Unit 2: Cells & Microscope

Unit 2: Cells& Microscope

Cell Objectives: 1. Know the Organization of life.

2. Know who first saw cells.

3. Know The Cell Theory.

4. Know the differences between Prokaryotic and Eukaryotic cells.

5. Know the 12 organelles in Eukaryotic cells.

6. Know the differences between plant and animal cells.

Cells

All living things are composed of cells.

A cell is a membrane-covered structure that contains all of the materials necessary for life.

An organism is anything that can live on its own.

Organisms can be unicellular or multicellular.

Unicellular: Made up of only one cell. They usually need to be seen using a microscope.

Multi-cellular: Made up of more than one cell. They have groups of cells that work together.

Discovery of CellsCells were discovered in 1665 by Robert Hooke.

He was looking at cork from the bark of a tree using a microscope.

Anton van Leeuwenhoek saw the first living cells in 1673.

He observed pond scum, blood and was the first person to see bacteria.

The Cell TheoryScientists later discovered a lot more about cells using

more powerful microscopes.

They developed The Cell Theory.

The Cell Theory States:

o Cells are the smallest living thing

o Every living thing is made of cells

o Cells divide to form new cells

Theodor Schwann developed the theory in 1839.

Organization of LifeFor Multi-cellular organisms:

cells

tissues

organisms

organ systems

organs

Make up

Make up

Make up

Make up

Types of CellsProkaryotic:

Eukaryotic:

Cells that do NOT have a nucleus

Do NOT have membrane bound organelles

Circular DNA

Bacteria

Cells that DO have a nucleus

Do have membrane bound organelles

Linear DNA

All other organisms

Cell Parts (Organelles)

• cytoplasm

• cell membrane

• cell wall

• nucleus

• nucleolus

• ribosomes

• endoplasmic reticulum

• mitochondria

• chloroplast

• Golgi complex

• vacuole

• lysosomes

Eukaryotic Cells:

Types of Eukaryotic Cells

Animal:

Plant:

Types of Eukaryotic Cells

Animal:

Plant:

Function of cell parts

1. Cytoplasm

Jelly-like fluid inside cell

Organelles are found floating here

Function of cell parts

2. Cell Membrane

Protects the cell

Keeps cytoplasm inside

Allows materials in and out of the cell

Function of cell parts

Provides strength and support to cell membrane

Found only in plant cells

Gives plant cells their square shape

3. Cell Wall

Cell wall

Cell membrane

Function of cell parts

Control center of the cell = “brain”

Where DNA is found

4. Nucleus

5. Nucleolus

Stores materials to make ribosomes

Found inside nucleus

Function of cell parts

Site of protein synthesis

Amino acids are joined together to make proteins.

Are found in cytoplasm or attached to endoplasmic reticulum

Smallest but most abundant organelle

6. Ribosomes

Function of cell parts

Internal delivery system

Makes lipids and other materials for inside and outside the cell.

Breaks down drugs and other harmful chemicals.

May be covered with ribosomes (Rough Endoplasmic Reticulum)

Found near nucleus

7. Endoplasmic Reticulum (ER)

Function of cell parts

Powerhouse of the cell

Energy for the cell is made here from nutrients

Surrounded by two membranes

8. Mitochondria

Function of cell parts

Absorbs sunlight to help plants make nutrients for energy

Contains chlorophyll (green pigment)

Found only in plant cells

9. Chloroplast

Function of cell parts

Materials are packaged in vesicles for shipment outside of the cell.

Located near the cell membrane

10. Golgi Complex

Function of cell parts

Stores water and other liquids

Large vacuoles found in plants

11. Vacuole

Contractile Vacuole:

Squeezes excess water out of the cell

Function of cell parts

Digest (breakdown) materials found in vesicles with enzymes (chemicals).

Get rid of wastes

Protect the cell against invaders

Found in Animal cells

12. Lysosomes

Golgi Complex

cell membrane

nucleolus

cell wall

chloroplast

nucleus

lysosome

ribosome

cytoplasm

DNA

ER

mitochondria

vacuole

Animal CellPlant Cell

Comparing Plant & Animal Cells

AnimalPlant

Both

lysosomesCell wall

Chloroplast

vacuole

Cell membrane

nucleus

cytoplasmmitochondria

Golgi complexribosomes

ER

nucleolus

DNA

Microscope Objectives:

1. Know the parts of the microscope.

2. Know the functions of microscope parts.

3. Know how to determine orientation of an object under the microscope.

4. Know how to determine magnification, field of view and size of an object.

5. Know proper technique to use microscope.

Microscope parts

Use this diagram to label your microscope picture

Microscope FunctionsEyepiece:The part you look through. Where you

place your eye.

Arm: Attaches eyepiece to the base.

Body tube: Supports the eyepiece

Coarse adjustment knob:

Fine adjustment knob:

This moves the stage up and down to get object into initial focus.

NEVER use under high power.Used to make small adjustments to the focus.

Microscope FunctionsNosepiece:Rotating piece that changes objectives (low &

high)

Objectives:

Stage:

Stage clips:

Diaphragm:

Light source:

Lens that magnify the object

The place where the specimen is placed.

Holds the specimen slide in place.

Allows different amounts of light through the slide.Reflects light onto the stage to observe specimen

Supports the entire microscopeBase:

Determining total magnification

Multiply the magnification of the eyepiece by the magnification of the objective.

Eyepiece = 10x Objective = 4x

Total magnification = 10 x 4 = 40x

Eyepiece = 10x Objective = 40x

Total magnification = 10 x 40 = 400x

Object Orientation

As you look through the eyepiece the image you see is upside down and backwards from the specimen on the slide.

e slidecover slip

If you move the slide to the left the object moves to the right in the eyepiece.

If you move the slide to the right the object moves to the left in the eyepiece.

Field of ViewEach mark = 1 mm or 1000 μm

Determine the field of view by counting marks under low power.

100x

100x

Field of view = 3mm or 3000 μm

Determining object size

Using the determined field of view:

1. Count the number of cells in a row.

2. Divide the number of cells into the field of view in μm.1. 6 cells

2. 3000 μm / 6 cells = 500 μm (size of one cell)