Parts of The Cell

BASIC PARTS OF THE CELL

Three Major Parts of the Cell:

1.Plasma Membrane

2.Cytoplasm

3.Nucleus

Cytoplasm

Cell Membrane

• Siomai-like

• Structure: Double layer of phospholipid molecules

• Proteins are embedded in it.

• Two Kinds of Protein: Integral and Peripheral Proteins

• Phosphate Head: Polar and Hydrophilic

• Lipid Tail: Nonpolar and Hydrophobic

Cell Membrane

Cell Membrane Structure: Fluid mosaic model

“Fluid” – configuration of the phospholipid molecules

“Mosaic” – presence of proteins

Lipid and other molecules move about in the membrane. The plasma membrane is not smooth.

Cell Membrane Functions:1. Selectively permeable2. Protects the cell3. Separates the cell from its environment4. Gives shape to the cell

“Plasma” – living Paramecium – pellicle

First structural part to be observed

Structure: Spherical in shape and located at the center of the cell

It has three parts:

1. Nucleoplasm

2. Nucleolus

3. Nuclear Envelope /

Nuclear Membrane

Nucleus

The Parts of the Nucleus1. Nucleoplasm - protein-rich protoplasm where nucleolus and chromatins are suspended - Chromatins become chromosomes when the cell is dividing.2. Nucleolus - Darker area, for synthesis and storage of RNA3. Nuclear Membrane / Nuclear Envelope - Double membrane separating the nucleus from cytoplasm - Prokaryotic Cell and Eukaryotic Cell - Not a solid barrier (has nuclear pores)

Types of Cells

Prokaryotes - cells with no distinct nucleus Ex. Bacteria

Eukaryotes- cells with distinct nucleus Ex.

Animal Cell

• Control Center of the Cell

• Contains most of the cell’s genetic material (DNA)

Nucleus

The Protoplasm Two Types:1. Cytoplasm – protoplasm lying around the nucleus2. Karyoplasm / Nucleoplasm – protoplasm lying inside

the nucleus

* The structure enclosed within the cell membrane and outside the nucleus is the cytoplasm.

Cytosol

Structures

Cytoplasm

• Material between the cell membrane and the nucleus

• Appears:

1. Clear

2. Viscous

3. Colloidal

Found in are different structures:

4. Endomembrane System

5. Organelles

6. Supramolecular Complex

Cytoplasm

Endomembrane System (Internal Membrane

System)

Endoplasmic Reticulum (ER) Structure: Network of membranes; tiny

canals formed by two parallel membranes

Two distinct regions:1. Rough ER 2. Smooth ER

Endoplasmic Reticulum (ER)

1. Rough ER Appears rough because of the presence of

ribosomes Many types of specialized cells secrete

proteins produced by the RER (Ex: White Blood Cell in a human).

Proteins destined for secretion are synthesized by ribosomes attached to RER (Ex: Glycoproteins).

Endoplasmic Reticulum (ER)

2. Smooth ER Its enzymes synthesize fats,

phospholipids, steroids, and other lipids.

Carbohydrate Metabolism – done by SER in the liver

Its enzymes detoxify drugs and other poisons.

Endoplasmic Reticulum (ER)

Serves as a channel for products produced in the cell

Internal Membrane System

Golgi Apparatus• Discovered by Camilo Golgi (nerve cell of an owl)• Flattened membranous sac

Golgi ApparatusFunctions:

• Works together with the ER.• Serves as the Package Counter of the Cell

After processing and packaging of substances in the golgi apparatus, a clean up is needed. Cleaning is done by the lysosome.

- Various structures like miniature organs that perform specific functions

Organelles

Organelles

1. Lysosomes Not commonly found in plant cells Membrane-bound organelles Contain hydrolytic enzymes These enzymes hydrolyze the cell when the

lysosomial membrane is damaged. What does hydrolytic enzyme do?

1. Breakdown of macromolecules (proteins, lipids, carbohydrates)

2. Destroys bacteria and other microorganisms3. Destroys old cells (Programmed cell destruction)

“Suicide Bag of Cell”

Organelles2. Mitochondrion May be single or few in some cells,

but most often a cell has hundreds or thousands of mitochondria.

Structure: Rod-shaped organelles Size ranges from being small to bigger

sauge-like structure. Has 2 membranes:

1. Outer membrane – smooth and separates mitochondria from the cytoplasm

2. Inner membrane – with an enfolding called Cristae (where important reactions in the mitochondria take place)

Organelles

Mitochondria Generates energy (Power House of the Cell)

Organelles

3. Cytoskeleton Network of fibers

floating through the cytoplasm

Functions:a. Gives mechanical

support to the cell

b. Transport for some proteins and organelles

c. Associated with motility

Organelles3. Cytoskeleton Has 3 components:a. Microtubules – for movement

(Ex: Cilia and Flagella)- contain Tubulinb. Microfilament – for muscle

contraction- contains Actinc. Intermediate Filaments –

reinforce the shape of the cell

Organelles

4. Vacuoles Mostly found in plant cells Fluid-filled sacs surrounded by a membrane Mature plant cells have a single large vacuole.

Plant Stem – cell sap

Organelles

5. Plastids Found in most plant cells Contain color pigments Two Kinds:

Chromoplast – colored plastidsEx: Chloroplast – contains chlorophyll

Leucoplast – colorless plastids; for storage of food substances

Supramolecular ComplexRibosomes Tiny dot-like structures

scattered throughout the cytoplasm

Site where proteins are assembled

“Protein Factories of the Cell”

Cell WallFunctions:1. Protects the cell from mechanical injury2. Gives rigidity to plant cell

Cell wall is porous. Composed mainly of cellulose Also contains lignin