Chapter 3THE MOLECULES OF CELLS

StandardsBy the end of the unit you should be able to:

Model synthesis and hydrolysis reactions and relate the reactions to the human body

Recognize carbs, lipids, proteins and nucleic acids in formula & skeleton form, chemical structure and describe their function in the human body

Recognize monosaccharides, disaccharides and polysaccharides and relate the molecules to how they function in the body

Recognize, describe the location of, and explain the importance of the following in the human body: neutral fats, steroids and phospholipids

I can list the major functions of nucleic acids (RNA & DNA), describe their structure with accurate detail and compare these 2 molecules

I can compare the following pairs: saturated and unsaturated fats, DNA & RNA

I can differentiate among the primary, secondary, tertiary and quaternary structure of proteins and explain how these levels of structure relate to protein functions

I can relate protein structure to protein specific examples from the human body

I ca draw the general structure of the ATP molecule in its role as the “energy currency” of cells

Biological Molecules

3.1 Life’s molecular diversity is based on the

properties of carbon

A carbon atom can form four covalent bonds

allowing it to build large and diverse organic

compounds

Organic Molecules – contain carbon atom

and a hydrogen atom

C can bond with up to 4 other atoms

Carbon chains vary in many ways

Hydrocarbons are composed of only hydrogen and carbon

Some carbon compounds are isomers: molecules with the same molecular formula but different structures

H H

HH

H H

Ethane Propane

HH

H H

H

H

H

H

H

H

Carbon skeletons vary in length.

H

H

H

H

H H

H H

H H

H H

H H

H H

H

H

H

H

H

H H H H

H

H

C

HHH

H H

H H

H

H

H

H H

H

H

H

H

H

H

H H

H

H

Butane Isobutane

Skeletons may be unbranched or branched.

1-Butene 2-Butene

Skeletons may have double bonds, which can vary in location.

C

C C

C

C

C

H

C

CC

C

C

C

Cyclohexane Benzene

Skeletons may be arranged in rings.

C C C C C

C C C C

C

C CC

CCCC CCCH H

Figure 3.1A

1

2

3

4

.

3.2 Functional

groups help

determine the

properties of

organic

compounds

Some examples

of functional

groups:

Table 3.2

Functional groups are particular groupings of

atoms that give organic molecules particular

properties

Female lion

Estradiol

HO

OH

OH

O

TestosteroneFigure 3.2

Male lion

Basic Vocab.

Monomer –is a small

molecule that may

become chemically

bonded to other

monomers to form a

polymer.

Polymer – a large

molecule that is made

of several monomers

bonded to each other

Reactions that form polymers &

monomers Hydrolysis and Synthesis Reactions

Reactions we will see for all biological

molecules

Cells make most of their large molecules by

joining smaller organic molecules into chains

called polymers

Cells link monomers to form polymers by a

dehydration reaction

H

OH H

OH

H O

H

Unlinked monomer

Dehydratio

n reaction

Longer polymer

Short polymer

OH H

H OH

Unlinked monomer

Dehydration

reaction

Short polymer

H2O

Figure 3.3A

Polymers are broken down to monomers by the

reverse process, hydrolysis

H

H2O

OH

HOH

OH H

Hydrolysis

Figure 3.3B

3.3 Cells make a huge number of large

molecules from a small set of small molecules

The four main classes of biological

molecules are carbohydrates, lipids,

proteins, and nucleic acids

Many of the molecules are gigantic and

are called macromolecules

CARBOHYDRATES 3.4 Monosaccharides are the simplest carbohydrates

The carbohydrate monomers are monosaccharides

A monosaccharide has a formula that is a multiple of

CH2O and contains hydroxyl groups and a carbonyl

group

Figure 3.4A

Carb Info:

Function of carbs for humans– source of

energy for the cell (cellular respiration)

CARBS contains carbon, hydrogen, and

oxygen in the ratio of 1:2:1. (empirical

formula)

