Cell Biology

Animal Cells Animal cells are surrounded by a layer of fat and protein—the cell membrane Inside is a jelly like substance—cytoplasm—that contains organelles Organelles are like the cell’s organs—each does a specific job for the cell The most important organelle is the nucleus, which contains the cell’s DNA Mitochondria are the motors of a cell, they convert sugar into energy

Plant Cells Like animal cells, plant cells are surrounded by a cell membrane Outside the cell membrane is another layer made of cellulose to protect and support the cell Many of the organelles in the cytoplasm of a plant cell are very similar to those of an animal cells Vacuoles in a plant cell tend to be much larger than in animal cells One type of organelle not found in animals is the chloroplast—each contains the chemical needed to transform water, carbon dioxide and sunlight into food Amylosplasts store the food (starch) made by the chloroplasts

Cell Membrane The cell membrane is a bag made of fat and protein that surrounds all cells. The fat makes the membrane flexible. The protein holds the membrane together and act like gates to let some molecules into and out of the cell.

Cell Wall Plant cells have a cell wall outside their cell membranes. Cell walls are made of cellulose (the stuff paper is made of) and help cells keep their shape.

Cytoplasm Cytoplasm is the jelly-like substance that fills all cells. The cytoplasm supports and cushions the organelles within the cell.

Nucleus Every cell has a nucleus that contains its DNA. We can think of the nucleus as the “brain” of the cell. It tell the rest of the cell what to do. In animal cells, nuclei are usually at the center of the cell. In plants they are usually on one side. Inside the nucleus is the nucleolus, the organelle that makes ribosomes.

Vacuole Vacuoles are sacs for cells to store food and water. In plant cells, vacuoles are usually much larger and, when filled with water, help to hold the plant up.

Mitochondrion Mitochondria are the cells engine. They turn sugar into the energy a cell needs to do its job. A mitochondrion is almost a cell within a cell. It contains many of the organelles found in “true” cells. It even has its own DNA.

Chloroplast Chloroplasts are small organelles in plant cells that contain chlorophyll. They react water and carbon dioxide to make sugar and oxygen.

Other Organelles Ribosomes make proteins. The Endoplasmic reticulum (ER) moves proteins and other materials throughout the cell. Golgi bodies sort and send proteins and other materials around and out of the cell. Centrosomes help to control and regulate cell processes. Lysosomes help to break down food and old parts of the cell.