Cell Structure and Function - Review Cell “plasma” Membrane Nucleus Mitochondrion Endoplasmic reticulum Golgi Body Lysosome ribosomes cytoplasm cytoskeleton View cell structure function

The Nucleus – the control center of the cell Return to animal Cell

Mitochondria All cells need energy to grow, reproduce, and function. Like the organisms they comprise, cells must "eat" in order to get the energy they need. One of the most important types of cellular food is a molecule called glucose, which is a type of sugar and a carbohydrate. Eukaryotic cells take in glucose through proteins that cross the plasma membrane and then transport it through the cytoskeleton to the mitochondria (mitochondria is plural; the singular is mitochondrion) in the cytoplasm. The mitochondrion is often called the cell's powerhouse. Take a look at this bad boy: “The powerhouse of the cell” Return to animal Cell

Both ER types are involved in making important cellular components. The rough endoplasmic reticulum (RER) is mainly responsible for the synthesis and processing of proteins that are either secreted from the cell or that end up stuck in the plasma membrane The Endoplasmic Reticulum – The Cell’s Assembly Line The smooth endoplasmic reticulum (SER) is primarily involved in the synthesis of lipids (fatty fat fats) and steroids, both very important components of cell membranes. The lipids made in the SER are combined with phosphorous to make phospholipids, the most abundant component of cell membranes. Return to animal Cell

The Golgi body also packages the lipids and steroids made in the SER into vesicles. Packaged lipids and steroids are transported to the edge of the cell, as well as to all organelles within the cell, where they are used to build or repair the cell and organelle membranes. The Golgi Body – packaging for export Return to animal Cell

Lysosomes Hmm…feels like we just mentioned these guys. Wait, we did! Lysosomes are small spheres of phospholipids made by the Golgi bodies and are responsible for breaking down cellular debris and material taken into the cell through the process of phagocytosis (the cell's swallowing up of things). The interior of a lysosome contains many enzymes and is slightly acidic so that material can be digested without harming the rest of the cell. Lysosomes maintain their acidity by pumping protons (hydrogen ions, or H + ions) across their membranes through integral channel proteins. Helpful tip: When you see "lys" as part of a word, think of cutting, chopping up, or breaking down. Lysosomes chop things up, glycolysis is the breaking down of sugar, and so on. There is a method to the madness… The Lysosome – Waste disposal and recycling Return to animal Cell

Ribosomes are small cellular machines made of proteins and ribosomal RNA. All cells, both eukaryotic and prokaryotic, have ribosomes. Site of Protein Synthesis The Ribosome – Protein factories Return to animal Cell

Eukaryotic Cytoplasm and Cytoskeleton The cytoplasm in eukaryotic cells is a gel-like, yet fluid, substance in which all of the other cellular components are suspended, including all of the organelles. The underlying structure and function of the cytoplasm, and of the cell itself, is largely determined by the cytoskeleton, a protein framework along which particles in the cell, including proteins, ribosomes, and organelles, move around. You can think of the cytoskeleton as a type of 3D "highway system" with roads running in every direction, including up and down. The cytoplasm is the thick fluid in which the "highway system" is suspended and through which cellular materials are transported. Helpful tip: Whenever you see "cyto" as part of a word, think "inside the cell." Return to animal Cell

The cell membrane regulates what enters and leaves the cell and also provides protection and support. The composition of nearly all cell membranes is a double-layered sheet called a lipid bilayer. As you can see in Figure 7-12, there are two layers of lipids, hence the name bilayer. The lipid bilayer gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroundings. Figure 7-12 Cell Boundaries Identification makers The Plasma Membrane The Plasma Membrane

Biology – Homeostasis Topics Investigate and analyze the cell as a living system including: Maintenance of homeostasis. Movement of materials into and out of cells. Essential Questions 1.How is homeostasis maintained? How are temperature, pH, blood glucose and water balanced? 2.What is the difference between active and passive transport? What is a semi permeable membrane? 3.What is osmotic pressure; can you predict changes? (isotonic, hypotonic, and hypertonic)

Homeostasis Homeostasis Overview Homeostasis Overview Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature, water balance or pH. Cellular Homeostasis Cellular Homeostasis

The Cell Membrane Overview of the cell “plasma” membrane structure Phospholipid bilayer Channel protein Protein with marker Receptor protein cholesterol Active transport protein

Why are the tails moving away?

Passive Transport Diffusion describes the spread of particles through random motion from regions of higher concentration to regions of lower concentration. Osmosis is the movement of water molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides Diffusion Active and Passive Transport Active and Passive Transport

Passive Transport Osmosis Virtual Lab diffusion

Tonicity is a measure of the osmotic pressure gradient (as defined by the water potential of the two solutions) of two solutions separated by a semipermeable membrane. It is commonly used when describing the response of cells immersed in an external solution. Hypotonic Solution If water molecules continue to diffuse into the cell, it will cause the cell to swell, up to the point that cytolysis (rupture) may occur Isotonic solution isotonic environment happens when an equal concentration exists inside and outside the cell Hypertonic Solution If water molecules continue to diffuse out of the cell, it will cause the cell to shrink, or crenate. Animal cell Plant cell Osmosis Demo Osmosis Demo

Active Transport is the movement of a substance against its concentration gradient (from low to high concentration) requiring the use of Energy. Endocytosis and Exocytosis Endocytosis and Exocytosis