Discovering Cells

10.2

What are Cells?

What is the Cell Theory?

How do Microscopes Work?

Pgs. 368-375

Cells and Life ProcessesMs. De Los Rios

6th Grade

Vocabulary 10.2

Microscope: instrument that makes small objects look larger, and the discovery of cells.

Cell Theory: explains the relationship between cells and living things

HeLa cells stained for the cell nucleus DNA

What are Cells? Pg. 368

Mushroom, tree, spider, and bird= Living organisms

Cells are the basic units of structure and function in living

things.

Cells--- form the parts of an organism ---- carry out functions.

Organism= are made of one or more cells

Cells carry out basic functions that let it: Live

grow

Reproduce

Cell functions can include:

obtaining food, water, and oxygen, getting rid of waste, and reproducing

by division.

Needs of CellsA single cell has the same needs as an entire

organism. What material moves in the direction shown by each blank arrow?

Fig. 1 Discovering Cells pg. 369

Assess your Und.

The Cell Theory TimelinePg. 370

Year of Discovery

Scientist Contribution

1665 Robert Hookediscovered the cellular composition of cork and

introduced the word cell to science

1674 Anton van Leeuwenhoekimproved magnification of microscopes by polishing

lenses

1676 Anton van Leeuwenhoek "animacules" (meaning little animals) were discovered

1683 Anton van Leeuwenhoekdiscovered bacteria from a sample of saliva from his

mouth

1838 Matthias Schleiden discovered the plants were made up of cells

1839 Theodor Schwann discovered that animals were made up of cells

1855 Rudolph Virchowstated that all living things come from other living things

“ ALL CELLS COME FROM CELLS”

  

Growth of Cell Theory pg. 370-371

LeeuwenhoeekMicroscope

Hooke’s drawings of cork

Hooke’s Microscope

Dog Cell Cell Reproducing

What is The Cell Theory? Pg. 371

The cell theory explains the relationship between cells and living things.

The cell theory was developed about two hundred years after the invention of the microscope, an instrument that makes small objects

look larger, and the discovery of cells.

The cell theory states the following:

•All living things are composed of cells.•Cells are the basic units of structure & function in living things.•All cells are produced from other cells.

Assess your Understanding

How Do Microscopes Work? Pg 372

Most cells are too small= can not be seen by the human eye

The development of the cell theory depended on observations made through microscopes.

Some microscopes focus light through lenses to produce a magnified image. Other microscopes use beams of electrons.

Microscopes 2 important jobs:

magnify & have good resolution

r. 2 P

Fig. 3

Microscope Beam Electron

Light microscope

Pg. 373

r both P

A compound microscope uses two lenses and focuses light from a lamp or reflected from a mirror. This type of microscope is often used in classrooms.

Fixed lens

2nd lens is chosen from group of 2 or 3 lenses revolving

How Do Microscopes Work?You can estimate the true size of an enlarged object by measuring the width of the circular field visible through the microscope and comparing the size of the object to the width of the field.

Objects viewed through a microscope are also more detailed than when viewed with the naked eye.

•Microscopes improve resolution: the

Ability to distinguish separate structures that

are close together.

•Electron microscopes have better resolution

and magnification than light microscopes.

A Compound Microscope

This microscope has a 10x lens in the eyepiece. The revolving nosepiece holds three different lenses: 4x, 10x, and 40x.

1.Find the three total magnification possible for this microscope. __________________________________________________________2. What would happen if the object on the slide were too thick for light to pass through it? __________________________________________________________

Eyepiecelens

Revolvingnosepiece

Lenses

SlideStageLens

Light rays

Light source

Fig. 4 Compound Microscope

ResolutionThe images in colorful photographs actually consist of only a few ink colors in the form of dots. This circle has been enlarged to show a tiny section of a

picture of a bird's wing.

Discovering Cells