Cholesterol is Less Polar Because it Has Only One Oxygen

Lecture Topic 3 1) Describe the properties and various functions of cholesterol. Properties: ● Cholesterol is less polar because it has only one oxygen ● Hydrocarbon ● Humans don’t need to eat foods with cholesterol, because we can make cholesterol from saturated fat Functions: ● Regulates fluidity of molecules in the membrane ○ Regulates how fast other molecules move based on temperature ○ In cold temperatures, molecules move slower, however cholesterol speeds up the molecule movement to increase warmth ● Combines with salts to form bile ○ Bile is stored in the gallbladder, and made in the liver ○ Dissolves fat droplets so digestive enzymes can digest fats ● Precursor for all steroid hormones ○ Anabolic steroids resemble testosterone to build up muscle mass, however this will significantly decrease the body’s natural production of testosterone. This is because a substitute is replacing the body’s naturally produced hormone, therefore the body will stop producing it. Taking these hormones also raises estrogen levels, causes infertility, back acne, and rage. It suppresses the immune system, increases the risk of heart disease and mental issues. 2) Describe the properties of phospholipids. How might a bunch of phospholipids behave if they are thrown in a bucket of water? Why? Properties: ● Glycerol + 2 fatty acids + a phosphate group (negatively charged) ● All membranes are made up of a phospholipid bilayer ● ● ● Phospholipid “Head”= Polar (Hydrophobic) Phospholipid “Tail”= Non-Polar (Hydrophilic) Polar molecule (charged) ● ● ● If thrown into water, molecules will bunch up with hydrophilic heads facing outwards, and hydrophobic tails facing inwards. This is because of the difference of polarity, the heads being polar and the tails being nonpolar. (self assembly) Fatty acid tails- hydrophobic/nonpolar Fatty acid heads- hydrophilic/polar 3) Describe the three basic components of all cells (plasma membrane, DNA, and cytoplasm). - Plasma Membrane- very fluid, they move a lot laterally (cannot flip-flop!) ● Made up of: ○ Primarily phospholipids ○ Cholesterol ○ Proteins: Important Roles= Some act as enzymes and some as transporters - Types of Membrane Proteins: - Integral Membrane Proteins: Actually embedded within the protein - Peripheral Protein: Loosely associated with membrane - DNA- genetic information - Cytoplasm- fluid that holds all organelles within a cell. Includes dissolved molecules, cytoplasmic microtubules, and water. 4) Discuss the idea of the “Fluid Mosaic Model” for the membrane of a cell. Describe the basic components of the plasma membrane (phospholipids, cholesterol, and proteins). - Fluid Mosaic Model- The membrane of an animal cell is not static (still), it moves fluidly. Phospholipid bilayer is able to freely move laterally. The bilayer/proteins/cholesterol CANNOT flip! The Fluid Mosaic Model is named because of the fluidity of the cell membrane, and the “mosaic” look of the cell membrane, with all the proteins and cholesterol uniquely pieced together and embedded on the cell membrane. - ● Proteins: ● Transport molecules across cell membrane ● Act as enzymes to aid in ATP breakdown 5) Describe two major types of membrane proteins. How do they interact with the membrane? Membrane Proteins: ● Integral Membrane Protein ○ integrated/embedded into the membrane ● Peripheral Membrane Protein ○ Loosely associated with the membrane ● Functions: ○ Enzymes (to help break down ATP) ○ Transporters 6) Describe the following transport mechanisms that ions and molecules use to get across membranes: passive transport (including simple diffusion, facilitated diffusion and osmosis) and active transport. - Passive Transport-molecules will flow from high to low ALWAYS. WITHOUT ENERGY ● Simple diffusion: ions and molecules diffuse through the phospholipid bilayer without any aid from proteins or energy ● Facilitated diffusion: ions and molecules diffuse through phospholipid bilayer with specific proteins made for that specific ion or molecule ● Osmosis: diffusion of water across cell membrane down it’s own gradient. Movement of solute will also cause water to move. - Active Transport- molecules move against the concentration gradient (low to high) with the aid of ATP/Energy Simple Diffusion Without aid Facilitated Diffusion With specific Proteins Osmosis Diffusion of Water --- --- Without Energy Passive Transport HIGH → LOW With