biological molecules lecture packet 3 reading: chapter 2 (pages 31-39) copyright 2008 pearson...

COPYRIGHT 2008 PEARSON EDUCATION

Biological Molecules

LECTURE PACKET 3

READING: CHAPTER 2 (PAGES 31-39)


Outline

▪ Carbohydrates▪ Lipids▪ Proteins▪ Nucleic Acids


Major molecules of life

▪ Large molecules, including many important biological molecules, are known as macromolecules. ▪ Macromolecules that consist of many small, repeating molecular subunits linked in a chain are called polymers.▪ Monomers are the small molecular subunits that form from the building blocks of polymer.


Dehydration synthesis: polymer formation

▪ One of the monomers donates OH-, and the other donates H+.


Hydrolysis: Polymer degradation

▪ The addition of water across the covalent bonds

- The H from the water attaches to one

monomer, while the OH attaches to the adjoining monomer, thus breaking the covalent bond between the two


Carbohydrates

▪ The carbohydrates, known commonly as sugars and starches, provide fuel (energy) for the human body. They are exclusively made entirely of carbon, hydrogen, and oxygen.

▪ Simple carbohydrates- Monosaccharides (one sugar)- Disaccharides (two sugars)

▪ Complex carbohydrates- Polysaccharide (many sugars)


Carbohydrates: monosaccharides

▪ Monosaccharides, also called simple sugars, are the smallest molecular units of carbohydrates.

▪ They are considered monomers. A chain of these monomers will form polymers.

▪ They can be characterized by how many carbon atoms they contain.

- A sugar that contains five carbons: pentose- Six carbons: hexose


Carbohydrates: monosaccharides


Carbohydrates: Oligosaccharides▪ Oligosaccharides are chains of a few monosaccharides joined together by dehydration synthesis.▪ A dissacharide is a double sugar that forms when two monosaccharides covalently bond to each other.

- Sucrose: glucose and fructose- Maltose: glucose and glucose- Lactose: glucose and galactose


Carbohydrates: Polysaccharides

▪ A polysaccharide is a complex carbohydrate that forms when monosaccharides join together in long chains. ▪ Short-term energy storage:

- In plants, the storage polysaccharide is starch.- In animals, the storage polysaccharide is glycogen.

▪ Structural integrity:- Cellulose is a structural polysaccharide found in the cell walls

of plants.


Carbohydrates’ function

1. Rapidly mobilized source of energy (glucose)2. Energy storage3. Structural support4. Coupled with protein to form glycoproteins for cell membranes


Structure of complex carbohydrates

▪ The differences between the complex carbohydrates is in the structure: branched, unbranched, coiled, hydrogen-bonded.

- Cellulose is tightly packed, uncoiled, and hard to digest.- Starch is coiled and may be branched and is easier to digest. - Glycogen is coiled with extensive branching and is even

easier to digest.


Structure of complex carbohydrates


Complex carbohydrate: Glycogen

▪ Function: Carbohydrates stored in animals for energy.▪ Structure: Coiled and branched▪ Very easy to digest (break down)▪ It’s stored mainly in liver and muscle.


Complex carbohydrate: Starch

▪ Function: Carbohydrates stored in plants for energy. It is stored in structures in the plan cell called amyloplasts. ▪ Structure: Coiled and may have some branching. ▪ It is used for energy:

- Examples of plants that are high in starch include potatoes, rice, carrots, and corn.


Complex carbohydrate: Cellulose

▪ Function: Carbohydrate used by plants for structure. ▪ Structure: Hydrogen bonds stabilize chains into tight bundles. ▪ Humans don’t have the enzyme that breaks cellulose down into individual glucose molecules. ▪ It is an important dietary fiber that helps fecal matter move through the large intestine.


Complex carbohydrate review


The complex carbohydrate stored in animals is…

1. Starch2. Glucose3. Cellulose


What monomer is starch composed of?

1. Amino acid2. Glycogen3. Fructose4. Glucose


Lipids

▪ Lipids, such as fats, are insoluble in water.

▪ Like carbohydrates, lipids are mainly composed of carbon, hydrogen, and oxygen, but they usually have many carbons and hydrogens.

▪ There are a few different types of lipids:- Triglycerides- Phospholipids- Steroids


Lipids: Triglycerides

▪ Fats and oils are triglycerides, compounds made of one molecule of glycerol and three fatty acids.▪ Fatty acids are chains of carbon atoms also bonded to hydrogens and have the acidic group COOH at one end.



▪ Triglycerides are classified as saturated or unsaturated. ▪ Saturated fatty acids have only single covalent bonds linking the carbon atoms.▪ Unsaturated fatty acids have one or more double bonds between carbon atoms.

