LIPIDS :: PART 2

FATTY ACIDS

-          These are long chain organic compounds containing 4-30 carbons.

-          These have a single carboxyl group and a long tail of non-polar hydrocarbon.

                               

-          Fatty acids that occur in natural fats have a ‘mono carboxyl group’ with even number of carbon atoms.

-          These are usually straight chain derivatives.

-           Fatty acids with ring structure are called cyclic fatty acids.

-          Fatty acids are bounded to each other by ‘ester linkage’.

                                           

-          Fatty acids are used as energy reserves in humans and other animals.

-          Fatty acids are classified into two types: -

.       Saturated fatty acids

                                    

.      Unsaturated fatty acids

Why Doesn’t Stomach Digest Itself??

Stomach is the organ that carries out the process of digestion. Not only in humans but in many other organism stomach performs this same function. Stomach has a number of enzymes and acids that does the process of digestion.

Stomach produces digestive juices and hydrochloric acid to digest food. The pH of these juices is so low that it can even dissolve metals. So how stomach protects itself from those digestive juices even though it is made up proteins??

              

The answer lies the other secretions made the cells on the inner side of stomach wall. These cells secrete mucus and bicarbonate. Mucus acts as a physical barrier between the acidic juices and the stomach wall. Bicarbonate is highly alkaline and very effective in neutralizing acids. This combination protects the stomach from digesting itself.   

LIPIDS:: PART 1

INTRODUCTION

-          Lipids are heterogeneous group of compounds related to fatty acids.

-          These include fats acids, oils and waxes.

                                  

-          These are insoluble in water but soluble in organic solvents such as chloroform.

-          All lipid molecules are amphiphatic which means they are both hydrophilic and hydrophobic.

-          These help in the formation of bio-membranes.

                          

what makes hair gray???

Basically human hair is made of two parts; root and shaft. Root is a part that is below your scalp and you cannot see that. Shaft is a part that is above your scalp and you can see it growing. The root of every hair strand is surrounded by a bulb like structure called the hair ‘follicle’. Each follicle is made up of hundreds of pigment cells.

              

Pigment cells continuously produce a pigment called melanin (melanin is protein that is dark brown to black in colour). This pigment gives hair shaft their colour. As we grow older the pigment cells in the hair follicle die gradually. Due to the lack this pigment hair also loses its colour from black to lighter shades. Hair with less number of pigment cells acquire grey, silver or white colour.

do animals have blood groups???

Human beings have mainly four blood groups-A, B, AB and O. In humans blood group is determined by a group of carbohydrates on our RBC. Human blood contains antibodies that will trigger a reaction if, a donor of a particular blood group is donating blood to the recipient of another blood group. Therefore, before a blood transfusion, we have to ‘type’ a person’s blood and find out which kind it is.

Do you think animals too have blood groups?? The answer is, yes they do have.

It was found out that dogs have eight basic blood types, though as many as 13 may exist. The types are numbered, and are structured differently than in humans. Dogs do not have naturally occurring antibodies against other blood types.

                            

Cats have three basic blood types. Cats do have natural antibodies against different blood types, like in humans. A cat can receive a transfusion only from a cat with the same blood type.  

PROTEINS:: PART 6

PRIONS

·         An infectious protein is called a prion.

                                     

·         These are often misfolded proteins.

·         Cellular prion proteins (PrPc) may act as acetylcholine      receptors and help in nerve transmission, these are normally found in cell membranes.

·         The infectious form is called prion proteins scrapie (PrPSc).

·         When PrPSc are injected into a body they convert PrPc into PrPSc.

                                           

·         PrPSc cause neurodegenerative diseases by aggregating in the central nervous system and disrupt the healthy tissue.

·         The best known disease caused by prions is Bovine spongiform encephalopathy (BSE) or commonly called the mad cow disease.

why do apples turn brown????

Each and every organism is made of cells; let it be a cat, dog, trees and even fruits. Each cell has thousands of enzymes that catalyze various cellular reactions. The actual mechanism of browning of apples is based on the action of enzymes.

