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.