Lecture 2, Cell Structure and Component Biology PDF

Lecture 2, Cell Structure and Component  Cell Structure and Components Simple Diffusion: Cell Membrane This is the movement The cell membrane is composed of lipids (fats), carbohydrates, and proteins which each have of molecules from an...

Lecture 2, Cell Structure and Component  Cell Structure and Components Simple Diffusion: Cell Membrane This is the movement The cell membrane is composed of lipids (fats), carbohydrates, and proteins which each have of molecules from an their own specific function. The cell membranes are composed of a phospholipid bilayer 1.1 that area of high to low is created by amphipathic molecules. This means that one end of the molecule is hydrophobic concentration; with (tail), and one end is hydrophilic (head) 1.2. The tail is composed of a hydrocarbon chain that concentration does not like water while the head of the molecule like water. These molecules arrange themselves gradient. It requires in a way that the tails and facing each other (inside cell membrane) and the heads are facing no energy and is outside. natural As mentioned, most cell membranes are composed of a bilayer structure 1.1 but, it can also Facilitated Diffusion: take other forms like Micelle which is a single, spherical layer where all the tails are buried This is the movement within the cell 1.3. There is also another structure that involves the bilayer, forming a structure of molecules from an called Liposome which is also spherical but has a hydrophilic centre due to the heads arranging area of high to low themselves in the middle 1.4. concentration; with concentration Cholesterol is also an amphipathic molecule like the phospholipids, which is only found in gradient. It requires animals. By being amphipathic, it is able to go in between the cell membrane. It acts as a buffer to no energy and is regulate cell membrane fluidity based on temperature. In cold temperatures, it prevents cell natural. The membrane from packing too tightly. In high temps, it makes it more stable by preventing difference between fluidity. this and simple is that facilitated Proteins in Membrane and Permeability requires proteins to Receptors: These proteins allow cells to receive signals from environment transport molecules. Enzymes: These proteins allow cells to catalyze chemical reactions Anchors: These allow cells to attach to other proteins in order to maintain shape and structure 1 1 Integral membrane: These are permanently attached to the inside of the cell membrane. Peripheral membrane: These are only temporarily accosiate with the membrane though weak non-covalent bonds with the head of phosplipids. 1 2. The cell membrane is selectively permeable it controls the movement of molecules in and out of the cell through the use of protein channels. If the molecules are small enough, they can diffuse through by themselves. If the molecules are big, they have to go through a protein channel or a carrier protein as it can not fit in between the cell membrane phospholipids 1.5. 1. 3 Osmosis This is the diffusion of water; with the concentration gradient. There are 5 effects of osmosis. The first one is hypertonic. This is when there is more solute outside of the cell, so water rushes out of the cell shrinking it. Isotonic is when it is equal and there is no net movement inside or outside of the cell. Hypotonic is when there is a lot of solute inside of the cell, so water rushes 1 4 into the cell, swelling it. If it is very hypotonic, the cell will burst (lysis) and it will become. lysed 1.6. The 5th effect is specific to plants. Because plant cells have cell walls, they can not become lysed as the cell wall prevents it from undergoing lysis. It is very rigid and keeps the structure of the cell preventing it from bursting open. The pressure exerted on the cell wall is called Turgor Pressure. Cell Theory: 1. 5 1. 6 All organisms are made up of cells The cell is the fundamental unit of life Cells only come from preexisting cells  Cell Structure and Components Pg 2 Antiporter: This is a Primary and Secondary Active Transport: transport protein Primary: This is a type of transport that goes against the concentration gradient; goes from low that moves to high concentration requiring energy. A very common example is the sodium potassium molecules in pump. It moves 3 sodium’s outside the cell and 2 inside the cell. This requires energy from ATP. opposite directions When ATP becomes ADP, it gets rid of 1 phosphorus and attaches to the pump. This is the energy like in sodium required. Since there are more protons going outside of the cell vs inside, it creates an potassium pump electrochemical gradient 2.1. Secondary: This type of active transport can only happen after primary because it needs an 2. I electrochemical gradient (substitute for ATP). It moves protons inside of the cell and molecules outside of the cell using an antiporter 2.2. Endomembrane System This is an interconnected system of membranes inside of the cell that includes: nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and 22. plasma membrane (cell membrane). Nuclear Envelope: The nucleus has its own membrane with nuclear pores. These pores are essential for the nucleus to communicate with the rest of the cell. An example is DNA being turned to mRNA, it then goes to ribosomes out of the cell through nuclear pores. Endoplasmic Reticulum: This is a large organelle in most eukaryotic cells. In here, many important lipids and proteins are produced that are used both inside and outside of the cell. The rough ER has ribosomes attached to surface giving it a Symporters/Co- rough look. The smooth ER has no ribosomes and is used to make lipids. transporters: This is a protein that moves 2 Ribosomes: This is the site of protein synthesis where RNA turns into amino acid different molecules in chains (proteins). the same direction Golgi Apparatus: It has 3 main functions: it further modifies proteins from ER, it sorts proteins and lipids as they move to their destination where required, it also synthesizes the carbohydrates needed for cells. Lysosomes: These degrade proteins, nucleic acid, lipids and complex carbs.