Energy Active Transport LOW → HIGH 7) Describe what is meant by the term, tonicity. Discuss the differences between an isotonic, hypertonic and hypotonic solution. - Tonicity- impermeable solute concentration, or concentration of a solute that is unable to cross the membrane. (always used in comparison of solutions on either side of the membrane) ● Isotonic- concentration of two solutions are equal  , and there is no  net movement of water to either side ● Hypertonic solution- solution with higher concentration of solute (lower concentration of water) ● Hypotonic solution- solution with lower concentration of solute (higher concentration of water) ● **Water will ALWAYS move from hypotonic solutions to hypertonic solutions!!! Isotonic Solution Equal No net movement Hypertonic Solution LOWER concentration of solute Water moves OUT of the cell Hypotonic Solution HIGHER concentration of solute Water moves IN to the cell 8) Describe the three main types of transporter proteins found in various membranes (channels, carriers and pores). Also, describe the function of membrane receptor proteins, providing a two examples. Channels ● Qualities: ○ Highly specific for solutes to transfer across the membrane ○ Used by ions (charged particles) ● Leak Channels ○ Open all the time ○ Ex. Sodium (Na+ ) and Potassium (K+ ) leak channels ● Gated Channels ○ Stimuli to open or close ■ 1. Voltage Gated (opened or closed by electricity [the flow of ions]) ■ 2. Ligand gated channel (specific molecule opens and closes the gate) Carriers ● Highly specific for solute(s) ● ● ● ● Pores ● ● ● Usually carries bigger, bulkier molecules CANNOT FLIP Examples: Insulin and glucose receptors in the pancreas Only found in certain organelles (not the plasma membrane) Looks like a channel Not solute specific Transporter Proteins: Channels, Carriers, and Pores Leak Channels  Always Open Gated Channels  Stimuli Needed Carriers Solute Specific Pores NOT Solute Specific 9) What is the most obvious difference between the receptors that function through signal transduction and those that function through receptor-mediated endocytosis? - Signal transduction only requires the attachment of a ligand to a receptor, but the ligand does not enter the cell, and only triggers a series of reactions within the cell. - Receptor-mediated endocytosis is when ligands attach to a receptor and enter a cell to do work inside the cell or stimulate a reaction of sorts. 10) What are the main differences between prokaryotic and eukaryotic cells. What do the terms, prokaryote and eukaryote mean? - Prokaryotes usually only have the bare minimum of structure to qualify as a cell: a membrane, genetic material (DNA) and cytoplasm. Eukaryotes are more complex and require more organelles for function. - Prokaryote = “before” kernel (nucleus) - Eukaryote = “true” kernel (nucleus) 11) Describe the main functions of the different membrane-bound organelles found in eukaryotic cells. Include the nucleus, mitochondria, endoplasmic reticulum, Golgi body, lysosomes, secretory vesicles, plant vacuoles, and chloroplasts. Also, discuss the function of the ribosomes found in nearly all cells. Nucleus- stores and reproduces genetic information (DNA) ● Nucleolus creates ribosome parts ● Has DOUBLE lipid bilayer to really protect that precious genetic info! Mitochondria- powerhouse of the cell (provides the cell with energy) ● Folds are called cristae Endoplasmic Reticulum● Rough ER ● ○ Has ribosomes attached ○ Protein Synthesis Smooth ER ○ Specialized synthesis ○ Does NOT synthesize proteins ○ Mainly synthesizes lipids and detoxifies 12) Describe how our genetic material (DNA) is arranged in the nucleus of our cells (as chromosomes). Draw a typical chromosome, and label the sister chromatids and the centromere. What are sister chromatids with respect to each other? What is the purpose of the centromere region during the cell cycle? - Sister chromatids are two identical copies of information held together by a centromere. The centromere is what holds together the two chromatids, until they get pulled apart by the spindle fibers during mitosis. 