Imp point for CSIR NET JUNE 2019

IMPORTANT TOPICS FOR JOINT CSIR-UGC NET/JRF

EXAM JUNE 2019 (LIFE SCIENCES)

Adaptation in animals and plants

Aminoacylation of tRNA,

Antibiotics production by microorganism and their role in inhibition of different enzymes

Apoptotic genes in C. elegans

 Autonomous and conditional specification

Biodiversity conservation strategies

 Biological species concepts

 Capacitation in mammals

Cell Cycle regulation

Cell junction

Cellular respiration

                                                                              Cleavage Pattern

Complete and partial linkage

 Different larval forms in animal kingdom

 DNA repair

Egg types, symmetry of egg

Endangered species

 Endocrinology and Reproductive Biology

 Endothermic and poikilothermic animals

Enzyme inhibition

Enzyme involved in C3, C4 cycle and their regulation

Epistasis pathways

Extra embryonic membranes in Human developments

 Extracellular Matrix

 Factors blameable for species extinction

Fertilization in Sea urchin

Fluctuation test and Replica plating experiment

Fluorescence tagged technique used to locate intracellular proteins

                                                        Food materials of Green, Brown and Red Algae

 Gastrulation in Xenopus

Gene interaction

 Gene mapping and gene order

 Genes involved in floral organ identity (ABC-Model) and floral meristem identity

 Genetic drift

 Geological time scale

G-Protein Coupled Receptors

 Hypersensitivity types

 Immunoglobulin functions and digestion with papain, trypsin and β-mercaptoethanol

 Inclusive fitness

Ion Channels(ligand gated, voltages gated and mechanically gated)

K and r strategy

 Kin Selection

Lac-Operon (merozygote cases)

 Location of photosynthetic pigments (PS-II, PS-I) and Chl, Bchl distribution

 Lox-P and Cre-recombinase

Maternal Inheritance

Membrane potential

Microarray

 Microbial Genetics (Conjugation, Transduction and Transformation)

 Microscopy

Microtubules and its function

Mode of Natural Selection

 Mutant in Drosophila

 Nitrogen fixation

 NMR

Ordered tetrad and Octad analysis in Neurospora crassa

Pathogens , bacterial and viral diseases

Pedigree Analysis

Phenogram and Phylogenetic tree

Phloem loading and unloading

Photomorphogenesis, light absorption and role of Phy-A,B,C,D,E, Cry-I,Cry-II and Phot-I,II.

Photoprotective mechanism in plants

 Photorespiration

 Plant and Animal Classification hierarchy

Plant pathogen interaction and Stress responses

 Plasma membrane composition

Pluripotent, multipotent and totipotent cells

Point and frameshipt mutation

 Polygenic inheritance

 Population ecology

Population regulation

                                                            Proof ready activity of DNA Pol (in PK/EK)

 Protein cleavages by trypsin, pepsin and chymotrypsin

 Protostome and Deutrostome

 Regeneration in development

Representative of different classes of Phyla (Annelids, Arthropod and Mollusca).

 Restriction Enzymes digestion

 Retinoic acid (Morphogen)

 RNA processing in Drosophila and Trypanosomes,

 Role of protein-53, Retinoblastoma and mdm2/Hdm in cancer

 Secondary metabolites (terpenes, alkaloids)

Secretory pathways of protein trafficking & techniques

 Signaling pathways and functions of different Phytohormones (Auxins, ethylene, GA)

Small silencing RNAs (miRNA, siRNA and piwiRNA)

Speciation

 Ti-plasmid

Top down ecosystem control

Transposable elements

Vaccination

X-ray crystallography,

 λ-Phage gene integration in E.coli (lysogenic and lytic cycle)

Glycolysis regulation

Regulation of glycolysis

In glycolysis glucose is partially oxidized to provide energy for the cell. Therefore, when the cell has plenty of energy available to meet its metabolic needs, the activity of critical enzymes will be reduced in order to suppress glycolysis. Alternatively, when the cell is in need of energy, it will turn glycolysis on by increasing the activity of these enzymes.

The regulation of this pathway occurs at three key points where the enzyme reactions involved are irreversible. These three enzymes are hexokinase, phosphofructokinase and pyruvate kinase. Inhibition of glycolysis is a mechanism to conserve energy by preventing the breakdown of adenosine triphosphate.

