Chemical Chemical Constituents of CellsConstituents of Cells

Chapter 2: Chemical Basis of Chapter 2: Chemical Basis of LifeLife

Unit 1: Levels of OrganizationUnit 1: Levels of Organization

Chemicals Chemicals

Chemicals that enter into Chemicals that enter into metabolic reactions or are metabolic reactions or are produced by them can be divided produced by them can be divided into two large groups.into two large groups.

– Organic SubstancesOrganic Substances

– Inorganic SubstancesInorganic Substances

Let Us Compare!Let Us Compare!

Inorganic SubstancesInorganic Substances: dissolve in : dissolve in water or react with water to release water or react with water to release ionsions

– They are electrolytesThey are electrolytes

Organic SubstancesOrganic Substances: can dissolve in : can dissolve in water, but are more likely to dissolve water, but are more likely to dissolve in organic liquids like ether or alcohol.in organic liquids like ether or alcohol.

– They are non-electrolytes because they They are non-electrolytes because they usually do not release ionsusually do not release ions

Inorganic SubstancesInorganic Substances

There are 4 key inorganic substances There are 4 key inorganic substances common in cells:common in cells:

– WaterWater

– OxygenOxygen

– Carbon DioxideCarbon Dioxide

– SaltsSalts

WaterWater

This is the most abundant This is the most abundant compound in living material and compound in living material and accounts for roughly 2/3 of the accounts for roughly 2/3 of the weight of an adult human.weight of an adult human.

– It is a major component of blood and It is a major component of blood and other body fluids (including those other body fluids (including those within cells)within cells)

What Does HWhat Does H22O Do?O Do?

It is an important It is an important solventsolvent, , allowing for most biochemical allowing for most biochemical reactions to occur in water.reactions to occur in water.

– Plays a key role in moving chemicals Plays a key role in moving chemicals within the body.within the body.

– The aqueous portion of blood!!!The aqueous portion of blood!!!

What Does HWhat Does H22O Do?O Do?

Has a high Has a high specific heatspecific heat

– It helps to It helps to regulateregulate body body temperature by absorbing and temperature by absorbing and transporting transporting heatheat..

– When sweat evaporates, it takes heat When sweat evaporates, it takes heat with itwith it

– Blood moves heat around the bodyBlood moves heat around the body

WaterWater

All the special properties of water All the special properties of water are due to the are due to the H-bondsH-bonds between between water moleculeswater molecules

OxygenOxygen

Molecules of oxygen enter the Molecules of oxygen enter the body through the respiratory body through the respiratory organs and are transported organs and are transported throughout the body by blood.throughout the body by blood.

– Cellular organelles use oxygen to Cellular organelles use oxygen to release energy from the sugar release energy from the sugar glucose and other nutrients. glucose and other nutrients.

– The released energy drives the cell’s The released energy drives the cell’s metabolic activities.metabolic activities.

Carbon DioxideCarbon Dioxide

It is produced as a waste product It is produced as a waste product when cellular respiration releases when cellular respiration releases energyenergy– Exhaled from the lungs.Exhaled from the lungs.

– Reacts with water to form Reacts with water to form carbonic carbonic acidacid

SaltsSalts

Salts are actually a group of Salts are actually a group of inorganic compounds.inorganic compounds.

– Provide many ions for important Provide many ions for important metabolic processes, including metabolic processes, including transport of substances into and out transport of substances into and out of the cell, muscle contractions, and of the cell, muscle contractions, and nerve impulses.nerve impulses.

Organic SubstancesOrganic Substances

These are the four major These are the four major macromoleculesmacromolecules (polymers) of life! (polymers) of life!

– CarbohydratesCarbohydrates

– LipidsLipids

– ProteinsProteins

– Nucleic AcidsNucleic Acids

CarbohydratesCarbohydrates

This molecule provides most of This molecule provides most of the the energyenergy that cells require to that cells require to participate in metabolism.participate in metabolism.

– Supply materials to Supply materials to buildbuild cellular cellular structures and are stored as structures and are stored as reservereserve energy supplies energy supplies

More CarbsMore Carbs

These molecules These molecules contain atoms of contain atoms of carbon, carbon, hydrogen, and hydrogen, and oxygen in a 1:2:1 oxygen in a 1:2:1 ratio.ratio.

– Example: glucose Example: glucose (C(C66HH1212OO66))

Carbohydrate Carbohydrate StructureStructure Sugars with 6 carbon atoms are called simple Sugars with 6 carbon atoms are called simple

sugars or sugars or MonosaccharidesMonosaccharides..