Cells in apple and potatoes have an enzyme known as polyphenol oxidase or tyrosinase. They also have an amino acid called tyrosine. When an apple is cut the tyrosine present in its cells is exposed to atmospheric oxygen and it oxidizes to dark coloured substance called melanin, and this process is catalysed by tyrosinase. This makes a cut apple turn dark.

 To prevent this sliced apples and potatoes should be kept in water so that tyrosine do not react with oxygen and turn the apple dark. 

                                      

The best way to preserve apples is to keep the cut pieces in a carbonated drink. Confused....... think over and comment your answers.

PROTEINS:: PART 5

PROTEIN STRUCTURES

·         Proteins can be divided into four categories based upon their structure.

·         Primary structure: -

Ø  Primary structure refers to the linear sequence of amino acids from the N-terminal to the C-terminal.

·         Secondary structure: -

Ø  In this a polypeptide chain is folded about itself to form alpha-helices and beta-sheets.

Ø  These structures are stabilizes by hydrogen bonds.

Ø  Alpha-helices: -

      These are spiral structures.

      These have right hands or left handed orientation.

      Stabilized by hydrogen bond between amine and carboxyl group.

      These fibres are insoluble.

      Keratin is an example of alpha-helices.

      These form hair, nails, hooves and horns.

Ø  Beta-sheets: -

      These are sheet like structures where two or more sections of polypeptides come together.

      Formed by parallel or anti-parallel arrangement of polypeptides in a plane.

      When all N-terminals are on one edge they are called parallel beta-sheets.

      When alternative chains of N-terminal and C-terminal lie on one edge they are called anti-parallel beta-sheets.

      Silk is an example of beta-sheets.

                            

·         Tertiary structure: -

Ø  This involves folding of a single polypeptide into a globular structure called its tertiary structure.

Ø  Myoglobin and ribonuclease are proteins that have a tertiary structure.

·         Quaternary structure(protein-protein interaction): -

Ø  Association of number of peptide chains into a complex and large sized molecule is called quaternary structure.

Ø  Haemoglobin is the best example of protein with quaternary structure.

What makes you age '8 times' faster??

 Progeria is rare genetic disorder also called 'Hutchinson-Gilford progeria syndrome'. The word progeria has originated from the Greek word 'geras' which means old age and 'pro' means early. As the name suggests this disorder is one of those progeroid syndromes that cause premature aging. The patients suffering from this disorder age eight times faster than an average person.

                                         

This disorder was first recognised by Dr. Jonathan Hutchinson in 1886 and Dr. Hastings Gilford in 1904. This disorder is due to abnormal modification of a protein. In healthy cell LMNA gene encodes for a protein Prelamin A which is converted into Lamin A, in progeric cells Prelamin is produced but is converted into Progerin instead of Lamin A. This change in the protein causes abnormality in the shape of the nucleus. Progerin also help cells in aging but due to this disorder cells age is accelerated by EIGHT TIMES. This causes the individual suffering from this disorder age eight times faster.

                           

Children with progeria appear normal at birth. During the first years of life progeria symptoms can be seen, they include:-

 -  Height and weight below average.

 -  Narrowed face and thin lips.

 -  Head appears larger than face.

 -  Alopecia (hair loss throughout body including eyelashes and    eyebrows).

 -  Visible veins.

 -  High pitched voice.

 -  Spotting and wrinkling of skin.

 -  Abnormal tooth formation.

 -  Fragile bones, stiff joints and hip dislocation.

 -  Insulin resistance.

 -  Several cardiovascular (heart) diseases.

                                         

This rare genetic disorder affects only 1 in 4000000. No treatment is effective to cure progeria. Doctors usually treat these patients to reduce complications like risk of cardiovascular diseases with bypass surgery or low aspirin doses. These patients are also advised to take a high energy diet, stay well hydrated and do regular physical activity. People around progeria patients should treat them equal and boost their morale.