CHAPTER 3 The Molecules of Cells

BIOLOGYCONCEPTS & CONNECTIONS

Fourth Edition

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor

From PowerPoint® Lectures for Biology: Concepts & Connections

CHAPTER 3The Molecules of Cells

Modules 3.4 – 3.10


Carbon Bonding


Functional groups influence the characteristics of the molecule and the reactions they undergo.


Monomers, Polymers, and Macromolecules


4 macromolecules

• Proteins , carbohydrates, lipids and nucleic acids.


• Monosaccharides are single-unit sugars

• These molecules typically have a formula that is a multiple of CH2O . Their formula is C6H12O6.

• Each molecule contains hydroxyl groups and a carbonyl group as their functional group. The hydroxyl group renders most sugars hydrophillic or water loving.

• Monosaccharides are the fuels for cellular work

3.4 Monosaccharides are the simplest carbohydrates. They are the monomers.

Figure 3.4A


Polar and ionic molecules have positive and negative charges associated with them and are therefore attracted to water because water is a polar molecule. They are said to be hydrophilic because they interact with (dissolve in) water forming hydrogen bonds.


• The monosaccharides glucose, galactose and fructose are isomers

– They contain the same atoms but in different arrangements

Glucose FructoseFigure 3.4B

Galactose


• Many monosaccharides form rings, as shown here for glucose

Abbreviatedstructure

Figure 3.4C


Large carbon molecules are built from small monomers.

The monomers, the polymers and the macromolecules…….

• For each of the four macromolecules we will fill in an organizer to study from. We will start with the simple sugars which, when linked together, form the carbohydrates.


• Monosaccharides can join to form disaccharides, such as sucrose (table sugar) and maltose (brewing sugar) and lactose (milk sugar)

3.5 Cells link single sugars to form disaccharides through dehydration synthesis.

Glucose Glucose

Maltose

Sucrose=fruc-tose + glucose

lactose


• Various types of molecules, including non-sugars, taste sweet because they bind to “sweet” receptors on the tongue. The tighter they bind the receptors, the sweeter the taste.

3.6 Connection: How sweet is sweet?

Table 3.6


Examples of some human thresholds

TasteSubstanc

e

Threshold for

tasting

Salty NaCl 0.01 M

Sour HCl 0.0009 M

Sweet Sucrose 0.01 M

Bitter Quinine0.000008

M

UmamiGlutamat

e0.0007 M

TAS2R38 locus = bitter PTC locusIf sooo bitter = supertasters


• Carbohydrates are a class of molecules

– They range from small sugars to large polysaccharides

– Polysaccharides are long polymers of monomers linked by dehydration synthesis.

CARBOHYDRATES


• Starch (plants) and glycogen (animals) are polysaccharides that store sugar for later use

• Cellulose (plants) is a polysaccharide in plant cell walls. It passes as “fiber” through our digestive tract for most animals can not hydrolyze it. How do termites and cows get nutrients from plants???? Hum….

Figure 3.7

Starch granules in potato tuber cells

Glucosemonomer

STARCH

GLYCOGEN

CELLULOSE

Glycogen granules in muscle tissue

Cellulose fibrils ina plant cell wall

Cellulosemolecules


Carbohydrate morphology

• Starch- coils of branched glucose, plants use it for energy.

• Cellulose-unbranched rods of glucose most abundant organic compound. B-glycosidic bonds prevent mammals from breaking it down to obtain glucose.

• Glycogen-stored in liver more branched than starch. Hydrolyzed in liver and digestive tract.


• These compounds are composed largely of carbon and hydrogen

– They are not true polymers

– They are grouped together because they do not mix with water. They are hydrophobic.

– Fats, oils, phospholipids and waxes are composed of glycerol and fatty acids.

3.8 Lipids include fats, which are mostly energy-storage molecules

Figure 3.8A


• Fats are triglycerides whose main function is energy storage in animals. Oils are analogous in plants.

• Triglycerides= 3 fatty acid chains and a glycerol. A triglyceride molecule consists of one glycerol molecule linked to three fatty acids

Figure 3.8B

Fatty acid


• Unsaturated fatty acid chains (common in plant oils) contain double bonds.

– These unsaturated fats form kinks which prevent them from solidifying at room temperature as they can not pack tightly together. They are better for you than saturated fats.

• Saturated fatty acid chains (common in animal lard) lack double bonds. They are solid at room temperature. They should be limited in the diet as they can pack tightly together and clog arteries and veins.

Figure 3.8C


Oleic acid Elaidic acid Stearic acid

Oleic acid is a cis unsaturated fatty acid

that comprises 55–80% of olive oil.

Elaidic acid is a trans unsaturated fatty acid often found in partially

hydrogenated vegetable oils.

Stearic acid is a saturated fatty acid found in animal fats and is the intended

product in hydrogenation.

These fatty acids are geometric isomers(chemically identical except for the

arrangement of the double bond).

This fatty acid contains more hydrogen and is not isomeric with the

previous.

The Cis and Trans fats


• Phospholipids are a major component of cell membranes. They are composed of two fatty acid chains, a glycerol, and phosphorus.

• Waxes form waterproof coatings. They are composed of one fatty acid chain and a glycerol. Waxes are found on plants and in your ears.

• Steroids are often hormones.

3.9 Phospholipids, waxes, and steroids are lipids with a variety of functions

Figure 3.9


• Anabolic steroids are usually synthetic variants of testosterone

• Use of these substances can cause serious health problems

• anadrol, oxandrin, dianabol

• winstrol, deca-durabolin

• equipoise.

3.10 Connection: Anabolic steroids and related substances pose health risks

Figure 3.10


Anabolic steroids are similar to testosterone

• Anabolic steroids are synthetic derivatives of the male hormone testosterone. The full name is androgenic anabolic steroids and they promote growth of the skeletal structure and increase lean body mass.

• Anabolic steroids are taken orally or injected. They are taken in continuous patterns called "cycling," which occur by starting, stopping and starting again over a period of weeks or months and changing the dosages of the steroids.

• Additionally, users will combine anabolic steroids often times with other drugs (stimulants, depressants, painkillers, anti-inflammatories) to maximize their effectiveness while minimizing negative effects.


More Negative Effects

• Arnolds, Asteroids, Ball Shrinkers, Gear, Gym Candy, Iron Brew, Juice, Liquid Gold, Pump-up pills, Roids, Sted, Rocket fuel, Sloop, Product, Stacking

• More serious dangers — including liver damage and cancer — are linked to long-term, high-dose use, which can be 100 times higher than standard therapeutic doses.

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CHAPTER 3 The Molecules of Cells