Cells and Heredity Cells and Organelles

Cell Structures Organic and inorganic molecules join to form cells. Cells are the smallest functional unit in an organism. Every living organism is made up of at least one cell.

Cell Structures Cells contain many smaller membrane bound structures called organelles. Organelles are specialized and each does a different job. They work together like the different parts of a factory.

Cell Structures Most organelles are found in both plant and animal cells. Cell walls and chloroplasts are found only in plant cells. Lysosomes and centrioles are found only in animal cells.

Cell Structures

Cell Structures The cell membrane forms a boundary for the cell. In plant cells it is just inside the cell wall. In animal cells it is the outer boundary. The cell membrane controls what enters or leaves the cell. the cytoplasm is a gelatin like substance. Most cell processes occur in the cytoplasm.

Cell Structures The nucleus controls cell activities. The nucleus is bound by a membrane. Chromosomes are found inside the nucleus. The chromosomes contain DNA and contains the information needed by each cell to function.

Cell Structures The nucleolus is a dense region of DNA and RNA found inside the nucleus. It is where ribosomes are produced.

Cell Structures The endoplasmic reticulum- ER forms a maze of passageways. The ER is used to transport proteins and other materials. Attached to the surface are ribosomes. The ribosomes are small grainlike structures. Ribosomes are also found floating in the cytoplasm. Ribosomes function to produce proteins.

Cell Structures The Golgi bodies are flattened sacs or tubes. They package proteins and other materials and send to other parts of the cell. The mitochondria are rod shaped structures. The mitochondria are where energy is produced. Very active cells such as muscle cells have many mitochondria.

Cell Structures Peroxisomes are small round structures that contain chemicals. The peroxisomes produce energy for the cell. They produce much less energy than the mitochondria. In plants, they are important in seed germination.

Cell Structures Vacuoles are water filled sacs in the cytoplasm. They are for water storage. Most plant cells have a single large vacuole. They keep the plant cells plump and firm Animal cells may contain small vacuoles or none at all.

Cell Structures Cell walls are found in plants only. The cell wall contains cellulose and is a rigid, nonliving framework. The cell wall gives the plant cell it’s shape and structure. Chloroplasts are also only in plant cells. Chloroplasts use sunlight to convert carbon dioxide and water into sugar and oxygen.

Cell Structures Animal cells contain lysosomes. They are small round structures that contain enzymes. The lysosomes break down old cell parts and food particles.

Cell Structures Animal cells also contain centrioles. They are small rodlike structures that are in pairs. They are used in cell division. They help form spindle fibers to guide chromosomes.

Cell Structures Cells that are similar form tissues. Tissues that have the same structure and function form organs. Organs that are similar and work together form systems. The organ systems form the complete organism.