13) Discuss what is meant by the term, “ploidy number”. What is the ploidy number for all of our body cells? What about sperm and eggs? Which is diploid and which is haploid? What is meant by the letter “n” when we are talking about chromosomes? What is “n” for all of our body cells? What about sperm and eggs? - Ploidy Number: the number of complete sets of chromosomes a cell contains - *Human body somatic (non-reproductive cells) cells have a ploidy number of 2 = diploid cell - *Human body germ cells (reproductive cells/ eggs and sperm) have a ploidy number of 1 = haploid cell - “n” : number of different types of chromosomes a cell contains - *Human somatic and germ cells have “n” = 23 14) Discuss maternal inheritance of mitochondrial DNA and how it can be used for criminal forensic studies. Describe the advantages of nuclear DNA over mitochondrial DNA and vice versa in forensics. - Mitochondrial DNA is inherited through the maternal (mother’s) chromosomes. Since the sperm only carries DNA, the egg has all sorts of organelles (including many many mitochondria). Therefore, everyone’s mitochondrial DNA is inherited from their mother. In forensics, nuclear DNA, if attainable, is more accurate in identifying a suspect, because nuclear DNA is unique to every individual. Therefore, if the suspect’s DNA sample matches to the nuclear DNA from the blood on scene, we can guarantee a match. The downside to that, is that blood/cells deteriorate rather quickly, so nuclear DNA is difficult to withdraw in a reasonable amount of time, especially because there is only 46 chromosome in each cell of the nucleus. Mitochondrial DNA may be easier to attain in this situation. Each blood cell contains many mitochondria, to ensure the cell has enough energy to perform work. Since mitochondria has its own DNA, the chances of finding a healthy mitochondria in a blood sample is more likely than a healthy nucleus. The downside is, however, the mitochondrial DNA could be of anyone who is maternally related to the suspect. 15) What is meant by the term, “endosymbiosis”? Discuss it as it relates to the evolution of mitochondria and chloroplasts. Be able to describe the Endosymbiotic Theory as it relates to the evolution of these organelles. - Endosymbiosis: when a smaller organism dwells inside a larger organism in a symbiotic relationship Mitochondria and chloroplasts are believed to have developed through evolution from bacteria that made its way into the cell of a eukaryotic organism. O2 cells entered non O2 cells so non O2 cells became O2 cells. MUTUALISM. Probably once little bacteria 16) Describe the three main cytoskeletal structures – microtubules, intermediate filaments, and microfilaments. Discuss the various roles that each type plays in the cell. Appearance Size Function ● Microtubules Hollow tube Widest Intermediate filaments Chromosome separation during cell division ● Directs vesicles using “railroad tracks” throughout cell ● Motor proteins (kinesin) move vesicles ● Ropelike Intermediately wide Anchors and holds down structures in cells ● Not broken down again until cell divides ● Permanent for the most part ● Microfilaments (Actin) Double helix Thinnest Necessary for muscle to function ● Fibers slide towards each other for muscle contraction ● Myosin is motor protein that helps contract muscle ● Facilitates whole cell shape changes by shortening or lengthening in cell Lecture Topic 4 (note: this lecture topic is covered during the tour of the cell, which is part of the lecture topic above) 1) What is the chemical equation for aerobic cellular respiration? What is the ultimate goal in aerobic cellular respiration? - The ultimate goal is to create as much ATP as possible for cellular and bodily use. 2) What is an oxidation? A reduction? How are these related to cellular respiration? What happens to glucose? Is it oxidized or reduced? What about oxygen? - Oxidation: removal of electrons and, consequently, hydrogen from an atom - Reduction: addition of electrons and, consequently, hydrogen from an atom - In cellular respiration, glucose is oxidized to form carbon dioxide by the removal of hydrogen while oxygen is reduced to form water by the addition of hydrogen. These reactions make up the process of aerobic cellular respiration. 