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Lipid & plasma memb.
Bio 2 Lecture 3
| Question | Answer |
|---|---|
| What are the 3 classes of lipids? | Neutral fats (triglycerides), phospholipids and steroids |
| What is special about lipids? | There the only group of macromolecules that are insoluble in water and are not true macromolecules since there are no monomers |
| What does having a high proportion of non-polar C-H bonds cause? | Makes the molecule hydrophobic |
| What is the role of neutral fats (triglycerides)? | They're used for energy storage, insulation in nerve cells and protect and cushion cells and organs. |
| What's the difference between carbohydrate and neutral fat energy storage? Why? | Neutral fats store twice as much energy as carbohydrates due to the high carbon to hydrogen ratio |
| What are the types of fatty acids? | Unsaturated fats, saturated fats and trans fats. |
| What is saturation in fatty acids? | It's the number of single bonds along a fatty acid and gives fat its consistency (liquid vs. solid) |
| So what kind of bonds do the 3 fatty acids have? | Saturated only has single bonds, unsaturated has one bouble bond and TRANS are artificially made. |
| What's the structure of neutral fats (aka triglycerides)? | It's one glycerol linked to 3 fatty acids chains. So 1 neutral fat=1 macromolecule composed of one glycerol and 3 fatty acids. They're linked by ester bonds |
| What's the role of phospholipids? | They form the plasma membrane of cells. |
| What are phospholipids composed of? | 1 glycerol, 2 fatty acids and a phosphate group. The 2 fatty acids are hydrophobic and the phosphate group is hydrophillic (bc it's charged). |
| What does amphipathic mean? What class of lipid is amphipatic? | It's when a molecule has both hydrophobic (non-polar) and hydrophillic (polar) parts. Phospholipids are amphipathic. |
| How does a phospholipid look like and what do the 2 parts do in presence of water? :) | Phospholipids contain both polar “heads” (phosphate group and glycerol) and nonpolar “tails” (2 fatty acids); so, in water the “tails” want to hide from the water on the interior of the bilayer |
| How can phospholipids spontanously form lipid bilayers? (See images slide 11) | Bc of their amphipathic nature. The FA tails are poorly soluble in wtr, phospholipids form bilayers in aqueous sln, with the hydrophobic tails buried in interior of membrane and the polar head groups exposed on both sides, in contact with water |
| What are the 3 types of bilayer? | There's the liposome (hollow center), the micelle (compact) and the bilayer sheet (a sheet lol). |
| What is the role of steroids? | It's used for chemical signalling (hormones) and for the integrity of the plasma membrane structure. |
| What's the structure of steroids? | A fused 4 carbon ring (like in Ochem) |
| What's the structure function relationship in cholesterol? | If there's testosterone, it becomes a male after week 5 after fertilization. If there's none, it's a female which will have progesterone |
| What is the role of cholesterol in cells? | Moderates fluidity in plasma membrane over range of temperatures (which enables it to change change) and reduces the permeability of the PM for neutral solutes sodium and hydrogen ions. |
| Apart from phospholipids, what else is amphibathic? | Cholesterol is |
| What is the structure of cholesterol? | It has a polar head group, a rigid steroid ring structure (steroid), and a non-polar hydrocarbon tail. |
| What is the role of the plasma membrane (PM)? | 1) Separates insides from the external environment 2) controls the passage of material across the membrane (selectively permeable) 3) receives and responds to signals for external envi 4) differentiates one cell type from another. |
| How did the plasma membrane function arise? | Due to increasing complexity caused from putting different macromolecules together |
| What does the lipid bilayer do? | Separates the inside of the cell from the outside. Both the lipid bilayer and the membrane choose which molecules can pass through the PM (selectively permeable) |
| What is the structure of the lipid bilayer? | It has an inner and outer face (the hydrohobic tail and the hydrophillic tail) |
| The lipid bilayer is selectively permeable. What goes through? | O2, CO2 and N2 pass through. They are small non-polar molecules. Water and glycerol pass through. They are small, uncharged polar molecules. |
| The lipid bilayer is selectively permeable. What doesnt goes through? | Glucose and sucrose can't pass through. They're large, uncharged polar molecules. Cl-, K+, and Na+ can't pass through. They're ions |
| What is the fluid mosaic model? | The fluid part refers to the motion of the phospholipid bilayer and mosaic refers the to mix of molecules embedded (cholesterol, proteins, glycolipids and glycoproteins). The membrane is a collage of proteins & other molecules embedded in the fluid matrix |
| So what is the cell membrane composed of? | (1)Lipids: Phospholipids, cholesterol (2)Proteins: transmembrane (integral) and peripheral (3)Glyco-molecules: glycolipids and glycoproteins |
| What does "glycol" refers to? | To carbohydrates like glycogen. In the plasma membrane, they exist as oligosaccharides (more than 2 monosccharides). |
| Draw a plasma membrane and label it | |
| What are the 6 functions of proteins in the plasma membrane ? Slide 28 and 27 (the first 3) | 1) transporters: form channels/pores to control movement of material 2) enzymes: Peripheral proteins, catalyze rxn at cell surface (digestive enzymes in gut) 3)cell surface receptors: detect chemical messages (insulin receptors allow glucose into cell) |
| What are the 6 functions of proteins in the plasma membrane ? Slide 28 and 27 (the last 3) | 4)cell surface identity markers: ID a cell type, and self 5)cell-to-cell adhesion proteins: bind cells together 6)attachments to the cytoskeleton: anchor cells to cytoskeleton |
| What are glycolipids? | Glycolipid = oligosaccharide bound to lipid |
| What are glycoproteins? | Glycoprotein = oligosaccharide bound to protein |
Created by:
Malayka
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