Biology 20

Biochemistry

Explain how the human digestive and respiratory system exchange energy and

matter with the environment

• Describe the chemical nature of carbohydrates, lipids, and proteins and their enzymes.

Biochemistry• Element - A substance consisting entirely of one

type of atom, for instance, carbon, hydrogen or oxygen. Elements can combine into compounds to form other substances.Ion – an atom or group of atoms that have a charge

Atom - The smallest particle of an element

Compound - A substance consisting of more than one atom or one type of element, e.g. carbon dioxide is a compound.

Biochemistry

Covalent bond - Chemical bond formed by the sharing of one or more electron pairs between two atoms

Ionic bond - Chemical bonding resulting from the transfer of one or more electrons from one atom or a group of atoms to another.

BiochemistrypH scale - scale is commonly used over a range 0 (acidic) to 14 (basic).

• Acid - Substances that have a pH of lower than 7 (neutral) that can dissolve in water.

Base - Substances that have a pH of higher than 7 (neutral) that can dissolve in water.

Buffer - Solution that resists change in pH;

Metabolism• Metabolism: All the chemical reactions

that occur within the cells.• Monomer: Basic subunit used to build

larger molecules. Eg. Amino acids• Polymer: Molecules composed of many

basic subunits bonded together– Eg. Many amino acids bond together to form

on protein.

Monomer: Amino acid

Polymer:Protein

Chemistry Review• Isomer - A chemical with the same

number and types of atoms as another chemical, but possessing different properties.

Catabolic Reactants

• Complex chemicals broken down into smaller units

• Eg. Breaking down food

Anabolic Reactions

• Small units combine to make larger molecules

• Eg. Plants and photosynthesis

Dehydration Synthesis

• The process by which larger molecules are formed by the removal of water from two smaller molecules.

+

H20

Hydrolysis

• The process by which a larger molecule is broken down into two smaller molecules. Water is taken up at the broken bond site.

+

H20

Chemistry Review

• Organic Compounds

– contain carbon atoms that are linked together

• Inorganic Compounds

– do not contain linked carbon atoms.

4 Types• There are 4 major types of organic molecules

important in biology.– Carbohydrates

• monosaccharides, disaccharides, polysaccharides– Lipids

• Triglycerides, Phospholipids, Waxes, Steroids– Proteins

• Primary, Secondary, Tertiary, Quaternary– Nucleic Acids

• DNA, RNA

Biochemistry

Carbohydrates

Types of Carbohydrates

Monosaccharides

Disaccharides

Polysaccharides

Carbohydrates

• Characteristics– A Carbohydrate can be a single sugar or a

polymer of many sugars.– Carbohydrates contain CHO

• Carbon, Hydrogen, Oxygen– Ratio of carbon, hydrogen, oxygen = 1:2:1

• Purpose– Source of energy for cellular respiration– Structural material

Purposes of Carbohydrates

StructuralMajor structural

component of cell organelles,

membranes and cytoplasm

EnergyProduced by

photosynthesis, carbohydrates are the major

energy source for cells. Energy is

released through cell respiration

Monosaccharides

Types of Monosaccharides

• Monosaccharides– Single sugar = C6H12O6

– Three common isomeres• Glucose

– blood sugar• Fructose

– fruit, honey, twice as sweet as glucose• Galactose

– milk sugar, rarely found alone.

Types of Monosaccharides

Three Monosaccharides

Glucose

Fructose Galactose

Three Monosaccharides

Disaccharides

Disaccharides

• Formed by the joining of 2 monosaccharides– Process called DEHYDRATION SYNTHESIS

Disaccharides

Dehydration Synthesis

Dehydration Synthesis

Disaccharides

• Formed by the joining of 2 monosaccharides– Process called DEHYDRATION SYNTHESIS– The reverse process is called HYDROLYSIS

Disaccharides• Three Common Isomers

– Sucrose• Glucose + Fructose• sugar cane, table sugar

– Maltose• Glucose + Glucose• found in seeds of germinating plants

– Lactose• Glucose + Galactose• Found in milk• Lactose Intolerance is common

Polysaccharides

Complex Carbohydrates

Important Polysaccharides

Polysaccharides• Formed by the union of may monosaccharides

by dehydration synthesis• Types:

– Starch• Multiple sub-units of glucose• Storage form of energy in plants

– Glycogen• Branched chains of glucose• Storage of of glucose in animals

– liver and muscle cells• High Blood Glucose -- Glycogen formed in the liver• Low Blood Glucose -- Glycogen converted to glucose

Cellulose• Structural material found in plant cell walls• glucose is linked together differently

compared to starch and therefore only organisms with cellulase can digest it.– Microbes in cow’s first stomach cleave the bonds

with cellulase– The cow regurgitates (vomits into his own mouth)– chews again (gross!)– swallows into second stomach (yummy)

• What is it good for??– Roughage -- retains water in feces = soft poo

Biochemistry

Lipids

Lipids• Structure

– Contains CHO– Ratio of H to O is greater than 2 to 1

• Purpose– Long Term Energy Storage

• 1 gram of lipids contains > twice the calories compared to carbohydrates or proteins

– Structural Material• cell membranes• cushion for organs• carriers for vitamins

• raw material for synthesis of some hormones

• insulator

Classification of Lipids

Types of Lipids

• Triglycerides– Formed from 1 glycerol and 3 fatty acids– formed by dehydration synthesis

Classification of Lipids

Triglyceride Formation

Triglyceride Formation

Types of Lipids• Triglycerides

– Formed from 1 glycerol and 3 fatty acids– formed by dehydration synthesis1) FAT

• usually from animals• saturated fatty acids only contain single bonds• Very Stable -- hard to break down• solid or semi-solid at room temperature• Example: Butter

