Cell Structure and Functions

• Cells are fundamental units of life with various components carrying out specialized functions.

Cell Components and Functions

• Inter-cellular space: Facilitates the movement of gases and water between cells
• Chloroplast: Site of photosynthesis
• Cell wall: Provides strength and shape to the cell
• Rough endoplasmic reticulum: Collects and transports proteins
• Ribosomes: Responsible for making proteins
• Cytoplasm: The main body of the cell where chemical reactions occur
• Vacuole: Stores water, metabolic waste products, and pigments
• Smooth endoplasmic reticulum: Transports proteins
• Plasmalemma: Controls the entry of substances into the cell
• Mitochondrion: Produces energy through cellular respiration
• Dictyosome: Collects and transports proteins
• Nucleus: Controls metabolism and holds genes
• Nuclear membrane: Forms the nucleus and protects DNA
• Nucleolus: Region in the nucleus where DNA makes RNA for protein manufacture
• Chromatin network and nucleoplasm: Chromatin network comprises DNA and contains hereditary information; nucleoplasm surrounds DNA in the nucleus
• Nucleopore: Facilitates the movement of substances in and out of the nucleus

Cell Wall (Plants Only)

• The cell wall is a rigid, non-living layer located outside the cell membrane and surrounds the cell.

Cell Wall Composition

• Plants, bacteria, and fungi have cell walls.
• In plants, the cell wall is composed of cellulose.
• Cellulose consists of three layers that help support the plant: middle lamella, primary cell wall, and secondary cell wall.

Functions of a Cell Wall

• Provides protection and support to the plant cell.
• Gives the plant a regular shape and supports the plant body.
• Allows water and mineral salts to pass through, distributing nutrients throughout the cell (permeability).
• Contains plasmodesmata (openings in the cell wall) which connects neighboring cells enabling communication and transport of molecules between them.

Cell Membrane

• The cell membrane, also referred to as the plasma membrane, physically separates the intracellular space (inside the cell) from the extracellular environment (outside the cell).
• It surrounds and protects the cytoplasm.
• It has a structure known as the Fluid Mosaic Model.
• Each phospholipid molecule has a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail.
• The phospholipid molecules are arranged tail-to-tail, so that the hydrophilic heads face outwards and the hydrophobic tails are projected.
• It consists of carbohydrates, proteins, cholesterol, and hydrophobic lipid tails.

Optical Parts of a Microscope

• Eyepiece
• Objectives: Consist of lenses that refract light to magnify the specimen

Mechanical Parts of a Microscope

• Clips: Holds the slide in place
• Base: Provides stability
• Arm: Used for carrying and support
• Focusing knob: Adjusts focus
• Body tube: Supports the eyepiece and prevents stray light from distorting the image.

Illuminating Parts of a Microscope

• Mirror
• Diaphragm
• Condenser: Primary function is to focus light on the specimen for clear viewing

Discoveries in Microscopy

• Anton van Leeuwenhoek (1632-1723) made a very powerful single-lens microscope.
• Leeuwenhoek was the first to see bacteria, yeast, and tiny organisms in water, calling them "animalcules".
• Robert Hooke (1635-1703) invented the compound microscope with two lenses.
• Hooke was the first to use the word "cell" after looking at a cork.
• Max Knott and Ernst Ruska (1931) created the electron microscope, which uses electrons instead of light.
• Electron microscopes can magnify up to 1 million times, but can't look at living things.

Types of Electron Microscopes

• TEM (Transmission Electron Microscopy): Shows 2D images of inside structures.
• SEM (Scanning Electron Microscopy): Shows 3D images of surfaces.

Explore cell components such as chloroplasts, cell walls, and endoplasmic reticulum. Understand how each part contributes to essential functions like photosynthesis, protein synthesis, and energy production within the cell.