Cells

4.1 Discovery of the Cell

“The truth is, the science of Nature has already been too long made only a work of the brain and the fancy. It is now high time that it should return to the plainness and soundness of observations on material and obvious things.” Robert Hooke Micrographia 1665

The CellCell- the smallest unit that

carries out all life processes

•Unicellular- one celled critters•Multicellular-

2+ celled critters

Cell size is limited by the surface area to volume ratio

Cell Size•The longest cell is 2 Meters long.

•The largest is the . . .

Cell discovery

Robert Hooke•English•Looked at cork cells in 1665

“I could exceedingly

plainly perceive it to be all

perforated and porous, much like a Honey-comb”

Anton van Leeuwenhoek

•Dutch•First to observe living cells

Schleiden & Schwann

•Botanist•All Plants have cells

•Zoologist•All animals have cells

Virchow•Cells only come from other cells

Cell Theory

1.All living things are composed of cells

2.Cells are the basic unit of structure

3.Cells only come from other living cells

Cell Membrane•Boundary of the cell•Made from a Phospholipid bilayer

•Selectively Permeable

Hydrophilic

Hydrophobic

Cytoplasm•Jelly like substance found inside the cell

•Contains: Water, Salts and Organic Molecules

•In constant motion

Nucleus•Contains the DNA•Information center of the cell

Nucleolus•Ribosome components are made here

Ribosome•Site of Protein Synthesis

Endoplasmic Reticulum

•Folded sacs and tunnels•Two types

–Smooth•Intracellular highway

–Rough•Covered with ribosomes which make proteins

Golgi Apparatus

•Processes, Packages and secretes proteins for the cell

•Stacks of membranes

Mitochondria•Power house of the cell

•Have their own DNA•Respiration occurs here

Lysosomes•Digestive organelle•Contains enzymes that breakdown food particles and old worn out organelles

Cilia and Flagella

•Both used in movement•Cilia

–Short hair-like structures

•Flagella–Whip like tail

Exclusive to Plants

1.Cell Wall2.Vacuole3.Chloropla

st

Cell Wall•Rigid covering of plant cells

•Gives cell strength

Vacuoles•Stores enzymes and waste products

•Similar to lysosomes in animals

Chloroplast•Contain chlorophyll

•Where plants absorb sunlight

•Site of photosynthesis