Cell Structure and Function 3 1 Cell Theory

Cell Structure and Function

3. 1 Cell Theory TEKS 3 F, 4 A The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. • More was learned about cells as microscopes improved.

3. 1 Cell Theory TEKS 3 F, 4 A The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. • More was learned about cells as microscopes improved. • The cell theory is a unifying concept of biology.

3. 1 Cell Theory TEKS 3 F, 4 A Early studies led to the development of the cell theory. • The Cell theory has three principles. – All organisms are made of cells.

3. 1 Cell Theory TEKS 3 F, 4 A Early studies led to the development of the cell theory. • The Cell theory has three principles. – All organisms are made of cells. – All existing cells are produced by other living cells.

3. 1 Cell Theory TEKS 3 F, 4 A Early studies led to the development of the cell theory. • The Cell theory has three principles. – All organisms are made of cells. – All existing cells are produced by other living cells. – The cell is the most basic unit of life.

Prokaryotes l Genetic material is not in a nucleus l Less complicated and smaller than eukaryotic cell l Example: Bacteria **An organism made of a prokaryotic cell is called a prokaryote.

Prokaryotic Cells

Eukaryotes l Genetic material is contained in a nucleus and separated from the rest of the cell l More complex and larger than prokaryotic cells l Example: Plants, animals, fungi, protists **An organism made of eukaryotic cell(s) is called a eukaryote.

Eukaryotic cells

Eukaryotic cell structure l. Two major parts: ¡Nucleus ¡Cytoplasm-portion of the cell outside the nucleus that contains organelles (parts or “organs” of the cell)

Nucleus-The control center l Structure: ¡ Surrounded by a double membrane called a nuclear envelope. It is dotted with many nuclear pores to allow materials (RNA, proteins, etc) in and out of the nucleus.

Nucleus l Function: ¡Contains almost all of the cell’s DNA for coding proteins and other molecules. ¡DNA is found on chromosomes which contain genetic information. ¡The Control Center of the cell!

Nucleolus l Structure: ¡ Small dense region in the center of the nucleus Function: o where ribosomes are made.

Ribosomes l Structure: ¡ Small pieces of RNA and protein found throughout the cell. ¡ Two subunits. l Function: ¡ Site of protein synthesis.

Rough Endoplasmic Reticulum l Structure: ¡ Membranous system ¡ Rough ER- has ribosomes on surface to assemble proteins ¡ Continuous with the nuclear envelope l Function: ¡ Site where lipid parts of cell membrane are made, along with proteins and other materials to export from the cell.

Smooth Endoplasmic Reticulum l Structure: ¡ Membranous system ¡ NO ribosomes on surface l Function: Synthesis of lipids and phospholipids for membranes Detoxifies drugs and toxins in the cell

Golgi Apparatus l Structure: ¡ Stack of closely packed membranes l Function: ¡ Modify, sort, and package proteins and other materials from the ER for storage in the cell or release from the cell. It puts the finishing touches on proteins.

Lysosomes l Structure: ¡ Small sac, filled with digestive enzymes l Function: ¡ Breakdown of lipids, carbohydrates and proteins into small molecules to be used by the rest of the cell ¡ Breakdown used up organelles ¡ Gets rid of all “stuff” in the cell ¡ The “Clean-up crew”

Vacuole l Structure: ¡ Sac-like ¡ Plant cells have one large central vacuole ¡ Animal cells have many small vacuoles l Function: ¡ Stores water, salts, proteins and carbohydrates

Mitochondria l Structure: ¡ Enclosed by two membranes with the inner folded membrane, called cristae. ¡ Contains it’s own DNA (Evidence for the Endosymbiotic Theory) l Function: ¡ Convert chemical energy in food into materials easier for the cell to use. This is called cell respiration.

Chloroplasts Structure: ¡ Surrounded by two membranes ¡ Stacks of membranes inside called thylakoids. ¡ Contains own genetic information like mitochondria ¡ Contains green pigment called chlorophyll ¡ Not found in animal cells! l Function: ¡ Captures energy from the sun (solar energy) and changes it into food (chemical energy) for plants (photosynthesis).

The History of the cell continued l In 1967, Lynn Margulis proposed that mitochondria and chloroplasts were descended from ancient symbiotic prokaryotes. This theory is called the Endosymbiotic Theory! Click on image to view video

Cytoskeleton- structure and support l Structure: ¡ Two types: microfilaments and microtubules- made of proteins Function: ¡ Helps maintain cell shape ¡ Helps with movement of the cell (i. e. flagella and cilia)

Flagellum l Structure: ¡ long, whip-like structure made of microtubules l Function: ¡ Allows the cell to swim through fluid

Cilia l Structure: ¡ small hair-like structures made of microtubules; beat rhythmically to move fluid outside the cell. l Function: ¡ This propels or anchors the cell.

Centrioles l Structure ¡ Pair of cylindrical arrangement of microtubules found perpendicularly to each other ¡ Region around centrioles called centrosome l Function ¡ help Divide the DNA in ANIMAL CELL division

Cell Membrane l Structure: ¡ Double membrane called a lipid bilayer ¡ Flexible structure that forms a strong barrier between the cell and its surroundings ¡ Phospholipids with integral proteins and cholesterol Function: ¡ Regulates what enters and leaves the cell ¡ Provides protection and support

Cell Wall l Structure: ¡ Lies outside the cell membrane ¡ Made of structural carbohydrates ¡ Found in plants, algae, fungi and many bacteria ¡ NOT FOUND IN ANIMAL CELLS! l Function: ¡ Provides support and protection for the cell

Levels of organization (smallest to largest) 1. Cells 2. Tissues: group of similar cells with specific function ¡ Four types: muscle, epithelial, nervous, connective tissue 3. Organs: groups of tissues working together 4. Organ systems: a group of organs that work together to perform a specific function ¡ Examples: Nervous system, digestive system