Methods of Regulation

Glycolysis is regulated by: The concentration of glucose in the blood, the relative concentration of critical enzymes, the competition for the intermediate products of glycolysis and the levels of certain hormones in the bloodstream.

Uptake of glucose from blood

The level of glucose present in a cell determines the availability of sugar for oxidation via glycolysis. Glucose transport in cell is regulated by several cell surface receptors which are under the control of insulin.

Insulin upregulates the level of glucose transporters Glut-3 or Glut-4 and increase the uptake of glucose from blood stream.

In addition, insulin also regulates breakdown of glycogen to increase the amount of available glucose.

Covalent Modification of Enzyme

Most of the typical protein kinases are regulated by a reversible phosphorylation and dephosphorylation.

In the presence of low glucose in blood, pyruvate kinase is getting phosphorylated by cytosolic enzymes and phosphorylated pyruvate kinase is less active. Similarly in the presence of high blood glucose level, it remains as unphosphorylated and that relive the inhibition caused by phosphorylation.

Allosteric regulation

All the three crucial enzymes Hexokinase, phosphofructokinase and pyruvate kinase of glycolysis are regulated allosterically.

In an allosteric regulation, an enzyme binds the allosteric molecules and this modulates the activity of the enzyme either in positive or negative manner.

Levels of hormone in blood stream

Humans and other mammals produce the hormone insulin in response to the ingestion of carbohydrates. High sugar levels stimulate the pancreas to produce insulin, which enhances the entry of glucose into the cell and increases the production of the critical glycolysis enzymes. These actions stimulate glycolysis and lower blood glucose levels.

Alternatively, low blood sugar levels depress insulin production and stimulate the pancreas to release the hormone glucagon, which inhibits glycolysis.

Regulation of Glycolysis takes place at three irreversible reactions:

1) Conversion of D-glucose into glucose-6-phosphate by Hexokinase

Link: http://easylifescienceworld.com/hexokinase-and-glucokinase-enzymes-and-regulation/

2) Conversion of fructose-6-phosphate to fructose- 1, 6-bisphosphate (FBP) by PFK 1

Link: http://easylifescienceworld.com/phosphofructokinase-1-pfk-1-regulation/

3) Conversion of phosphoenolpyruvate into pyruvate by pyruvate kinase

Link: http://easylifescienceworld.com/regulation-of-pyruvate-kinase/

Table: Summary of regulation of glycolysis

Operon

Inducible and repressible operon

An operon is a cluster of genes on the chromosome that is controlled by a single promoter.

They are two types of operons according to the functions they perform: Inducible operons and repressible operons.

Major difference:  Inducible operon is regulated by a substrate present in the metabolic pathway while repressible operon is regulated by the presence of a metabolic end product known as a co-repressor.

Inducible operon

Definition: Structural genes in the operon is normally ‘Off’ but can be turned on by an inducer.

In inducible operons, the genes are kept switched off until a specific metabolite inactivates the repressor.

The inducible operons function in catabolic pathways.

The nutrients utilized in the pathway activate enzyme synthesis.

An inducible operon is switched on by an inducer. An inducer functions by converting the repressor protein into an inactive form.

Example: Lac operon is an inducible operon

Allolactose acts the inducer molecule that binds to the repressor protein called as lac repressorproduced by the lacl gene (the regulatory gene of lac operon) and switches on the operon to transcribe the gene.

How the inducible operon is regulated?

The inducible operon is regulated in the presence of a chemical substance known as inducer. An inducer is usually the precursor/substrate for a metabolic pathway. In the presence of precursor, the operon is said to be switched on.

When no precursor is available, it would be wasteful for the cell to synthesize the enzymes needed to metabolize the precursor. So the operon remains switched off with the help of an active repressor.

As soon as precursor becomes available, some of it binds to the repressor, rendering the repressor inactive so that it unable to bind to the operator site.

Now RNA polymerase can bind to the promoter and transcribe the structural genes. The resulting mRNA is then translated into enzymes which convert substrate into product.

Figure 1: Regulation of an inducible operon

Repressible operon

Definition: Structural genes in the operon is normally ‘On’ but can be turned off by a co repressor

In repressible operons, genes are kept switched on until the repressor is activated by a specific metabolite

The repressible operons function in anabolic pathways.

The production is switched off by the end products of the pathway which repress enzyme synthesis.

The free repressor (aporepressor) cannot bind to the operator. Only the repressor/effector molecule (co-repressor) complex is active in binding to the operator.

