amino acid.doc

8/20/2019 amino acid.doc

1/15

Biomolecules (Chemistry)

Classification of Carbohydrates & Glucose - Preparation and Structure

• Carbohydrates are called saccharides.

• Classification

Classification of Monosaccharides

• Monosaccharides are classified based on the number of carbon atoms and the functional group present in them.

• Different types of monosaccharides arelisted in the given table.

Carbon atoms General term Aldehyde Ketone

3 Triose Aldotriose etotriose

! Tetrose Aldotetrose etotetrose

" #entose Aldopentose etopentose

$ %e&ose Aldohe&ose etohe&ose

' %eptose Aldoheptose etoheptose

Glucose

• Preparation of glucose

• By boiling sucrose ith dilute %Cl or %*+! in alcoholic solution


2/15

• By boiling starch ith dilute %*+!, at 3-3 , under pressure

• Structure

• lucose has been assigned the above structure based on the folloing evidences.

(i) Molecular formula / C$%0+$

(ii) *uggestion of straight chain

(iii) Confirmation of carbonyl (1 C 2 +) group

(iv) Confirmation of the presence of carbonyl group as aldehydic group

(v) Confirmation of the presence of five /+% groups


3/15

(vi) ndication of the presence of a primary alcohol

• The correct configuration of glucose is given by

• lucose is correctly named as D (4) / lucose

Cyclic Structure of Glucose

• The folloing reactions of glucose cannot be e&plained by its open5chain structure.

• Aldehydes give , !5D6# test, *chiff7s test, and react ith 6a%*+ ! to form the hydrogen sulphite addition product. %oever, glucose does not

undergo these reactions.

• The penta5acetate of glucose does not react ith hydro&ylamine. This indicates that a free /C%+ group is absent from glucose.

• lucose e&ists in to crystalline forms, α and β .

The α5form (m.p 2 !0- ) crystallises from a concentrated solution of glucose at 383 and the β 5form (m.p 2 !3 ) crystallises from a hot and saturated

a9ueous solution at 3'0 . This behaviour cannot be e&plained by the open5chain structure of glucose.

• lucose e&ists in to cyclic forms, hich e&ist in e9uilibrium ith the open5 chain structure.


4/15

• :epresentation of the cyclic structure of glucose by %aorth structure;

Structure of Fructose, Disaccharides & Polysaccharides

Structure of Fructose

• +pen5chain structure;

• Cyclic structure;

• :epresentation of the structure of fructose by %aorth structures


5/15

Disaccharides

lycosidic lin


6/15

• Lactose

• Commonly consists of to components / amylase and amylopectin


7/15

• Cellulose

• #redominant constituent of the cell all of plant cells.

• *traight5chain polysaccharide, composed of only β 5D5lucose

• Glycogen

• *torage5polysaccharide in animal body

• Also


8/15

• *ome amino acids ith their symbols are listed in the given table.

Name Side chain ! "hree#letter symbol $ne#letter code

0. lycine % ly

. Alanine / C%3 Ala A

3. ?aline (%3C)C%/ ?al ?

!. =eucine (%3C)C%/ C%/ =eu =

". solecucine le

$. =ysine % 6/ (C%)! / =ys

'. lutamic acid %++C / C%/ C%/ lu @

. Aspartic acid %++C / C%/ Asp D

-. Cysteine %* / C% / Cys C

08. Methionine %3C/ C% / C%/ Met M

00. #henylalanine C$%"/C% / #he

0. Tryptophan Trp

Classification of Amino Acids

• Based on the relative number of amino and carbo&yl groups, they are classified as acidic, basic and neutral.

• 6on5essential amino acids;

• Amino acids that can be synthesised in the body

• @&ample / lycine, alanine, glutamic acid

• @ssential amino acids;

• Amino acids that cannot be synthesised in the body, and must be obtained through diet

• @&ample / ?aline, leucine, isolecuine

Properties of Amino Acids


9/15

• Colourless and crystalline solids

• @&ist as dipolar ions,


10/15

• F5heli& structure of protein is as follos;

o G5pleated sheet structure of proteins is as follos;

•Tertiary structure of proteins; +verall folding of the polypeptide chains> results in fibrous and globular proteins> secondary and tertiary structuresof proteins are stabilised by hydrogen bonds, disulphide lin


11/15

Denaturation of Proteins

• =oss of biological activity of proteins due to the unfolding of globules and uncoiling of heli&.

• @&ample / Coagulation of egg hite on boiling, curdling of mil


12/15

Name of (itamins Sources Deficiency diseases

?itamin A ish liver oil, car rots,

butter and mil


13/15

• Bases in D6A; Adenine (A), guanine (), cytosine (C) and thymine (T)

• Bases in :6A; Adenine (A), guanine (), cytosine (C) and uracil (L)

• Structure of nucleic acids

o *tructure of a nucleoside;

• *tructure of a nucleotide;

• ormation of a di5nucleotide;


14/15

o n secondary structure, the helices of D6A are double5stranded hile those of :6A are single5stranded.

• The to strands of D6A are complementary to each other.

:eason; %5bonds are formed beteen specific pairs of bases.

• Double5strand heli& structure of D6A;

• Types of :6A;

• Messenger :6A (m5:6A)

• :ibosomal :6A (r5:6A)

• Transfer :6A (t5:6A)

• unctional differences beteen :6A and D6A;


15/15

5 !NA DNA

0. D6A is not responsible for heredity. D6A is the chemical basis of heredity.

.#roteins are synthesised by :6A molecules in

the cells.

D6A molecules do not synthesise proteins, but transfer coded messages for the synthesis

of proteins in the cells.

Documents

amino acid.doc