Chapter 2: Cell Structure and Function pg

Transcription

1 UNIT 1: Biochemistry Chapter 2: Cell Structure and Function pg Organelles are internal structures that carry out specialized functions, interacting and complementing each other. Animal and plant cells have the same organelles in common, but plant cells also have a cell wall and chloroplasts, not found in animal cells. Plasma membrane is a dynamic barrier that surrounds the cytosol of the cell. The plasma membrane creates a barrier that separates the external environment from the internal environment, cytosol. The plasma membrane regulates the movement of material into and out of the cell. Maintaining the internal environment allows the organelles to do their jobs. Organelles work in conjunction with each other to keep the cell healthy and functioning. Cell Theory: a. all living things are made up of cells b. All cells come from pre existing cells c. the cell is the smallest entity that expresses the characteristics of life.

2 2.1: Cell Structures pg The Nucleus All eukaryotic cells have a true nucleus and membrane bound organelles. The nucleus contains the DNA (genetic material), protects it, of the cell. DNA can also be found in two other organelles, mitochondria and the chloroplasts.

3 Nuclear Envelope Nuclear envelope is a bi-layer membrane that encloses the nucleus of a eukaryotic cell. The nuclear membrane is a bi-layer of phospholipids, which continues into a second organelle. The endoplasmic reticulum is attached to the nucleus. The membrane has proteins, receptors and transport, embedded into it, which allows materials to pass into and out of the nucleus. Table 1: Organelles of Eukaryotic Cells, pg. 73 Nucleolus The nucleolus is found within the nucleus, floating in the nucleoplasm of the nucleus. The nucleolus is responsible for producing a ribosome from protein and RNA. The Endo-membrane System Endo-membrane system is a group of interacting organelles between the nucleus and the plasma membrane. These organelles are responsible for the production of lipids, enzymes, and other proteins, along with the removal, recycling, and destroying toxins.

4 Endoplasmic Reticulum Endoplasmic reticulum (ER) is a membrane bound organelle that is folded into flattened sacs and tubes, and is often an outgrowth of the nuclear envelope in a eukaryotic cell. Smooth ER is an area of the endoplasmic reticulum without attached ribosomes. Rough ER is an area of the endoplasmic reticulum with attached ribosomes. The endoplasmic reticulum is a direct extension of the nuclear envelope. It forms a continuous compartment of tubes and flattened sacs. There are two kinds of endoplasmic reticulum, rough and smooth. The rough endoplasmic reticulum has ribosomes attached, and is the site of polypeptide chains. These proteins are then folded, into their complex structures. Smooth endoplasmic reticulum store enzymes, which produce lipids, and break down carbohydrates, fatty acids, drugs and some poisons.

5 Vesicles Vesicle is a small, membrane bound organelle that may transport, store, or digest substances within a cell. There are a many different types of vesicles that form from organelles or from the plasma membrane. Some transport proteins, some contain enzymes (peroxisomes), that digest fatty acids, hydrogen peroxide (by product of fatty acid digestion) into water and oxygen. Vacuole is a liquid-filled organelle that stores waste and aids in cellular metabolism and water balance. Vacuoles perform an important function; they isolate, and dispose of wastes, debris, and toxic materials. Plants have large central vacuoles, which contain amino acids, sugars, ions wastes and toxins, dissolved in water. These central vacuoles take up 50% to 90% of the cell. Lysosome is a small, membrane bound organelle that contains digestive enzymes that aid in waste disposal.

6 Golgi Body Golgi body is an organelle with folded membranes where the final packaging of proteins occurs. Golgi body looks like a stack of pancakes, and are responsible for modifying polypeptide chains and lipids that have be delivered by the vesicles from the endoplasmic reticulum. The finished products, membrane proteins, and enzymes are sorted and packaged into new vesicles to be shipped to the plasma membrane or lysosomes. Other Organelles Mitochondria is an organelle with two membranes, the site of most ATP synthesis during aerobic cellular respiration. All eukaryotic cells have mitochondria, which is responsible for the production of ATP through cellular respiration, in the presence of oxygen. The number of mitochondria found in a cell is dependent on the function of the cell. If the cell has a high demand for energy, then it will have a large number of mitochondria. The mitochondrion has two membranes, outer and inner mitochondrial membranes (cristae), which creates two different compartments. The intermembrane space is found between the outer and inner membrane and the second is found inside the cristae and is called the matrix.

7 The mitochondrion has its own DNA and is similar size to a bacterium. Mitochondrion is able to independently divide, and have their own ribosomes. It is theorized that the mitochondrion evolved from an aerobic bacteria and formed a symbiotic relationship in the eukaryotic cell, endosymbiosis. Plastids Photosynthetic cells of plants and algae contain chloroplasts, which are organelles responsible for the metabolic process of photosynthesis. The chloroplast has two outer membranes and semi-fluid interior called a stroma. The stroma contains enzymes, the chloroplast s DNA, a series of folded membranes called Thylakoid discs. Plastid is a membrane bound organelle that is involved in photosynthesis and storage in plants and algae. Chloroplast is a double membrane bound organelle that contains enzymes and pigments that are used to perform photosynthesis in eukaryotic cells. \\

8 Chromoplast is an organelle that makes and stores pigments other than chlorophyll. Amyloplast is an organelle that stores starch.

9 The Dynamic Cytoskeleton Microtubules and Microfilaments Cilia, flagella, and Pseudo pods The Cell Surface Cell wall is the outer barrier of a plant cell; the cell wall surrounds the plasma membrane and gives structure to the plant. Primary wall is a cellulose coating that surrounds the plant cell. Secondary wall is a coating that is added to plant cell wall; it is more rigid and often thicker than the primary cell wall. Extra-cellular matrix (ECM) is a molecular system that supports and protects a cell; a cell environment. Cell Junction is a structure that allows cells to interact with each other and the surrounding environment.