Cell Biology:Cell Compounds and Biological Molecules

Lesson 3 – Carbohydrates and Lipids (Inquiry into Life pg. 31-36)

Today’s Objectives Analyze the structure and function of biological molecules in

living systems, including carbohydrates, lipids, proteins, nucleic acids Demonstrate a knowledge of dehydration synthesis and hydrolysis

applied to organic monomers and polymers Differentiate among carbohydrates, lipids, proteins, and nucleic

acids with respect to chemical structure Recognize the empirical formula of a monosaccharide List the main functions of carbohydrates Differentiate among monosaccharides, disaccharides, and

polysaccharides Differentiate among starch, cellulose, and glycogen with respect to

function, type of bonding, and level of branching Describe the location, structure, and function of the following in the

human body: neutral fats, steroids, phospholipids Compare saturated and unsaturated fatty acids in terms of

molecular structure

2.4 Organic Molecules

Always contain: Carbon (C) and Hydrogen (H) A carbon atom may share electrons with

another carbon atom Can form long carbon chains (below)

Carbon Rings

Can also form carbon rings when a carbon chain turns back on itself

Called a ring compound Functional groups can be attached to

carbon chains or rings

Macromolecules Many molecules of life are

macromolecules.(macromolecules contain many molecules joined

together) Monomers:

Simple organic molecules that exist individually

Can also be called “unit molecules” Polymers:

Large organic molecules form by combining monomers

Macromolecules

Organic Molecules

A meal containing carbohydrates, lipids, and proteins.

Dehydration and Hydrolysis Reactions

Cells have mechanisms of joining monomers to build polymers Dehydration Reaction:

an -OH and -H are removed as a water molecule

Hydrolysis Reaction: the components of water are added

Dehydration and Hydrolysis Reactions

Dehydration and Hydrolysis Reactions Ex) dehydration of glucose

Practice

Pg. 42-43, #12, 17

Organic Molecules The 4 main types of organic polymers that

we will be looking at are: Carbohydrates Lipids (fats) Proteins Nucleic Acids

All are essential to life

2.5 Carbohydrates

Some Functions:Quick fuel*Short-term energy storage*Structure of organisms

* foremost function

Molecules characterized by presence of the grouping H-C-OH

Ratio of H to O is 2:1

Monosaccharides Simple Carbohydrates

Monosaccharides are sugars with 3 - 7 carbon atoms Sugars are vital fuel nutrients for cells

Pentose refers to a 5-carbon sugar All occur as ring structures with the formula C5H10Ox

Hexose refers to a 6-carbon sugarGlucose – found in our bloodFructose – found in fruitsGalactose – found in milk

All occur as ring structures with the formula C6H12O6

Exact shape of ring differs, as does arrangement of the –H and –OH groups attached

Monosaccharides - Glucose

Three ways to represent the structure of glucose.

Monosaccharides

GLUCOSE FRUCTOSE GALACTOSE

Disaccharides Disaccharides contain two bonded monosaccharides

Have a common formula C12H22O11

Common disaccharides: Maltose - two molecules of glucose Sucrose – one glucose, one fructose Lactose – one glucose, one galactose

Polysaccharides Polysaccharides are long polymers that

contain many glucose subunits. basic formula (C6H10O5)n

n= dozens to thousands of glucose units Three main types:

Starch is the storage form of glucose in plants. Glycogen is the storage form of glucose in

animals. Cellulose can be found in the cell walls of

plants.

Polysaccharides

Glycogen Starch Cellulose

Starch Storage form of

glucose in plants Few side chains of

glucose Linkage between

glucose units are the same

Figure 2.17 pg. 33

Glycogen “animal starch” stored

in the liver and muscle tissue

Storage form of glucose in animals

Many side chains of glucose

Linkage between glucose units the same

Figure 2.18 pg. 33

Cellulose Gives plants its

structure Found in the cell walls

of plants No side chains of

glucose Different linkages

between glucose units Fig. 219 pg. 33

Cellulose Our digestive

system is unable to digest this linkage.

