Ch. 5 Biological Macromolecules

Macromolecules are

large molecules formed by joining together several
small component molecules

Polymers are

macromolecules composed of multiple similar or identical
component molecules linked together with covalent bonds

Monomers are the “subunit” molecules that make up polymers.

The number and arrangement of different types of monomers gives variation

to biological molecules

A dehydration reaction is the process by which

monomers are joined into polymers through the removal of a hydrogen (H) and a hydroxyl group (OH- ) from the molecule to form water (H2O)

Hydrolysis is the process by which

polymers are separated into monomers through the addition of water (H2O) to the molecule, adding either a hydrogen (H) or a hydroxyl group (OH - ) to each monomer

Carbohydrates (“carbs”) are

organic molecules consisting of a simple sugar or multiple simple sugars joined together

Carbohydrates will always be a combination of

carbon, hydrogen, and oxygen Example: Glucose – C 6H12O6 **You should be able to recognize this formula

All carbohydrates are

hydrophilic and can be dissolved in water

Monosaccharides are

simple sugars

Monosaccharides have a

carbonyl group and multiple hydroxyl groups, which leads to isomeric shapes depending upon the location of the carbonyl group

Aldoses have carbonyl groups at the

“end” of the chain

Ketoses have carbonyl groups in the

“middle” of the chain

The presence of asymmetric carbons also produce a variety of

isomers

Monosaccharides can also be classified by the number of

carbons: Hexoses have six carbons, pentoses have five carbons, and trioses have three carbons

Monosaccharides form rings in an aqueous solution because it is

more stable

Disaccharides are

“double sugars” formed through the dehydration of two monosaccharides

A glycosidic linkage is the specific name for a covalent bond formed between

two monosaccharides through a dehydration reaction

In order to be used to produce cellular energy, disaccharides must be

broken down into their monosaccharide components; Lactose (milk sugar) is formed from glucose and galactose
• Maltose is (malted sugar used in beer) formed from two glucose
• Sucrose (table sugar) is formed from glucose and fructose

Polysaccharides (aka “complex carbohydrates”) are

carbohydrate polymers made of many monosaccharides joined by glycosidic linkages

Starch is a polysaccharide formed from

long single strings of glucose; Starch is used as a stockpile of glucose molecules in plants which can be used to generate
energy or grow
• Most organisms are able to hydrolyze starch, making it a universal source of glucose
• Glucose monomers in starch are joined by “1 – 4” glycosidic linkages with the number 1
carbon bonding to the number 4 carbon of other glucose molecules
• In starch, glucose molecules are bound in the α position with the “number 1” hydroxyl
positioned above the plane of the ring
• This bond pattern makes glucose helical

Glycogen is a polysaccharide formed

from long branched strings of glucose; Glycogen is used as a stockpile of glucose molecules in animals to generate energy
• Glycogen is stored in muscles and liver, which is why you “carbo-load” before working out
• Glycogen is highly branched, making it easier to break down into glucose molucles

Cellulose is a polysaccharide formed from

many cable-like fibrils (formed from multiple long strings of glucose); Cellulose provides structural support for plant cells
• Cellulose cannot be digested by animals
• Glucose monomers in starch are joined by “1 – 4” glycosidic linkages with the
number 1 carbon bonding to the number 4 carbon of other glucose molecules
• In cellulose, glucose molecules are bound in the β position with the “number 1”
hydroxyl positioned opposite the “number 1” hydroxyl group of the previous glucose
molecule, creating and alternating pattern
• This bond pattern makes cellulose fibrils straight

Chitin is a nitrogenous polysaccharide formed from

repeating units of a modified sugar that has nitrogen bonded to its carbon atoms

Lipids are a

diverse group of hydrophobic, hydrocarbon-based molecules

Lipids typically are made of

non-polar carbon – hydrogen bonds

Lipids include

Fats and “oils”, Steroids, Waxes, Phospholipids

Steroids are lipids composed of a carbon skeleton made of four fused rings with various functional groups attached

Fatty acids is a

long carbon skeleton (usually 16 – 18 carbons long) composed of carbon – hydrogen bonds with a carboxyl group at one end

Fats are lipids composed of

three fatty acids linked to one glycerol molecule; Another name for fats are “triglycerides” or “triacylglycerol”

an ester linkage is a bond between a

hydroxyl and a carboxyl group in the formation of fats

Saturated fatty acids are fatty acids that have

the maximum number of hydrogen atoms bound to the carbon skeleton and only have single covalent bonds

Saturated fats tend to be solid at room temperature with

their fatty acids tightly packed together

Unsaturated fatty acids are fatty acids that

do not have the maximum number of hydrogens due to having one or more double covalent bonds in their carbon skeleton

Unsaturated fats tend to be liquid at room temperature

because their fatty acids are unable to be packed closely together

Phospholipids are lipid molecules made up of a

glycerol molecule bound to two fatty acids and a phosphate group

The structure of phospholipids gives parts of the molecule different behaviors
with

water
• The fatty acid “tails” are hydrophobic
• The phosphate “head” is hydrophilic

Phospholipids are essential to life as they make up the

cell membrane, which serves to separate the inside of the cell from the environment as well as regulate what kind of molecules are moved to and from the cell

Nucleic acids are polymers consisting of

nucleotide monomers

There are two types of nucleic acids

DNA and RNA

DNA is the “code book” of life and contains all the

unique genetic information to produce proteins necessary for life

The process of going from DNA to RNA to protein is called

gene expression

Nucleotides are the monomer for

nucleic acids and consist of ribose (a five-carbon sugar) covalently bonded to a nitrogenous base and a phosphate group

