Exploring the Microscopic World: Cells, Organelles, and Cellular Processes

Chapter 1: Introduction to Cells and Microscopy

1.1 What are Living Things?

Organism: A living thing made up of cells.

Cell: The smallest living part of a living thing.

Unicellular: Single-celled organisms.

Multicellular: Organisms made of many cells.

Characteristics of All Living Things:

• Responds to its environment
• Needs energy
• Grows
• Reproduces
• Gets rid of wastes that build up in its body

Exploring the Microscopic World:

Compound Microscope: Combines two lenses to magnify objects.

Light Microscope: Uses light to view an object.

Resolving Power: The ability of a microscope to focus on two objects or details that are close together.

Magnification Power: The ability of a microscope to make an object appear larger.

Eyepiece: The lens you look through to magnify the image made by an objective lens, typically with a magnification power of 10x.

Objective Lens: Lenses with different magnification powers to magnify the object.

Stage: The platform where you place the object you want to view.

Light Source: Shines light through the object you view.

Arm: Supports the eyepiece.

Coarse Focus Knob: Focuses an object at low or medium power.

Fine Focus Knob: Focuses an object at high power.

Power Magnification:

• Low power: 4x
• Medium power: 10x
• High power: 40x

Scanning Electron Microscope: One type of electron microscope.

Electron Micrograph: A picture that appears on camera film or a screen, taken with an electron microscope.

1.2 Cells: The Building Blocks of Life

Cell Theory:

• The cell is the basic unit of all life.
• All living things are made up of one or more cells.
• All cells come from other living cells.

Eukaryotic Cells: Cells with organelles that have a membrane around them, such as plant and animal cells.

Prokaryotic Cells: Cells that do not have organelles with membranes around them, such as bacteria, which live almost everywhere on Earth and can cause diseases.

Viruses: Non-living things that must be present inside a host cell to reproduce; they are not cells.

Organelles: The Cell's Tiny Helpers

Organelles: Specialized structures within cells that help the cell survive. Animal cells and plant cells share many of the same organelles, but animal cells lack a cell wall and chloroplasts.

Cell Membrane: Like a skin that surrounds the whole cell, it keeps the inside of the cell separate from the outside and controls what enters and leaves the cell.

Nucleus: Controls all the cell's activities.

Cytoplasm: Clear, jelly-like fluid that holds the organelles of the cell in place.

Mitochondria: Bean-shaped structures that are the energy producers of the cell.

Vacuoles: Store materials, such as wastes, for a short time. Plant cells usually have one large vacuole, while animal cells have many smaller ones.

Cell Wall: Surrounds the cell membrane of plant cells, providing protection and support for its box-like shape.

Chloroplasts: Green-colored structures in plant cells that trap the Sun's light energy and change it to chemical energy for use by the cell.

1.3 Cellular Transport: How Cells Move Substances

Diffusion: The movement of particles from a place where there are more of them to a place where there are fewer of them.

Concentration: The amount of a substance in a certain place.

Osmosis: The diffusion of water through a selectively permeable membrane. This happens when water particles move from an area of higher concentration to an area of lower concentration.