Example: Trp operon is a repressible operon.

The amino acid tryptophan can be synthesized by bacterial cells. If a sufficient supply of tryptophan is present in the environment or culture medium, then there is no reason for the organism to expend energy in synthesizing the enzymes necessary for tryptophan production.

A mechanism has therefore evolved whereby tryptophan plays a role in repressing the transcription of mRNA needed for producing tryptophan-synthesizing enzymes.

 How the repressible operon is regulated?

The repressible operon is regulated in the presence of a chemical substance known as co-repressor. A co-repressor is always an end product of a metabolic pathway. In the presence of a co-repressor, the operon is said to be switched off.

The concentration of the co-repressor is directly proportional to the regulation of transcription within the cell. With the increment of the co-repressor concentration, apo-repressor and co-repressor complex is formed. (The apo repressor is a protein and is coded by the regulator gene present in the operon). This complex binds to the operator region and stops the transcription of structural genes.

During low level of co-repressor concentrations, the joining of apo-repressor and operator gene is prevented. This enables the continuation of the formation of co-repressor. As a result its concentration again increases.

Then the apo-repressor and co-repressor complex combines with the operator gene and turns off the gene expression. This prevents the process of transcription and thereby stops the synthesis of enzymes.

Figure 2: Regulation of a repressible operon

Gene regulation

Gene regulation

Gene regulation

Organisms do not want all of their genes to be expressed all of the time. This would use up too many resources and energy. So, cells have evolved mechanisms for controlling gene expression. By turning off the expression of genes when their products are not needed, an organism can save energy and can utilize the conserved energy to synthesize products that maximize growth rate.

Definition: Any mechanism used by a cell to increase or decrease the production of specific gene products (protein or RNA). Cells can modify their gene expression patterns to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources.

There are three broad levels of regulating gene expression in bacteria:

Transcriptional control (whether and how much a gene is transcribed into mRNA)

Translational control (whether and how much an mRNA is translated into protein)

Post-translational control (whether the protein is in an active or inactive form and whether the protein is stable or degraded)

In case of eukaryotes gene expression can be regulated at post transcriptional level too.

Based on our shared evolutionary origin, there are many similarities in the ways that prokaryotes and eukaryotes regulate gene expression; however, there are also many differences.

All three domains of life use positive regulation (turning on gene expression),negative regulation (turning off gene expression) and co-regulation (turning multiple genes on or off together) to control gene expression, but there are some differences in the specifics of how these jobs are carried out between prokaryotes and eukaryotes.

The regulatory mechanisms with the largest effects on phenotype act at the level of transcription.

Figure 1: Gene expression in bacteria can be regulated at three levels

Regulation of Transcription

Regulating transcription enables a cell to determine when a gene is transcribed. It also allows a cell to increase or decrease the amount of mRNA generated from each gene.

There are five different ways that RNA polymerase (the enzyme that makes RNA from a DNA template) can be affected:

A cell can change the specificity of RNA polymerase for promoters. It does this by using specificity factors. These regulatory proteins will make RNA polymerase more or less likely to bind to a promoter. An example is the sigma factors used in prokaryotic transcription.

Repressor proteins can be used to bind an upstream coding sequence called an operator to inhibit the ability of RNA polymerase to transcribe the gene. This causes decreased expression of a gene.

Activator proteins can bind to the operator region to increase the attraction of RNA polymerase for the promoter. This action increases the expression of the gene.

There are also regulatory regions that lie far upstream to their target gene. These are called enhancer regions. Binding of an activator to enhancer causes the DNA t form loop, which brings the enhancer next to its target gene. This causesincreased expression of the target gene.

When a cell wants to completely turn off the expression of a gene, it uses silencer regions. When a silencer is bound by transcription factors, the gene is silenced.This means there is no expression of genes.

The various regulatory mechanisms used to control transcription seem to fit into two general categories:

Mechanisms that involve the rapid turn-on and turn-off of gene expression in response to environmental changes.

Regulatory mechanisms of this type are important in microorganisms because of the frequent exposure of these organisms to sudden changes in environment.

They provide microorganisms with considerable “plasticity,” an ability to adjust their metabolic processes rapidly in order to achieve maximal growth and reproduction under a wide range of environmental conditions.

Mechanisms referred to as preprogrammed circuits or cascades of gene expression.