Cellulose passes through our system as fiber or roughage.

May be important for good health and prevention of colon cancer

Summary of Carbohydrates 1) Source of short-term energy for all

organisms: Animals – glycogen Plants – starch Energy is released as the carbohydrates are

broken down by hydrolysis 2) Structural molecules in plants - cellulose

Practice

Pg. 42-43, #7, 9, 29

2.6 Lipids Include:

Fats and Oils Phospholipids Steroids

We eat lipids as part of our food. Our bodies are capable of producing them as well as metabolizing them

Next to glucose, fats are the second most important energy molecule for us

Unfortunately, we store them in adipose (fat) cells

Lipids Some functions:

Long-term energy storage Insulation against heat loss Protection of major organs Primary component of the cell membrane

Molecules also contain carbon, hydrogen, and oxygen but the H:O ratio is greater than 2:1

Lipids do not dissolve in water (non-polar) Lipids are electrically neutral

Lipids Fats and Oils

Fats (saturated fats) Usually of animal origin Solid at room temperature Fats provide long-term energy storage,

insulate against heat loss, and protect major organs

Ex.) lard, butter Oils (unsaturated fats)

Usually of plant origin Liquid at room temperature Ex.) vegetable oils

Formation of Fats Fats and oils form when one glycerol

molecule reacts with three fatty acid molecules

A fat molecule is sometimes called a triglyceride because of its three-part structure

The term neutral fat is sometimes used because the molecule is non-polar

Neutral Fat Structure

Synthesis and degradation of a fat molecule

Fatty Acids Saturated and Unsaturated Fatty Acids

Fatty acids are hydrocarbon chains that end with an acidic group -COOH.

Saturated fatty acids: No double covalent bonds between carbon

atomsCarbon atoms are “saturated” with as many

hydrogen atoms as they can hold

Unsaturated fatty acids: Have some double bonds between carbon

atoms (wherever the number of hydrogens is less than two per carbon atom)

Fatty Acids

Saturated Fatty Acid

Unsaturated Fatty Acid

-COOH acidic group

Carbon double bond

Phospholipids Phospholipids are a variation of a

triglyceride where one of the 3 fatty acids is replaced with a phosphate and nitrogen-containing group

Primary components of cellular membranes

Phospholipids The phosphate group creates a polar

region on one end of the phospholipid This allows phospholipids to mix with both

polar (hydrophilic) and non-polar (hydrophobic) materials

Phospholipids The heads of

the phospholipids are polar and are said to be water loving (hydrophilic)

The tails of the phospholipids are non-polar and are said to be water fearing (hydrophobic)

Phospholipid Structure

Cell Membrane The structure of phospholipids make them

a very important part of cells as they form much of the cell membrane

Steroids Assist in protein synthesis Insoluble in water All steroids have four adjacent carbon rings. Examples:

Cholesterol important part of the cell membrane Protective cover around nerve fibers Precursor of sex hormones

Testosterone Male sex hormone

Estrogen Female sex hormone

Structure of Steroids

All steroids have four adjacent carbon rings, but their attached groups differ. The effects on the body largely depend on the difference in the attached groups (shown in blue)

Cholesterol Formed by the body and also enters

body as a part of our diet Important part of the cell membrane and

protective cover around nerve fibers Cholesterol is important but often results in

fatty deposits inside arteries which narrows the pathway for blood to the heart

Can result in high blood pressure

Summary of Lipids 1) Source of long term energy storage 2) Insulate against heat loss 3) Protect internal organs 4) Saturated and Unsaturated fatty acids 5) Include fats and oils, phospholipids, and

steroids

Practice

Pg. 42-43, # 15, 28

Review Quiz Organic Molecules always contain which elements?

C and H What reaction joins monomers to form polymers?

Dehydration synthesis What reaction breaks down a polymer into

monomers? Hydrolysis

Monomers are also known by which name? Unit molecules

The unit molecules of carbohydrates are? Monosaccharides (such as glucose)

The unit molecules of lipids are? Glycerol and 3 fatty acids