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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mcq biology

MCQ on Lipids and Fats (Biochemistry MCQ 009) with Answer Key

Fat triglyceride shorthand formula

An Unsaturated Fat (source wikipedia)

MCQ on Lipids, Fats & Waxes
Biochemistry MCQ 008
(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). Which of the following molecule can act as molecular chaperons for assisting the folding of proteins?

a.      Carbohydrates
b.      Vitamins
c.       Lipids
d.      Amides

(2). Which of the following macro-molecule can be most structurally diverse among living world?

a.      Carbohydrates
b.      Proteins
c.       Nucleic acids
d.      Lipids

(3). Fat storing cells of vertebrates are called

a.      Hepatocytes
b.      Asterocytes
c.       Adipocytes
d.      Melanocytes

(4). The enzyme abundantly distributed in adipocytes and germinating seeds are

a.      Proteases
b.      Lipase
c.       Cellulase
d.      Nuclease

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biological chemistry

Enzyme Regulation Mechanisms: The Molecular Methods to Regulate Enzymes and Enzymatic Acitvity

what are regulatory enzymes

What are enzymes?

Ø  All living organisms in the world should possess TWO fundamental properties

Ø  They are:

(1). Must be able to self-replicate

(2). Must be able to catalyze chemical reactions efficiently and selectively

Ø  Enzymes are the molecules which enables each living entity to do these two fundamental activities

Ø  Enzymes are better known as biological catalysts

Ø  Almost all enzymes are highly specialized proteins

Ø  Ribozymes: RNA molecules with catalytic properties

Ø  Abzymes: antibodies with catalytic properties

What is enzyme regulation?

Ø  Enzyme regulation definition: “Process, by which cells can turn on, turn off, or modulate the activities of various metabolic pathways by regulating the activity of enzyme”

Ø  Enzymes have extraordinary catalytic power

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Molecular Biology Tutorials

Nucleotide Excision Repair (NER) in Prokaryotes (DNA Repair Mechanism: Part IV)

The UvrABC Endonuclease (Excinuclease) Repair of DNA in Prokaryotes

What is Nucleotide Excision Repair (NER)?

As the name suggests it is a type of DNA repair mechanism. In nucleotide excision repair or NER, the damaged base along with a short stretch of healthy strand is removed and later the gap is refilled with correct nucleotides. Thus the NER pathway operates by ‘cut and patch’ mechanism. Even though nucleotide excision repair mechanism is present in prokaryotes and eukaryotes, the components of the pathways in both groups shows considerable variations. The prokaryotes shows relatively simple nucleotide excision repair mechanism, where as in eukaryotes, the NER pathway is quite complex with many enzymes.

UvrABC Excinuclease repair

Image source: wikipedia

Nucleotide Excision Repair can repair a variety of bulky lesions of the DNA such as pyrimidine dimers formed by UV irradiation and it can also remove chemically modified bases.

Classification of NER:

(1). UvrABC Endonuclease NER in Prokaryotes

(2). NER in Eukaryotes

There are two types of NER mechanism in eukaryotic cells

(a). Transcription Coupled Nucleotide Excision Repair (TC-NER)

(b). Global Genomic Nucleotide Excision Repair (GG-NER)

In this post, we will discuss only the NER mechanism of prokaryotes. The NER mechanism in prokaryotes is better known as UvrABC Endonuclease repair.

Enzymes involved in NER pathway of prokaryotes:

Nucleotide excision repair pathway in prokaryotes is orchestrated by UvrABC endonuclease complex. The NER method is also assisted by DNA polymerase I and DNA ligase enzymes. UvrABC endonuclease complex is a special class of endonuclease enzyme involved in DNA repair of prokaryotes. The name is derived from the root term ultraviolet radiation, since the level of most of these enzymes will be elevated in the bacterial cells when the cells are exposed to UV light.

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