The basic units of living organisms

1
Cells

• The basic units of living organisms

2
The Cell Theory

• All organisms are composed of one or more cells
• The cell is the basic unit of organization of
  organisms
• All cells come from preexisting cells

3
History of the Cell Theory

• 1600s - Anton van Leeuwenhoek
• Described living cells as seen through a simple
  microscope
• 1665 - Robert Hooke (English scientist)
• Observed corks
• Composed of tiny, hollow boxes similar to
  honeycomb
• 1830 Mattias Scheiden Thomas Schwann
• Schleiden plants are composed of cells
• Schwann animals are composed of cells

4
Two Basic Cell Types

• Prokaryotic (prokaryotes)
• Internal structures not membrane-bound
• Mostly single-celled organisms

• Eukaryotic (eukaryotes)
• Membrane-bound organelles
• Unicellular or multicellular

5
Eukaryotic Cell
6
The Eukaryotic Cell Structure
7
Boundaries

• Plasma membrane
• Controls movement in and out of cell to maintain
  chemical balance
• Flexible
• Phospholipid bilayer

8
Boundaries

• Cell wall
• Inflexible, surrounds plasma membrane
• Thicker
• Made of different substances in different
  organisms
• Plants, fungi, almost all bacteria, some protists

9
Cell control

• Nucleus
• Largest
• Manages eukaryotic cell functions
• DNA
• Forms chromatin and packed in chromosomes
• Nucleolus
• Involved in protein synthesis
• Ribosomes
• Sites of protein assembly

Nucleus
10
Assembly, Transport, Storage

• Cytoplasm
• Clear fluid outside nucleus
• Chemical reactions take place
• Surrounds organelles

11
Assembly, Transport, Storage

• ER (Endoplasmic reticulum)
• Folded membrane forming a network
• Site of lipid synthesis
• Rough ER studded with ribosomes
• Smooth ER no ribosomes
• Serves as cells delivery system

Smooth ER
12
Assembly, Transport, Storage

• Golgi apparatus
• closely stacked, flattened membrane sacs
• Receives proteins lipids from ER
• Distributes to plasma membrane other cell
  organelles
• Vesicles membrane-bound transport packages

vesicles
13
Assembly, Transport, Storage

• Vacuoles
• Temporary storage
• Stores food, enzymes, waste, water
• Plants larger vacuole, stores water

14
Assembly, Transport, Storage

• Lysosome
• Digest excess or worn out cell parts, food
  particles, invading viruses bacteria
• Digest the cell that contain them

15
Energy Transformers

• Mitochondria
• Where food molecules are broken down to release
  energy

16
Energy Transformers

• Chloroplast
• Tranform light energy
• Found in green plants and some protists

17
Support and Locomotion

• Cytoskeleton
• Maintains cell shape
• Types of cytoskeleton
• Microtubules- thin, hollow cylinders made up of
  proteins
• Microfilaments - thin, solid protein fibers

18
Support and Locomotion

• Cilia
• short, numerous, hairlike projections from plasma
  membrane
• Flagella
• Longer projections
• Moves with whiplike motion
• One or two per cell

Flagella
Cilia
19
Summary

• Plant cell
• Larger
• Chloroplasts
• Cell wall
• Few, larger vacuoles

• Animal cell
• Smaller
• Centriole
• Cell membrane
• Many, small vacuoles