Prentice Hall - Science Explorer - Cells and Heredity
Chapter 1- Cell structure and Function
Section 2- Looking inside Cells
Questions - Comment - Key Words - Connections
Cell Wall
Cell Membrane
Nucleus
Cytoplasm
Mitochondria
Endoplasmic Reticulum
Ribosomes
Golgi Bodies
Chloroplasts
Vacuoles
Lysosome
Main Ideas; Visuals + Predictions
Enter the Cell
Cell Wall Cell wall: A rigid layer of nonliving material that surrounds the cells of plants and some other organisms. * Animal cells don't have a cell wall. * A plant’s cell wall helps to protect and support the cell. * The cell wall is made out of tough cellulose but some materials such as water and oxygen can pass through it easily.
Plant cell Structure
* This figure shows the different structures of a plant cell and its functions.
Cell Membrane Cell Membrane: A cell structure that controls which substances can enter or leave the cell.
* For cells with cell wall the Cell membrane is located just inside the cell wall. * In other cells the cell membrane forms the outside boundary that separates the cell from its environment.
Cell Wall & Cell Membrane
* This image shows the cell membrane both in a onion root cell and in a Paramecium. * The onion root cells have both a cell wall and a cell membrane. * The single-celled paramecium has only a cell membrane.
Sail on the Nucleus
Nucleus: A cell structure that contains nucleic acids, the chemical instructions that direct all the cell’s activities.
* You can think of the nucleus as the cell’s control center, directing all of the cell’s activities.
Nuclear envelope
* This image shows the nuclear envelope.
*The nuclear envelope is a membrane surrounding the nucleus to protect it.
Chromatin * Thin strands floating directly ahead in the nucleus are called chromatin. They contain genetic material and the instructions for directing the cell’s functions. ex: the instructions in the chromatin ensure that leaf cells grow and divide to form more leaf cells.
Nucleolus * The small object floating in the nucleus is a structure called the Nucleolus. This structure, is where ribosomes are made. *Ribosomes are the organelles where proteins are produced. Proteins are important chemicals in cells.
Organelles in the Cytoplasm
Cytoplasm: The region between the cell membrane and the nucleus; in organisms without a nucleus, the region located inside the cell membrane. * It's a gel-like fluid that is constantly moving.
Mitochondria Mitochondria: Rod-shaped cell structures that convert energy in food molecules to energy the cell can use to carry out its functions.
* Mitochondria are like the “powerhouses” of the cell because they convert energy in food molecules to energy the cell can use to carry out its functions.
Endoplasmic Reticulum Endoplasmic Reticulum: A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another.
Ribosomes Ribosomes: A small grain-like structure in the cytoplasm of a cell or attached to some surfaces of the endoplasmic reticulum, where proteins are made. *Ribosomes function as factories to produce proteins. * Some newly made proteins are released through the wall of the endoplasmic reticulum. * From the interior of the endoplasmic reticulum, the proteins will be transported to the Golgi bodies.
Golgi Bodies Golgi bodies: A structure in a cell that receives proteins and other newly formed materials from the endoplasmic reticulum, packages them, and distributes them to other parts of the cell.
* They also release materials out of the cell
Chloroplasts Chloroplasts: A structure in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food for the cell.
Vacuoles Vacuoles: A sac inside a cell, floating in the cytoplasm, that acts as a storage area.
Lysosomes Lysosome: A small, round cell structure containing chemicals that break down large food particles into smaller ones.
* They also break down old cell parts and release the substances so they can be used again.
ex: They are seen like a clean up crew of a cell.
Specialized Cells
* In many-celled organisms, cells are often organized into tissues, organs, and organ systems.
Bacterial Cells
* Bacterial cells are smaller but they do have a cell wall, a cell membrane and ribosomes. * However, it does not contain a nucleus. * The bacterial cell’s genetic material, looks like a thick, tangled string, found in the cytoplasm.