Chapter Six , genetics

8/2/2019 Chapter Six , genetics

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Chapter six : the chemistry of life

It's important to know how does bacteria live? how does it multiply?what does it need to be alive? So biochemistry is very important to micro

organisms, we will talk about the organic chemistry of macro molecules :carbohydrates, lipids, proteins and nucleic acids.

Organic chemistry : the study of compounds that contain carbon(carbohydrates, lipids, proteins, and nucleic acids) and other organic

compounds like O, N & H. they could be in the living cells or out of

them.

Biochemistry: the chemistry of living cells.

Organic Chemistry

- Organic compounds contain carbon, which are carbohydrates,

lipids, nucleic acids and proteins.

- Organic chemistry is the branch of science that studies organic

compounds.

- Organic compounds are not necessarily related to living organisms;

although some organic compounds are associated with living

organisms, many are not.

- Organic chemistry involves fossil fuels, dyes, drugs, paper, ink,

paints, plastics, gasoline, rubber tires, food, and clothing all of

them have carbon atoms.

Carbon Bonds

- Carbon atoms have a valence of 4, meaning that they can bond tofour other atoms.

- There are 3 ways in which carbon atoms can bond to each other:

single bond , double bond, and triple bond , for example C & N the

attach by single ,double or triple bonds and C with H we could

have CH3 CH4.

- A covalent bond is one in which a pair of electrons is shared, it is

one of the strongest bonds that u can find in biochemistry, The

covalent bond one of the strongest bonds that you can find in



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biochemistry , the outer shell electrons of one atom can be shared

with another atom.

- When atoms of other elements attach to available carbon bonds,

compounds are formed.

- A series of carbon atoms bonded together is referred to as a

chain(when there is a carbon connected to another carbon and

another and another).

- If only hydrogen atoms are bonded to the available carbon bonds,

hydrocarbons are formed.

- Therefore, a hydrocarbon is an organic molecule that contains only

carbon and hydrogen atoms; some examples of simple

hydrocarbons are shown here: “examples of single double & triple bonds of Carbon”

Cyclic Compounds

- When carbon atoms link to other carbon atoms to close a chain,

they form rings or cyclic compounds.

- Benzene is a cyclic compound with six carbons and six hydrogen.



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Biochemistry

Biochemistry is the study of biology at the molecular level; it is the

chemistry of living organisms, which related to the structure of the cell,so we look inside the cell to study the chemical reactions, for example the

cell membrane is a phospholipid bilayer which is one of the lipid (organic

compound), also the proteins imbedded in it are organic contain carbon

atoms.

Biochemistry involves the study of biomolecules present within living

organisms; biomolecules in living organisms are usually large molecules

called macromolecules.

- Amino acids : they are the building blocks of proteins, we have 20amino acids in nature, they are grouped “ acidic ,basic & neutral

A.A.” each one have different characteristics but all of them share

the same atoms mostly C, N & H forming the shared groups ( NH2,

H & the R group which is the differential group)

- Also there are carbohydrates in the cell ex. Glycoprotein, starch &

glycogen which are made of mainly of C & H.

- Macromolecules include carbohydrates, lipids, proteins, and

nucleic acids.

• Other examples: vitamins, enzymes, hormones, and energy-

carrying molecules such as adenosine triphosphate (ATP).

- Humans obtain their nutrients from the foods they eat.

• Carbohydrates, fats, nucleic acids, and proteins contained in

the foods are digested; their components are absorbed and

carried to every cell in the body, where they are broken

down and rearranged by the cells as there need to use in thebiological life.

- Microorganisms also absorb their essential nutrients into the cell by

various means.

- The nutrients are then used in metabolic reactions as sources of energy and as “building blocks” for enzymes, structural

macromolecules, and genetic materials.

- Glycolysis : is the metabolic pathway that

converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+.

http://en.wikipedia.org/wiki/Metabolic_pathway

http://en.wikipedia.org/wiki/Glucose

http://en.wikipedia.org/wiki/Pyruvate

http://en.wikipedia.org/wiki/Pyruvate

http://en.wikipedia.org/wiki/Glucose

http://en.wikipedia.org/wiki/Metabolic_pathway



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The free energyreleased in this process is used to form the high-

energy compounds ATP (adenosine triphosphate) and, it is

different in some steps of aerobic or anaerobic ( it will use another

electron acceptor not the O so the ATP will be less) organism or

bacteria.

- Nucleotides are the building blocks for DNA which are built from

nitrogenous base, Phosphate group and d-ribose (pentose ) sugar ..and all these building blocks contain mainly C, H, N, O & P.

Carbohydrates

- Carbohydrates are biomolecules composed of carbon, hydrogen,

and oxygen (in the ratio 1:2:1) 1 C , 2 H & 1 O.

- Examples include:

- Examples: Glucose, fructose, sucrose, lactose, maltose, starch,

cellulose, and glycogen.

- Categories of carbohydrates include monosaccharides (Glucose,

fructose), disaccharides, and polysaccharides (starch, cellulose).

Monosaccharides

- Monosaccharides are the smallest and simplest of the

carbohydrates. Mono means one, referring to the number of ringsin the structure.

- Glucose (C6H12O6) is the most important monosaccharide innature; it may occur as a chain or in alpha or beta ring

configurations “ the dr will not ask us about the structure!!”

- Monosaccharides contain from 2 to 9 carbon atoms – most contain

5 to 6.