- Double bonds produce “kinks” in the fatty acids and prevent

molecules to pack tightly into a solid.



▪ Some examples of triglycerides include: butter, lard (animal fat), and vegetable oils.

▪ The main difference is in the structure of the fatty acids.


Lipids: Fatty Acids

▪ Saturated fatty acids contain no double bonds.

▪ Unsaturated fatty acids contains at least one double bond.- Monounsaturated fatty acids have one double bond.- Polyunsaturated fatty acids have more than one double

bond.

▪ Unsaturated fatty acids tend to be more liquid at room temperature.


Lipids: Fatty Acids


Lipids: Triglyceride examples

▪ Animal fats contain mainly saturated fatty acids.- Solid at room temperature

▪ Vegetable oils contain mainly unsaturated and polyunsaturated fatty acids.

- Liquid at room temperature

▪ Hydrogenated oils are unsaturated oils that have been chemically saturated so they will be solid at room temperature (Crisco). They’re trans fats.


Lipids: Trans fats

▪ Hydrogenation is the process of adding hydrogen to monounsaturated and polyunsaturated oils to saturate them.▪ This process can also create unsaturated fats that now have a different configuration than the original oil.

▪ Examples:- Cookies, French fries, cakes, popcorn, and many other

packaged foods.

▪ Labeled as “partially hydrogenated oil”


Lipids: Trans fats


Lipids: Trans fats

▪ Addition of hydrogens means that there are fewer double bonds.


Lipids: fatty acids and health

▪ Heart disease is caused by plaque collecting in the blood vessels leading to the heart.▪ Cholesterol in the blood leads to more plaque building up in the vessels.

LDL (bad cholesterol): transports cholesterol from the liver to the heartHDL (good cholesterol): transports cholesterol to the liver and away from the heart

▪ The type of fatty acids you eat can change the levels of HDL and LDL in your blood!


Lipids: fatty acids and cholesterol

▪ Trans fats: worst type of fat; raise the bad cholesterol (LDL) and lower the good cholesterol (HDL). ▪ Saturated fats raise the bad cholesterol

- Animal fats, dairy products, and some plant oils (palm and coconut)▪ Polyunsaturated fats do not raise the bad cholesterol but slightly lower the good cholesterol.

- Many vegetable oils (corn and safflower)▪ Monounsaturated fats do not increase either.

- Olive, canola, and peanut oils, and avocado


Lipids: Omega-3 Fats

▪ Omega-3s are a type of unsaturated fat.▪ This fat has a carbon double bond located three carbons from the end (end = omega).▪ This is the healthiest type of fat. ▪ It protects you against heart disease by reducing bad cholesterol.

Sources: fatty fish (salmon, tuna), walnuts


Which of these fats is the least healthy?

1. Polyunsaturated2. Omega 3 unsaturated3. Trans Fat4. Saturated


Which type of fatty acid does not contain a double bond?

1. Polyunsaturated2. Omega 3 unsaturated3. Trans Fat4. Saturated


Triglycerides are composed of 3 fatty acids and…

1. Amino acid2. Glucose3. Glycerol4. Glycogen


Lipids: Phospholipids

▪ A phospholipid consists of a molecule of glycerol bonded to two fatty acids and a negatively charged phosphate group. Another small molecule of some kind, called the variable group, is linked to the phosphate group. ▪ Glycerol + 2 fatty acids + charged phosphate group + “R” group



▪ Function: Form the cell membrane

▪ Phosphate end of molecule is polar, and therefore soluble in water.

▪ Fatty acid end is nonpolar, and therefore is not soluble in water.

▪ A phospholipid is amphipathic! In this case, it means that one end loves water (hydrophilic) and the other end hates water (hydrophobic).


Lipids: Steroids

▪ A steroid is a type of lipid made up of four carbon rings attached to molecules that vary from one steroid to the next.


Lipids: Steroids


Lipids: Steroids

▪ Some athletes take testosterone like compounds to enhance their performance.▪ There is a down side to taking steroids:

- Increase in body odor, baldness, acne, breast enlargement in men, kidney disease, decreased testicular size, low sperm

count, impotence, high cholesterol, high blood pressure, heart damage, liver dysfunction, liver cancer, stunted growth if taken during development, personality changes including rage and delusions, etc


This type of lipid is an important component of membranes

1. Triglycerides2. Phospholipids3. Steroids4. Proteins


Proteins

▪ A protein is a polymer made of one or more chains of amino acids. Amino acids are the building blocks of proteins.

- There are 20 different amino acids, each with a different side chain, or R group.


