Bio 112 UBC LATEST SOLUTION 2025 GUARANTEED GRADE A+

Bio 112 UBC LATEST SOLUTION 2025 GUARANTEED GRADE A+ What does the cell theory state? 1. all organisms are made up of cells 2. cells are the basic units of structure and function in organisms 3. cells come only from preexisting cells because cells are self-reproducing All cells include what 4 things? 1. DNA 2. Cell membrane 3. Cytoplasm 4. Ribosomes What is the central dogma? It's the basic flow of information in a cell, it's the two step process of transcription and translation by which information in the genes flow into proteins. What is the purpose of the cellular membrane? To control the movement of materials into + out of the cell What are the 3 domains of life? Bacteria, Archaea = prokaryotes Eukarya = Eukaryotic What does metabolism mean? The chemical reaction by which cells convert energy from one form to another ATP allows cells to do what? Growth, division + moving substances in and out of the cell What are some traits of prokaryotic cells? - Does not have a membrane bound nucleus (it has a nucleoid region) - Much smaller then Eukaryotic cells - No organelles - Different promoter recognition - DNA is a single circular chromosome What are some traits of eukaryotic cells? - Has a membrane bound nucleus - Cholesterol is present in the cell membrane - Much larger then Prokaryotic cells - Contains organelles - DNA is linear What are some traits that Prokaroytic and Eukaryotic cells share? - Contain protein, water and DNA - Contain Ribosomes - Has a cellular membrane What are the 4 major categories of macromolecules in cells? 1. Protein 2. Nucleic Acid 3. Lipids 4. Carbohydrates What is the monomer of Protein + what is its bond? Monomer: Amino Acid Bond: Peptide bond What is the directionality of protein + the reason for it? The amino group (of one amino acid) attaches to the carboxyl group of another amino acid = "N" terminus (is how it starts) to "C" terminus (how it always finishes) What is the monomer for Nucleic Acid + what is its bond? Monomer: nucleotides Bond: phosphodiester bond What is the directionality of Nucleic Acids? The phosphate group of one nucleotide covalently bonds to the sugar unit in another nucleotide 5' - 3' (A 5' attaches to a 3') What is the monomer for carbohydrates + what is its bond? Monomer: monosaccharides Bond: Glycosidic bond What is the directionality for carbhydrates? The 4' end is added to the 1' end of the 1st monosaccharide (the should be lined up spout - handle) What is the monomer for Lipids + what is its bond? Monomer: Fatty acids Bond: Ester What is the directionality of Lipids? The fatty acid tail is added to the glycerol head (different fatty acids have a different number of tails) Structure of a nucleotide? Structure of a Protein? Structure of a Carbohydrate? Structure of a Lipid? What is the difference between a Saturated and a Unsaturated Fat? Saturated: Will be saturated in C atoms (it has double bonds) = this fat is good Unsaturated: It is not saturated in C atoms (no double bonds) = this fat is bad Arrange O,N,C,S,P,H from most - least electronegative. 1. O 2. N 3. C + S 4. P + H What does it mean when an atom is nonpolar? The two atoms share electrons equally = there electronegativity is less than 0.4 What does it mean when an atom is polar? The electrons forming the bond are unequally shared between atoms = one end will have a -'ive charge and one end will have a +'ive charge, the elctronegativity is greater than 0.4 What does amphipathic mean? having both hydrophilic and hydrophobic regions When two nonpolar molecules react what kind of dipoles are formed? ID-ID When two polar molecules react what kind of dipoles are formed? PD-PD Hydrogen bonds are the same as what kind of dipoles? PD-PD What 3 molecules indicate polar bonds? S,O,N List the dipoles from strongest to weakest. 1. Ionic 2. Ion - PD 3. PD-PD/Hydrogen bonds 4. PD-ID 5. ID-ID What kind of structures will form when lipids are mixed with water? (3 options) 1. Micelles = lipids with bulky heads + a single fatty acid tails = they are wedge shaped 2.Bilayer = less bulky heads + two hydrophobic tails (kind looks like a sandwich with the tails in the middle) 3. Liposomes = structure that surround a central space (donuts). They are usually formed in a lab and form when the pH of water is similar to that of a cell How does Thermodynamics + the spontaneous formation of the lipid bilayer work? The lipid bilayer will formed as long as the concentration of free phospholipids is high enough + the pH of the solution is similar to that of a cell = This is driven by thermodynamics, towards a stabilizing system What is entropy + enthalpy? Entropy: Measure of disorder/randomness of a system Enthalpy: Sum of the internal energy of a system + the product of the pressure and volume of the system How does the structure of phospholipids dictate the structure of the lipid bilayer? They have a hydrophilic head and a hydrophobic tail. Their heads face the water where as their tails face inwards away from the water (creating a sandwich) Explain membrane fluidity. refers to the viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane. Lipid packing can influence the fluidity of the membrane. What factors influence fluidity? 