Problem Set 3 - Macromolecules

What class of biomolecules is shown in the image below?

protein This is an amino acid, specifically valine (you do NOT need to know that this is valine, just that this is an amino acid). Valine is a branched-chain essential amino acid. This means your body does not make it and you must get it through your diet. Branched-chain amino acids are used in your body to help make energy. Valine is found mainly in protein food sources such as meats, fish, soy, and dairy. Amino acids are the monomers for proteins.

What is the predominant role of phospholipids in organisms? A. Synthesizing hormones. B. Creating semi-permeable membranes. C. Storage of fuel (energy). D. Catalysis of chemical reactions.

B. Creating semi-permeable membranes. Phospholipids are used to build membranes. They are the predominant components of membranes.

In the protein structure hierarchy, quaternary structure: **This question has 2 correct answers, please select them both for full credit** A. is only possible when all subunits are identical. B .results from the aggregation of two or more polypeptide subunits. C. is differential predominantly by the location of R-groups. D. defines a protein's overall function. E. is the overall 3D structure of a polypeptide.

B. and D. = results from the aggregation of two or more polypeptide subunits, defines a protein's overall function. Is the overall structure of the protein that results from the aggregation of two or more polypeptide subunits. The tertiary structure is the overall 3D structure of the polypeptides.

The construction of macromolecules requires the forming _____________ bonds between monomers thru a series of ______________ reactions. A. denaturation; ionic B. covalent; dehydration C. hydrophilic; covalent D. dehydration; covalent E. hydrolysis; polymer

B. covalent; dehydration

When a protein is heated beyond its optimal max temperature, it loses all levels of organization besides the primary level. When this happens, the protein is said to be: A. hydrolyzed B. denatured C. plasmolyzed D. lysed C. dehydrated

B. denatured Denaturation is an irreversible process in which proteins lose their quaternary, tertiary, and secondary structures. This is often due to environmental factors such as pH shifts, radiation, or temperature changes. If proteins in a living cell are denatured, this results in disruption of cellular activity and possibly cell death. Protein denaturation is also a consequence of cell death.

When a macromolecule goes through hydrolysis, the products are A. individual atoms. B. monomers. C. polymers. D. salts. E. ions.

B. monomers. Macromolecules are polymers built up of monomers. Therefore when macromolecules are broken apart via hydrolysis, monomers are left.

Based on your understanding of biological macromolecules, the number of unique monomer molecules that is common to living organisms is closest to which number? A. 1,000 B. >100000 C. 10,000 D. <100

D. <100 This question is intended to get you thinking about those biological concepts that are likely to place limits on what the number of common monomer building blocks is across biology. Consider how increasing the number of monomers determines the diversity of polymers, the complexity of metabolism to create all the monomers, and how evolution might constrain either of these. There's a 95% chance I am going to ask this question (or one very similar to it) on you exam.

Which of the following is NOT one of the four major elements that make up biological macromolecules? A. Nitrogen B. Hydrogen C. Oxygen D. Calcium E. Carbon

D. Calcium Living organisms are made of organic molecules, which have C, H, O, and N as the four major elements. Calcium is an important signalling molecule in biological systems, but is not itself a major component of biological macromolecules.

Most organisms cannot digest cellulose, however cows can. How does the cow do it? A. Because humans have special enzymes which recognizes cellulose material and stops digestion. B. Because cellulose has a lot of branched regions making it difficult for the enzymes to find the cleavage points for complete digestion in most organisms. C. Selective breeding by ranchers has altered the evolutionary trajectory of the cow's stomach, making it possible for them to eat a lot of grass (therefore they are far cheaper to feed). D. Cows have special microbes in their stomachs to help facilitate this process of digestion.

D. Cows have special microbes in their stomachs to help facilitate this process of digestion. Most organisms lack the enzyme which recognizes β-1,4-glycosidic linkages in the cellulose molecules; however the cows have them due to the actions of special gut microbes at work.

Which of the following is correct regarding the comparison of DNA to RNA? A. DNA is FAR more unstable than RNA. This means that DNA is very dynamic, normally varying by the hour in most organisms. B. RNA is the entire collection of nucleic acid found in an organism. For example, it represents the 3 billion bases found in the nucleus of every human cell. C. Uracil replaces adenine in DNA molecules. D. DNA is usually double stranded and RNA is usually single stranded.

D. DNA is usually double stranded and RNA is usually single stranded.

Which of the following is NOT true about hydrocarbons? A. They are only composed of hydrogens and carbons (but can make bonds with other compounds). B. They are absent (without other bonds) in most living organisms. C. They have hydrophobic regions. D. They easily dissolve in water.

D. They easily dissolve in water. Hydrocarbons are non-polar, therefore they do NOT dissolve easily in polar water. Remember: "like dissolves like".

Which level of protein organization includes the folding/coiling of the polypeptide into a repeating configuration. (Often seen as alpha helix or beta pleated sheets). A. primary B. tertiary C. None of the above D. secondary E. quaternary

D. secondary Secondary structure, refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. (The backbone just refers to the polypeptide chain apart from the R groups - so all we mean here is that secondary structure does not involve R group atoms.) The most common types of secondary structures are the α helix and the β pleated sheet. Both structures are held in shape by hydrogen bonds, which form between the carbonyl O of one amino acid and the amino H of another.

Hydrolysis is involved in each of the following except: A. the conversion of glycogen to glucose B. the conversion of triacylglycerol to a mixture of fatty acids and glycerol C. the conversion of a DNA strand into a mixture of four nucleotides D. the conversion of amino acids into polypeptides.

