Anatomy Unit 4: Cell Theory & Cellular Structures
Anatomy Unit 4:
Cell Theory & Cellular Structures
Cell Theory
• Term “cell” was coined in 1665 by Robert Hooke when he looked at a slice of dried cork. He also observed that:
1. All living things are comprised of cells.
2. Cells are the smallest “living” unit in an organisms.
3. Cells come from previously existing cells.
Some Random Cell Facts
• The average human being is composed of around 100 Trillion individual cells!!!
• It would take as many as 50 cells to cover the area of a dot on the letter “i”
1673- Used a handmade microscope to observe pond scum & discovered single-celled organismsHe called them “animalcules”
He also observed blood cells from fish, birds, frogs, dogs, and humansTherefore, it was known that cells are found in animals as well as plants
Cell Diversity
• Lots of shapes and sizes
Typical Cell
Cell Organization
Cell Organization
• The cell includes two basic parts:
1. Cell Membrane (outer covering of cell)
2. Cytoplasm
• Cytosol (fluid portion of the cytoplasm)
• Organelles (cell “organs” or functional parts)
Cell Membrane
• Outer boundary• Comprised of two layers of lipid (fat)
– Outer and inner layers
• Proteins• Proteins give the cell its unique
“personality” or function
http://www.cellsalive.com/cells/cell_model.htmhttp://www.susanahalpine.com/anim/Life/memb.htm
Cell Membrane
Function of Membrane Proteins
1. Transport (in and out of cell)
2. Receptors
3. Cell adhesion
4. Cell recognition
Cell Organization
Cytoplasm
• Is comprised of:
1. Cytosol (fluid portion of the cytoplasm)
2. Organelles (cell “organs” or functional parts)
Cytosol
• Intracellular fluid
• Contains dissolved nutrients, ions, proteins and waste products
Organelles
1. Endoplasmic reticulum (ER)
• A network of membrane-bound tunnels throughout the cytoplasm
ERRough ER
Smooth ER
Ribosomes
• Particles attached to ER are ribosomes.
• Ribosomes are the site of protein synthesis within every cell.
RIBOSOME
• 2 parts that make proteins.
RNA
Ribosome
Live Cell
Golgi Apparatus
• Flattened membranes
• Involved in packaging and secretion of proteins
Golgi Apparatus
Mitochondria
• Bean shaped
• Outer and inner membranes
Mitochondria
• Inner membrane folded into cristae
• Adenosine triphosphate (ATP) produced on cristae.
• ATP is high energy compound.
• ATP only produced in mitochondria.
Nucleus
Nucleus
• Control center of cell
• Contains DNA/chromosomes
• Genetic repository for ~ 35,000 genes
• Genes control the synthesis of proteins in each cell.
• Red blood cells don’t have a nucleus.
• Skeletal muscle cells have multiple nuclei.