Glycolysis Steps -DMLT Final year

Glycolysis is the metabolic process that serves as the foundation for both aerobic and anaerobic cellular respiration. In glycolysis, glucose is converted into pyruvate

Step 1: Hexokinase

The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. The enzyme that catalyzes this reaction is hexokinase. In this step 1 molecule of ATP has been consumed.

Step 2: Phosphoglucose Isomerase

The second reaction of glycolysis is the rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) by glucose phosphate isomerase (Phosphoglucose Isomerase). this reaction involves an isomerization reaction.

Step 3: Phosphofructokinase

Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1,6 -bisphosphate. The enzyme that catalyzes this reaction is phosphofructokinase (PFK).

Step 4: Aldolase

The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate  (DHAP) and glyceraldehyde 3-phosphate (GAP).

Step 5: Triphosphate isomerase

The enzyme triophosphate isomerase rapidly inter- converts the molecules dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). Glyceraldehyde phosphate is removed / used in next step of Glycolysis.

Step 6: Glyceraldehyde-3-phosphate Dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate. The enzyme that catalyzes this reaction is glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

 

Step 7: Phosphoglycerate Kinase

Phosphoglycerate kinase transfers a phosphate group from 1,3-bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate. by the enzyme phosphoglycerate kinase (PGK). we actually synthesize two molecules of ATP at this step.

Step 8: Phosphoglycerate Mutase

The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate.

Step 9: Enolase

The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).

Step 10: Pyruvate Kinase

The enzyme pyruvate kinase transfers a P from phosphor-enol-pyruvate (PEP) to ADP to form pyruvic acid and ATP Result in step 10. we actually generate 2 ATP molecules.

Steps 1 and 3 = – 2ATP
Steps 7 and 10 = + 4 ATP
Net “visible” ATP produced = 2

TCA Cycle - DMLT Final year

                                              It is also known as TriCarboxylic Acid (TCA) cycle. In prokaryotic cells, the citric acid cycle occurs in the cytoplasm; in eukaryotic cells, the citric acid cycle takes place in the matrix of the mitochondria. 

STEP 1: Formation of Citrate

The first reaction of the cycle is the condensation of acetyl-CoA with oxaloacetate to form citrate, catalysed by citrate synthase. 

STEP 2: Formation of Isocitrate

The citrate is rearranged to form an isomeric form, isocitrate by an enzyme acontinase.

In this reaction, a water molecule is removed from the citric acid and then put back on in another location.

STEP 3: Oxidation of Isocitrate to α-Ketoglutarate

In this step, isocitrate dehydrogenase catalyzes oxidative decarboxylation of isocitrate to form α-ketoglutarate.

In the reaction, generation of NADH from NAD is seen.

STEP 4: Oxidation of α-Ketoglutarate to Succinyl-CoA

Alpha-ketoglutarate is oxidized, carbon dioxide is removed, and coenzyme A is added to form the 4-carbon compound succinyl-CoA.

During this oxidation, NAD+ is reduced to NADH + H+. The enzyme that catalyzes this reaction is alpha-ketoglutarate dehydrogenase.

STEP 5: Conversion of Succinyl-CoA to Succinate

CoA is removed from succinyl-CoA to produce succinate.

The energy released is used to make guanosine triphosphate (GTP) from guanosine diphosphate (GDP) and Pi by substrate-level phosphorylation.

GTP can then be used to make ATP. The enzyme succinyl-CoA synthase catalyzes this reaction of the citric acid cycle.

STEP 6: Oxidation of Succinate to Fumarate

Succinate is oxidized to fumarate.

During this oxidation, FAD is reduced to FADH2. The enzyme succinate dehydrogenase catalyzes the removal of two hydrogens from succinate.

STEP 7: Hydration of Fumarate to Malate

The reversible hydration of fumarate to L-malate is catalyzed by fumarase (fumarate hydratase).

Fumarase continues the rearrangement process by adding Hydrogen and Oxygenback into the substrate that had been previously removed.

STEP 8: Oxidation of Malate to Oxaloacetate

Malate is oxidized to produce oxaloacetate, the starting compound of the citric acid cycle by malate dehydrogenase. During this oxidation, NAD+ is reduced to NADH + H+.

Proteins- Definition, Classification and Properties for dmlt ddt dotat and paramedical students

Proteins- Definition, Classification and Properties: 

Contents:

1. Definition of Proteins
2. Biological Importance of Proteins
3. Classification of Proteins.
4. Important Tests of Proteins
5. Estimation of Proteins

1. Definition of Proteins

Proteins may be defined as the high molecular weight mixed polymers of α-amino acids joined together with peptide linkage (-CO-N H-).
Proteins are the chief constituents of all liv­ing matter. 
They contain carbon, hydrogen, nitro­gen and sulphur and some contain phosphorus also.