– Most in theMost in theshape of a ringshape of a ring– Glucose and fructoseGlucose and fructose

Carbohydrate Carbohydrate StructureStructure Complex carbohydrates involve the linking of Complex carbohydrates involve the linking of

2 or more simple sugars.2 or more simple sugars.

– DisaccharidesDisaccharides (double sugars) each contain two (double sugars) each contain two simple sugar building blockssimple sugar building blocks

Two rings bonded togetherTwo rings bonded together Sucrose and lactoseSucrose and lactose

Carbohydrate Carbohydrate StructureStructure

– PolysaccharidesPolysaccharides are made up of 3 or more simple are made up of 3 or more simple sugar building blockssugar building blocks

Hundreds (or thousands) of rings bonded togetherHundreds (or thousands) of rings bonded together Plant starch and animal (human) glycogenPlant starch and animal (human) glycogen

LipidsLipids

Lipids are organic substances that are Lipids are organic substances that are insolubleinsoluble in water. in water.

– Include fats, phospholipids, and steroids.Include fats, phospholipids, and steroids.

– Fatty acids are the building blocksFatty acids are the building blocks

– All of these compounds have vital All of these compounds have vital functions in cells.functions in cells.

FatsFats

Used primarily to Used primarily to store energystore energy for for cellular activities.cellular activities.

– Provide about 3x more energy (gram for Provide about 3x more energy (gram for gram) than carbohydrate molecules.gram) than carbohydrate molecules.

3 fatty acid molecules and 1 glycerol 3 fatty acid molecules and 1 glycerol combine to produce a single fat combine to produce a single fat ((TriglycerideTriglyceride) molecule.) molecule.

Fat TypesFat Types

Fatty acid molecules differ in the Fatty acid molecules differ in the length of their carbon atom length of their carbon atom chains, and the way the carbon chains, and the way the carbon atoms combine.atoms combine.

– SaturatedSaturated

– UnsaturatedUnsaturated

– PolysaturatedPolysaturated

Saturated FatsSaturated Fats

Fatty acids that contain carbon Fatty acids that contain carbon atoms all joined by single carbon-atoms all joined by single carbon-carbon bonds.carbon bonds.

– Each carbon atom is bound to as many Each carbon atom is bound to as many hydrogen atoms as possible, and is hydrogen atoms as possible, and is thus “saturated” with hydrogen atoms.thus “saturated” with hydrogen atoms.

– These fats are solid at room temp.These fats are solid at room temp.

Unsaturated FatsUnsaturated Fats

These fatty acids are not bound These fatty acids are not bound by the maximum number of by the maximum number of hydrogen atoms possible because hydrogen atoms possible because they contain one or more they contain one or more double-double-bonds bonds between carbon atoms.between carbon atoms.

– Fatty acid molecules with many Fatty acid molecules with many double-bonded carbon atoms are double-bonded carbon atoms are called called PolyunsaturatedPolyunsaturated

– These fats are liquid at room temp.These fats are liquid at room temp.

Health ConnectionHealth Connection

A diet high in A diet high in saturated fats saturated fats increases the increases the change of change of developing developing AtherosclerosisAtherosclerosis, which obstructs , which obstructs arteries.arteries.

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PhospholipidsPhospholipids

The main The main constituent of the constituent of the cell membranecell membrane

Two fatty acidsTwo fatty acids GlycerolGlycerol Phosphate headPhosphate head

PhospholipidsPhospholipids

Heads are Heads are polarpolar Two tails are Two tails are

nonpolarnonpolar Create Create lipid lipid

bilayerbilayer

SteroidsSteroids

Complex structures that include Complex structures that include four connected rings of carbon four connected rings of carbon atoms.atoms.

– The most important steroids are The most important steroids are cholesterol (occurs in body cells, and is cholesterol (occurs in body cells, and is used to synthesize other steroids) and used to synthesize other steroids) and sex hormones (estrogen, progesterone, sex hormones (estrogen, progesterone, and testosterone)and testosterone)

ProteinsProteins

Composed of carbon, hydrogen, Composed of carbon, hydrogen, oxygen, nitrogen, and sulfur.oxygen, nitrogen, and sulfur.

– Proteins serve as structural materials, Proteins serve as structural materials, energy sources, and hormones.energy sources, and hormones.

– Some proteins combine with carbs Some proteins combine with carbs ((GlycoproteinsGlycoproteins) and function on cell ) and function on cell surfaces as surfaces as ReceptorsReceptors

– Some acts as Some acts as AntibodiesAntibodies in your immune in your immune response.response.