The sugar-nitrogenous base combination is called a

nucleoside

Pyrimidines are composed of a

single six-carbon ring with nitrogen components; Cytosine (C), Thymine (T), and Uracil (U) are pyrimidines

Purines are larger and are composed of a five-carbon structure fused to a six-carbon structure; Adenine (A) and Guanine (G) are purines

Ribose is found in

RNA

Deoxyribose is found in

DNA and is a ribose molecule that lacks an oxygen atom on the number 2 carbon of the ribose ring

Nucleic acids are formed from the phosphodiester linkage of adjacent nucleotides, with the sugar of one bonding to the phosphate group of another; This creates an alternating “sugar-phosphate backbone”

Because of the bonding pattern the ends of each polynucleotide are

different from each other; The phosphate group is attached to the 5’ carbon, so the end with the phosphate
“free” is referred to as the “5’ end”; The ribose is attached to other nucleotides by phosphodiester bonds at the 3’
carbon, so the end with the “free” sugar is referred to as the “3’ end”

DNA – deoxyribonucleic acid;

a double-stranded polymer that uses deoxyribose (ribose lacking oxygen) based nucleotides

DNA forms a double helix composed of

two strands wound together in a spiral

The double helix is formed antiparallel with the

5’ end and 3’ end opposite each other paired bases

The strands of DNA are held together through

hydrogen bonds that form between paired nitrogenous bases

The 4 nitrogenous bases of DNA are

adenine (A), thymine (T )**, guanine (G), cytosine (C)

Guanine forms bonds with cytosine through

three hydrogen bonds, which are harder to break apart

Adenine forms bonds with thymine through

two hydrogen bonds

The DNA strands are

complimentary and are paired with their nucleotide counterparts

Some sections of DNA are non-coding (introns) and

do not provide information that produces functional proteins, but they serve other functions within the molecule, such as attachment points for replication or transcription proteins

Some sections of DNA are coding (exons) and serve as the

specific nucleotide sequences that functional proteins are built from

RNA – ribonucleic acid is

a single-stranded polymer that uses ribose based nucleotides

mRNA (messenger RNA) is made to

compliment the DNA sequence of a gene and serves as the intermediate between DNA and polypeptide sequences

tRNA (transfer RNA) serves as

the link between mRNA and individual amino acids, “carrying” them to cellular machinery responsible for the formation of polypeptides

rRNA (ribosomal RNA) is non-coding and serves as a

component in the cellular machinery responsible for forming polypeptides

The strands of RNA are temporarily held to DNA or other RNA molecules through

hydrogen bonds that form between paired nitrogenous bases

Adenine forms bonds with

uracil through two hydrogen bonds

Polypeptides are

polymers of amino acids held together through peptide bonds

Proteins are biologically functional molecules that consist of one or more

polypeptides that are further folded, coiled, or structured into function-specific
three-dimensional shapes

Proteins are the functional unit of

all living systems and are the physical
expression of nucleic acids and genetic material

Proteins are essential for the replication of DNA and RNA and are essential for the

reproduction and continuation of lineages of organisms

Amino acids are organic molecules composed of a

hydrogen, a carboxyl group, an amino group, and a “radical (R) group” bound to a central asymmetrical carbon

There are 20 amino acids that are

essential for life on Earth and cellular function

Amino acids are classified by the properties of their

radical groups

Polypeptides are

chains of amino acids formed through repetitive peptide bonds

Peptide bonds are covalent bonds between the

carboxyl group of one amino acid and the amino group of the neighboring amino acid

The repeating sequence of amino acids form a “polypeptide skeleton” with

the R groups extending from it

The N-terminus amino acid is the

last amino acid in the polypeptide chain

Protein structure is what gives each protein its

unique function

Protein structure is governed by the interactions of amino acids in their

polypeptide sequences

The primary structure of a proteins is its

linear sequence of amino acids

The secondary structure of a protein is formed by hydrogen bonds within

the carbon skeleton between oxygen atoms and hydrogen atoms

An α helix is formed through

hydrogen bonds between every fourth amino acid

A β pleated sheet is formed through

hydrogen bonds between “parallel” sections

The tertiary structure of proteins is the three-dimensional shape formed by the

interactions and bonds between the amino acid R groups

Hydrophobic interactions are caused by

peptide bonds that “exclude water”, causing non-polar amino acids tend to be grouped together

Disulfide bonds form where amino acids that have sulfhydryl groups (particularly cysteine)are held together as a result of

further folding of the polypeptide

The quaternary structure of proteins is the

final protein that results from the association and bonding of two or more polypeptides

Proteins go through several

“intermediate structures” before their final shape

If the “ideal” conditions of a protein’s environment are no-longer maintained the
protein will

denature

Denaturation is the process in which a protein (and other molecules)

unravel and lose its
native shape, making it biologically inactive

DNA sequencing is a general name for a number of techniques that

“read” or determine the sequence of an organisms’ DNA sequences (either full or partial)

A genome is the

complete set of all genetic material present in a normal cell of an organism (this excludes sex-cells)

Genomics is the study of

genomes

“Genetics” refers to the study of parts of

genomes

A proteome is the complete set of all proteins that are able to be produced by

an organism

Genomics and proteomics can study full or parts of genomes and proteomes, depending upon the

type of study

Bioinformatics is a

joint field that uses specialized computers, software, and mathematical models to process and analyze biological data from extremely large data sets, particularly genetic, genomic, and proteomic data