Cells: The Basic Units of Life In 1665 Robert Hooke looked at a thin slice of cork and he saw that the cork looked like little boxes. So he called them cells. The word “cell” in Latin means “Little rooms.”

The Cell Theory All organisms are composed of one or more cells. The cell is the basic unit of life in all living things. All cells come from existing cells. Matthias Schleiden (German Scientist) conclude that all plant parts are made of cells. Theodor Schwann also a German Scientist concluded that all animal parts are made of cells. Because of his knowledge of Schleiden’s theory, Schwann wrote the first two parts of the cell theory which are stated in the slide. About 20 years later another scientist, Rudolf Virchow, discovered that cells couldn’t develop from anything but other cells. Students should write this down on their worksheets.

Organelles Organelles are chemicals and structures that enable the cell to live, grow and reproduce. Read from the slide, tell students that all cells have organelles, however not all cells have membrane covered organelles.

Two Types of Cells Prokaryotic Cells: Have no membrane covered nucleus Have no membrane - covered organelles Have circular DNA Are bacteria These types of cells have no membrane covered nucleus. They are bacteria cells. Ask students if they think that all bacteria is bad: Explain to them that not all bacteria is bad, that there is good bacteria. It is in food, like yogurt, cheese and some other dairy products. It is used in medicine as Antibiotics. Some bacteria can live in extreme conditions, such as: - In the crust of the ocean ridges, where hot gases are leaking out constantly. - In the very bottom of the sea, where the pressure is so great that it would crush any other living thing and the temperature is very low. Have students fill out Prokaryotic worksheet portion.

Two Types of Cells Eukaryotic Cells: Have a nucleus Have a membrane - covered organelles Have linear DNA Are all other cells More complex than bacteria cells They make up anything that is living, such as: - Plants - Animals - Fungi - Protists Anything but bacteria Some have a cell wall and some do not. Have students complete the eukaryotic part of the worksheet.

Hereditary Material and Cytoplasm Hereditary Material in the cell is DNA. DNA controls all the activities of the cell. Cytoplasm is the fluid contained in the cell. Read the slide

Cell Membrane Keeps cytoplasm inside the cell Provides a barrier between the inside and the outside of the cell Allows nutrients into the cell and wastes outside of the cell Made from phospholipids layers. Cell Membrane

Cell Wall Found only in plant cells Made of cellulose Provides strength and support for the cell When too much water enters the plant cell, the wall prevents it from exploding. The strength of billions of cell walls ill be able to make a tree stand up tall and bear huge limbs. Cell walls are made up of a material called cellulose. Cellulose is a material that is intertwined together. It resembles a blanket or even like hashbrown potatoes all piled up. When the plant cells are stacked on top of each other and next to each other it looks like building blocks, or for another example, like Tupper ware plastic containers stacked up together.

The Nucleus The largest most visible organelle in the cell The control center of the cell Contains the Cell’s DNA DNA Could be considered the library of the cell. It contains all of the genetic materials used by the cell like DNA and info on how to make all of the cell’s proteins. The nucleolus in the nucleus stores materials that will be used to make ribosomes and cytoplasm. Nucleolus Nuclear Membrane

Ribosomes Smallest most abundant organelles Found in all cells The site where amino acids are hooked together to make proteins Does not have a membrane Makes proteins, which make up the cells.

Endoplasmic Reticulum Membrane covered compartment Makes lipids and other materials for use inside and outside the cell Breaks down chemicals that can damage the cell It is the internal delivery system for the cell Endoplasmic Reticulum The ER is like the FedEx or UPS of the cell. Substances move through tubular connections from one place to another. The ER is responsible for delivering proteins to different parts of the cell. Ribosomes

Mitochondria Site where ATP is made It is surrounded by two membranes Outer Membrane Site where ATP is made It is surrounded by two membranes Can only work if Oxygen is present Mitochondria is considered the power plant of the cell. They must have oxygen to make ATP(which is the cell’s energy) So that is why we need to breath. For very active cells, there are thousands of mitochondria. Inner Membrane

Chloroplasts Found only in plant cells Has two membranes Contains chlorophyll, which makes chloroplasts green Sun’s energy is trapped in chlorophyll to make sugar This process is called photosynthesis Inner Membrane Plant cells need energy too! Because plant’s don’t ingest food like we do or animals do, they have to make their own food. Chloroplasts uses the sun’s light energy to make sugar. The sugar is then used by the mitochondria to make energy. Outer Membrane

Golgi Complex Where proteins and other materials are processed and shipped Lipids and proteins are modified here for different functions Final products are enclosed in a piece of membrane that breaks off and transports to other parts of the cell or outside of the cell Remember the lipids and proteins that were being delivered by the ER? When the Golgi complex or apparatus gets them, they modify and package the proteins and lipids and ship them out of the cell. IT is called Golgi because it was discovered by an Italian scientist named Camillo Golgi (he was the first to discover the organelle.) Talk about Vesicles and how they are formed by pinched off ER and Golgi complex.

Vacuole Found only in Plants Large membrane - covered chamber Stores water and other liquids Vacuoles are found only in plants. Can anyone tell me what happens when you don’t water a plant for a couple of days or week? It goes limp and the leaves droop. Vacuoles that are full of water and air, support the cell. When the water and air is lost, the plants go limp. That is why we have to water plants! The pressure that the water uses to keep the plant up right is called Turger pressure. Ask students what Trees are made of. What makes them so big? Water and air!

Lyosomes Found in animal cells Digests food particles and cell parts Protects cell by digesting foreign invaders When they break they cause the destruction of the cell Special vesicles that contain enzymes. When a cell engulfs a particle, the lyosomes bump into it an pour enzymes into it. Then the particle is digested by the enzymes. Sometimes lyosomes break open and pour out the enzymes into the cytoplasm. This will kill the cell. - this is why tadpoles lose their tails - this is why humans don’t have webbed feet. The lyosomes kill the cells that make up the tails and webbing. This act is a theory on how we age.

Plant or Animal Cell? Nucleus Golgi Complex Mitochondrion Chloroplasts Found in Plant and Animal cells: Found only in Plant Cells: Nucleus Golgi Complex Mitochondrion Lyosomes Endoplasmic Reticulum Cell Membrane Ribosomes Chloroplasts Vacuoles Cell Wall Make sure to write this down on your worksheet.