1 biochemistry of cells copyright cmassengale. 2 carbon-based molecules although a cell is mostly...

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Biochemistry of Cells

Copyright Cmassengale

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Carbon-based MoleculesAlthough a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules

Organic chemistry is the study of carbon compounds


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Carbon is a Versatile Atom

It has four electrons in an outer shell that holds eight


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Carbon can use its bonds to::

Attach to other carbons

Form an endless diversity of carbon skeletons


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HydrocarbonsThe simplest carbon compounds …

Contain only carbon & hydrogen atoms


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Large Hydrocarbons:Are the main

molecules in the gasoline we burn in our cars

The hydrocarbons of

fat molecules provide energy for our bodies


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Shape of Organic Molecules

Each type of organic molecule has a unique

three-dimensional shape


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Uses of Organic MoleculesAmericans consume an average of 140 pounds of sugar per person per year

Cellulose, found in plant cell walls, is the most abundant organic compound on Earth


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Uses of Organic MoleculesA typical cell in

your body has about 2 meters of DNA

A typical cow produces over 200 pounds of methane gas each year


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Functional Groups are:Groups of atoms that give properties to

the compounds to which they attach

Gained Electrons Lost ElectronsCopyright Cmassengale

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Common Functional Groups


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Giant Molecules - PolymersLarge molecules are called polymers

Polymers are built from smaller molecules called monomersBiologists call them macromolecules


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Examples of PolymersProteins

Lipids

CarbohydratesNucleic

Acids


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Most Macromolecules are Polymers

Polymers are made by stringing together many smaller molecules called monomers

Nucleic Acid

Monomer


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Linking MonomersCells link monomers by a process

called

Remove H

Remove OH

H2O Forms


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Breaking Down PolymersCells break

down macromolecules by a process called hydrolysis (adding a molecule of water)

Water added to split a double sugar


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Macromolecules in OrganismsThere are four categories of large

molecules in cells:


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CarbohydratesCarbohydrates include: Small sugar molecules

in soft drinksLong starch molecules in pasta and potatoes


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Monosaccharides:Called simple sugars

Include glucose, fructose, & galactoseHave the same chemical, but different structural formulas


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MonosaccharidesGlucose is found in sports drinksFructose is found in fruitsHoney contains both glucose & fructoseGalactose is called “milk sugar”

-OSE ending means SUGARCopyright Cmassengale

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IsomersGlucose & fructose are isomers because they’re structures are different, but their chemical formulas are the same


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RingsIn aqueous (watery) solutions,

monosaccharides form ring structures


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Cellular Fuel

Monosaccharides are the main fuel that cells use for cellular work

ATPCopyright Cmassengale

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DisaccharidesA disaccharide is a double sugarThey’re made by joining two monosaccharidesInvolves removing a water molecule (condensation)Bond called a GLYCOSIDIC bond


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Disaccharides

Common disaccharides include:


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DisaccharidesSucrose is composed of glucose + fructose

Maltose is composed of 2 glucose moleculesLactose is made of galactose + glucose GLUCOSE


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PolysaccharidesComplex carbohydrates

Composed of many sugar monomers linked together


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Examples of Polysaccharides

Starch

Glycogen

Cellulose

Glucose Monomer


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StarchStarch is an example of a

polysaccharide in plants

Potatoes and grains are major sources of starch in the human diet


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GlycogenGlycogen is an example

of a polysaccharide in animals

Animals store excess sugar in the form of glycogen


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CelluloseCellulose is the most abundant

organic compound on Earth

It forms cable-like fibrils in the tough walls that enclose plants

It is a major component of woodIt is also known as dietary fiber


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Cellulose

SUGARSCopyright Cmassengale

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Dietary CelluloseMost animals cannot derive

nutrition from fiberThey have bacteria in their digestive tracts that can break down cellulose


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Sugars in WaterSimple sugars and double sugars

dissolve readily in water

They are hydrophilic, or “water-loving”

WATER MOLECULE

SUGAR MOLECULE


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LipidsLipids are hydrophobic –”water

fearing”

Includes fats, waxes, steroids, & oils

Do NOT mix with water

FAT MOLECULE


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Function of LipidsFats store energy, help to insulate

the body, and cushion and cushion and protect organs protect organs


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Triglyceride

Monomer of lipids

Composed of Glycerol & 3 fatty acid chainsGlycerol forms the “backbone” of the fat Organic

Alcohol (-OL ending)


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Types of Fatty Acids

Unsaturated fatty acids h

Saturated fatty acids


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Types of Fatty Acids

Single Bonds in Carbon chain

Double bond in carbon chain


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Triglyceride

Glycerol Fatty Acid Chains


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Fats in OrganismsMost animal fats have a high

proportion of saturated fatty acids & exist as solids at room temperature (butter, margarine, shortening)


