The Cell Theory & Cell StructureChapter 3, sections 1 and 2

The Cell Theory

• All living things are made of cells

• Cells are the basic unit of structure & function

• All cells come from pre-existing cells

Scientists and their Contributions

• 1655 – Robert Hooke coins the term “cell” after viewing cork under an early microscope

A drawing of Hooke’s cork cells

Hooke would have used a microscope like this

Scientists and their Contributions

• 1674 – Anton van Leeuwenhoek observes the first living cells under a microscope

Scientists and their Contributions

• 1838 – Matthias Schleiden determines that all plant tissues are made of cells

• 1839 – Theodor Schwann determines that all animal tissues are made of cells

Scientists and their Contributions

• 1855 – Rudolf Virchow asserts that every cell comes from a pre-existing cell

Prokaryotes vs. Eukaryotes

Characteristic

Prokaryote Eukaryote

Outer boundary

Cell wall and cell

membrane always present

Cell membrane always; cell

wall sometimes

Nucleus NO YES

Prokaryotes vs. Eukaryotes

Characteristic

Prokaryote Eukaryote

DNA YES YES

Ribosomes YES YES

Prokaryotes vs. Eukaryotes

Characteristic

Prokaryote Eukaryote

Other organelles

NO YES

Kingdoms (classification)

Eubacteria, Archaebacteria

Protista, Fungi, Plantae, Animalia

Prokaryotes vs. Eukaryotes

• Prokaryotes: cell that does not have a nucleus or any other membrane-bound organelles

• Eukaryotes: cell that does have a defined nucleus and other membrane-bound organelles

Plants vs. Animals

Characteristic

Plants Animals

Outer boundary Cell wall and cell membrane

Cell membrane only

Nucleus YES YES

Plants vs. Animals

Characteristic

Plants Animals

DNA YES YES

Mitochondria YES YES

Plants vs. Animals

Characteristic

Plants Animals

Chloroplasts YES NO

Vacuoles One large, central vacuole

Many smaller vacuoles throughout

Plants vs. Animals

Characteristic

Plants Animals

Trophic role autotrophic

(producer)

heterotrophic

(consumer)

Kingdom (classification)

Plantae Animalia

Cells vary between and within organisms.

• Cells come in all sizes ex: bacterial cells are much smaller than a typical animal cell

• Some cells may have differences based upon their requirements ex: cells that need to produce lots of energy, like muscle cells, might have more mitochondria (since mitochondria are the “powerhouses” of the cell).

Key Organelles

(1) Nucleus – control center of cell; contains deoxyribonucleic acid (DNA); enclosed by a nuclear membrane with pores; only in eukaryotes

Key Organelles

(2) Ribosomes – site of protein synthesis some are free-floating, some are attached to rough ER

Key Organelles

(3) Endoplasmic reticulum – “highway” of cell; provides path for other substances to travel along; may be smooth (w/o ribosomes) or rough (w/ ribosomes)

Key Organelles

(4) Golgi Apparatus – “post office” of cell; modifies and packages protein & lipids before they are sent out of the cell

Key Organelles

(5) Mitochondria – “powerhouse” of cell; converts food energy into chemical energy (ATP); has a double membrane and its own DNA (which can be considered evidence of endosymbiosis)

Key Organelles

(6) Lysosomes – enzyme-filled sacs that digest cellular wastes

Key Organelles

(7) Chloroplast – site of photosynthesis; converts solar/light energy into sugar (glucose); found in plant cells, some bacteria, and some protists; has a double membrane and its own DNA (which can be considered evidence of endosymbiosis)

Key Organelles

(8) Vacuoles – storage tank; primarily for water but also holds some minerals and other dissolved solids; plant cells have one large central vacuole while animal cells multiple, smaller vacuoles

Make sure you can…

• Label the key organelles on a plant and / or animal cell diagram!

• Compare and contrast:– Prokaryotes and Eukaryotes– Plant and Animal cells