3) What does "glycolysis" mean? What happens during glycolysis? Where does it occur in the cell? Is oxygen required for glycolysis? What molecule carries the electrons and hydrogen stripped from glucose? (it's called an "electron carrier"). What are the final products of glycolysis, and how many ATP are produced? - Glycolysis: the first step of the breakdown of glucose in a cell that occurs in the cytoplasm and does not require oxygen - NAD+ = the “electron carrier” that carries the electrons and hydrogen stripped from glucose - The final product of glycolysis are 2 pyruvates, 2 charged NAD+ (NADH), and 2 ATP. *The pyruvates combine with NADH to uncharge NADH changing it back to NAD+ 4) Describe the two possible fates of glucose when no oxygen is available (fermentation). Which of these occurs in mammals and which occurs in microorganisms such as yeast? What is the purpose of fermentation? Two Types of Fermentation: - Lactic Acid: byproduct of glycolysis in mammals when no oxygen is present - Ethanol/CO2: Byproduct of glycolysis in microorganisms when no oxygen is present - Fermentation occurs in order to allow ATP to be produced more quickly when oxygen is in short supply. Glycolysis occurs to produce a small, but immediate amount of ATP, but it also produces pyruvates that cannot enter the mitochondria because they are charged. These charged pyruvates are left to ferment. 5) How many ATP can be produced (theoretically) from 1 molecule of glucose in most of our cells in the presence of oxygen? - In the presence of oxygen, 1 molecule of glucose should produce about 30-32 ATP. - Without oxygen, only about 2 ATP can be produced 6) Define photosynthesis, autotroph, heterotroph, chloroplast, thylakoid membrane, granum and stroma. - Photosynthesis is a reaction that produces a certain chemical (glucose) by using light. (light dependent reaction) - Autotroph is an organism that can produce its own food (glucose) Heterotroph is an organism that must consume different things in order to receive all the nutrients it needs for survival. 7) What is the chemical equation for photosynthesis? 8) Discuss the reason why leaves appear green to us. What is the molecule responsible for the color? Is the green color reflected or absorbed? What makes the hood of a black car sizzling hot in the sun? - Leaves appear green to us because they reflect the green color on the light spectrum. Chlorophyll in plants are a green pigment that are responsible for this effect. The hood on a black car is sizzling hot in the sun, because the color black absorbs the most light, causing the car to be sizzling hot with all the energy absorbed. 9) In the photosynthesis equation carbon dioxide and water are used to make what products? Is carbon dioxide oxidized or reduced? What about water? Does the oxygen that is released come from carbon dioxide or water? - In the photosynthesis equation, carbon dioxide and water are used to make glucose and ATP. Oxygen is released as a waste product. Carbon dioxide is reduced (by adding an oxygen) and water is oxidized? Oxygen that is released comes from the water. 10) Briefly discuss the process of photosynthesis; where do the light-dependent reactions take place? Where is the sugar made in the choloroplast? What is the electron carrier used in photosynthesis? - Light dependent reactions occur in the thylakoid membrane. The sugar is made during the Calvin Cycle in the chloroplast (stroma?) The electron carrier used in photosynthesis is NAD (add PH to make NADPH) Quizzes Quiz #6 1. The plasma membrane consists of: a. a double layer of phospholipids with the hydrophobic tails facing towards each other and the polar heads facing out. 2. Which of the following statements about the plasma membrane is NOT true? a. A protein that is embedded in the membrane is called a peripheral membrane protein. 3. Which of the following would you expect to be freely permeable to the plasma membrane? a. Testosterone 4. Which of the following statements is NOT correct about the plasma membrane? a. Charged molecules and ions readily move from inside the cell to outside the cell. 5. When a bottle of perfume is opened, the majority of the perfume molecules move from a region of higher concentration to a region of lower concentration. This process is called a. simple diffusion 6. Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment surrounding the protozoan a. is hypotonic to the inside of the protozoan. 