Questions and Answers
What does R represent in amino acids?
Which amino acid has a methyl group as its R group?
Which of the following amino acids must be supplied in the diet for animals?
What characterizes the alkyl side chains of valine, leucine, and isoleucine?
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Which amino acid is derived from alanine and contains an alcohol group?
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Which amino acid is synthesized by animals but not cysteine?
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What forms when two cysteine molecules link via a disulfide bond?
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Which statement about cysteine is correct?
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What is the purpose of hydrolyzing a protein molecule?
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What chemical is commonly used to hydrolyze proteins?
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Which method allows for the separation of amino acids after hydrolysis?
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What is the role of ninhydrin in amino acid determination?
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What does Edman degradation accomplish?
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Why is trypsin used before Edman degradation?
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How many amino acids can typically be sequenced using Edman degradation?
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What is the role of the α-amino group in Edman degradation?
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What is the role of chlorophyll-a in the light reaction of photosynthesis?
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What happens to chlorophyll-a when it absorbs light energy?
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During photolysis of water, what is one of the products formed?
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What is phosphorylation in the context of photosynthesis?
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What characterizes the dark reaction of photosynthesis?
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What role do NADPH and ATP play in the dark reaction?
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What happens to the excited electron from chlorophyll-a during photosynthesis?
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Where does the dark reaction of photosynthesis occur?
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What type of linkage is primarily found in amylose?
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What is the role of carbohydrates as an energy source?
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Which carbohydrate is characterized by a helical structure?
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Which of the following is NOT a function of carbohydrates?
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What does the term 'hydrophobic' refer to in lipids?
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Which of the following properties does NOT apply to carbohydrates?
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Amylopectin differs from amylose because it contains what type of linkage at branching points?
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What is the importance of carbohydrates for brain function?
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What do plants produce during photosynthesis?
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Which carbohydrate is considered a monosaccharide?
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What percentage of carbohydrates is typically composed of carbon?
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Which of the following is classified as a disaccharide?
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How many carbon atoms classify a pentose carbohydrate?
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What type of carbohydrate is glycogen classified as?
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Which of the following is a characteristic of monosaccharides?
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Which carbohydrate classification has three to fifteen sugar units?
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Study Notes
Photosynthesis Process
- Different chloroplast pigments absorb light at various visible spectrum wavelengths.
- Light energy absorbed is transferred to chlorophyll-a, which participates in the light reactions.
- Excited chlorophyll-a releases energy and an electron, resulting in its oxidation.
- Photolysis of water during pigment system II activation splits water into OH⁻ and H⁺ ions, releasing O₂.
Light Reactions
- Reaction: 4H₂O → 4H⁺ + 4(OH⁻) and 4(OH) → 2H₂O + O₂ + 4e⁻
- Electrons from chlorophyll-a travel through an electron carrier system to reduce NADP to NADPH.
- Light energy carried by electrons helps form ATP from ADP and inorganic phosphate, known as phosphorylation.
Dark Reactions
- Dark reactions are enzymatic, occurring in the stroma, independent of light, but require assimilatory power (NADPH + H⁺ and ATP).
- CO₂ is converted to carbohydrates during dark reactions.
Amino Acids
- R groups in amino acids can indicate straight or branched carbon chains; examples include alanine and branched amino acids like valine and leucine.
- Nonpolar alkyl side chains suggest limited water affinity but mutual attraction.
- Essential amino acids (e.g., valine, leucine, isoleucine) must be acquired through diet, unlike alanine and glycine.
Amino Acid Derivatives
- Serine and cysteine, derived from alanine, differ by functional groups (alcohol vs. mercapto).
- Cysteine predominantly exists in proteins in its oxidized form as cystine, linked by disulfide bonds.
Protein Analysis Techniques
- Hydrolytic cleavage of peptide bonds is necessary for amino acid quantification, usually done with concentrated hydrochloric acid.
- Chromatography and ninhydrin staining allow for separation and visualization of amino acids.
- Edman degradation reveals amino acid sequences by stepwise degradation, limited to about 30-50 amino acids.
Carbohydrates Composition and Structure
- Composed of carbon (40-45%), hydrogen (6-7%), oxygen (45-50%), and sometimes nitrogen, sulfur, or phosphorus.
- Monosaccharides: Single sugar units (glucose, fructose).
- Disaccharides: Two sugar units (sucrose, lactose).
- Polysaccharides: Long chains (starch, cellulose, glycogen).
Carbohydrate Classification
- Classified based on carbon number: triose (3 C), tetrose (4 C), pentose (5 C), hexose (6 C).
- Classified by sugar units: monosaccharides (1), disaccharides (2), oligosaccharides (3-15), and polysaccharides (many).
Amylose and Polysaccharides
- Amylose consists solely of glucose linked by α 1,4 linkages, accounting for 15-30% of starch in plants.
- Polysaccharides may have varying structural forms such as amylopectin with branch points.
Carbohydrate Properties
- Solubility: Ability to dissolve in water.
- Sweetness: Varying degrees per carbohydrate type.
- Viscosity: Flowability and thickness.
- Fermentability: Breakdown by microorganisms.
- Crystallinity: Ability to form crystals.
Functions of Carbohydrates
- Serve as the main energy source for cells.
- Structural roles in cell walls and connective tissues.
- Storage of energy as glycogen and starch.
- Facilitate cell recognition and signaling.
- Fiber aids in digestive health and nutrient absorption.
Importance of Carbohydrates
- Essential for brain function and physical performance.
- Provide energy for muscle activity.
- Indigestible fibers improve digestive health.
Lipids Overview
- Lipids are biomolecules insoluble in water but soluble in organic solvents.
- Serve various essential functions in living organisms, with a hydrophobic characteristic.
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Description
Explore the intricate processes of photosynthesis, including both light and dark reactions. This quiz covers chloroplast pigments, the role of chlorophyll-a, and the transformations of light energy into chemical energy. Dive into the details of how water is split and carbohydrates are formed from CO₂.
