Class Eleven: Biology

Any compound which is able to rotate the plane polarized light,i.e.light which oscillates in just one plane, to the right is referred to as dextrorotary molecule. Dextrorotation refers to the right handed movement of the ppl.

Easy trick you can follow is remember the name Kedar

R is not a vitamin and remaining four are fat soluble.

It will be easy to remember.

The collection of all the biomolecules present inside the cell is called cellular pool.

The identifying characteristics of structural polysaccharides are as follows:

i) They have comparatively higher molecular weight than other carbohydrates

ii) They are non reducing sugar.

iii) They are insoluble in water and don't taste sweet.

Amino acids are the organic acids having a basic amino (-NH₂) group attached to the chain containing acidic carboxyl

(-COOH) group . Since they have at least one basic amino group and one acidic carboxyl group, they are amphoteric in nature.

The binding site and the catalytic site of an enzyme are collectively called as active site of an enzyme.

Enzymes as a whole are not involved in catalytic activity, only a small part of it gets actively involved in substrate before going catalysis (binding site) and another small part involved in catalytic process (catalytic site)

two examples of polysaccharides are starch and cellulose.

1. Water is the universal solvent. It acts as a solvent for many inorganic and organic compounds
2. Water serves as a good dispersion medium for the colloids of the cells.
3. Water has low density and viscosity which permits rapid diffusion of molecules in the cytoplasm.
4. Water is a raw material for photosynthesis
5. Water is necessary for the germination of seeds and spores.
6. Water helps in maintaining the constant pH in cells.

They are:

• It is the principal genetic material that carries genetic information from generation to generation.
• It controls all the biological activities of a cell. For example. protein synthesis.
• It can replicate and form its own carbon copies.
• It can synthesize RNA by the process of transcription.
• The mutation is caused by changes in the sequence of nitrogen bases in DNA.

Well it's your misconception that every ester is lipid. Only the esters of fatty acids are lipids and in the above reaction ester is formed by the removal of a molecule of water. This is simply a general formula . In the same case if the akyl group(-R) is replaced by fatty acid (which is itself a hydrocarbon chain) then that's lipid. Hope you understood.

Storage polysaccharides are a polysaccharide that occurs in a living organism as a form of stored energy.

Storage polysaccharides include the glycogen in animals and the starch and fructosan in plants.

Examples of polysaccharides : Starch, cellulose and glycogen.

Polysaccharides are also formed as products of bacterial, for example, in yogurt production.

Because the fats have a higher percentage of C and H and lower percentage of O in their molecular structure than the carbohydrates.

When hydroxyl group of one monomer comes to lie adjacent to the hydrogen of another amino acid then through dehydration reaction ie by the loss of one water molecule, a covalent bond is formed which is termed aglyosidicbond.

Polysaccharides, or polycarbohydrates , are the most abundant carbohydrate found in food which provides very important dietary elements for human nutrition. It can be starch , cellulose or glycogen. They are important class of biological polymers. It's function in living organism is generallly either energy storage or structual support.

Watson and Crick described DNA as a double helix that contained two long, helical strands wound together. In their model, each DNA strand contained individual units called bases, and the bases along one DNA strand matched the bases along the other DNA strand. Some characteristics of this DNA are,

a.) DNA consists of about 10^10 deoxyribonucleotides.

b.) The diameter of DNA is about 20 Angstrom.

c.) Nitrogen bases are of two types: purines (Adenine and Guanine) and pyrimidines (Cytosine and...

Amino acids are molecules that combine to form protein. Some of the important function of amino acids are;

a.) Amino acid are building block of proteins .

b.) Amino acids are amphoteric(able to react both as an acid and a base), thus they can buffer in solutions, resisting change in pH .

c.) Histidine are found in active site of enzymes where it causes making and breaking of bonds.

d.) Cysteine links chain together by forming disulfide bonds.

e.) The non- protein amino acids are useful compounds...

Maintaining the constancy of internal environment of an organism ishomeostasis. Water plays an important role in maintaining homeostasis which are mentioned below;

1. Water dissolves gases thus, helps in exchange and transportation of oxygen and carbondioxide.
2. Water , when excreted removes water soluble toxins from the body.
3. Water helps to remove excess heat from body in form of sweat that helps to regulate body temperature.

When the carboxyl group of one amino acid comes to lie adjacent to the amino group of another amino acid then with the loss of one H20 molecule (i.e through dehydration) a covalent bond is formed in between them which is called a peptide bond.