7. Ions (like Na+ and K+) use _________ to move down their concentration gradient across a membrane. This is a type of ___________, and it ____________ require energy. a. channels; facilitated diffusion; does not 8. Which of the following transporters is least specific with respect to the solute that can be transported through it? (channels, carriers, or pores). All of these transporters move solutes through a process called _______________ a. pores; facilitated diffusion 9. If a ligand binds a receptor, and causes a response in the cell without the ligand ever getting in the cell, what type of receptor are we talking about? A receptor that works through a. signal transduction 10. Let’s pretend that you have a special balloon that is permeable to water but not glucose. The balloon is almost filled with a solution of 60% glucose and 40% water and is immersed in a beaker containing a solution of 50% glucose and 50% water. Which of the following will occur? a. water will enter the balloon but glucose will not move Quiz #7 1. The first phase of cellular respiration does not require oxygen, and the term for it means “sugar splitting”. What is this first phase called? ____________ This phase results in the formation of 2 molecules of ___________, and you get ____ ATP. a. glycolysis; pyruvate; 2 2. Oxidation refers to the _____________. a. loss of electrons and/or hydrogen atoms. 3. If a cell has no oxygen, and must undergo fermentation, the total yield of ATP is _____ per glucose. If a cell does have oxygen, the total ATP yield is approximately _____ per glucose. a. 2; 30-32 4. Which of the following would you expect to have different mitochondrial DNA? Assume everyone is related (i.e. no adoptions, no cheating, etc). a. They all have the same mitochondrial DNA. 5. During photosynthesis, plants use _______ and ________ to produce glucose and a by-product of oxygen gas. The oxygen gas comes from the splitting of _________. a. carbon dioxide; water; water 6. Carboxypeptidase is an enzyme that lives inside the cell’s “stomach” and digests defective molecules. Which of the following best describes the route of carboxypeptidase from its production to its final destination? a. rough ER, vesicles, Golgi apparatus, vesicles, lysosome 7. Which organelle in the secretory pathway is responsible for sorting proteins to their final destination? ___________ Which organelle has a pH considerably lower than the rest of the cell? ____________ a. Golgi apparatus; lysosome. 8. What is assembled in the nucleolus? a. ribosome parts 9. You have found a new organism that has a total of 30 chromosomes in its cell and the cell is triploid. How many different types of chromosomes does this cell contain? ________ How many full sets of chromosomes does this cell contain? _________ a. 10; 3 10. Which of the following is not associated with the smooth ER? a. protein synthesis in all cells Quiz 8 1. What specific type of cell eats a bad guy and then displays parts of the bad guy on the surface of its cell? a. Macrophage 2. Cells acquire LDL cholesterol by a. receptor-mediated endocytosis 3. What type of cytoskeletal fibers are used to transport vesicles from the ER to the Golgi? ________ When this fiber transports vesicles, what type of protein that breaks down ATP is also required to move the vesicles along the fibers? _______ protein a. microtubules; motor 4. Which of the cytoskeletal fibers is involved in muscle contraction? __________ What type of protein makes up this cytoskeletal fiber? ___________ a. microfilaments; actin 5. As a baseball flies through the air after being hit, it contains ___________ energy. A frisbee stuck up in a tree exhibits ____________ energy. As atoms of oxygen gas move through the air, they exhibit ____________ energy. The energy stored covalent bonds is an example of ____________ energy. a. kinetic; potential; kinetic; potential 6. The thermodynamic quantity that expresses the degree of disorder in a system is ____________, and it is ___________ in the universe. When we talk of disorder, we are referring to the _______ Law of Thermodynamics. a. entropy; continually increasing; 2nd 7. A reaction that releases energy is called an __________ reaction. In this reaction, the products have __________ energy than the reactants, and the overall reaction is ___________. a. exergonic; less; spontaneous 8. ATP is the energy currency we use in our bodies. The energy that is released from ATP when it is broken down comes from the ___________. We use the energy released from the oxidation of glucose (exergonic) to make ATP from ADP and phosphate (endergonic). This process is called a(n) ____________ reaction. a. phosphate group; coupled 9. Which of the following statements is NOT correct about enzymes? a. Enzymes raise the energy of activation for a reaction. 10. Which of the following statements is NOT correct? a. Non-competitive inhibition of an enzyme can be overcome by a huge level of substrate