WorksheetsB10 Stereochemistry in biomolecules
Total questions: 21
Worksheet time: 11mins
What is the difference between D and L isomers of the carbohydrates
D isomers have the hydroxyl group on the left side
The difference lies in the orientation of hydroxyl group on the chiral carbon furthest from carboxyl group
L isomers have the hydroxyl group on the left side
The difference lies in the orientation of the hydroxyl group on the chiral carbon furthest from carbonyl group
D-Ribose and L-Ribose are
Enantiomers
Diastereomers
non-superimposable
mirror image
These two carbohydrates molecules are isomers
True
False
Epimers are diastereomers that differ in the configuration of how many chiral carbon
(a)
What is the characteristics of cellulose
A polymer of B-glucose
Monomers bind by 1,4 glycosidic links
Branched structure
Low mechanical strength
Structure shown is
B-glucose
a-glucose
a-fructose
B-fructose
What form of Vitamin A involves in vision mechanism
Retinol
Retinoic acid
Retinal
Characteristics of Rhodopsin
Made up of trans-retinal and opsin protein
Made up of cis-retinal and opsin protein
Light-sensitive pigment
Can be broken down and regenerate
Conversion of cis-retinal to trans-retinal involves
Lights
Enzymes
Generation of electrical signals to be sent to the brain
What happen if we are lack of Vitamin A
Maintained rhodopsin amount
Healthy eyes
Reduced rhodopsin amount
Night blindness
Which of the following best describes stereoisomerism?
Molecules with identical sequences of atoms but different types of chemical bonds.
Molecules with the same arrangement of atoms in space but different sequences of atoms.
Molecules with the same sequence of atoms and chemical bonds but different arrangements of atoms in space.
Molecules with different sequences of atoms and chemical bonds, but identical arrangements of atoms in space.
Which term accurately describes stereoisomers that are incapable of interconversion without the rupture of a covalent bond and encompasses two distinct classes: cis-/transisomers and optical isomers?
Constitutional isomers
Stereochemical isomers
Regioisomers
Configurational isomers
Which of the following statements accurately describes the stereochemistry of amino acids?
All amino acids exhibit cis-/transisomerism due to the arrangement of the amino and carboxyl groups.
Amino acids possess configurational isomerism, with the exception of glycine, which lacks a chiral center.
Optical isomerism in amino acids arises from the different arrangements of side chains around the chiral centre
Amino acids exhibit conformational isomerism, primarily influenced by the rotation of the peptide bond.
Why are 2-amino acids chiral molecules?
Due to the presence of an amino group and a carboxyl group on the same carbon atom.
As a result of the arrangement of functional groups around the α-carbon.
Because they exhibit configurational isomerism, resulting from the arrangement of atoms in space.
Because they contain four different substituents attached to the same carbon atom.
What is the primary distinction between a D-amino acid and its L-isomer?
D-amino acids have an amino group on the right side of the Fischer projection, while L-isomers have it on the left.
The D-amino acid rotates polarized light clockwise, while the L-isomer rotates it counterclockwise.
The D-amino acid is optically inactive, whereas the L-isomer is optically active.
L-amino acids are found in proteins, while D-amino acids are exclusively used in peptide synthesis.
What is a primary distinction in the biological functions between D and L isomers of amino acids?
D-amino acids are primarily involved in enzymatic reactions, while L-amino acids serve as structural components in proteins.
D-amino acids are typically found in the cell membrane, while L-amino acids are involved in cellular signaling pathways.
D-amino acids have specific roles in certain biological processes, such as peptidoglycan formation, while L-amino acids are more widely used in protein synthesis across various organisms.
Why do naturally occurring unsaturated fatty acids typically exhibit a cis-configuration of their double carbon-carbon bonds?
The cis-configuration allows for greater flexibility in the hydrocarbon chains, facilitating membrane fluidity in cells.
The cis-configuration prevents the hydrocarbon chains from adopting linear conformations, thereby reducing intermolecular forces and enhancing membrane permeability.
The cis-configuration restricts the conformational flexibility of the hydrocarbon chains, promoting tighter packing in lipid bilayers.
The cis-configuration minimizes steric hindrance between adjacent carbon atoms, optimizing energy efficiency during lipid metabolism.
Which of the following benefits is commonly associated with the hydrogenation of vegetable oils in the food industry?
Improved nutritional profile due to the absence of cholesterol.
Enhanced flavor and aroma resulting in a controlled texture.
Increased spreadability without the need for additional additives.
Elevated resistance to heat and oxidation leading to extended shelf life.
What is the primary consequence of incomplete hydrogenation in the production of vegetable oils?
The formation of cis-unsaturated triglycerides, which are prone to oxidation and rancidity.
The generation of saturated triglycerides, resulting in a decrease in the oil's viscosity and spreadability.
The presence of trans-unsaturated triglycerides, commonly known as trans-fats, which pose health risks.
Enhanced stability of the oil due to the absence of double bonds, leading to prolonged shelf life.
Why do trans-fatty acids and their triglycerides have a tendency to adopt rod-like conformations with stronger intermolecular forces compared to their cis-isomers?
The presence of trans-double bonds allows for more linear alignment of the hydrocarbon chains, resulting in stronger van der Waals interactions.
The absence of kinks in the trans-hydrocarbon chains enables closer packing, leading to enhanced dipole-dipole attractions.
Trans-fatty acids exhibit a more compact molecular arrangement due to the absence of cis-configuration, promoting stronger hydrogen bonding between molecules.
The rigidity of trans-hydrocarbon chains facilitates the formation of extended, parallel arrangements, resulting in increased London dispersion forces.
Which of the following adverse health effects is associated with the consumption of trans fats?
Decreased risk of coronary heart disease.
Reduced likelihood of obesity and diabetes.
Lower levels of LDL cholesterol in the bloodstream.
Increased risk of coronary heart disease, obesity, diabetes, and Alzheimer’s disease.