D. the conversion of amino acids into polypeptides.

What would be the molecular formula for a polymer made from seven glucose (C6H12O6) molecules linked together by dehydration reactions? **Think about this before you rush to answer. What actually happens during a dehydration reaction?** A. C60H120O60 B. C42H84O42 C. C36H72O36 D. C6H12O6 E. C42H72O36

E. C42H72O36 For dehydration reactions, for each molecule linked, it loses 2 H and 1 O atom Seven glucose molecules would result in C42H84O42. However, to link those 7 glucose molecules, you need six dehydration synthesis reactions and each rxn would result in the loss of one water molecule (H20)x6. Therefore, you would subtract 12 H and 6 O from your total.

Shown below is a structure of the chitin monomer. Which of the following is TRUE regarding chitin? A. Chitin is very useful in the medical field because of its analgesic properties. B. Chitin is a structural polysaccharide found in all organisms. C. Chitin usually contains sulfur which gives some arthropods a distinctive odor. D. Fungi use chitin to synthesize their unique psychedelic properties. E. Chitin provides the structural framework for the exoskeleton of arthropods.

E. Chitin provides the structural framework for the exoskeleton of arthropods.

Which statements regarding macromolecules is correct? A. Monomers can be broken down into polymers. B. Polymers can be bonded together to make monomers. C. Polymers and monomers are basically the same thing. D. Monomers are usually much larger than their polymer counterparts. E. Polymers can be broken down into monomers.

E. Polymers can be broken down into monomers. Monomers are the units -- "mono-" means "one." Linking many monomers together and you get a polymer. "Poly-" means many.

Which of the following is NOT a function of a lipid? A. Component of cellular membranes B. Long-term energy storage C. Building blocks for some hormone synthesis D. Insulation from the environment E. Store genetic information

E. Store genetic information Lipids do a lot of things, however they do not store genetic info...that's a job for nucleic acids

Which of the following is true about all macromolecules? A. Are monomers are made of smaller polymers. B. They all function to recycle or store energy in one form or another. C. They are all about the same size (weight and number of monomers present). D. None of them are soluable in water. E. They all contain carbon and are organic.

E. They all contain carbon and are organic. Macromolecules are polymers made of smaller monomers. By stringing together many many monomers, they can reach enormous molecular weights.

What type of reaction is depicted above and what it happening? A. dehydration reaction - polymer being broken down B. hydrolysis reaction - polymer being broken down C. None of these D. hydrolysis reaction - polymer being built E. dehydration reaction - polymer being built

E. dehydration reaction - polymer being built The picture is showing a water molecule leaving after two monomer are linked up. Therefore, you are looking at the linking of monomers into a polymer via a dehydration reaction.

Which of the following class of biomolecules is NOT considered as a true polymer? A. Lipids B. Nucleic acids C. Carbohydrates D. Proteins

A. Lipids

Which of the following are the building blocks of proteins? A. amino acids B. monosaccharides C. nucleotides D. peptides E. fatty acids

A. amino acids Amino acids --> polypeptides --> proteins monomer --> intermediate --> polymer

Saturated fatty acids __________________. A. increase the amount of HDL or "good" cholesterol. B. increase the amount of LDL or "bad" cholesterol. C. are generally liquid at room temperature. D. are composed of kinked chains of hydrocarbons with a C=C bond. E. are more commonly found in plant fats as compared to animal fats.

A. increase the amount of HDL or "good" cholesterol.

You are a scientist at a prestigious university and you are studying the effects of various temperatures on the function of a particular fictitious cellular protein, "toxeliminator" or "TEP" for short. The function of the protein in the cell is to break apart and eliminate toxins that invade the cell. TEP is an enzymatic protein that functions optimally at normal human body temp and neutral pH. The following chart depicts your experimental set-up. Test TubeTest Tube Temp (*C)Contents of test tubeA37*2 ml toxin; 2 ml toxeliminator proteinB57*2 ml toxin; 2 ml toxeliminator proteinC77*2 ml toxin; 2 ml toxeliminator proteinD97*2 ml toxin; 2 ml toxeliminator protein For your data analysis, you measure the amount of toxin still left in each test tube 10 minutes after you have mixed the test tube ingredients. You have written down your results, but somehow, you mixed up the tubes and now you don't know which measurement goes with which tube! The following is your data. Amount of toxin left in tube (ml) 1.3 2.0 0.1 1.8 Which piece of data most likely corresponds to tube D. A. 1.8 B. 1.3 C. 2.0 D. None of these data make sense for Tube D. E. 0.1

C. 2.0 The higher the temperature, the less effective the TEP is TEP functional optimally at normal human body temp (which is 37C). Therefore, in test tube A, optimal activity should take place and the toxeliminator protein should effectively remove all (or most of the toxin). This corresponds to the result of 0.1 ml remaining. In tube D, you have it at 97*C, WAY over the optimal temp for those enzymes to function. Therefore, your toxeliminator protein has most likely degraded. If this protein is degraded, it cannot remove your toxin, thus leaving all the the 2.0 ml in the tube.

Which of the following is FALSE concerning glycogen: A. Glycogen consists of glucose monomers. B. Glycogen is a storage polysaccharide. C. Glycogen is the major storage form of glucose in plants. D. Glycogen is most abundantly found in muscle and liver tissues.

C. Glycogen is the major storage form of glucose in plants.

What is one function of triglycerols living organisms? A. Catalysis of chemical reactions. B. Synthesis of hormones. C. Storage of fuel (energy). D. Cell structure. E. Storing genetic information.

C. Storage of fuel (energy). Triglycerides serve a necessary function, without them your body would run out of energy unless you were eating constantly. They provide your body with energy, but their main function is to store energy for later use. The food you eat contains calories in the form of carbohydrates, protein and fat. When you consume more calories than your body can use, it stores those calories in the form of triglycerides. Fat cells hold the triglyceride molecules until your body needs energy, such as between meals. Hormones signal the fat cells to release the triglycerides for your body to use.