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Questions and Answers
What type of ring is formed by aldohexoses in Haworth projections?
Which type of monosaccharide is associated with forming furanose rings?
What is the common form of D-ribose in the biological context according to Haworth projections?
How does D-Fructose exist in terms of structure in Haworth projections?
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What is the characteristic view of a Haworth projection?
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Which statement accurately describes pyranose?
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What component of a Haworth projection is located at the upper right in a six-membered ring?
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What distinguishes the Dextro and Levo designation in Haworth projections?
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How many chiral carbons are present in an aldohexose?
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Which of the following represents the number of chiral carbons in a ketopentose?
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In the Fischer projection, which lines represent bonds projecting forward from the stereocenter?
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What is the characteristic of a D-monosaccharide in terms of its penultimate carbon?
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Which of the following carbohydrates has no chiral carbons?
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Which type of sugar has the highest number of chiral carbons among aldoses?
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In a Fischer projection of an L-monosaccharide, where is the -OH located on the penultimate carbon?
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How many chiral carbons are found in an aldotetrose?
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In the D form of glucose, where is the CH2OH group positioned?
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Which statement is true concerning the L form of glucose?
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What shape does the six-membered ring of pyranoses adopt for better representation?
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In the chair conformation of b-D-glucopyranose, what is the orientation of groups on carbons 1-5?
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How can Haworth projections and chair conformations be related?
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Which of the following accurately describes a characteristic of the chair conformation?
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What feature distinguishes the D and L forms of sugars in terms of orientation?
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What is typically NOT a characteristic of the L form of glucose?
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Which group replaces the -OH group in amino sugars?
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What is another name for glucose?
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Which monosaccharide is used to differentiate between blood types?
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Which of the following statements about glucose is true?
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Which statement correctly describes galactose?
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Which of the following is NOT a common amino sugar?
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What type of sugar is primarily found in the brain?
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Which of these characteristics applies to glucose?
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What type of glycosidic bond links the two monosaccharides in maltose?
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Which disaccharide is composed of a β-D-galactose unit and a D-glucose unit?
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Which of the following statements is true about sucrose?
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What is the structural composition of cellobiose?
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Which of the following is a characteristic of lactose?
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How many monosaccharide units are found in oligosaccharides?
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What is the primary reason why cellobiose cannot be digested by humans?
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Which food sources commonly contain oligosaccharides?
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Study Notes
Chirality in Carbohydrates
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Aldoses and Chiral Carbons:
- Aldotriose: 1 chiral carbon
- Aldotetroses: 2 chiral carbons
- Aldopentoses: 3 chiral carbons
- Aldohexoses: 4 chiral carbons
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Keto sugars and Chiral Carbons:
- Ketotriose: no chiral carbons
- Ketotetroses: 1 chiral carbon
- Ketopentoses: 2 chiral carbons
- Ketohexoses: 3 chiral carbons
Fischer Projection
- A method for representing tetrahedral stereocenters in two dimensions.
- Horizontal lines indicate bonds projecting forward.
- Vertical lines signify bonds projecting backward.
- Only the stereocenter is in the plane.
L- and D-Monosaccharides
- Assignments of D- and L- to enantiomers of glyceraldehyde established by Emil Fischer in 1891.
- D-monosaccharide: -OH on the penultimate carbon is on the right in Fischer projection.
- L-monosaccharide: -OH on the penultimate carbon is on the left in Fischer projection.
Haworth Projections
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Represent cyclic forms of monosaccharides.
- Pyranose: Six-membered ring, formed by aldohexoses.
- Furanose: Five-membered ring, formed by aldopentoses and ketohexoses.
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Aldopentoses typically form cyclic hemiacetals, predominantly as furanoses in nature.
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D-Fructose also forms a five-membered cyclic hemiacetal.
Dextro and Levo Designation
- In Haworth projections, the orientations of groups determine D or L forms.
- D form: CH2OH is above the ring.
- L form: CH2OH is below the ring (less common in biochemistry).
Chair Conformation
- Pyranoses can be represented accurately in a strain-free chair conformation.
- In β-D-glucopyranose:
- Carbons 1-5 group orientations are up, down, up, down, and up, all equatorial.
Converting Between Haworth and Chair
- The positions (up and down) in Haworth projections translate to chair conformations.
Carbohydrate Derivatives
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Amino sugars: Contain an -NH2 group replacing an -OH group.
- Three common amino sugars in nature.
Biologically Relevant Carbohydrates
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Monosaccharides:
- Glucose: Most abundant; also known as grape, blood sugar, or dextrose; six-membered cyclic form essential for nutrition.
- Galactose: Known as "brain sugar" and "milk sugar"; differentiated in blood types; six-membered cyclic form.
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Disaccharides: Composed of two monosaccharides linked by glycosidic bonds.
- Maltose: Composed of 2 D-glucose units, linked via α(1→4) glycosidic linkage; digestible by humans.
- Lactose: Composed of β-D-galactose and D-glucose linked by β(1→4) glycosidic linkage; hydrolyzed by lactase.
- Sucrose: Most abundant disaccharide, also known as table sugar, found in plants.
- Cellobiose: Comprising two D-glucose units linked via β(1→4) glycosidic linkage; indigestible for humans.
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Oligosaccharides: Contain 3-10 monosaccharide units, bonded via glycosidic linkages; commonly found in foods like onions and whole wheat.
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Description
Explore the concepts of chirality and the number of chiral carbons in aldoses and ketoses. This quiz covers various types of sugars including aldotrioses, aldoses, and ketoses. Test your knowledge on the structural aspects of these carbohydrates.
