Section 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

Robert 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

Rudolph Virchow (1855)
 Proposes that all cells come from existing cells
 Where did the first cell come from?

1.
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 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 cm 3
 We could fit 1,000,000 cells
Cells Alive

1. 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

Prokaryotic Eukaryotic
-No Nucleus
-Cell wall
(plants and
-Less complex bacteria)
-Smaller Ribosomes -Cell membrane less complex
-DNA is circular
-DNA
-Cytoplasm
-Ribosomes
-Nucleus
-Complex
-Membrane bound organelles
- Ribosomes larger and complex
-DNA is linear

Plant Cell - Eukaryotic
Prokaryotic
Animal Cell - Eukaryotic

 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


Nuclear Envelope

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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.

 Chromatin


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Found: between the nucleolus and the nuclear membrane
Structure: DNA bound to proteins
Function: contain genetic information


Nucleolus


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Found: In center of the nucleus
Structure: a small, dense, round sphere
Function: Produces the ribosomes .

Found: In the cytoplasm of the cell
Structure: a sphere covered by a porous membrane
Function:
Contains the cell’s DNA and all instruction for making protein and directing cell activities.
Nucleolus
Chromatin
Nuclear
Envelope
Nucleus

Found: 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



Microfilaments (7nm)


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Thread like structures made of protein
(actin)
Support the cell
Responsible for cytoplasm streaming – the movement of cytoplasm within a cell
(amoeba crawls)
Microtubules (25 nm)

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Tube-like structure made of proteins
(tubulins)
Important in cell division
Used to build cilia and flagella


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Found: In the cytoplasm
Structure: Saclike


Very large in plant cells
Smaller in animal cells
Function: Storage (water proteins, carbs, salts)


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Found: In the cytoplasm
Structure: membrane bounded sac
Function: transports and/or stores cellular products

“The Cells Clean-up Crew”
 Found: In the cytoplasm

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Structure: Small enzyme filled organelles
Function: Breakdown large organic molecules, and old nonfunctioning organelles

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
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Found: In the cytoplasm
Structure: Small and grain-like, made of large and small subunits
Function: produce proteins from directions given by DNA


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Found: just outside the nucleus
Structure: a maze of membranes
 Rough ER: (ribosomes imbedded in membrane) produces and transports
Smooth ER: (no proteins.
ribosomes) produces lipids and detoxifies drugs .



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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.

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)

“Powerhouse of the Cell”
Found: In the cytoplasm
Structure: Rod-shaped with a folded double membrane
Function: Provide the cell with energy .

Found: Located outside the cell membrane
Structure: Fibers of carbohydrate, cellulose in plant cells
Function: Provide support and protection for the cell

Found: 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

Found: Within the cytoplasm only in animal cells
Structure: Made of a microtubules (tubulin)
Function: Help organize the cell during cell division.
Centrioles - Miosis