Cell Theory & Cellular Organelles Biology A
Student learning Goals Students 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
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: ProtectionGives 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! What kind of cell is this?