Cell Theory and Structure Discoveries Look at cells Cell Theory Cell Structures Organelles

Discoveries In 1665 Robert Hooke observed a thin slice of cork from an oak tree What he saw reminded him of the rooms in which monks lived so he called what he saw under the microscope a “cell”

Discoveries In 1670 Anton van Leeuwenhoek used the first “real” microscope to view pond water He saw living creatures that we now call single celled organisms

Looking at Cells -Cells are the smallest unit of life that can carry out all the functions of a living organism -Not discovered until the invention of the microscope

Looking at Cells  Some living organisms are unicellular (only made of only 1 cell)  They are the smallest of all living organisms Ex. Some bacteria, many protists These are what Leeuwenhoek noticed under the microscope in 1670

Looking at Cells Some living organisms are multicellular (made of many cells) Ex. Plants, Animals, Fungi

Looking at Cells Shape is related to Function Blood Cell-hemocyte; round to move through vessels Nerve-neuron; long to carry message to spinal cord Muscle-for contraction and relaxation

Cell Theory The Cell Theory was established by 3 men: M. Schleiden 1838, botanist, “all plants are made of cells” T. Schwann 1839, zoologist, “all animals/organisms are made of cells” R. Virchow 1855, physician, “all new cells come from other cells” (biogenesis)

Cell Theory 1.Cells are the basic units of all life 2. All organisms are made of 1 or more cells 3. All cells come from other cells

Cell Structure Many components make up a cell and carry out specific activities Each component works together, like a factory, to keep the cell functioning These components are called organelles

Cell Structure Organelles Typical Animal Cell

Cell Structure Organelles Typical Plant Cell

Organelles Cell Membrane: Structure: Made of phospholipids and proteins -2 phospholipid layers called a bilayer - Semipermeable (a.k.a. selectively permeable) - Hydrophilic (H2O loving) head - Hydrophobic (H2O fearing) tail

Organelles Cell Membrane Function: maintain homeostasis 1. Controls what enters and leaves 2. Boundary separating the cell from its environment

Organelles Cell Wall Structure: - Found only in plants - composed of proteins and carbohydrates Function: - Provides support and protection - Helps maintain square shape

Organelles Cytoplasm: Structure: Jelly like base throughout the cell - consists of mainly water and cytosol (an organic compound) -contains the cytoskeleton Function: Contains or “suspends” organelles inside the cell

Organelles Cytoskeleton Structure-composed of protein fibers 3 types: actin fibers – contract and expand to give the cell its shape microtubules – “highway system”; transport information from nucleus to parts of the cell intermediate fibers – framework for ribosomes/enzymes to be organized for metabolic pathways Function-provides support and a place to “anchor” other structures

Organelles Centrioles Structure -Found in animal cells only - 9 sets of 3 protein fibers Function - Aid in the the division of chromosomes in mitosis.

Organelles Microtubules Structure - Throughout the cell’s structure - Thick filaments made of protein Function - Gives structure and shape to cells - Anchors organelles

Organelles Microfilaments Structure - found throughout cell structure - hollow, thin protein tubes Function - allow for elasticity and movement within cells.

Organelles Nucleus Structure: - Found in the cytoplasm - Contains the genetic material (chromosomes made of DNA & proteins) - Surrounded by a nuclear envelope (double membrane) -Contains the nucleolus that makes ribosomes

Organelles Nucleus Function: Control headquarters for the cell (brain)

Organelles Nucleolus -Found inside of nucleus Structure - Knot of chromatin Function - Produces ribosomes

Organelles Nuclear Envelope Structure- double lipid bilayer with small holes Function- encloses genetic material (DNA) in eukaryotic cells and the holes allow mRNA to leave during transcription

Organelles

Ribosomes Structure- spheres composed of RNA and protein Function-site of protein synthesis Free ribosomes make proteins that remain inside the cell Attached ribosomes make proteins that become part of the cell or are exported from the cell (usually attached to the ER)

Free Floating Attached to the ER

Organelles Endoplasmic Reticulum (ER) Two types: 1. The rough ER - has ribosomes attached 2. The smooth ER - does not have ribosomes

Organelles Rough ER Structure: - Network of folded membranes near nucleus - Contains ribosomes on surface Function: - Transports proteins that were made by the attached ribosomes through the cell to the golgi.

Organelles Smooth ER Structure: - Network of folded membranes throughout cell - Contains no ribosomes on surface Function: - Makes lipids and breaks down toxic substances.

Organelles Golgi Apparatus Structure - Closely stacked, flattened membrane sacs - Found in the cytoplasm - Near nucleus

Organelles Golgi Apparatus Function - Stores, packages, and transports products inside for use outside -Releases vesicles (a bit of the golgi pinched off) for transport of stored materials.

Organelles Vesicles Structure - bits of membrane from the plasma membrane or from the golgi apparatus - found inside or outside of the plasma/cell membrane

Organelles Vesicles Function - Vesicles fuse with the cell membrane - may be used to release or transport chemicals in or out of the cells: oExocytosis out of the cell oEndocytosis into the cell - Transports chemicals to lysosomes or vacuole

Organelles Lysosomes Structure - not found in plant cells - saclike - contain digestive enzymes Function - Digests food particles - Digests old organelles

Organelles Vacuole Structure - Found in cytoplasm - Sac of fluid surrounded by a membrane Plants: Large in size (have one central vacuole) Animals: small in size (have many)

Plants have one large central vacuole

Organelles Vacuole Function - Sites of storage of water, ions and some nutrients. - Plants: allows plants to maintain turgor pressure

Organelles Mitochondria Structure - Oval - Inside is a complex matrix of folded membranes to increase surface area. Function - Changes energy stored in food into a more useful form - ATP is formed inside as a product of cellular respiration - powerhouse of the cell

Organelles Chloroplast Structure - Found in plant cells (and some protists) - Double phospholipid bilayer. Inner layer Stacks = grana Non stacked area = stroma

Organelles Chloroplast Function - Capturing radiant energy and converting it to chemical energy during photosynthesis - Chlorophyll is the green pigment that traps the energy from the sun

Organelles Flagella and Cilia Structure - Found outside of the cell Cilia: short hair-like Flagella: long whip-like Function Locomotion (movement) Cilia: tiny, flutters of movement. Flagella: one big wave motion will cause a large amount of movement