The monosaccharides glucose and fructose

are isomers that contain the same atoms but in

different arrangements

C

C

C

C

C

C

C

C

C

C

H

H

H

H

H

H

H H

H

H

H

HO

H

H

H

C

O

HO

OH

OH

OH

OH OH

OH

OH

C O

OH

Glucose FructoseFigure 3.4B

Monosaccharides can also occur as ring structures

H

H

H

H

H

H H

H

HH

OC

C

C C

O

OHOH HO OH

OH

CH2OH

CH2OH

C

OH

OH

O

OH

Structural

formulaAbbreviated

structure

Simplified

structure

6

5

4

3 2

1

Figure 3.4C

3.5 Cells link two single sugars to form

disaccharides

Monosaccharides can join to form

disaccharides such as sucrose (table sugar)

and maltose (brewing sugar)

H

HH H

HH

H

H

H

H

H

H

H

H

H HH

H

H

H

OH OH

OHOHOH

HO

O O

O

OH

OH

OH

CH2OH CH2OH

CH2OH CH2OH

H2O

OH

HO

O

OH O

H

Glucose Glucose

Maltose

O

OH

Figure 3.5

CONNECTION 3.6 How sweet is sweet?

Various types of molecules, including

nonsugars taste sweet because they bind to

“sweet” receptors on the tongue

Table 3.6

3.7 Polysaccharides are long chains of sugar units Polysaccharides are polymers of monosaccharides

linked together by dehydration reactions

Starch and glycogen are polysaccharides that store sugar for later use

Cellulose is a polysaccharide found in plant cell walls

Starch granules in

potato tuber cells

Glycogen

granules in

muscle tissue

Cellulose fibrils in

a plant cell wall

Glucose

monomer

Cellulose

molecules

STARCH

GLYCOGEN

CELLULOSE

O O

OOOOOO

O O O

O

OO

OO

OO

OO

OO

OO

O

OO

OO

OO

OO O

OOOOOO

OOOOOO

O

OH

OH

Figure 3.7

3.8 Fats are lipids that are mostly energy-storage

molecules

Lipids are diverse compounds that consist mainly of

carbon and hydrogen atoms linked by nonpolar

covalent bonds

Lipids are grouped together because they are

hydrophobic

Figure 3.8A

LIPIDS

Fats, also called triglycerides (neutral fats) are

lipids whose main function is energy storage

Consist of glycerol linked to three fatty acids

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

H2O

H H

HH

OHOH OH

H

HO

C O

C C C

Fatty acid

Glycerol

H HH

H H

CH2

O O O

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

CH2

CH2

CH2

CH2

CH2

CH3

C C C OOO

C C C

H

Figure 3.8B Figure 3.8C

3.9 Phospholipids, waxes, and steroids are

lipids with a variety of functions

Phospholipids are a major component of cell

membranes

Waxes form waterproof coatings

Steroids are often hormones

HO

CH3

CH3

H3C CH3

CH3

Figure 3.9

CONNECTION 3.10 Anabolic steroids pose health risks

Anabolic steroids are synthetic variants of testosterone that can

cause serious health problems

3rd group of Bio Cules -

Proteins2 types

StructuralFunctional

Found in ligaments,

bones, tendons, skin

Ex – keratin, collagen

Enzymes – hydrolytic-

(lysosomes, digestive)

3.11 Proteins are essential to the structures and

activities of life

A protein is a polymer constructed from amino acid

monomers

Proteins are involved in almost all of a cell’s

activities

As enzymes they regulate chemical reactions.

Figure 3.11

PROTEINS

3.12 Proteins are made from amino acids linked by

peptide bonds

Protein diversity is based on different arrangements of a

common set of 20 amino acid monomers

Each amino acid contains An amino group

A carboxyl group

An R group, which distinguishes each of the 20

different amino acids

H

H

N

H

C

R

C

O

OH

Amino

group

Carboxyl (acid)

group

Figure 3.12A

Each amino acid has specific properties based on its structure

H

H

N

H

C

CH2

CH

CH3 CH3

C

O

OH

H

H

N C

H

CH2

OH

C

O

OH

H

H

N C

H

C

O

OHCH2

C

OH O

Leucine (Leu) Serine (Ser) Aspartic acid (Asp)

Hydrophobic Hydrophilic

Figure 3.12B

Cells link amino acids together by dehydration

synthesis

The bonds between amino acid monomers are

called peptide bonds

H

H

N C C

O

OH H

H

N+ C

H

R

C

O

OH

H2O

H

H

N C C N C C

R H R OH

O

Peptide

bond

DipeptideAmino acid

Dehydration

reaction

Amino

group

H

R

Amino acid

Carboxyl

group

H O H

Figure 3.12C

Peptide Bonds The N of one a.a. bonds to C of carboxyl of another

a.a.