1. Temperature (heat up the membrane) = the molecules gain more kinetic energy and thus move around more freely making they membrane more fluid 2. The composition of the membrane = lipids with shorter tails are less stiff and more susceptible to changes in kinetic energy 3. Cholesterol = it stabilizes the membrane and raises it's melting point. What is the fluid mosaic model? The idea that lipids + proteins coexist in the membrane and that both are able to move freely in the plane of the membrane. Arrange the molecules by their permeability across the lipid bilayer (high to low) 1. Small, nonpolar molecules 2. Small, uncharged molecules 3. Large, uncharged molecules 4. Ions What is selective permeability of biological membranes? The plasma membrane maintains homeostasis by selective permeability. It lets some molecules in + out freely, other under certain conditions, and prevents some from passing through at all. What structural features contribute to the selective permeability? The combination of lipids + embedded proteins = the membrane is composed of a hydrophobic interior and that prevents ions and charged polar molecules from diffusing freely. Compare and Contrast the transport proteins, carriers vs. channels. Channel: Provides an opening between the inside and outside of the cell within which certain molecules can pass (some are gated and open in response to some sort of chemical or electrical signal) Carrier: Binds to and transports specific molecules = it has two conformations. 1. Open to one side of the cell 2. Open to the other side of the cell What is the difference between diffusion and osmosis? Diffusion: Spontaneous movement of particles from an area of high concentration to an are of low concentration Osmosis: Spontaneous movement of water across a semipermeable membrane (water moves from an area of low concentration of solute to high concentration of solute) What are some strategies to deal with osmotic pressure? Plants: Contract Vacuole = take up excess water from inside the cell and expel it into the environment Eukaryotic: Cholesterol = stabilizes the membrane making it less permeable to water Explain Simple diffusion. - Passive transport - Random movement of molecules - Substances move from higher concentration to lower concentration Explain facilitated diffusion. - Move by diffusion through membrane proteins and by passes the lipid bilayer - Random movement of molecules - Needs a concentration difference Explain Active transport. - Move molecules from areas of lower concentration to areas of higher concentration (against the concentration gradient) - Uses energy (ATP) since its moving "uphill" What is an induce dipole? ID are fleeting and only occur in non-polar molecules due to random unequal distribution of electrons (which is why hydrophobic molecules participate in ID-ID interactions) What are permanent dipoles? Polar molecules for PD, it is when there is a large difference in electronegativity. As one end with be slightly +'ive and the other slightly -'ive. What kind of bond are hydrogen bonds the same as? PD-PD Why does increasing the length of a fatty acid chain increase its melting point? There is more intermolecular interaction and it takes more energy to break the vanderwaal interactions. List the bonds from strongest to weakest 1. Covalent 2. Ionic 3. Ion - PD 4. PD - PD/hydrogen bonds 5. PD - ID 6. ID - ID Molecule that has a molecular group with a polar bond is overall considered? Hydrophilic (polar bonds are hydrophilic because water is polar) When two atoms are involved in a polar covalent bond, what is the charge on each? One has a permanent partial +'ive and the other a permanent partial -'ive When two atoms are involved in a nonpolar covalent bond what is the charge on each atom? Both atoms fluctuate between partial +'ive and -'ive charge Name the different ways that the cell can adapt to deal with osmotic pressure. - Stay small - Change shape (increase SA to Volume ratio) - Compartmentalize - Get things moving (cytoplasmic streaming) Cell size adaptation - Dilution - Compartmentalization in eukaryotic cells (membrane enclosed regions for specific functions) CONTINUED..