Cells

Objectives List scientists who contributed to the cell theory List the components of the cell theory Compare prokaryote and eukaryote cells Label a plant and an animal cell Know the functions of cell organelles

Early Contributions Robert Hooke - The first person to see cells, he was looking at cork and noted that he saw "a great many boxes. (1665) Anton van Leeuwenhoek - Observed living cells in pond water, which he called "animalcules" (1673)

Theodore Schwann - zoologist who observed that the tissues of animals had cells (1839) Mattias Schleiden - botanist, observed that the tissues of plants contained cells ( 1845) Rudolf Virchow - also reported that every living thing is made of up vital units, known as cells. He also predicted that cells come from other cells. (1850 )

The Cell Theory 1. Every living organism is made of one or more cells. 2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions. 3. All cells arise from pre-existing cells. *Why is the Cell Theory called a Theory and not a Fact?

Cell Features Most cells have these parts: Ribosomes – make protein for use by the organism Cytoplasm – fluid material within the cell DNA – genetic material Cytoskeleton – internal framework of the cell Cell Membrane – outer boundary, some things can cross the cell membrane

Prokaryotic Cells The first cells to inhabit the earth Simple cells Bacteria These cells do NOT have a nucleus, their DNA is circular and floats in the cytoplasm Some bacteria have a tail-like structure called a flagella, that helps it to move. A capsule surrounds some bacteria and helps them avoid the body’s immune system

Bacteria Images Bacteria that causes Anthrax E. coli

Comprehension Checkpoint Answer true or false 1.Robert Hooke was the first person to see cells. 2.Bacteria cells have a cell membrane and cell wall. 3.The Cell Theory was developed by a single scientist. 4.Plant cells have cytoplasm. 5.Cells can only come from pre-existing cells. 6.It only took five years to develop the Cell Theory.

Eukaryotic Cells Cells found in plants, animals, protists, and fungi The cell is composed of 4 main parts 1.Cell membrane 2.Cytoplasm 3.Nucleus – the “control center” of the cell, houses DNA 4.Organelles (“little organs”)– small structures that carry out specific functions

CELL MEMBRANE Selectively permeable; it regulates what comes into the cell and what leaves the cell It is composed of a double layer of phospholipids with proteins embedded throughout

Nucleus Usually found at the center of the cell It has a nuclear envelope, nuclear pores, and the cell’s DNA inside. It also contains an organelle called the nucleolus – which makes the cell’s ribosomes

Cell Organelles Mitochondria –It turns food in to chemical energy called ATP The mitochondria is sometimes called the “powerhouse” of the cell ATP molecule

Remember those macromolecules PROTEINS that had 4 structures?

Protein example….

Protein Production The cell is like a factory. It’s product is protein which go to the body to serve different functions. 1.DNA has the instructions to build the protein 2.These instructions are sent to the ribosomes 3.The ribosomes build the protein and can send it to the endoplasmic reticulum 4.The proteins are often delivered to the golgi apparatus where they are completed and “tagged” for export outside the cell Path of a Secretory Protein

Endoplasmic Reticulum – Transports proteins - - "intracellular highway“ Ribosomes are positioned on the rough ER, and proteins made by these ribosomes enter the ER for transport.

Cell Organelles Golgi Apparatus – processes, packages and secretes proteins. It is comparable to a factory or a post office.

Cell Organelles Lysosome – Contains digestive enzymes, breaks things down.

Cell Organelles Cytoskeleton – functions in support and contains many microfilaments and microtubules Flagella (tail like structure) Vacuole – storage area for water and other substances, plant cells usually have a large central vacuole movie (in class only) organelles

Plant Cells Additional structures: CELL WALL – surrounds the membrane and provides additional support CHLOROPLASTS – contain green pigment, function in photosynthesis CENTRAL VACUOLE – large water container in the center of the cell

THE ANIMAL CELL Exploratorium: Traits of Life: Exhibits: Cell Explorer

PLANT CELL Can you identify the parts?

Cheek Cells Seen Through Microscope

Anacharis Cells Viewed With a Microscope