Proteins

▪ Proteins have a lot of important functions in the body, including, but not limited to:

- Speed up chemical reactions (enzymes)- Transport molecules- Movement of muscles- Structure- Cell signaling- Nutrition- Defense- Components of cell membrane- Immune response


Proteins

▪ Amino acids that form proteins are linked by bonds called peptide bonds. ▪ Peptide bonds are formed through dehydration synthesis reaction.


Proteins

▪ Chains of only a few amino acids are called peptides.

▪ Chains of 10 or more amino acids are called polypeptides.

▪ Polypeptide chains of at least 50 amino acids are called proteins. - Proteins are usually folded.


Proteins

▪ ala = alanine▪ gln = glutamine▪ ile = isoleucine


Protein structure

▪ Proteins have four distinct structure that affect their function in the body.

- Primary- Secondary- Tertiary- Quaternary


Protein structure


Protein structure: Primary

▪ Primary structure of a protein is the particular sequence of amino acids.

▪ This sequence dictates a protein’s structure and function.


Protein structure: Secondary

▪ Secondary structure of proteins consists of patterns known as pleated sheets and helices.

- Primary structure determines secondary structure.- Hydrogen bonding between amino acids in the protein

shape α- helix and β-pleated sheets.

- A polypeptide chain can contain both α- helix and β-pleated sheets.


Protein structure: Tertiary

▪ Tertiary structure is the overall three-dimensional shape of the protein.

- Determined by size and placement of amino acids in protein.- Hydrogen, ionic, and covalent bonds may all contribute.- Chaperone proteins aid in the folding of polypeptide chains. - A protein can lose its shape under some conditions, and this

is known as denaturation.


Protein structure: Tertiary

Hydrogen

Ionic

Hydrophobicinteraction

Disulfide bond


Protein structure: Quaternary

▪ Quaternary structure is the structure that results from the assembled units of multiple chains of polypeptides.


Protein: shape and health

▪ The change of one amino acid in a sequence can cause a detrimental effect.


Protein: Enzymes

▪ Enzymes are substances—almost always proteins—that speed up chemical reactions without being consumed in the process. ▪ They speed up reactions that would happen eventually, but these reactions would probably take days to years.


Protein: Enzyme Properties

1. They are usually specific for their substrates.

2. They are not consumed (destroyed) in the process.

3. They have optimal conditions- pH- Temperature


Protein: Enzyme examples

▪ Pepsin and trypsin are digestive enzymes.▪ Pepsin is found in the stomach and trypsin is found in the intestine.

Rat

e o

f re

acti

on

pH

Trypsin

Pepsin


Protein: Enzyme mechanism

▪ Substrate = the molecule that is being changed in the reaction▪ Active site = place in the enzyme where the substrate binds▪ Product = the end result


Nucleotides▪ Their functions include:

- Energy (ATP)- Coenzymes that aid enzyme function (NAD+) or are

messengers between and within cells (ADP)▪ Every nucleotide monomer consists of a five-carbon (pentose) sugar bonded to one of five nitrogen-containing bases and at least one phosphate group. ▪ There are 5 nucleotides because there are five different bases:

- Adenine, Thymine, Uracil, Guanine, and Cytosine


Nucleotides: Structure


Nucleotides: examples▪ Adenosine triphosphate and adenosine diphosphate (ATP and ADP)

- Energy transferring molecules▪ Guanosine triphosphate and guanosine diphosphate (GTP and GDP)

- Intracellular signaling molecules and energy transferring molecules▪ Nicotinamide adenine dinucleotide (NAD)

- Energy transferring molecule


Nucleotides: example


Nucleic acids▪ Nucleic acids are polymers consisting of long chains of nucleotides.▪ Two types of nucleic acids:

- Deoxyribonucleic acid (DNA)- Ribonucleic acid (RNA)

▪ Functions:- Blueprint to make proteins (DNA)- Protein synthesis (RNA)


Ribonucleic acid (RNA)▪ RNA is single-stranded.▪ It has the sugar ribose.▪ It is composed of these nitrogenous bases:

- Adenine, guanine, cytosine, and uracil


Deoxyribonucleic acid (DNA)▪ DNA is double stranded, and forms a double helix.▪ It has the sugar deoxyribose.▪ It has the nitrogenous bases adenine, guanine, cytosine, and thymine.


DNA and RNA review

biological molecules lecture packet 3 reading: chapter 2 (pages 31-39) copyright 2008 pearson...

Documents

pearson education slide

monosaccharides copyright

sugars copyright

carbohydrates function

galactose copyright

hexose copyright

polymer degradation

cell membranes copyright