CH. 3 ~ CELLS

Robert Hooke1665

• Looked at thin slices of cork under a microscope

• Did not know at the time about their structure and function.

• What IS a cell?

A cell is the smallest unit of life that can carry out all the

activities necessary for life.

THE CELL THEORYOne of the foundations of modern biology. It states: 1. All living things are made up of one or more cells2. Cells are the most basic unit of life; they originate from pre-existing cells3. Energy Flow (metabolism) occurs within cells; they must maintain an internal balance (homeostasis)4. Cells contain DNA (hereditary information) so they

can reproduce. Pass this genetic material from one generation to another.

TYPES OF

CELLS

Why are cells so different?

Specialized Functions!

What Limits the Size of a Cell?• Human Body consists of

about 100 trillion cells• (A string 100 trillion

inches long could be wrapped around Earth more than 63,000 times)

• Cell grows- needs to take in food and get rid of waste through the cell membrane.

• Cell cannot grow so large that their surface area becomes too small to take in enough food and remove enough wastes

• Cells volume increases faster than its surface area.

• Surface area = 6s2

• Volume = l x w x h

Which has bigger cells?Person with strep throat?

Cells of the bacteria that causes strep?

Eukaryotic vs. Prokaryotic CellsEukaryotic Cells• Large• Have chromosomes• Have membrane-bound

organelles– Nucleus–Mitochondria– Centrioles– (theory of

endosymbiosis)

Prokaryotic Cells• Small• No chromosomes,

only small circle of DNA (plasmid)

• No membrane-bound organelles.

Eukaryotic Cells are Larger than Prokaryotic cells

Organisms that are Eukaryotic:Every organisms that isnot bacteria:

– Animals– Plants– Fungus– Protists

Organisms that are Prokaryotic:

Every bacterial cell– Eubacteria– Archeabacteria

Eukaryotic and Prokaryotic Cells

HOMEWORK

Choose any TWO Cell Parts from the Plant Diagram and any TWO from the Animal Cell Diagram in your notes to define (must be 4 DIFFERENT CELL PARTS/ORGANELLES).

Using information from your textbook, Chapter 3:For EACH CELL PART?ORGANELLE that you chose:1. Explain the structure and function.2. Is it found in a plant cell, animal cell or BOTH?3. Is it found in a Eukaryotic Cell, Prokaryotic cell or

BOTH?