Chapter 10: The Cell is the Basic Unit of Life
What are living things made of?
-Early idea that scientist had: all living things are made of air, fire and water
-Modern theory (now): scientist know that all living things are made of cells (cell theory)
-Cell: the smallest, most basic, functional system of any living thing
-The Cell Theory states:
-the cell is the basic unit of life
-all living things are made of one or more cells
-all cells come from other living cells
-The cell is a living system that exhibits the four characteristics of life
The 4 Characteristics of Life in Living Things are:
1. Growth
2. Movement
3. Response to Stimuli
4. Reproduction
1) Growth
-A result of the cells in your body increasing in number. New cells grow to replace old cells that die
2) Movement
-A change in position, shape or location
3) Response to Stimuli
-Stimulus: anything that causes an organism to react
-May be external (cat hissing at dog’s approach) or internal (hunger)
4) Reproduction
-Producing more of the same kind (offspring)
Parts of a Compound Light Microscope
Part / FunctionEyepiece / Used for viewing and contains a lens that magnifies
Barrel (Tube) / Holds the eyepiece and objective lenses at proper distance from each other
Arm / Supports the eyepiece and used for carrying
Coarse Adjustment Knob / Brings an object into focus at low or medium power
Fine Adjustment Knob / Brings an object into focus at high power
Objective Lenses / Magnify the image (3 or 4 lenses)
Revolving Nosepiece / Holds the three objective lenses
Stage (May have clips) / Supports the slide
Iris Diaphragm / Controls the amount of light reaching the specimen
Light Source/Lamp / Supplies the light needed to view the slide
Base / Supports the entire microscope
Development in Optical Technologies
- Optical technologies have developed from Leeuwenhoek’s single lens microscope which allowed us to see organisms for the first time to the advancement of scanning electron microscopes which produce realistic 3D images of organisms
- Science is a dynamic and changing process. As new technologies and inventions are created then we begin to make new discoveries in science. We improve our tools (ie: microscopes) and improve the quality of our measurements and observations. This is used to create new theories or modify those that already exist.
*Core Lab Activity 10-1A
“Setting Up and Using a Microscope” (Page 384-385)
Important Concepts from Lab:
Field of View – when you look through a microscope on low power the field of view 4.2 mm.
You can use the field of view to estimate the size of an organism. For example: if you look through a microscope on low power and the object takes up approximately half of the field of view you know that the object size is about 4.2 mm ÷ 2 = 2.1 mm. If you could possibly fit 4 across then the object size would be: 4.2 mm ÷ 4 = 1.05 mm.
* All students must demonstrate that they can create a wet mount slide and use a microscope appropriately during their chapter test.
Cell Organelles
Organelle – the different parts of a cell that have specific jobs to do are called organelles
Organelles
1. Cell membrane
-Found in both plant and animal cells
-Surrounds and protects the contents of the cell
-Controls the movement of the materials in and out of the cell
2. Cytoplasm
-Found in both plant and animal cells
-Jelly-like fluid in which the organelles float
-Helps to move materials such as food and oxygen to different parts of the cell
3. Cell wall
-Found only in plant cells
-Tough, rigid structure that gives plant cells their box-like shape
-Made mostly of cellulose
4. Nucleus
-Found in both plant and animal cells
-Large round structure often visible
-Contains the chromosomes
-The “control centre” of the cell
5. Vacuole
-Balloon-like spaces within the cytoplasm
-Store materials that cannot be used right away
-Found in both plant and animal cells (smaller and more numerous in animal cells)
6. Mitochondria
-Oval, bean-like structures
-Produces energy by breaking down food particles to release stored energy
-Found in both plant and animal cells
7. Chloroplast
-Green structures that contain chlorophyll
-Capture the sun’s energy for photosynthesis
-Found only in plant cells
*All these cell organelles are found in plants cells. All of them are found in animal cells except cell wall and chloroplast.
Three differences between plant and animal cells are:
1. Plant cells have chloroplasts
2. Plant cells have cell walls which give them a rectangular, regular shape
3. Plant cells have fewer and larger vacuoles
-Growth and Reproduction depend on cell division
-Mitosis is the process by which cells divide to produce more identical cells.
-Example of cell division for growth: skin cells divide to produce more skin cells to heal a cut or injury.
-Example of cell division for reproduction: a bacteria cell divides to become two cells
-Mitosis occurs in body cells and Meiosis occurs in sex cells (egg and sperm)