIVE PROCESS (Uphill)

Cells requires energy (use up ATP) to move substance (Lower to Higher)

- Active transport, Secondary Active Transport, Endocytosis (Phagocytosis/Pinocytosis), Exocytosis.

CONT:

NEXT LESSON:The pH and the Buffer

SystemPlease bring Calculator!

THANK YOU!