Three Major Parts of the Cell:1. Plasma Membrane2. Cytoplasm3. Nucleus
• 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
Structure: Fluid mosaic model “Fluid” – configuration of the phospholipid molecules “Mosaic” – presence of proteins Lipid and other molecules move about in themembrane. The plasma membrane is not smooth.
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
1. Nucleoplasm - protein-rich protoplasm where nucleolus and chromatinsare 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)
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)
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.
• Material between the cell membrane and the nucleus• Appears: 1. Clear 2. Viscous 3. ColloidalFound in are different structures: 1. Endomembrane System 2. Organelles 3. Supramolecular Complex
Endoplasmic Reticulum (ER) Structure: Network of membranes; tiny canals formed by two parallel membranes Two distinct regions: 1. Rough ER 2. Smooth 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).
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.
Serves as a channel for products produced in the cell
Golgi Apparatus• Discovered by Camilo Golgi (nerve cell of an owl)• Flattened membranous sac
Functions: • Works together with the ER. • Serves as the Package Counter of the CellAfter 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
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 microorganisms 3. Destroys old cells (Programmed cell destruction) “Suicide Bag of Cell”
Organelles 2. 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)
Mitochondria Generates energy (Power House of the Cell)
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
3. 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
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
5. Plastids Found in most plant cells Contain color pigments Two Kinds: Chromoplast – colored plastids Ex: Chloroplast – contains chlorophyll Leucoplast – colorless plastids; for storage of food substances
Ribosomes Tiny dot-like structures scattered throughout the cytoplasm Site where proteins are assembled “Protein Factories of the Cell”
Functions:1. Protects the cell from mechanical injury2. Gives rigidity to plant cell Cell wall is porous. Composed mainly of cellulose Also contains lignin