Cell Theory & Cellular Organelles

Biology A

Student learning GoalsStudents will... Explain how cells are

the basic unit of structure and life for all living things.  

Identify the parts of plant and animal cells.

Compare prokaryotic and eukaryotic cells.

Cell History

1665: First cells seen and named "cells" by Robert Hooke

1674: First protists seen swimming in a drop of water by Anton van Leeuwenhoek

1838: Matthias Schleiden said all plants were made of cells.

Cell History- 2 1839: Theodor

Schwann said all animals were made of cells.

1855: Rudolf Virchow said all cells come from existing cells.

Cell Theory (1838-1855) All living things are

made of cells. Cells are the basic

unit of structure and function in living things.

New cells come from existing cells.

Robert Hooke’s 1665 drawing of the first cells seen under the microscope. (Cork cells)

Two Kinds of Cells

Eukaryotic Prokaryotic

More complex cells Well defined

organelles (cell parts) Cell wall (in some

cells) and a complex, well defined membrane.

Highly organized  Protists, high level

plants, and animals

More simple cells Few to no

recognizable organelles (cell parts)

Cell wall and a simple membrane

Appears more disorganized

Bacteria cells

Parts of a Cell

Cellular Organelles

Eukaryotic Cells

Organelle: Cell Membrane

Form: thin double layer of lipids and proteins surrounding the cell

Function: Controls what gets in and out of the cell.Protects cell contents from environment.

Found in: all cells

Organelle: Cell WALL Form: rigid covering

surrounding cell membrane made of cellulose in

plants, and algae (protists)

made of chitin in fungi made of peptidoglycan

in bacteria Function: Protection

Gives shape Found in: Plants,

Bacteria, Fungi, Some Protists

Additional layers in Prokaryotes Prokaryotes add

additional layers of protection between their cytoplasm and their environment.

They can have: A second cell

membrane A capsule outside the

cell wall

Organelle: Cytosol

Form: Fluid “soup” inside the cell, surrounding the organelles

Cytoplasm = cytosol + organelles

Function: cushions and protects organelles

Found in: all cells(except the nucleus)

Human cheek (squamous epithelial) cells What is the most

obvious organelle?

Organelle: Nucleus Form: large, round

organelle w/ Nuclear membrane Nuclear pores Chromatin

(chromosomes) (DNA) Nucleolus (makes

ribosomes) Function: Directs

and controls cellular activities Holds the DNA

Found in: Eukaryotic cells

The Nucleoid Prokaryotes have a

Nucleoid region which is the chromatin / DNA

Organelle: Mitochondrion Form: bean-shaped,

with inner and outer membranes

Function: Supply energy to the cell by breaking down sugar molecules by cellular respiration

Found in: All Eukaryotic cells.

plural= mitochondria

Organelle: Chloroplast Form: bean-shaped,

with pigment chlorophyll

Function: photosynthesis

Found in: Plants and protists

Organelle: thylakoid Some prokaryotes

can also photosynthesize, using a membrane called a thylakoid.

Organelle: Endoplasmic Reticulum Form: a folded

membrane stretching between the nuclear membrane and the cell membrane smooth ER w/o

ribosomes rough ER w/ ribosomes

Function: assembles components of cell membrane, modifies proteins, and synthesis of lipids

Found in: all Eukaryotic cells.

Organelle: Ribosome Form: little grainy

bumps in the cytoplasm and on the surface of the rough E.R.

Function: Makes protein molecules using instructions from DNA

Found in: All cells.

Organelle: Golgi Apparatus Form: folded

membranes with bubbles pinching off the sides

Function: Packages and ships molecules

Found in: Eukaryotic cells.

Organelle: Vacuole Form: membrane-

bound bubble in cytoplasm, large and central in plant cells, small and numerous in animal cells

Function: stores molecules, in plants it also provides support through turgor pressure and stores waste products

Found in: Eukaryotic cells

Organelle: Lysosome Form: like a

vacuole, a membrane-bound bubble

Function: Digestion – breaks down carbohydrate, protein and lipid molecules into smaller molecules

Found in: Animal cells

Organelle: Microtubules Form: hollow tubular

rods Function: structure

and support (cytoskeleton) “tracks” to move cellular organelles around the cell

Found in: Eukaryotic cells.

Organelle: Centrioles Form: paired

bundles of microtubules located near the nucleus (in animal cells only)

Function: cell division

Found in: Animal cells

Organelle: Flagellum Form: a whip-like

tail composed of bundled microtubules

Function: propels cell through its environment

Found in: Bacteria, protists, animal sperm cells

plural= flagella

Organelle: Cilia

Form: tiny, hair-like extensions covering the surface of a cell.

Function: Movement, increase of surface area, move food towards "mouth"

Found in: Bacteria, Protists, animal epithelial cells

Organelle: Pilus

Form: extension of cell membrane that look like little hairs

Function: Helps prokaryotic cells stick to surfaces. There is a second type

used in conjugation (sexual reproduction in bacteria)

Found in: Prokaryotic cells

Plural: pili

Cell Models Review Go to the Cells Alive! Web site:

http://www.cellsalive.com/cells/cell_model.htm

Organelles: Test yourself!

Organelles: Test yourself!

What kind of cell is this?

Organelles: Test yourself!

Organelles: Test yourself!

Organelles: Test yourself!