7.1 Life is Cellular

• Janssen 1590

Invented the first compound microscope

Discovery of CellsRobert Hooke (1665) - English Scientist - used a light microscope to observe cork (dead plant

cells) - observed many small “boxes” and named them cells

Cell Wall

Anton van Leeuwenhoek - 1674

• Dutch Lens Maker• Looked at pond water under a microscope

and saw green, single cell organisms moving around!

• Also looked at teeth scrapings through his microscope and noticed bacteria.

VOLVOX UNDER DARK FIELD

Robert Brown (1832)

• Botanist• Identified cell nuclei

Matthias Schleiden (1838)

• Suggested that plants are composed of cells!

Theodor Schwann (1839)

• German Physiologist• Stated that the cell was the basic unit of

structure in animals.

Rudolf Virchow (1855)• German Doctor• Stated that new cells come from existing cells

–Cells divide to make more

Ernst Ruska (1939)

• Won the Nobel Prize in physics for electron optics.–Invented the electron microscope

Compound Light Microscope

• Description– Most common microscope – Uses two lenses and light to

view specimen • Maximum Magnification

– Up to 1500x • Image of Specimen

– Allows you to view specimen that light can pass through.

Compound Light Microscope

• Benefits – Most affordable – Can be used to view living specimen – Easy to use

• Disadvantages – Limited magnification – Requires light to function– Must stain some specimen in order to see

them. (No longer alive)

Scanning Electron Microscope (SEM)

• Description – Shoots electrons at a specimen and collects them

as they bounce off the surface of organisms• Helps scientists study the exterior structure of

specimen.• Maximum Magnification

• Up to 500,000x magnification• Description of Image

– Used to view exterior structures in great detail. – Images are viewed on a developed film or

computer screen

Scanning Electron Microscope (SEM)

• Benefits – Very high magnification and detailed images. Able to view the exterior structures of the specimen in 3D.

• Disadvantages – Can only view dead or non-living specimen. Difficult to prepare specimen for viewing. Very expensive to purchase and maintain.

Scanning Electron Microscope (SEM)

• Bounces electrons off specimens to study SURFACE structures.

Scanning Electron Microscope (SEM)

Simple but Amazing SEM images

Dentist Drill Velcro

Split end of a hair

Mites on skin

Scanning Electron Microscope

• A scanning electron microscope picture of a nerve ending. It has been broken open to reveal vesicles (orange and blue) containing chemicals used to pass messages in the nervous system.

Transmission Electron Microscope (TEM)

• Electrons pass through specimens to study the INTERIOR structures

Transmission Electron Microscope (TEM)• Description

– Shoots electrons through specimens – Allows scientists to study the INSIDE of specimen at

great detail.

• Maximum Magnification – Up to 5,000,000x magnification

• Description of Image– Used to view interior structures of the specimen in great

detail. – Images are viewed on a developed film or computer

screen

Transmission Electron Microscope (TEM)

• Benefits – Very high magnification and detailed images. Able to view interior structures of the specimen.

• Disadvantages – Can only view dead or non-living specimen. Difficult to prepare specimen for viewing. Very expensive to purchase and maintain. 2D images only.

Transmission Electron Microscope

Transmission Electron Microscope

Lesson Overview

7.2 Cell Structure

Lesson Overview Life Is Cellular

The Cell Theory:1. All living things are made up of

cells.

2. Cells are the basic units of structure and function in living things.

3. New cells are produced from existing cells.

The Discovery of the Cell

– Prokaryote = • Cell that do not

contain a nucleus or membrane bound organelles.

– Eukaryote= • Cells that contain a

nucleus and membrane bound organelles.

nucleus

cell membrane

organelles

Prokaryotes and Eukaryotes

Lesson Overview Life Is CellularProkaryotes and Eukaryotes

Lesson Overview Life Is Cellular

• Prokaryotic cells are generally smaller and simpler than eukaryotic cells.

• They are SIMPLE yet, still fully alive!!

• Example: Bacteria

Prokaryotes

Lesson Overview Life Is CellularEukaryotes • Eukaryotic cells are generally larger and

more complex.• Most contain dozens of structures and

internal membranes.• Many eukaryotes are highly specialized.

• Types of eukaryotes: plants, animals, fungi, and Protists.

Cell Diversity· Size· Shape· Function · Location· Parts

Slide 3.19a

Cell Diversity

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 3.7; 1, 2

Slide 3.19b

Cell Diversity

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Differences between Plant Cells and Animal Cells

• Cell wall• Large central vacuole• Chloroplasts• Box-like shape

• No cell wall• Many small vacuoles• No chloroplasts• Rounded shape

Plant Cell: Animal Cell:

Lesson Overview Life Is CellularCell OrganizationEukaryotic cells can be divided into two major parts: • Nucleus • Cytoplasm.

