Chapter 7: Cell Structure and FunctionSection 7-1: Life is Cellular Harvard - Inner Life of the Cell

The observations and conclusions of many scientists helped to develop the current understanding of the cell

Put it in perspective:

1605 – English settlers found the colony at Jamestown, Virginia

The Cell TheoryRobert Hooke (1665)

English physicist used primitive compound microscope to look at plant tissue (cork).

He called the chambers

“cells” because they reminded him of the small rooms in a monastery

The Cell TheoryRudolph Virchow (1855) Proposes that all cells come from existing

cells Where did the first cell come from?

THE CELL THEORY1. All living things are composed of cells.

2. Cells are the basic unit of structure and function in living things.

3. New cells are produced from existing cells.

How small are cells?How much is a micrometer?

1 micrometer (µm) = 1/1,000,000 m

Typical cell size = 5 to 50 µm in diameter In a dice that is 1 cm3

We could fit 1,000,000 cells

Cells Alive

How small are cells?

Two categories of cells1. Prokaryotic Cells

pro = before; karyon = nucleus or kernel• contain cell membranes and cytoplasm but no

nucleus• DNA is scattered through cytoplasm

examples: bacteria

2. Eukaryotic Cells

eu = true; karyon = nucleus or kernel

contain a nucleus that holds DNA and membrane bound organelles that have specific functions

examples: all plants, animals, some fungi, some microorganisms

Two categories of cells

Two categories of cells

Prokaryotic Eukaryotic

-No Nucleus -Nucleus

-Smaller Ribosomes less complex

-Less complex

-DNA is linear

- Ribosomes larger and complex

-Membrane bound organelles

-Complex-Cell wall (plants and bacteria)

-DNA is circular

-Cell membrane-DNA-Cytoplasm-Ribosomes

Animal Cell - Eukaryotic

ProkaryoticPlant Cell - Eukaryotic

7-2 Cell Structures Organelle – a specialized structure that

performs a specific function inside a cell

Cytoplasm Found – between the nucleus and cell

membrane Structure – a clear jelly-like fluid Function – supports the organelles

The Nucleus Nuclear Envelope

Found: around the outside of the nucleus Structure: two thin membranes with

thousands of pores Function: allows materials to move in and

out of the nucleus.

The Nucleus

Chromatin

Nuclear Envelope

Nucleus

Found – In cytoplasm near middle of cell

Structure – filled with chromatin (tightly coiled DNA)

Function: Contains the cell’s DNA, the instructions for making protein and directing cell activities.

CytoskeletonFound: Throughout the cell

Structure: A network of protein filaments

Microtubules (25 nm) Microfilaments (7nm)

Function: Helps support the cell & maintain shape

Involved in several types of movement

Vacuoles Found: In the cytoplasm Structure: Saclike

Very large in plant cells Smaller in animal cells

Function: Storage (water proteins, carbs, salts)

Vesicles Found: In the cytoplasm Structure: membrane

bounded sac Function: transports

and/or stores cellular products

Lysosomes“The Cells Clean-up Crew” Found: In the cytoplasm Structure: Small enzyme filled organelles Function: Breakdown large organic

molecules, and old nonfunctioning organelles

Ribosomes Found: In the cytoplasm Structure: Small and grain-like, made of

large and small subunits Function: produce proteins from directions

given by DNA

Endoplasmic Reticulum

Found: just outside the nucleus

Structure: a maze of membranes

Rough ER: (ribosomes imbedded in membrane) produces and transports proteins.

Golgi Apparatus Found: In the cytoplasm Structure: A stack of membranes Function: to modify, sort and package

materials from the ER for storage or to be transported outside the cell.

Chloroplast

Found: In the cytoplasm of plant cells

Structure: Stack of membranes that contain photosynthetic pigments (chlorophyll)

Function: Use energy from the sun to make food (photosynthesis)

Mitochondria “Powerhouse of the Cell”Found: In the cytoplasm

Structure: Rod-shaped with a folded double membrane

Function: Provide the cell with energy.

Cell WallFound: Located outside the cell membrane

Structure: Fibers of carbohydrate, cellulose in plant cells

Function: Provide support and protection for the cell

Cell MembraneFound: Located around the perimeter of the

cell

Structure: Made of a phospholipid bilayer

Function: Regulates what leaves and enters the cell and provides protection and support

CentriolesFound: Within the cytoplasm only in animal

cells

Structure: Made of a microtubules (tubulin)

Function: Help organize the cell during cell during division.

Centrioles - Miosis

1. What are the three parts of the cell theory.

2. Who is credited with discovering cells?

3. What is the typical size range for cells in micrometers?

4. How did plant cells appear under the microscope?

5. What type of cell is this and name an organism it could have come from.

Warm up questions.

Read the passage about prokaryotic and eukaryotic cells.

Complete a Venn Diagram like the one in your notes detailing the similarities and differences between prokaryotic and eukaryotic cells.

Lastly, based on the passage write a short paragraph detailing how we think eukaryotic cells may have evolved from prokaryotic cells.

Eukaryotic and Prokaryotic Cells

Bryson Reading: Bacteria Multiplying White blood cell vs. bacterium Bonnie Bassler

According to endosymbiotic theory, what two eukaryotic organelles are believed to have been former prokaryotic cells?

Bonus question (3 pts.)

Get a book from the back and turn to pages 162-163. In your notebook construct a Venn diagram that compares and contrasts prokaryotic and eukaryotic cells

After exam:

Prokaryotic Eukaryotic

3.

2.1.