Learn: Biology: Organic Molecules, Proteins, Lipids, and Nucleic Acids

neutralization reaction

a reaction in which an acid and a base react in an aqueous solution to produce a salt and water

carbohydrates

contains carbons , hydrogen & oxygen

includes sugars & starches

monosaccharides

Single sugar molecules

disaccharides

two simple sugars sucrose, lactose, maltose

Polysaccharides

large macromolecules formed from monosaccharides

starch & glycogen

Lipids

most abundant are the triglycerides phospholipids and steroids

Insoluble in water but soluble in other lipids

Triglycerides (neutral fats)

Found in fat deposits (subcutaneous tissue and around organs); protect and insulate the body organs; the major source of stored energy in the body.

Phospholipids

Found in cell membranes; participate in the transport of lipids in plasma; abundant in the brain and the nervous tissue in general, where they help to form insulating white matter

Steroids

Cholesterol

The basis of all body steroids.

Bile salts

A breakdown product of cholesterol; released by the liver into the digestive tract, where they aid in fat digestion and absorption.

Vitamin D

A fat-soluble vitamin produced in the skin on exposure to U V (ultraviolet) radiation (sunshine); necessary for normal bone growth and function.

Sex hormones

Estrogen and progesterone (female hormones) and testosterone (a male hormone) produced from cholesterol; necessary for normal reproductive function; deficits result in sterility.

Corticosteroids (adrenal cortical hormones)

Cortisol, a glucocorticoid, is a long-term antistress hormone that is necessary for life; aldosterone helps regulate salt and water balance in body fluids by targeting the kidneys.

Vitamin E

Taken in via plant products such as wheat germ and green leafy vegetables; may promote wound healing and contribute to fertility, but not proven in humans; an antioxidant; may help to neutralize free radicals (highly reactive particles believed to be involved in triggering some types of cancers).

vitamin k

Made available largely by the action of intestinal bacteria; also prevalent in a wide variety of foods; necessary for proper clotting of blood.

Prostaglandins

Derivatives of fatty acids found in cell membranes; various functions depending on the specific class, including stimulation of uterine contractions (thus inducing labor and miscarriages), regulation of blood pressure, and control of motility of the gastrointestinal tract; involved in inflammation.

Lipoproteins

Lipoid and protein-based substances that transport fatty acids and cholesterol in the bloodstream; major varieties are high-density lipoproteins (H D L s) and low-density lipoproteins (L D L s).

Glycolipids

Component of cell membranes. Lipids associated with carbohydrate molecules that determine blood type, play a role in cell recognition or in recognition of foreign substances by immune cells.

Triglycerides (fats)

composed of 1 glycerol + 3 fatty acids

found in fat deposits

source of stored energy

saturated fat

Contain only single covalent bonds

Chains are straight

Exist as solids at room temperature since molecules pack closely together

unsaturated fats

Contain one or more double covalent bonds, causing chains to kink

Exist as liquid oils at room temperature

"Heart healthy"

trans fats

Oils that have been solidified by the addition of hydrogen atoms at double bond sites

Increase risk of heart disease

omega 3 fatty acid

Found in cold-water fish and plant sources, including flax, pumpkin, and chia seeds; walnuts and soy foods

Appear to decrease risk of heart disease

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

Steroids

Made of four rings of carbon.

cholesterol, bile salts, vitamin D & some hormones

proteins

-Account for over half of the body's organic matter

-Provide for construction materials for body tissues

-Play a vital role in cell function

-Act as enzymes, hormones, and antibodies

-Contain carbon, oxygen, hydrogen, nitrogen, and sometimes sulfur

-Built from building blocks called amino acids

protein structure

-Polypeptides contain fewer than 50 amino acids

-Proteins contain more than 50 amino acids

-Large, complex proteins contain 50 to thousands of amino acids

-The sequence of amino acids produces a variety of proteins

primary structure

sequence of amino acids "beads"

secondary structure

chains of amino acids twist or bend

alpha helix

resmebles a metal ring

beta pleated sheet

sheet-like secondary structure of proteins

teritary structure

compact ball like structure

quaternary structure

result of a cominatio of two or more polypeptides chains

Fibrous (structural) proteins

Appear in body structures

Exhibit secondary, tertiary, or even quaternary structure

Bind structures together and exist in body tissues

Stable proteins

Examples include collagen and keratin

Globular (functional) proteins

Function as antibodies, hormones, or enzymes

Exhibit at least tertiary structure

Hydrogen bonds are critical to the maintenance of structure

Can be denatured and no longer perform physiological roles

Active sites "fit" and interact chemically with other molecules

Antibodies (immunoglobulins)

Highly specialized proteins that recognize, bind with, and inactivate bacteria, toxins, and some viruses; function in the immune response, which helps protect the body from "invading" foreign substances.

Hormones

Help to regulate growth and development. Examples include

Growth hormone—an anabolic hormone necessary for optimal growth.

Insulin—helps regulate blood sugar levels.

Thyroid hormone—regulates the rate at which glucose used by body cells.

Transport proteins

Hemoglobin transports oxygen in the blood; other transport proteins in the blood carry iron, cholesterol, or other substances.

Enzymes (catalysts)

Essential to virtually every biochemical reaction in the body; increase the rates of chemical reactions by at least a millionfold; in their absence (or destruction), biochemical reactions cease.

Enzymes

Act as biological catalysts

Increase the rate of chemical reactions

Bind to substrates at an active site to catalyze reactions

Can be recognized by their -ase suffix

Hydrolase

Oxidase

Nucleic acids

Form genes

Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus atoms

Largest biological molecules in the body

Two major kinds:

D N A

R N A

Nucleic acids are built from building blocks called nucleotides

Nucleotides contain three parts

A nitrogenous base

A = Adenine

G = Guanine

C = Cytosine

T = Thymine

U = Uracil

Pentose (five-carbon) sugar

A phosphate group

Deoxyribonucleic acid (D N A)

The genetic material found within the cell's nucleus

Provides instructions for every protein in the body

Organized by complementary bases to form a double-stranded helix

Contains the sugar deoxyribose and the bases adenine, thymine, cytosine, and guanine

Replicates before cell division

Ribonucleic acid (R N A

Carries out D N A's instructions for protein synthesis

Created from a template of D N A

Organized by complementary bases to form a single-stranded helix

Contains the sugar ribose and the bases adenine, uracil, cytosine, and guanine

Three varieties are messenger, transfer, and ribosomal R N A

Adenosine triphosphate (A T P

Composed of a nucleotide built from ribose sugar, adenine base, and three phosphate groups

Chemical energy used by all cells

Energy is released by breaking high-energy phosphate bond

A D P (adenosine diphosphate) accumulates as A T P is used for energy

A T P is replenished by oxidation of food fuels

Three examples of how A T P drives cellular work are shown next

A D P (adenosine diphosphate) accumulates as A T P is used for energy

A T P is replenished by oxidation of food fuels

Three examples of how A T P drives cellular work are shown next