Prokaryotic cells have cytoplasm, but not a nucleus

Lesson Overview Life Is Cellular

• Organelles – specialized structure that performs important functions within a cell. • Literally “Little Organ”

• Similar to a body organ!!

Cell Organization

Lesson Overview Life Is Cellular

The Nucleus • Cellular Control Center

• Contains DNA (Genetic Information)

• Prokaryotic – DNA is in cytoplasm• Three main parts

• Nucleolus• Nuclear envelope• Chromatin

Cell Structure

Lesson Overview Life Is Cellular

Nuclear Envelope • Membrane that surrounds the nucleus

• Controls what enters and exits!

Cell Structure

Lesson Overview Life Is Cellular

Chromatin

• DNA bound to proteins and condensed.

Cell Structure

Lesson Overview Life Is Cellular

Nucleolus • Small dense region in the nucleus. • Creates ribosome

Cell Structure

Cytoplasm· Mostly H20 and Nutrients · Suspends organelles - fills up all the

space between the cell membrane and nucleus.

Cell Structure

Lesson Overview Life Is Cellular

Vacuoles

• Membrane enclosed structure that is used to store materials.» Ex: water, salts, proteins, and

carbohydrates.

Cell Structure

Lesson Overview Life Is Cellular

Vesicle • Small membrane-enclosed structures

used to move materials between organelles, as well as to and from the cell surface.

Cell Structure

Lesson Overview Life Is Cellular

Lysosome• Small organelles filled with enzymes

that breakdown and recycle organic molecules or harmful bacteria.

• “Waste” removal crew for the cell.

Cell Structure

Lesson Overview Life Is Cellular

Ribosome• Small organelles that produce proteins.

• Found in the cytoplasm and on the ER

Cell Structure

Lesson Overview Life Is Cellular

Endoplasmic Reticulum • Internal membrane system• Assembles lipids, proteins and other

materials• Known as the “ER”

Cell Structure

Lesson Overview Life Is Cellular

Rough Endoplasmic Reticulum• Has ribosomes all over its surface.

• Involved in the production of proteins

Cell Structure

Lesson Overview Life Is Cellular

•Smooth Endoplasmic Reticulum • NO ribosomes on its surface.

»Production of membrane lipids.»Detoxification of chemicals.

Cell Structure

Lesson Overview Life Is Cellular

Golgi Apparatus • Appears as a stack of flattened

membranes. • Modifies, packages, and ships proteins

and lipids around the cell or out of the cell.

Cell Structure

Lesson Overview Life Is Cellular

• From the Golgi apparatus, proteins or lipids are “shipped” to their final destination inside or outside the cell.

Cell Structure

Lesson Overview Life Is Cellular

Mitochondria• The power plant of the cell.

• Converts chemical energy stored in food (glucose) into useable energy!

Cell Structure

Lesson Overview Life Is Cellular

Chloroplasts

• Captures light energy and converts it into food (glucose).

• Only in plant cells!

• Photosynthesis

Cell Structure

Lesson Overview Life Is Cellular

Cytoskeleton• Tough and flexible framework that

supports the cell.• Made of protein• Plays a role in cell division.

Cell Structure

Cell Wall

Cell Wall • Outer-most layer of plant cells• Protects, supports, and maintains the

shape of plant cells. –Made of cellulose, pectin and lignin

Cell Structure

Lesson Overview Life Is Cellular

Cell MembraneWhat is the function of the cell membrane?

• It is the cell’s gate keeper!!• Regulates what enters and leaves the

cell.• The cell membrane is Selectively

Permeable • Some substances can cross the

membrane easily, while others cannot!

Cell Structure

Lesson Overview Life Is CellularCell Membrane • Cell membranes are made of double-layer

of Phospholipids. • Called the phospholipid bilayer.

• This makes the membrane a strong and flexible barrier between the cell and its surroundings.

Lesson Overview Life Is CellularThe Properties of Lipids Phospholipid Review• Fatty acid portions of such a lipid are

hydrophobic, or “water-hating” • The opposite end of the molecule is

hydrophilic, or “water-loving.”

Lesson Overview Life Is CellularThe Properties of Lipids

• The hydrophobic fatty acid “tails” cluster together

• The hydrophilic “heads” are attracted to water. • A lipid bilayer is the result.

Lesson Overview Life Is CellularThe Fluid Mosaic Model • There are also carbohydrates and

proteins embedded in the membrane. • The membrane contains several different

molecules, but remains flexible (Like a liquid)

Slide 3.18

Special Structures on some cell membranes· Cilia - Movement or to moves materials

across the cell surface. · Flagellum - propel the cell.

Cilia

Flagella

Cell Structure

Cilia vs. Flagella Movement