Types of Lipids

2) Oil• usually from plants• polyunsaturated fatty acids have some double

bonds between carbon atoms• more reactive than fats therefore more easily

broken down• liquid at room temperature• Example: Canola oil

Types of Lipids• Phospholipids

– Have a phosphate molecule attached to a glycerol backbone

Classification of Lipids

Types of Lipids• Phospholipids

– Have a phosphate molecule attached to a glycerol backbone

– Polarized molecule• one side is relatively hydrophilic, other side

hydrophobic– Major component of membranes

• Waxes– Very stable – Insoluble in water– valuable waterproof coatings for plant

leaves, animal feathers and fur

Types of Lipids

• Steroids– structure = four fused carbon rings

Classification of Lipids

Types of Lipids

• Steroids– structure = four fused carbon rings– Made from cholesterol

Biochemistry

Proteins

Proteins

• After water, protein is the most abundant

molecule in body

– 17% of body weight

• 1000’s of types: species specific and individual

specific

Proteins• Purpose

1) Cell Structure• Major part of muscle, skin, nerves …• Required for the building, repair and maintenance of cell

structure.2) Cell Function

• Chemical messenger -- hormones• Transport -- hemoglobin• Movement -- contractile proteins• Catalysis of cell reactions -- enzymes• Defence against foreign substances -- antibodies

Proteins

• Structure– Contains CHON– Carbon, Hydrogen, Oxygen, NITROGEN

• Terms– Protein

• A large molecule made of one or more polypeptide chains folded and coiled into a specific shape.

– Polypeptide Chains • polymers of amino acids arranged in a specific

order and linked by peptide bonds

Proteins– Peptide Bond

• Covalent bond between adjacent amino acids– Amino Acids

• The structural subunit of proteins• 20 Different types• 8 are “essential”

– Cannot be manufactured by the body– Must be obtained from food

• Structure...

Levels of Protein Structure

• Primary protein structure– linear arrangement of amino acids in the

polypeptide (like beads on a string)– exact sequence of amino acids determines

overall protein structure(analogy: different arrangements of letters spell out words with different meanings)

– all proteins have primary structure

Primary Protein Structure

Levels of Protein Structure

• Secondary Protein Structure– The coiling and folding of amino acid chains

(polypeptides)• coils are like springs• folding produces sheet-like structure• this type of structure is held together by hydrogen

bonding between amino acids– Some proteins have lots of secondary

structure, some have none

Secondary Structure

Levels of Protein Structure

• Tertiary Protein Structure– The coiled and folded polypeptide is further

twisted into n overall 3-D shape• Shape held together by hydrogen bonds,

covalent bonds, ionic bonds– Refers to the polypeptide as a whole– Polypeptides may have an overall shape

(tertiary structure) that is either• Globular (like a big blob), or• Helical (like a long, coiled spring)

Tertiary Structure

Levels of Protein Structure

• Quaternary Protein Structure– arrangements of polypeptide subunits,

when a protein is made up of more than one polypeptide

– Held together by hydrogen bonds, ionic bonds, covalent bonds• Example: hemoglobin, many enzymes

Quaternary Structure

• (a) The primary structure of a protein is the sequence of amino acids in the polypeptide strand.

• (b) Hydrogen bonds that form with nearby amino acids coil and fold the polypeptide into α-helices and β-pleated sheets; these constitute the polypeptide’s secondary structure.

• (c) The polypeptide folds further to form its tertiary structure. These folds are stabilized by R-group interactions.

• (d) The clustering of two or more polypeptides in a tertiary structure generates the quaternary structure of a protein.

Protein Changes• Denaturation

– Changes in the shape of the protein by physical or chemical factors such as heat, radiation or pH changes.

– Protein may uncoil or assume a new shape.– Protein’s physical properties and biological

properties are changed.• Coagulation

– Permanent change in the shape of the protein• e.g. boiling and cooling egg white

Biochemistry

Vitamins and Minerals

Vitamins

• Characteristics:– Organic molecules

– Not used for energy construction

– Cannot be synthesized from food

– Needed in small amounts for bodily functions

Inorganic Molecules

• Minerals– building materials for cell structures and

hormones -- calcium, iron, iodine– coenzymes -- magnesium activates enzymes

in protein synthesis– regulating body’s acid-base balance --

potassium– regulates the body’s water balance -- sodium

Inorganic Molecules

• Water– Most abundant molecule in the body– 60% of adult weight– Functions:

• excellent solvent• involved in chemical reactions

– hydrolysis• maintains constant body temperature

Biochemistry

Chemical Tests

Chemical Test• Chemical tests are used to determine the

presence of different types of organic molecules.

• Some important tests include:Benedicts ReagentIodine TestBiuretSudan IV Dye

Benedicts Reagent

• Tests for the presence of simple sugars• Negative test: After heating the benedict

solution remains blue• Positive test: After heating the blue

benedict solution turns yellow to orange.

Benedicts Test

Negative Test: Blue

No simple sugar is present

Positive Test: Orange

Simple sugar is present

Iodine Test

• Test for Starch• Negative Test: The iodine solution

remains amber when no starch is present• Positive Test: The iodine solution turns

blue black when starch is present

Iodine Test for Starch

Negative Test: Solution remains amber

No starch in present

Positive Test: Solution turns blue black

Starch is present

Biuret Test for Protein• Biuret solution is blue• Negative Test: When added to a

substance not containing protein, the solution remains blue

• Positive Test: When added to a substance containing protein, the substance turns purple

Biuret Test for Protein

Negative Test: Solution remains blue

Positve Test: Solution turns violet

Sudan IV & translucence test • Test for fats• If fat is present in the sample tested, a red

or pink colour will result Translucence test• The presence of fats can be detected by

rubbing samples on a piece of unglazed paper