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

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

Mitochondria “The powerhouse of the cell” 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

The Endoplasmic Reticulum – The Cell’s Assembly Line 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 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 – packaging for export 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. Return to animal Cell

The Lysosome – Waste disposal and recycling 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… Return to animal Cell

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

Cell Boundaries 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. The Plasma Membrane Identification makers Figure 7-12

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

Homeostasis 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. Homeostasis Overview Cellular Homeostasis

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

Why are the tails moving away? Hydrophilic – “water loving” phosphate head region Hydrophobic – “water fearing” Lipid tail region

Passive Transport Diffusion describes the spread of particles through random motion from regions of higher concentration to regions of lower concentration. Diffusion Definition Diffusion Explained

Passive Transport 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 How osmosis works

Passive Transport Facilitated diffusion is a type of passive transport that allows substances to cross membranes with the assistance of special transport proteins. 

Gummy Bear Lab The Method: Set up the experiment as shown below using your chosen gummies Osmosis Rap

Vitual 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. Osmosis Demo Animal cell Plant cell

Passive Transport – Comparing Osmosis and Diffusion

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

Active Transport is the movement of a substance against its concentration gradient (from low to high concentration) requiring the use of Energy. Endocytosis “ Entering the Cell” Phagocytosis “Cell Eating” Pinocytosis “Cell Drinking” Exocytosis “Exiting the Cell” Endocytosis and Exocytosis