In these cases, some event triggers the expression of one set of genes. The product(s) of one or more of these genes functions by turning off the transcription of the first set of genes or turning on the transcription of a second set of genes. Then, one or more of the products of the second set acts by turning on a third set, and so on.

In these cases, the sequential expression of genes is genetically preprogrammed, and the genes cannot usually be turned on out of sequence.

Such preprogrammed sequences of gene expression are well documented in prokaryotes and the viruses that attack them.

Example: When a lytic bacteriophage infects a bacterium, the viral genes are expressed in a predetermined sequence, and this sequence is directly correlated with the temporal sequence of gene-product involvement in the reproduction and morphogenesis of the virus.

Glycolysis

Enzyme catalysed reactions of glycolysis step by step (glycolysis part

Enzyme catalysed reactions of glycolysis step by step

In the first half of glycolysis, energy in the form of two ATP molecules is required to transform glucose into two three-carbon molecules.

 Step 1: Phosphorylation of glucose (First priming reaction)

A glucose molecule is energized and activated for subsequent reactions by the addition of a high-energy phosphate from ATP, forming glucose-6-phosphate.

Enzyme catalysing the reaction: Hexokinase(Requires Mg²⁺ cofactor)

Type of the reaction: Phosphoryl transfer

Phosphoryl group donor: ATP

Nature of the reaction: Irreversible under intracellular conditions

Phosphorylation site on glucose: Hydroxyl group on C-6 of glucose

(Kinases are enzymes that catalyze the transfer of the terminal phosphoryl group from ATP to an acceptor nucleophile. The acceptor in the case of hexokinase is a hexose, normally D-glucose, although hexokinase also catalyzes the phosphorylation of other common hexoses, such as D-fructose and D-mannose)

Why the Hexokinase require Mg²⁺ ion as cofactor?

Because the true substrate of the enzyme is not ATP^4- but the MgATP^2-

Mg²⁺ shields the negative charges of the phosphoryl groups in ATP, making the terminal phosphorus atom an easier target for nucleophilic attack by an OH of glucose.

This step is notable for two reasons:

(1) Glucose 6-phosphate cannot diffuse through the hydrophobic interior of the plasma membrane, because of its negative charges. The cell lacks transporters for G6P. So it can no longer leave the cell.

(2) The addition of the phosphoryl group begins to destabilize glucose, thus facilitating its further metabolism.

Additional point to remember: This reaction consumes ATP, but it acts to keep the glucose concentration low, promoting continuous transport of glucose into the cell through the plasma membrane transporters.

Step 2: Conversion of Glucose 6-Phosphate to Fructose 6-Phosphate

Isomerization of glucose 6-phosphate (an aldose) to fructose 6-phosphate (a ketose)

Enzyme catalysing the reaction: Phosphohexose isomerase (phosphoglucose isomerase)

Type of the reaction: Isomerization

Nature of the reaction: Reversible under normal cell conditions

However, it is often driven forward because of a low concentration of F6P, which is constantly consumed during the next step of glycolysis. Under conditions of high F6P concentration, this reaction readily runs in reverse.

(This isomerization has a critical role in the overall chemistry of the glycolytic pathway, as the rearrangement of the carbonyl and hydroxyl groups at C-1 and C-2 is a necessary prelude to the next two steps. The phosphorylation that occurs in the next reaction (step 3 ) requires that the group at C-1 first be converted from a carbonyl to an alcohol, and in the subsequent reaction (step 4 ) cleavage of the bond between C-3 and C-4 requires a carbonyl group at C-2).

Step 3: Phosphorylation of Fructose 6-Phosphate to Fructose 1, 6- bisphosphate(Second priming reaction)

PFK -1 catalyzes the transfer of a phosphoryl group from ATP to fructose 6-phosphate to yield fructose 1, 6-bisphosphate

Enzyme catalysing the reaction: Phosphofructokinase-1 (PFK-1)

Type of reaction: Phosphoryl transfer

Phosphoryl group donor: ATP

Nature of the reaction: Irreversible under cellular conditions

It is the first “committed” step in the glycolytic pathway; glucose 6-phosphate and fructose 6-phosphate have other possible fates, but fructose 1, 6-bisphosphate is targeted for glycolysis.

(Phosphofructokinase -1 is a regulatory enzyme. It is the major point of regulation in glycolysis).

