Chapter 5: Macromolecules

Critically important large molecules of living things fall into 4 categories:

a. Carbohydrates

b. Lipids

c. Proteins

d. Nucleic Acids (DNA + RNA)

What are the 3 macromolecules?

Carbs, Proteins, Nucleic Acids

Polymers

a long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomers

the building blocks of polymers; the repeating units of smaller molecules

Dehydration Reaction

a reaction in which two molecules are covalently bonded to each other through the loss of a water molecule

Enzymes

specialized macromolecules to speed up chemical reactions in cells

Hydrolysis Reactions

used to disassemble polymers

(the reverse of dehydration rxn)

Carbohydrates

include sugars and polymers of sugars called saccharides

Monosaccharide

the simplest carbohydrate

one sugar

Disaccharide

carbohydrate with double sugars; formed by glycosidic bonds

Disaccharides are formed with what kind of bonds?

Glycosidic bonds

Trademark of sugar

Carbonyl (C=O) and multiple Hydroxyl (OH) groups

Glucose

the most important sugar that is also an Aldose

The carbon skeleton is ??? carbons long.

3-7

Examples of hexoses include…

6-Carbon sugars (C6H12O6)

glucose, fructose, galactose

True or False: Sucrose is the most common disaccharide.

True

Sucrose is made up of…?

Glucose + Fructose

Disaccharides are joined by _________________ which is a covalent bond formed by a dehydration reaction.

Glycosidic linkages/bonds

Glycosidic linkages/bonds

covalent bonds formed by dehydration reactions

Polysaccharides

polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages

Polysaccharide uses…

1) storage of sugar

2) building material for protective structures

Storage of polysaccharides

in plants: starch

in animals (humans too): glycogen

In our body, how long do glycogen stores last?

24 hours

Where is glycogen stored in our body?

liver and muscle cells

Simplest form of starch

amylose

2 forms of starch

1) amylose: simplest form, no branches

2) amylopectin: branched, complex

*both are made of glucose

Cellulose

a polymer of glucose, but has different glycosidic linkages than in starch

Cellulose key points

1) Major component of cell wall in plants

2) Most abundant organic compound on Earth

3) Few organisms possess enzymes that can digest cellulose

Cellulose is the most abundant organic compound on Earth, such as in what 2 things?

1. it is a major constituent of the tough wall of plant cells

2. it is the ONLY component of cotton

True or False: humans cannot digest cellulose

True

True or False: Cellulose is not considered a nutrient for humans, but it is still part of a healthy diet.

True

Whole grains, vegetables, etc. are rich in….

cellulose

“Insoluble fiber” on food packages is actually what?

Its actually cellulose

True or False: some prokaryotes can digest cellulose

True

How do cows and termites digest cellulose?

they have prokaryotes doing it for them

Chitin

a structural polysaccharide

-in the cell wall of fungi

-used to make surgical thread

True or False: lipids are macromolecules

False —> they are not large enough to be considered macromolecules.

All lipids share one important trait. They mix poorly, if at all, with…

Water

Lipids are polar (uneven electronegativity) so the only mix with…

Other polar substances

3 classes of lipids

1) Fats

2) Phospholipids

3) Steroids

Fats

constructed from Hydroxyl (COOH) and 3 fatty acid chains

Triacylglycerol (fat)

3 fatty acids linked to one glycerol molecule

Two classifications of fats

Saturated and Unsaturated

Saturated fats at room temperature are ____.

solid

Why are saturated fats solid at room temp?

The molecule is fully saturated with Hydrogen. There are no double bonds.

Unsaturated fats at room temperature are ______.

liquid

Why are unsaturated fats liquid at room temp?

because of kinks in some of their fatty acids carbon chain

-not saturated with Hydrogen

-therefore have 1+ double bonds

Hydrogenation Process

In hydrogenated vegetable oil, unsaturated fats are synthetically converted into saturated fats by adding hydrogen atoms. This process (used in foods like peanut butter and margarine) helps prevent the lipids from separating and forming an oil layer.

A diet rich in saturated fats can lead to a disease known as..

atherosclerosis

How do unsaturated fats become saturated?