- A 3 carbon monosaccharide is called a triose; a 4 carbon one is atetrose; a 5 carbon one is a pentose; a 6 carbon one is a hexose; a

7 carbon is a heptose; and so on.

http://en.wikipedia.org/wiki/Thermodynamic_free_energy

http://en.wikipedia.org/wiki/Adenosine_triphosphate

http://en.wikipedia.org/wiki/Adenosine_triphosphate

http://en.wikipedia.org/wiki/Thermodynamic_free_energy



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- The main and the simplest source of energy for body cells isglucose.

- The three forms of glucose are shown above.

- Glucose is carried in the blood to cells where it is oxidized to

produce energy-carrying ATP. ATP is the main energy source used

to drive most metabolic reactions.

Disaccharides

(di means : two )

Disaccharides are double ringed sugar that result from the combination

of two monosaccharides . The synthesis of disaccharides from two

monosaccharides by the removal of water molecule is called

dehydration synthesis reaction.

Example :

Sucrose is a disaccharides made by joining together a glucose molecule

and a fructose molecule .

Disaccharides react with water in a process called a hydrolysis reaction,which causes them to break down into two monosaccharides. (reverse

reaction)



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Peptidoglycan :

Recall that peptidoglycan is found in the cell walls of all members of

the Domain Bacteria; peptidoglycan is a repeating disaccharide attachedby proteins to form a lattice that surrounds and protects the bacterial cell.

( this layer is a differentiating layer between germ positive and germnegative , we said that germ positive it has a thick layer of peptidoglcan

awhile in germ negative this layer is thin .)

Carbohydrates composed of 3 monosaccharides are called

trisaccharides; those composed of 4 are called tetrasaccharides;those composed of 5 are called pentasaccharides, and so on …

until we come to polysaccharides.

Polysaccharides :

Carbohydrate polymers containing many monosaccharides that

linked to each other by glycosidic bonds , which is a bond that attach

two monosaccharides together .

Serve two main function :

1. Storing energy .

2. Structural support and protection.

Polysaccharides are examples of polymers – molecules that consist of

many similar subunits. In the presence of the proper enzymes or acids,

polysaccharides may be hydrolyzed or broken down into

disaccharides, and then into monosaccharides.

For example starch is a polysaccharide (repetitive glucose units

held together by α – glycosidic bonds ) which is the storage

molecule in plants.

- Some bacteria produce polysaccharide capsules for protection from

phagocytes.



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- Plant and algal cells have cellulose (a polysaccharide) cell walls to

provide support.

- Some protozoa, fungi, and bacteria have enzymes that can break

down cellulose.

- When polysaccharides combine with other chemical groups

(amines, lipids and amino acids), complex macromolecules are

formed.

For example, chitin, the main component of the hard outer

covering of insects, spiders, and crabs and found in the cell

walls of fungi.

Lipids

- An important class of biomolecules.

- Most lipids are insoluble in water, but soluble in fat solvents, suchas ether, chloroform, and benzene.

- Lipids are essential constituents of most living cells.

- Lipids can be classified into the following categories:

Waxes

Glycolipids

Fats and oils

Steroids Phospholipids Prostoglandins and leukotrienes

Lipids fatty acids

- Fatty acids are the building blocks of lipids; they are long-chain

carboxylic acids that are insoluble in water.

- Saturated fatty acids contain 1 single bond between carbon atoms;

they are solid at room temperature.

- Monounsaturated fatty acids have 1 double bond in the carbon

chain; found in butter, olives, and peanuts which the best to beused and eaten!



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- Polyunsaturated fatty acids contain 2 or more double bonds; found

in soybeans, safflowers, and corn.

- Essential fatty acids cannot be synthesized in the human body and

must be provided in the diet.

Lipid waxes :

- A wax consists of a saturated fatty acid and a long-chain alcohol.

– Examples: the wax coating on fruits; leaves; skin, fur, and

feathers of animals.

– The cell wall of Mycobacterium tuberculosis (the causative

agent of tuberculosis) contains waxes.

-These waxes protect M. tuberculosis from digestion

following phagocytosis by white blood cells , (thiscapsule help it to survive insde the macrophage !)

-These waxes make M. tuberculosis difficult to stainand de-stain; explains why M. tuberculosis is acid-

fast.

Lipids fats and oils

- Fats and oils are the most common types of lipids. They are also

known as triglycerides because they are composed of glycerol and3 fatty acids.

If its level elevate in the blood may cause closure of artries

- Most fats come from animal sources (e.g, beef); most oils come

from plant sources (e.g., olive oil).

Phospholipids

- contain glycerol, fatty acids, a phosphate group, and an alcohol.

There are 2 types:

– Glycerophospholipids (also known as phosphoglycerides)

– Sphingolipids

Glycerophospholipids are the most abundant lipids in cell

membranes.



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– A cell membrane is a lipid bilayer, consisting of 2 rows of

phospholipids, arranged tail-to-tail.

Glycolipids are abundant in the brain and in the myelin sheath of nerves.

Steroids are complex, 4-ringed structures; examples arecholesterol, bile salts, steroid hormones, and fat-soluble vitamins

(A, D, E and K).

Prostaglandins and leukotrienes are derived from a fatty acid called

arachidonic acid.

– Both have a wide variety of effects on body chemistry such

as controlling blood pressure or hormones; leukotrienes can

produce long-lasting muscle contractions.

Done by :

Baraah Salamat

Abeer Dirawi



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Good luck

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Chapter Six , genetics