Additional information:

The prefix bis- in bisphosphate means that two separate monophosphate groups are present, whereas the prefix di- in diphosphate (as in adenosine diphosphate) means that two phosphate groups are present and are connected by an anhydride bond.

Step 4: Cleavage of Fructose 1, 6-Bisphosphate

This is the “lysis” step that gives the pathway its name.

The modified sugar fructose-1, 6-bisphosphate is unstable, which allow it to split in half and form two phosphate-bearing three-carbon sugars (triose phosphates)

Fructose 1, 6-bisphosphate is cleaved to yield two different triose phosphates:

Glyceraldehyde 3 phosphate (an aldose)

Dihydroxy acetone phosphate (a ketose)

Enzyme catalysing the reaction: Fructose 1, 6-bisphosphate aldolase (simply aldolase)

Type of reaction: Aldol cleavage or aldol condensation

Nature of the reaction: Reversible

(Aldolase: This enzyme derives its name from the nature of the reverse reaction, an aldol condensation).

Step 5: Interconversion of the Triose Phosphates

Type of reaction: Isomerization

Only one of the two triose phosphates formed by aldolase (glyceraldehyde 3-phosphate) can be directly degraded in the subsequent steps of glycolysis.

The other product, dihydroxy acetone phosphate, is rapidly and reversibly converted to glyceraldehyde 3-phosphate by triose phosphate isomerase.

(Isomerase catalyzes the reversible conversion between the two three-carbon sugars. This reaction never reaches equilibrium in the cell because the next enzyme in glycolysis uses only glyceraldehyde-3-phosphate as its substrate (and not dihydroxy acetone phosphate). This pulls the equilibrium in the direction of glyceraldehyde-3-phosphate, which is removed as fast as it forms. Thus, the net result of steps 4 and 5 is cleavage of a six-carbon sugar into two molecules of glyceraldehyde-3-phosphate; each will progress through the remaining steps of glycolysis).

Here ends the first phase of glycolysis.

 To summarize: In the preparatory phase of glycolysis the energy of  2 ATP is invested, raising the free-energy content of the intermediates, and the carbon chains of all the metabolized hexoses are converted into a common product, glyceraldehyde 3-phosphate.

The payoff phase of glycolysis (Phase of energy generation)

The energy gain comes in the payoff phase of glycolysis.

Step 6: Oxidation of Glyceraldehyde 3-Phosphate to 1, 3-Bisphosphoglycerate

Enzyme catalysing the reaction:Glyceraldehyde 3- phosphate dehydrogenase

Type of reaction: Phosphorylation coupled to oxidation

Nature of the reaction: Reversible

The reaction catalyzed by glyceraldehyde 3- phosphate dehydrogenase is really the sum of two processes:

1) The oxidation of the aldehyde to a carboxylic acid by NAD⁺

2) The joining of the carboxylic acid and orthophosphate to form the acyl-phosphate product

 Explanation in detail

First reaction:  The sugar is oxidized by the transfer of electrons and H⁺ to NAD+, forming NADH (a redox reaction).

The acceptor of hydrogen in the glyceraldehyde 3- phosphate dehydrogenase reaction is NAD⁺

H⁺ ion from the aldehyde group of glyceraldehyde 3-phosphate reduces the coenzyme NAD⁺ to NADH.

The other hydrogen atom of the substrate molecule is released to the solution as H⁺

This reaction is very exergonic, and the enzyme uses the released energy to attach a phosphate group to the oxidized substrate, making a product of very high potential energy. The source of the phosphates is the pool of inorganic phosphate ions that are always present in the cytosol.

1, 3-Bisphosphoglycerate is an acyl phosphate (carboxylic acid anhydride with phosphoric acid). Such compounds have a high phosphoryl-transfer potential.

One of its phosphoryl groups is transferred to ADP in the next step in glycolysis.

Step 7: Formation of ATP from 1, 3-Bisphosphoglycerate

 Type of reaction: Phosphoryl transfer

Nature of the reaction: Reversible

Enzyme catalysing the reaction:Phosphoglycerate kinase

 Reaction: Enzyme catalyzes the transfer of the phosphoryl group from the acyl phosphate of 1, 3-

bisphosphoglycerate to ADP. ATP and 3-phosphoglycerate are the products.

Steps 6 and 7 of glycolysis together constitute an energy-coupling process in which 1, 3-bisphosphoglycerate is the common intermediate.

