Chapter 3 - Organic Molecules, Cell Structure

Biomolecules

large, complex molecules synthesized by living organisms for a variety of specific functions

Popular biomolecules

polymers or macromolecules

What do biomolecules contain?

carbon atoms

Why are biomolecules considered ORGANIC compounds?

they contain carbon atoms so they are organic compounds

How many outer orbital electrons does carbon have?

four

Due to carbon having four outer orbital electrons what does this mean?

carbon forms four covalent bonds with other atoms, letting it form large, complex molecules that are stable in structure

What are the small repeating units that make up BIOMOLECULES?

monomers

What do monomers do?

form covalent bonds to one another

Often times what happens with monomers?

there are chemically important functional groups that bond to them which can impact the reactivity of the compound itself

Important function groups

- hydroxyl groups

- sulfhydryl groups

- phosphate groups

- carboxyl groups

- amino groups

Two major types of reactions

- condensation (dehydration) reactions

- hydrolysis (decomposition) reactions

Condensation (dehydration) reactions

reactions in which monomers bond together to form biomolecules. in these reactions, there is a loss of water. these reactions build up large biomolecules

Hydrolysis (decomposition) reactions

reactions through biomolecules are broken down into monomers. water is used in these reactions to remove monomers from biomolecule. both sets of these reactions are often regulated by enzymes

Enzymes

proteins that speed up biological reactions

Four classes of important biological molecules

- carbohydrates

- lipids

- proteins

- nucleic acids

Carbohydrates

sugars and related compounds. these are composed of simple sugars (monosaccharides) that bond together

Monosaccharides

simple sugars

Lipids

fats, oils, and waxes. these are composed of fatty acids that bond to the alcohol glycerol

Proteins

these are composed of amino acids that covalently bond together

Nucleic acids

these are composed of nucleotides that covalently bond together

What three elements do carbs always have?

carbon, hydrogen, and oxygen

What is the ratio for carbon, hydrogen, and oxygen in Carbs?

1:2:1 so C1H2O1

How do Carbohydrates appear?

in a variety of different shapes

What do carbs primarily serve as?

as an energy source for living cells and they can serve as a support molecule

What kind of molecules are carbs?

they are polar molecules, meaning they easily dissolve in water

Classes of carbohydrates

- monosaccharides

- disaccharides

- polysaccharides

Monosaccharides

the major monomer for larger carbs

Examples of monosaccharides

glucose, fructose, galactose

Isomers

compounds with the same formula but different structures

Monosaccharides are ___

isomers

Two other important monosaccharides

ribose and deoxyribose are

Disaccharides

formed by the covalent bond between two monosaccharides

Example of disaccharides

sucrose (table salt)

Polysaccharides

formed by covalent bonds between numerous monosaccharides

Examples of polysaccharides

starch, glycogen, cellulose, chitin

Glycogen

stored form of sugar in humans

Starch

stored sugar in plant cells

Cellulose

forms the cell wall of plant cells

Chitin

in insects and bugs

Function of lipids

pads and cushions structures, serve as a source of stored energy make up cell membranes and are a part of the structure of some hormones

Lipids are composed of what?

mostly carbon and hydrogen atoms

What are lipid bonds bonded by?

nonpolar covalent bonds; due to this they do not dissolve in water

Classes of lipids

triglycerides, phospholipids, eicosanoids, sterioids

Triglycerides

formed when three fatty acids bond to the individual carbon atoms of glycerol (3 carbon atoms)

What do the fats in triglycerides do?

they can be used to synthesize ATP

What happens to stored triglycerides in adipose tissue?

it can be released into the blood where they can be used for energy production in the liver

What can any excess fatty acids be converted into?

ketones

The buildup of ketones

ketosis

Ketosis

is a common sign of diabetes mellitus

Types of fatty acids in triglycerides

saturated and unsaturated fats

Saturated fats

do not contain double bonds between any of their carbon atoms. these are known as animal fats

Unsaturated fats

contain double bonds between some of their crabon atoms

Monounsaturated fats vs Polysaturated fats

cis vs trans fatty acid

Phospholipids

these contain two fatty acid chains attached to glycerol and a group bonds to the third glycerol carbon.