– Some act as catalysts and are called Some act as catalysts and are called EnzymesEnzymes

Proteins ContinuedProteins Continued

The building blocks of proteins are The building blocks of proteins are Amino AcidsAmino Acids

– 20 different kinds of amino acids occur 20 different kinds of amino acids occur commonly in the proteins of lifecommonly in the proteins of life

Proteins are formed by joining amino acids with Proteins are formed by joining amino acids with peptide bonds to form a chain (polypeptide peptide bonds to form a chain (polypeptide chain) that varies in length from less than 100 chain) that varies in length from less than 100 to more than 5,000 amino acids.to more than 5,000 amino acids.

– A human body has more than 100,000 different A human body has more than 100,000 different types of proteins.types of proteins.

Protein StructureProtein Structure

Proteins have several levels of Proteins have several levels of structures: structures: Primary, Secondary, Primary, Secondary, and and Tertiary Tertiary levels. levels. AnimationAnimation

– Hydrogen and covalent bonding Hydrogen and covalent bonding between atoms in different parts of between atoms in different parts of the polypeptide give the final the polypeptide give the final protein a complicated 3-D shape or protein a complicated 3-D shape or ConformationConformation..

THE CONFORMATION OF A PROTEIN THE CONFORMATION OF A PROTEIN DETERMINES ITS FUNCTION!!!DETERMINES ITS FUNCTION!!!

Examples of Examples of ConformationConformation Long and fibrous: Long and fibrous: KeratinKeratin protein protein

forms hair, and forms hair, and FibrinFibrin knits a knits a blood clot.blood clot.

– Many proteins are globular and Many proteins are globular and function as enzymes, ion channels, function as enzymes, ion channels, carrier proteins, or receptors.carrier proteins, or receptors.

Examples: Myoglobin and hemoglobinExamples: Myoglobin and hemoglobin

A Change in ShapeA Change in Shape

When hydrogen bonds break, the When hydrogen bonds break, the unique shape of the protein is unique shape of the protein is altered altered – Called Called DenaturedDenatured..

– This causes the protein to lose its This causes the protein to lose its special properties.special properties.

Example: heat denatures the protein in Example: heat denatures the protein in egg white (albumin), changing it from a egg white (albumin), changing it from a liquid to a solid.liquid to a solid.

Nucleic AcidsNucleic Acids

Nucleic AcidsNucleic Acids act as the act as the molecules of heredity.molecules of heredity.

– Contain atoms of carbon, hydrogen, Contain atoms of carbon, hydrogen, oxygen, nitrogen, and phosphorous.oxygen, nitrogen, and phosphorous.

– The building blocks of nucleic acids The building blocks of nucleic acids are are NucleotidesNucleotides

Types of Nucleic AcidsTypes of Nucleic Acids

RNARNA (ribonucleic acid) is composed of (ribonucleic acid) is composed of molecules whose nucleotides contain the molecules whose nucleotides contain the sugar ribosesugar ribose

– Single stranded molecule used in protein Single stranded molecule used in protein synthesissynthesis

DNADNA (deoxyribonucleic acid) is (deoxyribonucleic acid) is composed of molecules whose composed of molecules whose nucleotides contain the sugar nucleotides contain the sugar deoxyribose.deoxyribose.

– Double stranded molecule that stores the Double stranded molecule that stores the information needed to synthesize protein information needed to synthesize protein molecules.molecules.

Clinical ConnectionClinical Connection

The discovery of The discovery of Prion ProteinsPrion Proteins overturned the long-held idea overturned the long-held idea that a protein can only assume that a protein can only assume one conformation.one conformation.

– A prion can assume up to a dozen A prion can assume up to a dozen different conformations.different conformations.

Some prions are infectious, and can Some prions are infectious, and can bind to “normal” proteins converting bind to “normal” proteins converting them into infectious prions as well.them into infectious prions as well.

Abnormal PrionsAbnormal Prions

Abnormal prions cause diseases Abnormal prions cause diseases called called Transmissible Transmissible Spongiform EncephalopathiesSpongiform Encephalopathies..

– More than 80 species of mammals More than 80 species of mammals are subject to these diseases.are subject to these diseases.

Examples: bovine spongiform Examples: bovine spongiform encephalopathy (mad cow disease) and encephalopathy (mad cow disease) and Creutzfeldt-Jakob diseaseCreutzfeldt-Jakob disease

– Both turn parts of the brain into spongy Both turn parts of the brain into spongy masses with steady loss of mental function.masses with steady loss of mental function.