BIS 2A 2023

BIS 2A 2023 What are proteins made of? - CORRECT ANSWER-Proteins are made up of amino acids linked together by peptide bonds, as well as the R groups attached to the amino acids (which make them unique and give certain characteristics) Proteins are formed through the process of condensation, when the carboxylic group and the amine group of the amino acids bind together to produce water, forming a peptide bond. How the various levels of organization (primary, secondary...) affect the structure and activity of an enzyme? - CORRECT ANSWER--3D structure and pattern of charges/hydrophobic patches allow enzyme to bind to correct substrates How the concentration of a catalyst influences the rate of a reaction. Under what circumstances is the rate is limited by the [catalyst] vs. [substrate]? - CORRECT ANSWER--When there is a high concentration of substrate, the rate of reaction is limited by the catalyst. -When there is a low concentration of substrate, the rate of reaction is limited by how many times the substrate and enzyme/catalyst bump into each other. Primary structure, secondary structure, tertiary structure, and quaternary structure - CORRECT ANSWER-Primary: the chain of amino acids connected by peptide bonds Secondary: Stabilized by hydrogen bonds, consist of alpha helix and beta pleated sheets. Sequence can be predicted by R groups Tertiary: Determined by R groups, very hard to predict. Stabilized by a bunch of weak reactions between R groups and amino acids (ionic bonds) Quaternary: also stabilized by a bunch of weak ionic reactions between R groups and amino acids. How do biological catalysts (proteins) make catalytic binding surfaces? - CORRECT ANSWER-Catalytic binding surfaces are determined by R groups aka the pattern of charges/hydrophobic patches on the 3D structure of the protein. How is reaction rate controlled by catalysts? - CORRECT ANSWER-Catalysts control reaction rate by providing an alternate, faster route through the reaction. When there is a high concentration of substrate, the rate is limited by the enzymes. How changes in shape at one part of a protein can affect activities in another part - CORRECT ANSWER-Allosteric inhibition: -Inhibitor binds to allosteric site, shape of active site changes and substrate can no longer bind -Inhibitor can also bind to allosteric site close to active site and block substrate -If substrate cannot bind then enzyme is not activated Why is the "first dedicated step" is a smart place to regulate a long metabolic pathway - CORRECT ANSWER-You don't want to inhibit the production of the original amino acid; you just want to regulate the production of the product. **Why biologists interested in Origins find methanogens particularly fascinating - CORRECT ANSWER-Methanogens can be heterotrophs or autotrophs Arguments and evidence against a heterotroph as the first possible life form - CORRECT ANSWER-Heterotrophs use oxidative phosphorylation to produce their energy, so the environment would have had to be O2 heavy. This was not the case, so heterotrophs were probably NOT the first life form. Why increasing cell size creates a crisis in the relationship between the cell and its environment - CORRECT ANSWER-Surface area to volume ratio gets smaller as the diameter of cells increase. This is not good because there is not enough membrane space for the metabolic activities that the cell needs to do, in relation to the size. -Reason why big cells are long and thin Why cell walls can be handy - CORRECT ANSWER-Cell walls maintain the shape of the cell, resist osmotic pressure. What's the difference between proks and euks? - CORRECT ANSWER-Euks have organelles and proks don't; also, eukaryotes are usually larger than prokaryotes Why are archeans considered a new "domain" of life, and why did it take so long to discover them? - CORRECT ANSWER-Distantly related to bacteria, it was hard to discover these "extremophiles" due to the environments that they thrived in. How are the three domains related to each other? - CORRECT ANSWER-Archaea and Eukaryotes share 3 RNA polymerases, histones, and introns in genes -More closely related than bacteria Bacteria and Archaea are both simple cells, but bacteria differs from archaea and eukaryotes bc they have 1 RNA polymerase, no histones, and no introns in genes "fermenting predator" vs. the "hydrogen hypothesis" models for the origins of eukaryotes? - CORRECT ANSWER-Fermenting Predator: A protoeukaryote had all of the components of a cell but not a way to generate energy. Invented ATP transporter, fed to pyruvate and found a way to make more ATPs per glucose. Hydrogen Hypothesis: