Does the structure of the onion’s cells determine its overall size and shape? Explain. If one cell were changed or damaged, would it affect the overall structure or function of the plant? If one cell is not important to the survival of the plant, why is each individual cell still important overall?

The first microscope was developed in the late 1600s. Thinking question: How did this change the study of BIOLOGY? A. Cell Theory

2. Closer study of the cell lead to the CELL THEORY, which has three parts: a. All organisms are made of one or more cells. -UNICELLULAR or MULTICELLULAR

b. Cells are the basic unit of structure/organization of all living things. Thinking question: What are the levels of organization? -Cells, Tissues, Organs, Organ Systems, Organism

c. Cells can only arise from previously existing cells c. Cells can only arise from previously existing cells. -UNICELLULAR organisms reproduce; MULTICELLULAR organisms replace dead cells Cell Theory Vid

B. Microscope Technology 1. Different microscopes are designed to view different objects. a. COMPOUND LIGHT MICROSCOPES use light to make something appear larger. B. Microscope Technology

-They magnify up to 1000 times their size, and are used to study things at a CELLULAR level.

b. ELECTRON MICROSCOPES magnify objects up to 500,000 times their size b. ELECTRON MICROSCOPES magnify objects up to 500,000 times their size. -They are used to study objects at an atomic level.

1. The parts of a COMPOUND LIGHT MICROSCOPE: a 1. The parts of a COMPOUND LIGHT MICROSCOPE: a. OBJECTIVE LENSES - Lenses that magnify objects at different powers. C. Microscope Use

-There are three levels of magnification of objective lenses: -Low power – 4x -Medium power –10x -High power – 40x

b. The EYEPIECE is the lens you look through. Its magnification is 10x b. The EYEPIECE is the lens you look through. Its magnification is 10x. -Total magnification of an object is 10 x the amount of the objective lens. Ex: The 40x objective lens magnifies at 400 times an object’s size.

c. The ARM attaches the lens to the bottom (for safe holding).

d. Slides are clipped to the STAGE for examination.

e. The DIAPHRAGM allows you to adjust the light coming through the stage. - More light is needed to view certain specimen.

f. COARSE FOCUS (larger knob) moves the stage up/down very quickly. g f. COARSE FOCUS (larger knob) moves the stage up/down very quickly. g. FINE FOCUS (smaller knob) focuses the image slowly and carefully.

h. The LIGHT source illuminates your slide. i h. The LIGHT source illuminates your slide. i. The BASE supports the instrument.

Label the Microscope

1. Every cell has a PLASMA MEMBRANE, a boundary that controls what enters and leaves the cell. C. Cell Types

a. Most cells contain DNA, and can break down molecules to make energy.

b. There are two kinds of cells, EUKARYOTIC and PROKARYOTIC cells b. There are two kinds of cells, EUKARYOTIC and PROKARYOTIC cells. Thinking question: What is the difference between them?

2. EUKARYOTIC CELLS contain ORGANELLES, small structures that do special jobs. a. They have a NUCLEUS, an ORGANELLE which holds the DNA.

b. Most EUKARYOTES are multicellular organisms, though some are single celled (ex: amoeba, paramecia, yeast).

3. PROKARYOTIC CELLS do not contain ORGANELLES. a 3. PROKARYOTIC CELLS do not contain ORGANELLES. a. Their DNA floats around inside the cell because there is no NUCLEUS.

b. All PROKARYOTES are simple, single-celled organisms b. All PROKARYOTES are simple, single-celled organisms. Most bacteria are PROKARYOTES.

4. PROKARYOTIC CELLS are smaller than EUKARYOTIC CELLS 4. PROKARYOTIC CELLS are smaller than EUKARYOTIC CELLS. Thinking question: Why? https://www.youtube.com/watch?v=zZtcMBTQaS4

Thinking question: Why? 5. ALL CELLS CONTAIN: Plasma Membrane Cytoplasm Ribosomes DNA Thinking question: Why?