mcq biology

MCQ on Membrane Lipids with Answer Key & Explanations (Biochemistry MCQ 010)


easybiologyclass, Archaebacterial ether lipids of plasma membrane

For details: Membrane lipids

MCQ on Membrane Lipids
Biochemistry MCQ-010
(Multiple Choice Questions in Biology / Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT BET JRF, GATE, ICAR NET, PG Entrance)


(1). A genetic disorder caused by mutation in the hexosaminidase enzyme A which hydrolyze the GM2 to GM3 during membrane lipid turnover:

a.       Tay-Sachs syndrome
b.      Fabryi disease
c.       Gauche’s disease
d.      Niemann-Pick disease

(2). The simplest hydrophilic moiety present in the membrane lipid is:

a.       Phosphate group
b.      Hydroxyl group
c.       Amino group
d.      Glucose

(3). Which of the following cellular event can be best regulated by prostaglandins?        

a.       Synthesis of inter cellular cyclic AMP
b.      Synthesis of intra cellular cyclic AMP
c.       Synthesis of inter cellular cyclic GMP
d.      Synthesis of intra cellular cyclic GMP

(4). Which of the following statement is true regarding the solubility of steroids in biological fluids?

a.       Steroids and cholesterols are equally soluble
b.      Steroids are more soluble than cholesterol
c.       Cholesterol are more soluble than steroids
d.      Cholesterol and steroids are completely insoluble

(5). The potent molecular signal molecule Platelet Activating Factor (PAF) is an example for:

a.       Glycolipid
b.      Phospholipid
c.       Ether lipid
d.      Ceramide

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mcq biology

MCQ on Fatty Acids with Answer Key (Biochemistry MCQ-9)


Difference between cis and trans fatty acid

‘cis’ and ‘trans’ fatty acids (source wikipedia)

MCQ on Fatty Acids
Biochemistry MCQ 009
(Multiple Choice Questions in Biology / Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT BET JRF, GATE, ICAR NET, PG Entrance)


(1). Most commonly occurring fatty acids in nature are:

a.       Even number of carbon atoms in an un-branched chain of 12 – 24 carbons
b.      Odd number of carbon atoms in an un-branched chain of 12 – 24 carbons
c.       Even number of carbon atoms in a branched chain of 12 – 24 carbons
d.      Odd number of carbon atoms in a branched chain of 12 – 24 carbons

(2). In most of the naturally occurring mono-unsaturated fatty acids, the double bonds will be placed between ____________.

a.      C6 – C7
b.      C7 – C8
c.       C8 – C9
d.      C9 – C10

(3). Which of the following molecule acts as a sugar carrier in animals?

a.       Warfarin
b.      Ubiquinone
c.       Plastoquinone
d.      Dolichol

(4). The best source of trans fatty acid in diet is ____________.

a.       Vegetables
b.      Ground nut
c.       Dairy products
d.      Fruits

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biological chemistry

Difference Between Animal Fats and Plant Fats


Saturated fats and Unsaturated fats

Animal fats Vs Plant Fats
Similarities and Difference between Animal Fats and Plant Fats

Fats, oils and waxes are the general terms describing a structurally diverse bio-macromolecule called ‘lipids’. Lipids are esters of glycerol and fatty acids. One glycerol molecule is esterified with three fatty acid residues to form a triglyceride. Physical, chemical and structural diversity of fats varies with the fatty acid composition in the triglycerides. Lipids with saturated fatty acids (saturated fat) tend to be solid at room temperature (25oC) and hence we generally call it as ‘fat’. On the other hand, lipids with unsaturated fatty acids (unsaturated fat) tend to be liquid at room temperature and thus they are called ‘oils’. Lipids are present in all living organisms including Archaebacteria. They are very abundant in plants and animals. Fats of animal origin are called as ‘animal fat’ and those of plants are called ‘plant fats’. In this post we will discuss about what are the difference between animal fats and plant fats.


Similarities between animal fats and plant fats

Ø  Both animal and plant fats are triglycerides (one glycerol esterified with three fatty acid residues)

Ø  Both are food reserve of the cell

Ø  Unsaturated and saturated fats occurs in both plants and animals

Ø  Majority of the physical and chemical characters of animal and plant fats are same


Difference between Animal fats and plant fats

Animal fats (Fats)

1. Example for animal fat: Butter fat, Beef fat

2. Animals fats are relatively rich in saturated fatty acids

3. Animals fats due to their saturation, tend to stay solid at room temperature, hence commonly known as ‘fats’

4. Iodine number of animal fats will be relatively less (iodine number denote the degree of un-saturation in fatty acids)

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biological chemistry

Biochemistry of Plasma Membrane Lipids: Properties, Structure and Classification (Biochemistry Lecture Notes)

PLASMA MEMBRANE LIPIDS
Biochemistry, Properties, Structure and Classification of Lipids of Plasma Membrane

 “Good fences make good neighbors”
Robert Frost, “Mending Wall”, 1914


Biological membrane system: Biological membranes are highly dynamic two layers thick sheath like structures formed by the non-covalent assemblage of lipids, proteins and carbohydrates. They form closed boundaries between different compartments of the cells such as separation of nucleoplasm from the cytoplasm by nuclear membrane in all eukaryotes. They act as barriers to the passage of polar molecules and ions. The thickness of membrane varies among different classes of organisms and the average width ranges from 60 Å (6 nm) to 100 Å (10 nm) in most of the cases.

Even though membrane contains carbohydrates and proteins, the major structural components of bio-membrane are a special class of lipids called membrane lipids. In storage lipids (triglycerides) the three –OH groups of glycerol moieties are esterified by three fatty acids and thus they are completely non-polar. However in membrane lipids, the hydroxyl group at C1 and C2 are esterified with fatty acids and the remaining third –OH group (at C3) will combine to a polar molecule. Thus membrane lipids are amphipathic because they have hydrophilic head (polar) at one end and hydrophobic tail (nonpolar) at the other end. The long hydrocarbon chain of fatty acids forms the hydrophobic part. The hydrophilic moieties of membrane lipids are of different types and which may be as simple as –OH or may be much complex like carbohydrates or amino acids or their derivatives. We commonly call the polar part of membrane lipid as ‘Head’ group and the nonpolar part as ‘Tail’ group.

easybiologyclass, membrane lipid: polar head and non-polar tail group

easybiologyclass, plasma membrane structure and organization, lipid bi-layer of plasma membrane.

The hydrophobic interactions of the nonpolar parts among themselves and the hydrophilic interaction with water are responsible for the packing of lipids in the membrane. These hydrophilic and hydrophobic interactions are also responsible for the bilayer organization of membranes in the cells.

Classification of membrane lipids:

Membrane lipids are classified based on the properties of ‘Head’ group. The membrane lipids of Prokaryotes, Eukaryotes and Archaebacteria are grouped into four major categories:

.

1.   Phospholipids

2.   Glycolipids

3.   Sterols

4.   Archaebacterial ether lipids

 easybiologyclass, mind map membrane lipid classification chart

.

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