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Fats in OrganismsMost plant oils tend to be low in

saturated fatty acids & exist as liquids at room temperature (oils)


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FatsDietary fat consists largely of the

molecule triglyceride composed of glycerol and three fatty acid chains

Glycerol

Fatty Acid Chain

Condensation links the fatty acids to Glycerol


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Lipids & Cell Membranes

•Cell membranes are made of lipids called phospholipids

•Phospholipids have a head

•Phospholipids also have 2 tails


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SteroidsThe carbon skeleton of steroids is bent to form 4 fused ringsCholesterol is the “base steroid” from which your body produces other steroidsEstrogen & testosterone are also steroids

Cholesterol

TestosteroneEstrogen


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Synthetic Anabolic SteroidsThey are variants of testosteroneSome athletes use them to build up their muscles quicklyThey can pose serious health risks


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ProteinsProteins are polymers made of

monomers called amino acids

All proteins are made of 20 different amino acids linked in different orders


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Four Types of Proteins

Structural

Contractile

Storage

TransportCopyright Cmassengale

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Structure of Amino Acids

Amino acids have a central carbon with 4 things boded to it:Amino group –NH2

Carboxyl group -COOH

Hydrogen -HSide group -R

Amino

group

Carboxylgroup

R group

Side groups

Leucine -hydrophobic

Serine-hydrophillic


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Linking Amino AcidsCells link amino acids together to make proteinsThe process is called condensation or dehydration

Carboxyl

Amino Side

Group

Dehydration Synthesis

Peptide BondCopyright Cmassengale

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20 Amino Acid Monomers


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Primary Protein StructureThe primary structure is the specific sequence of amino acids in a proteinCalled polypeptide

Amino Acid


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Protein Structures

Secondary protein structures occur when protein chains coil or foldWhen protein chains called

polypeptides join together, the tertiary structure forms because R groups interact with each otherIn the watery environment of a cell, proteins become globular in their quaternary structure


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Protein Structures or CONFORMATIONS

Hydrogen bond

Pleated sheet

Amino acid

(a) Primary structure

Hydrogen bond

Alpha helix

(b) Secondary structure

Polypeptide(single subunit)

(c) Tertiary structure

(d) Quaternary structure


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Proteins as EnzymesMany proteins act as biological

catalysts or enzymes

Thousands of different enzymes exist in the body


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Enzymes

Their folded conformation creates an area known as the active site.

Enzymes are globular proteins.

The nature and arrangement of amino acids in the active site make it specific for only one type of substrate.


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Enzyme + Substrate = Product


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How the Enzyme Works

Enzymes are reusable!!!Active site changes SHAPECalled INDUCED FIT


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Denaturating ProteinsChanges in temperature & pH can denature (unfold) a protein so it

no longer worksCooking denatures protein in eggs

Milk protein separates into curds & whey when it denatures


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Changing Amino Acid Sequence

Substitution of one amino acid for another in hemoglobin causes

sickle-cell disease

(a) Normal red blood cell Normal hemoglobin

1 2 34 5

6 7. . . 146

(b) Sickled red blood cell Sickle-cell hemoglobin

2 314 5

6 7. . . 146


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Other Important Proteins

•Blood sugar level is controlled by a protein called insulin•Insulin causes the liver to uptake and store excess sugar as Glycogen


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INSULIN

Cell membrane with proteins & phospholipids


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Nucleic AcidsStore hereditary information

Contain information for making all the body’s proteinsTwo types exist --- DNA & RNA


64 Copyright Cmassengale

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Nucleic AcidsNitrogenous base

(A,G,C, or T)

Phosphategroup

Thymine (T)

Sugar(deoxyribose)

Phosphate

BaseSugar

Nucleic acids are polymers of nucleotides

NucleotideCopyright Cmassengale

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Nucleotide – Nucleic acid monomer


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BasesEach DNA nucleotide has one of the following bases:

Thymine (T) Cytosine (C)

Adenine (A) Guanine (G)


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Nucleotide MonomersForm long chains called DNA

Backbone

Nucleotide

Bases

DNA string

Nucleotides are joined by sugars & phosphates on the side


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DNA

Basepair

Double helix


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RNA – Ribonucleic AcidRibose sugar has an extra –OH or hydroxyl groupIt has the base uracil (U) instead of thymine (T)

Nitrogenous base(A,G,C, or U)

Sugar (ribose)

Phosphategroup

Uracil


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ATP – Cellular Energy

•ATP is used by cells for energy

•Adenosine triphosphate•Made of a nucleotide with 3

phosphate groups


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Summary of Key Concepts


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Nucleic Acids


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Macromolecules


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Macromolecules


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End


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