2.Biologicalmportance of Proteins.

i.Proteins are the essence of life processes.

ii. They are the fundamental constituents of all protoplasm and are involved in the struc­ture of the living cell and in its function.

iii Enzymes are made up of proteins.

iv. Many of the hormones are proteins.

v. They are involved in blood clotting through thrombin, fibrinogen and other protein factors.

vi. They act as the defence against infections by means of protein antibodies.

3.Classificationof Proteins.

I. Simple proteins

(i) Albumins:

Soluble in water, coagulable by heat and precipitated at high salt concentrations.   Examples – Serum albumin, egg albumin, lactalbumin (Milk), leucosin (wheat), legumelin (soyabeans).

ii) Globulins:

Insoluble in water, soluble in dilute salt solutions and precipitated by half  saturated salt solutions.

Examples – Serum globulin, vitellin (egg yolk), tuberin (potato), myosinogen (muscle), legumin (peas).

(iii) Glutelins:

Insoluble in water but soluble in dilute  acids and alkalis. Mostly found in plants.

Examples – Glutenin (wheat), oryzenin (rice).

(iv) Prolamines: Insoluble in water and absolute alcohol  but soluble in 70 to 80 per cent alcohol.

Examples – Gliadin (wheat), zein (maize).

(v) Protamines:

Basic proteins of low molecular weight.  Soluble in water, dilute acids and alkalis,  Not coagulable by heat. Examples– Salmine (salmon sperm).

(vi) Histones:

Soluble in water and insoluble in very I dilute ammonium hydroxide.   Examples– Globin of hemoglobin and thymus histones.

II. Conjugated Proteins

(i) Nucleoproteins:

Composed of simple basic proteins (pro­tamines or histones) with nucleic acids,   found in nuclei. Soluble in water.

Examples – Nucleoprotamines and nucleohistones.

(ii) Lipoproteins:

Combination of proteins with lipids, such as fatty acids, cholesterol and   phospholipids etc.

Examples – Lipoproteins of egg-yolk, milk and cell membranes, lipoproteins of blood.

(iii) Glycoproteins:

Combination of proteins with carbohydrate (mucopolysaccharides).

Examples – Mucin (saliva), ovomucoid (egg white), osseomucoid (bone).

(iv) Phosphoproteins:

Contain phosphorus radical as a prosthetic group.

Examples – Caseinogen (milk), ovovitellin (egg yolk).

(v) Metalloproteins:

Contain metal ions as their prosthetic  groups. The metal ions generally are Fe, Co. Mg, Mn, Zn, Cu etc.

Examples – Siderophilin (Fe), ceruloplasmin (Cu).

III. Derived Protein

A. Primary derivatives

(i) Proteans:

Derived in the early stage of protein hydrolysis by dilute acids, enzymes or alkalis.     Examples– Fibrin from fibrinogen.

(ii) Metaproteins:

Derived in the later stage of protein hydrolysis by slightly stronger acids and alkalis.   Examples– Acid and alkali metaproteins.

(iii) Coagulated:

They are denatured proteins formed by the action of heat. X-rays, ultraviolet rays etc .   Example: Cooked proteins, coagulated albumins.

B. Secondary derivatives

(i) Proteoses:

Formed by the action of pepsin or trypsin. Precipitated by saturated solution of ammonium sulphate, incoagulable by heat.

Examples – Albumose from albumin, globulose from globulin.

(ii) Peptones: .

Further stage of cleavage than the proteoses. Soluble in water, incoagu­lable by heat and not precipitated by saturated ammonium sulphate solutions.

(iii) Peptides:

Compounds containing two or more amino acids. They may be di-, tri-, and porypeptides.

Examples – Glycyl-alanine, leucyl-glutamic acid.

Deliquescent AND Hygroscopic for ddt,dotat students

                         Deliquescent  AND  Hygroscopic:

Deliquescent substances are solid matter that can get dissolved by absorbing water vapor. The resulting solution is an aqueous solution.  This process is known as deliquescence. These deliquescent substances have a high affinity to water.
for example: sodium hydroxide, potassium hydroxide, ammonium chloride, sodium nitrate, calcium chloride, etc.

Hygroscopic:

Hygroscopic substances are solids that can absorb or adsorb water from its surroundings. When water vapor is absorbed by hygroscopic substances, the water molecules are taken into the spaces of the crystal structure. This causes the volume of the substance to increase. Hygroscopy can result in changes in the physical properties of the hygroscopic substances; such properties include color, boiling point, viscosity, etc.

Some examples: are Zinc chloride (ZnCl2), sodium chloride (NaCl) and sodium hydroxide (NaOH).