Adding Hydrogen

3 Major Functions of Fats

1) cushion vital organs

2) store energy

3) insulation

True or False: The fastest energy comes from carbs

True

Fats have 2x energy per 1g compared to carbs

-fats take longer to get

-more energy rich per 1 gram

Phospholipids make up…?

cell membranes

Phospholipid structure

-2 fatty acids attached to a Glycerol.

-a 3rd fatty acid attached to a Phosphate Group.

-hydrocarbon tails + phosphate head

Hydrocarbon tails of a phospholipid are…

Hydrophobic

Phosphate head of a phospholipid is…

Hydrophilic

True or False: many of our hormones are steroids.

True!

Steroids

lipids characterized by Carbon skeleton consisting of 4 fused rings

Cholesterol (a steroid)

a precursor from which other steroids are synthesized

-made in liver

-sex hormones are steroids produced by cholesterol

True or False: sex hormones are steroids, often produced by cholesterol.

True

True or False: Proteins make up the dry mass of most cells.

True

Enzymes are…

proteins

Enzymes

chemical agents that selectively speed up chemical reactions without being consumed by the reaction

Polypeptides

polymers of amino acids

All proteins are constructed from the same set of __ amino acids.

20

How many amino acids are there?

20

Protein

one or more polypeptides each folded and coiled into a specific 3D structure

ALL amino acids have what???

A carboxyl group!!!
COOH + amino group

All amino acids used in a protein are the same enantiomer which is…?

L form

Enantiomer

pair of molecules that are mirror images of eachother

True or False: For amino acids, some are polar and some are non-polar.

True

True or False: For amino acids, some are acidic and some are basic. (** only the groups on SIDE CHAINS)

True

Peptide bonds

covalent bonds formed by dehydration rxns

*link the COOH group from one AA to the NH2 group of another AA.

Functional Protein

1 or more polypeptides precisely twisted, folded, and coiled into a molecule of unique shape.

**a polypeptide is NOT synonymous with a functional protein

True or False: A polypeptide is NOT synonymous with a function protein.

TRUE! Think about it….

Are threads of yarn synonymous with a sweater? No.

Therefore, just because a polypeptide is present does not mean there is a protein.

A proteins specific structure determines its…

function

Protein Structures

Primary, Secondary, Tertiary, Quarternary

Primary Protein Structure

unique sequence of amino acids determined by its inherited genetic info

Secondary Protein Structure

Segments of polypeptide chain that are coiled and folded; there is a reaction between the backbone constituents

Tertiary Protein Structure

Overall shape resulting from interactions of side chains of the various amino acid groups

Quaternary Protein Structure

Overall protein structure that results from aggregation of polypeptide subunits

Protein Denaturation

when a protein unravels and loses its native shape

causes: pH changes, salt concentration, temperature, chemicals

A denatured protein is biologically _______.

inactive

Denaturation in the body

-excessively high fevers can be fatal

-proteins in the blood can denature at very high body temps

-in the test tube, a protein can sometimes renature.

Sickle cell enema cause

one amino acid substitution in DNA

Nucleic Acids function

store, transmit, and express genes

2 types of nucleic acids

DNA and RNA

DNA and RNA

nucleic acids that enable organisms to reproduce their components from one generation to the next

DNA directs…

-directs for its own replications

-also directs mRNA synthesis (making proteins!)

DNA

the genetic material that organisms inherit from their parents

-each chromosome contains one long DNA molecule, usually carrying hundreds of genes.

-DNA molecules are copied and passed along.

True or False: each chromosome contains one long DNA molecule, usually carrying hundreds of genes.

True

DNA is information that programs all the cell’s activities.

Each gene along the DNA molecule directs synthesis of… ???

mRNA

Central Dogma

DNA —(transcription)—> mRNA —(translation)—> Protein

mRNA directs production of

polypeptide

Ribosomes

-site of protein synthesis

-found in cytoplasm + rough ER

Structure of Nucleic Acids

Nucleic acids are long polymers made of nucleotides. (monomers)

CONSIST OF: sugar, a phosphate group, and a nitrogenous base

Nucleoside

a nitrogenous base + 5 carbon sugar

Each nucleotide contains..

a nucleoside and a phosphate group

2 types of nitrogenous bases

1) Purines: C, T, U

2) Pyrimidines: A, G