The outcomes of the reactions catalyzed by glyceraldehyde 3-phosphate dehydrogenase and phosphoglycerate kinase are:

Glyceraldehyde 3-phosphate (an aldehyde) is oxidized to 3-phosphoglycerate (a carboxylic acid).

NAD⁺ is reduced to NADH.

ATP is formed from Pi and ADP at the expense of carbon oxidation energy.

The formation of ATP by phosphoryl group transfer from an organic substrate such as 1, 3-bisphosphoglycerate is referred to as a substrate-level phosphorylation.

(Reason: The phosphate donor (1, 3-BPG) is a substrate with high phosphoryl-transfer potential).

Point to remember: Because of the actions of aldolase and triose phosphate isomerase, two molecules of glyceraldehyde 3- phosphate were formed from single glucose and hence two molecules of ATP were generated. These ATP molecules make up for the two molecules of ATP consumed in the first stage of glycolysis.

Additional information

(Substrate-level phosphorylations involve soluble enzymes and chemical intermediates (1, 3-bisphosphoglycerate in this case). Respiration-linked phosphorylations, on the other hand, involve membrane-bound enzymes and transmembrane gradients of protons).

Step 8: Conversion of 3-Phosphoglycerate to 2-Phosphoglycerate

 Type of reaction: Phosphoryl shift

Enzyme catalysing the reaction:Phosphoglycerate mutase

Nature of the reaction: Reversible

 Reaction: Intramolecular shift of the phosphoryl group between C-2 and C-3 of glycerate.

This step prepares the substrate for the next reaction. Mg²⁺ cofactor is essential for this reaction

Step 9: Dehydration of 2-Phosphoglycerate to Phosphoenolpyruvate

Type of the reaction: Dehydration

Nature of the reaction: Reversible

Enzyme catalysing the reaction: Enolase

 Reaction: Removal of a molecule of water from 2-phosphoglycerate to yield phosphoenolpyruvate (PEP)

 This enzyme causes a double bond to form in the substrate. The electrons of the substrate are rearranged in such a way that the remaining phosphate bond becomes very unstable, preparing the substrate for the next reaction. An enol phosphate has a high phosphoryl-transfer potential.

 Why does phosphoenolpyruvate have such a high phosphoryl-transfer potential?

The phosphoryl group traps the molecule in its unstable enol form. When the phosphoryl group has been donated to ATP, the enol undergoes a conversion into the more stable ketone namely, pyruvate.

Step 10: Transfer of the Phosphoryl Group from Phosphoenolpyruvate to ADP

Type of reaction: Phosphoryl transfer

Nature of the reaction: Irreversible

Enzyme catalysing the reaction: Pyruvate kinase

 Reaction: Transfer of the phosphoryl group from phosphoenolpyruvate to ADP, which requires K⁺ and either Mg²⁺ or Mn²⁺.

The products of the reaction is 2 ATP molecule/glucose and 2 pyruvate/glucose

(Pyruvate is the ionized form of pyruvic acid)

ATP generation occurs via substrate level phosphorylation

Since the molecules of ATP used in forming fructose 1,6-bisphosphate have already been regenerated, the two molecules of ATP generated from phosphoenolpyruvate are “profit.”

Overview of glycolytic pathway

Biology Quiz

Biology

1. In which of the following bacteria the codon UGA encodes the amino acid TRYPTOPHAN instead of the usual STOP CODON

A. Mycobacterium
B. Mycoplasma
C. Methanococcus
D. All of the above

2. L-form of bacterial attacks

A. Cell wall
B. S-layer
C. Membrane pores
D. Phosphoserine

3. Which of the following required cell to cell contact?

A. Conjugation
B. Transformation
C. Transduction
D. All of the above

4. Genotypic variation can NOT happen via

A. Mutation
B. Sporulation
C. Conjugation
D. Transduction

5. Inhibits DNA synthesis in bacteria

A. Cyclosporine
B. Tetracycline
C. Polymyxin
D. Quinolones

6. FG repeat refers to

A. Functional gradient repeat

B. Phenylalanine glycine repeat

C. Fusogenic glycine repeat

D. Formyl glycine repeat

7. Permeases are

A. Protein channels
B. Protein carriers
C. Lipid vesicles
D. Cell-surface carbohydrates

8. OXA complex means

A. Oxygen affinity complex in chloroplast

B. Oxidase assembly complex in chloroplast

C. Oxygen affinity complex in mitochondria

D. Oxidase assembly complex in mitochondria