What kind of group do phospholipids bond to?

hydrophilic (polar) groups

What is unique about phospholipids?

they have a polar region and a nonpolar region

Amphipathic

having both a hydrophilic (polar) region and a hydrophobic (nonpolar) region

Phospholipids are ____ _____ of cell membranes

major constituents

Eicosanoids

modified fatty acids that function in intercellular communication

Examples of eicosanoids

prostaglandins and leukotrienes

Prostaglandins

involved in the inflammation response

Thromboxanes

involved in blood clotting

Steriods

these are composed of complex carbon rings

Cholesterol

the most common sterioid in the human body

What kind of molecule is cholesterol?

amphipathic molecule

Why is cholesterol an important molecule?

in cell membranes and it is a precursor of other steroids (cortisol, testosterone)

What are proteins

polymers composed of amino acids that are covalently bonded together

Covalent bonds that make up proteins

peptide bonds

What are proteins often reffered to as?

polypeptides

Amino acids

there are 20 naturally occuring amino acids in

What are amino acids composed of?

a central carbon atom that is bonded to an amino group, a carboxyl group, and a hydrogen atom

How do amino acids differ?

R group

How are amino acids bonded together?

via condensation reaction in a process known as TRANSLATION

How are chemical properties of a protein defined?

the arrangement of amino acids in the structure of the proteins

Function of proteins

- forming numerous fibers in the body (fibrin)

- transporting materials (hemoglobin)

- making up keratin

- forming enzymes

- making up myosin and tropomyosin in muscle tissue

Keratin

a thick, protective protein

Parts of a proteins structure

- primary structure

- secondary structure

- tertiary structure

- quaternary structure

Primary structure

simple chain of bonded amino acids

Secondary structure

some folding between amino acids. hydrogen bonds often form in this structure

Tertiary structure

extensive folding with bonding between R groups in a protein. this extensive folding is created by ionic and covalent bonding and hydrogen bonds

Quaternary structure

involves bonding and folding between multiple protein chains

What are nucleic acids?

these are polymers that are composed of NUCLEOTIDES that are covalently bonded together

What is the function of nucleic acids?

transferring energy within cells and they form the genetic material in living cells. these can also act as chemical signatling molecules

Nucleotides

serve as the major monomer for nucleic acids

All nucleotides are composed of three primary groups

- a five-carbon sugar

- a phosphate group

- a nitrogenous base

The two carbohydrates found in nucleotides are?

deoxyribose and ribose

2 classes of nitrogenous bases in nucleotides

purines and pyrimidines

Pyrimidines

these contain a single carbon ring

Three pyrimidines found in nucleic acids are?

cytosine, thymine, and uracil

Purines

have a double ring

Two purines found in nucleic acids are?

adenine and guanine

Types of nucleic acids

- deoxyribonucleic acid (DNA)

- ribonucleic acid (RNA)

- adenosine triphosphate (ATP)

- cyclic AMP (cAMP) / cyclic GMP (cGMP)

Deoxyribonucleic acid (DNA)

found in a cell's nucleus; these compounds stores a cell's genetic material. composed of the sugar deoxyribose and the bases adenine, thymine, guanine and cytosine

DNA forms a....

double helix

Complementary base pairing in DNA

A-T

G-C

How are the bases held together in DNA?

hydrogen bonds

Ribonucleic acid (RNA)

several types, all types of RNA work together to express genetic information in living organisms

What is RNA composed of?

of the sugar ribose and contains bases adenine, uracil, guanine, and cytosine

How is the structure of RNA?

single stranded

Complementary base pairing of RNA

A-U, C-G