Bacterial cell - Structure and Functions

                    Bacterial cell 

              Structure and Function:

Bacterial are unicellular prokaryotic organism.

Bacterial cell have simpler internal structure. 

It lacks all membrane bound cell organelles such as mitochondria, lysosome, golgi, endoplasmic reticulum, chloroplast, peroxisome, glyoxysome, and true vacuole.

A typical bacterial cell have following structure.

A. Structure Outside cell wall

1. Capsule
2. Flagella
3. Pili
4. Cell wall
5. Cytoplasmic membrane
6. Nucleoid
7. Mesosomas
8. Ribosome
9. cytoplasm
10. Spore.

1.Capsule:

• Capsule is 0.2µm thick viscus layer outer layer to the cell wall.
• Capsule is 98% water and 2% polysaccharide or glycoprotein/ polypeptide or both.
• There are two types of capsule.
• It helps in attachments as well as it prevent the cell from desiccation and drying.
• Capsule resist phagocytosis by WBCs.

2. Flagella:

• It is 15-20 nm hair like helical structure emerges from cell wall.
• Flagella is not straight but is helical. It is composed of flagellin protein (globular protein) and known as H antigen.
• Flagella has three parts. Basal body, Hook and filament
• It helps motility of the bacteria

3. Pili or fimbriae:

• Pili are hollow filamentous and non-helical structure.
• They are numerous and shorter than flagella
• Pili is the characteristic feature of gram –ve bacteria.
• Pili is composed of pilin protein.
• Bacteria containing pili: Shigella, Proteus, Neisseria gonorrhoae, E. coli
• Attachment: pili helps the bacteria to attach the host cell surface. Most of the human pathogens of respiratory tract, urinary tract are attached with the help of pili.
• Pili (fimbriae) possess antigenic property
• Specialized function: some pili are modified for specialized function. Eg. Sex pilus (F-pili) help in transfer of DNA from donor to recipient cell during conjugation.
• F-pili also act as receptor for bacteriophage.

4. Cell wall:

• It is an important structure of a bacteria.
• It give shape to the organism.
• On the basis of cell wall composition, bacteria are classified into two major group ie. Gram Positive and gram negative.

Gram positive cell wall

Cell wall composition of gram positive bacteria.

1. Peptidoglycan
2. Lipid and Teichoic acid

Gram negative cell wall

Cell wall composition of gram negative bacteria

1. Peptidoglycan
2. Outermembrane:
   • Lipid
   • Protein
   • Lipopopysaccharide (LPS)

• Peptidoglycan layer is present in cell wall of both gram positive as well as gram negative bacteria. However, gram positive have thick layer of peptidoglycan.
• It is the major surface antigen of gram positive bacteria
• It is an additional layer present in gram negative bacteria.
• It is composed of lipid bilayer, protein and lipo-polysaccharide.

 5.Cell membrane:

• Cell membrane is the inner layer that lies inside the cell wall and encloses the cytoplasm.
• It is also known as cytoplasmic membrane or plasma membrane.
• It is about 80nm thick.
• Cell membrane of bacteria is composed of phospholipid and proteins.
• It is selectively permeable as it allows to pass selective substances such as sugar, aminoacids across it.

6. Nucleus:

• Nucleus is the most important part of the cell.
• It controls and directs all the cellular activities and stores hereditary information of cell
• Bacterial nucleus is known as nucleoid; it lacks nuclear membrane, nuceloplasm and nucleolus.
• Bacterial DNA is naked (lacked histone protein)
• It contains and stores hereditary information of the cell.
• It controls all cell activities.

7. Ribosome:

• Bacterial ribosome is of 70s type.
• Ribosomes are rounded granules found freely floating in the cytoplasm
• Ribosomes are known as universal cell organelle because it is found in both bacterial cell and eukaryotic cell.
• Chemically the ribosomes are made up of nucleic acids (particularly RNA and proteins).
• It helps in protein synthesis. 

8. Mesosome:

• Mesosome is a spherical or round sac like structure found commonly in gram positive bacteria.
• Function: It is the site for respiration in bacterial cell

9. Cytoplasm:

• It is colorless, viscus fluid present inside cell membrane.
• All the cell organelles and inclusions are found floating in cytoplasmic fluid.
• It contains proteins, lipid, minerals, nucleic acids, glycogen, water etc.
• It helps to distribute water, oxygen as other substances throughout the cell.
• Literally, all the cellular content including nucleus, and other cell organelle are floating in cytoplasm.

10. Spores (endospore):

• Spore is metabolically dormant structure produced during unfavourable condition by the process called sporulation
• Sporulation occur during late log phase or early stationary phase
• Under favourable condition spores germinate to give vegetative cell.

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