Chapter 7

Cell Structure and Function

Unit 3

Cytology: the study of cells

Robert Hooke

Robert Hooke

• Mid-1600s• England• Used microscope to

observe living tissues• Named chambers

“cells”

Sketches from Micrographia

Anton van Leeuwenhoek

• Mid-1600s• Holland• Used hand lens

microscope to observe pond water

• Observed microscopic life

Leeuwenhoek Microscope

Leeuwenhoek painting by Robert A. Thom

This painting appeared in "Great Moments in Medicine" published by Parke Davis & Company, in 1966.

German cell biologists1830s: Matthias Schleidan: concluded all plants made from cells

1830s: Theodor Schwann: concluded that all animals made from cells

Rudolph Virchow

• 1855• Germany• New cells can only be

produced from existing cells, confirmed by French scientist Louis Pasteur

Pasteur painting by Robert A. Thom

This painting appeared in "Great Moments in Medicine" published by Parke Davis & Company, in 1966.

Lynn Margulis

• Organelles in larger, complex cells may have been free-living prokaryotic cells in the past.

Cell theory• Cells are made from

preexisting cells.• Cells are the smallest

units of life.• All living things are

made from at least one cell.

Cells dividing

Properties of life• Metabolism

• Homeostasis

• Growth & reproduction

• Cellular basis

Microscopy

• the use of microscopes to study cells

• Different types of microscopes– Light microscope– Transmission electron

microscope– Scanning electron

microscope

Light microscope

• visible light passes through specimen glass lenses

Sample of light microscope image (cork):

Transmission electron microscope

• TEM

• studies cellular interiors

Sample of TEM image:

Scanning electron microscope

• SEM

• studies cellular surfaces

Sample of SEM image:

Cellular basis of life

• Multicellular: organisms made up of more than one cell– Ex: protist, fungus, plant, animal

• Unicellular: organisms made up of only one cell– Ex: bacteria, protist, fungus

To be a cell…• Plasma membrane: cell membrane,

made of 2 layers of phospholipids• Cytoplasm: carbohydrate and water

based solution that suspends all internal parts of the cell

• Ribosomes: produces proteins• DNA: genetic material made of nucleic

acids

Two types of cells• Prokaryote: bacteria, archaebacteria

• Eukaryote: protist, fungus, plant, animal

Prokaryotic cell• No nucleus

• No organelles

• Small

• Simple

• Plasma membrane, ribosome, cytoplasm, DNA

Prokaryotic cell• Capsule: durable outer covering that

some bacteria have for protection against water, acids, and viruses

• Flagella: movement

• Cell wall: protective layer around plasma membrane

• Pili: anchoring and DNA exchange

Eukaryote• Complex• 4 basic components +

organelles• Organelles: small

compartments that carry out specialized functions within a cell

• Many variations

CytoskeletonCell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

Microtubules

• Internal support system (like mini-skeleton)

• Helps with muscle contractions

Smooth ER

• Endoplasmic reticulum

• produces lipids

Rough ER

• dotted with ribosomes, packages proteins made by ribosomes

Golgi apparatus (body)

• Modify, package, and sort protein packages for secretion, outside of cell

Mitochondria

• Organelle responsible for breaking down glucose molecules into ATP energy molecules

Chloroplast

• Organelle in plants and algae that produces sugar molecules by photosynthesis

Lysosome

• Organelle that produces enzymes to destroy foreign molecules and waste

• Organelle that stores water, salt, food or waste

Vacuole

Nucleus

• Stores DNA

• DNA helps to regulate protein production.

• Proteins regulate cellular activity.

Plant Cell

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

Animal Cell

Animal Cell

Centrioles

Nucleolus

Nucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrion

CellMembrane

Ribosome(free)

Ribosome(attached)