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.