Organelles 7th Grade Biology

Outer Cell Cell Wall- The cell wall is a rigid layer of nonliving material that surrounds the cells of plants and some other organisms. Animals cells do not have a cell wall. A plant’s cell wall helps to protect and support the cell. The cell wall is made mostly of cellulose. Materials such as water and oxygen can pass through. Cell Membrane- All cells have a cell membrane. In cells with cell walls the membrane is located just inside the cell wall. In other cells, the cell membrane forms the outside boundary that separates the cell from the environment.

Continued… The cell membrane controls what substances come into and out of the cell. Everything the cell needs, from food to oxygen, enters through the cell membrane. Harmful wastes leave through the membrane.

Nucleus The nucleus acts like the “brain” of the cell. It directs all of the cell’s activities. Nuclear Envelope- The nuclear envelop protects the nucleus. Materials pass in and out of the nucleus through pores in the envelope. Chromatin- Are strands that contain genetic material, the instructions for directing the cell’s functions. Nucleolus- This is where ribosomes are made. Ribosomes are the organelles where proteins are produced.

Cytoplasm Cytoplasm is the region between the cell membrane and the nucleus. It is thick gel-like fluid. This cytoplasm is constantly moving. It is home to many organelles.

Mitochondria Mitochondria are rod shaped structures. They are known as 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 A maze of passageways. These passageways carry proteins and other materials from one part of the cell to another. They are similar to hallways in a building. Ribosomes are the spots on the rough endoplasmic reticulum or “ER”.

Ribosomes Attached to the endoplasmic reticulum are grain like bodies called ribosomes. Some ribosomes float in the cytoplasm. Ribosomes function like a factory to produce proteins. Proteins are released through the wall of the “ER”. Then they are transported to the Golgi bodies.

Golgi Bodies Golgi bodies look like flattened sacs and tubes. They can be thought of as the cell’s mail room. The Golgi bodies receive proteins and other newly formed materials from the endoplasmic reticulum. The Golgi bodies then package them, and distribute them to other parts of the cell. The Golgi bodies also release materials outside the cell.

Chloroplasts Large green structures that float in the cytoplasm. Only plants have the green organelles called chloroplasts. Chloroplasts capture energy from sunlight and use it to produce food for the cell. Chloroplasts make leaves green.

Vacuoles A large water filled sac called a vacuole. The vacuole floats in the cytoplasm. Vacuoles are the storage area of cells. Most plant cells have one large vacuole. Some animal cells do not have vacuoles. Vacuoles store food and other materials needed by the cell. They can also store waste products.

Plant Vacuole In mature plant cells, vacuoles tend to be very large and are extremely important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth. Many plant cells have a large, single central vacuole that typically takes up most of the room in the cell (80 percent or more). Vacuoles in animal cells, however, tend to be much smaller, and are more commonly used to temporarily store materials or to transport substances.

Lysosomes Lysosomes are small, round structures containing chemicals that break down certain materials in the cell. Some chemicals break down large food particles into smaller ones. Lysosomes also break down old cell parts and release the substances so they can be used again. Lysosomes are the cleanup crew of the cell.