Methanogen (autotroph) and bacteria (heterotroph) developed a relationship where the heterotroph supplied H2 when O2 was available. You should understand why a lipid bilayer is a stable structure in an aqueous environment - CORRECT ANSWER-Tightly packed together, consists of polar head and non polar tails with opposite ends stuck together. You should be able to tell a friend why and how concentration gradients can be used to harvest energy (as ATP) and/or provide the energy for other endergonic processes - CORRECT ANSWER--Proton gradient in plants; protons can diffuse down gradient if another compound is pumped up the gradient. -ATP breaks apart into ADP (exergonic reaction) which couples to an endergonic reaction such as one involving a transport protein/channel. You should be able to identify the concepts shared between protein-based catalysts and protein-based transporters - CORRECT ANSWER-Catalysts provide an alternate route for the reaction, transporters provide an alternate route for substances that need to pass through the cell membrane. You should be able to identify molecules that can or can't diffuse through a lipid bilayer - CORRECT ANSWER-CAN: small non polar molecules CANNOT: large polar molecules Why do eukaryotic cells have elaborate intracellular transportation systems? - CORRECT ANSWER-There are many different kinds of proteins specific for transport (cells are really picky) How does a vesicle know it has arrived at its destination? - CORRECT ANSWER-There are snare proteins that send out signals when the vesicle has reached its destination, and from there the vesicle is kind of sucked into the cell where it drops off its neurotransmitters. Why is segregation of the genome into two daughter cells such a big, elaborate deal, when the segregation of, say, glucose is not? - CORRECT ANSWER-This requires preparation of the parent cell, as well as replication of the genome Compare and contrast the segregation of the eukaryotic and prokaryotic genomes into daughter cells - CORRECT ANSWER-Prokaryotic genomes have only one circular DNA with replication origin and termination. We cannot do this for eukaryotic chromosomes, because there are too many origins and terminations You should be able to describe the difference between a sexual and asexual life cycle, and tell us where mitosis, meiosis, and fertilization fit in - CORRECT ANSWERTell us how the cell figures how to get one version of each chromosome to each gamete - CORRECT ANSWERHow does this differ from mitosis? - CORRECT ANSWER- How is diversity generated during meiosis? - CORRECT ANSWER--Crossing over during prophase I -Independent assortment during metaphase I You should be able to discuss the adaptive advantages and disadvantages of a sexual life cycle. - CORRECT ANSWERDescribe how some bacteria manage to undergo genetic recombination, in spite of their asexual life cycle. - CORRECT ANSWERWhat did Mendel learn about inheritance? - CORRECT ANSWER--Traits can be dominant or recessive -Traits do not blend -Inheritance of one trait has nothing to do with inheritance of another ALSO: traits segregate differently during independent assortment, this is why progeny can have different combos of alleles than their grandparents What evidence strongly suggested the hypothesis that DNA is the chemical basis of inheritance? Why did people doubt that this hypothesis was correct? - CORRECT ANSWER-Avery MacLeod and Mccarthy's experiment that demonstrated the extraction of RNase, protease, and DNAse and this interaction with a transforming substance. This transforming substance was given DNase and then destroyed so IT MUST BE DNA that is the genetic material!! People doubted that this hypothesis was correct because they did not believe it could contribute anything to inheritance. What does a "gene" actually do in the cell? - CORRECT ANSWER-genes = DNA, DNA is used to make RNA, and RNA is used to make proteins which are VERY important Where are the genes in the cell? - CORRECT ANSWER-In the nucleus What are genes made of? - CORRECT ANSWER-5 carbon sugar, phosphate group, nitrogenous base How do progeny get just one version from each parent? - CORRECT ANSWERMEIOSIS You should be able to describe the experiments that convinced people DNA was "the molecule of inheritance" You should understand why people doubted that DNA could do this. - CORRECT ANSWER-Avery Macleod and McCarthy experiment (showed that DNase destroyed the genetic substance) Griffith experiment (altered streptococcus pneumoniae S strain was virulent and R strain was benign. Proved that even if cells are killed, the chemical inside can still survive)