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 ( )  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:

Organelles: Test yourself!

What kind of cell is this?

Organelles: Test yourself!