Dipeptide – has 1 peptide bond & 2 a.a.

Tripeptide – has 2 bonds & 3 a.a

Polypeptides – many amino acids

GrooveGroove

Figure 3.13BFigure 3.13A

3.13 A protein’s specific shape determines its

function

A protein consists of one or more polypeptide

chains folded into a unique shape that

determines the protein’s function

3.14 A protein’s shape (and therefore its

function!) depends on four levels of structure

Primary Structure

A protein’s primary structure is the sequence of

amino acids forming its polypeptide chains

Levels of Protein Structure

Primary structure GlyThr

Gly GluSer Lys

Cys

Pro

Leu Met

Val

Lys

Val

Leu Asp Ala Val Arg Gly SerPro

Ala

Ile

Asn Val

Ala

ValHis

Val

Amino acids

PheArg

Figure 3.14A

Secondary structure

A protein’s secondary structure is the coiling or

folding of the chain, stabilized by hydrogen

bonding between a.a. on different parts of the

strand

Figure 3.14B

Secondary structure

C

N

O C

C

N H

O C

C

H

Hydrogen

bond

O C

N H

C

CO

N H

O C

C

N H

C

N

O C

C

N H

O C

C

N H

CO

C

H

N H

CO

H C R

HN

Alpha helix

CN

H

C C

H HO

N

R C C

O

N

H

O

CC N

H

C C

O

N

H

O

CC N

H

C

O

C N

H

O

CC N

H

C

O

O

CC

N

H

C C

O

N

H

CC

O

N

H

CC

O

N

H

CC

O

N

H

CC

O

N

H

CC

O

N

H

CC

O

H

N

C

Pleated sheet

Amino acids

Tertiary Structure

A protein’s tertiary structure is the overall three-

dimensional shape of a polypeptide

This 3D shape is the result of interactions between

the R groups of the a.a.s

Tertiary structure

Polypeptide

(single subunit

of transthyretin)

Figure 3.14C

Quaternary Structure

A protein’s quaternary structure results from the

association of two or more polypeptide chains

EX: hemoglobin

Quaternary structure

Transthyretin, with

four identical

polypeptide subunits

Figure 3.14D

Polypeptide

chain

Collagen

TALKING ABOUT SCIENCE 3.19 Linus Pauling contributed to

our understanding of the chemistry

of life

Linus Pauling made important

contributions to our understanding

of protein structure and function

Discovered the alpha helical

structure in proteins (secondary

level) and also the difference in the

structure of hemoglobin in regular

blood vs sickle cell anemia blood

Figure 3.15

NUCLEIC ACIDS 3.20 Nucleic acids are information-rich or

energy carrying polymers of nucleotides

There are 3 ex: DNA, RNA, ATP

Nucleic acids such as DNA and RNA serve as

the blueprints for proteins and thus control the

life of a cell

ATP serves as the energy currency of the cell

The monomers of nucleic acids are nucleotides

Composed of a 5 carbon sugar, phosphate,

and nitrogenous base (ATCGU)

Sugar

OH

O P O

O

CH2

H

O

H H

OH H

H

N

N

H

N

N H

HH

N

Phosphate

group

Nitrogenous

base (A)

Figure 3.16A

Different Nucleotides: Note

same basic shape!

The sugar and phosphate form the backbone

for the nucleic acid or polynucleotide

Sugar-phosphate

backbone

T

G

C

T

A Nucleotide

Figure 3.16B

DNA consists of two polynucleotides twisted

around each other in a double helix, the two

strands run antiparallel to each other Stretches of a DNA molecule called genes program the amino

acid sequences of proteins

C

TA

GC

C G

T A

C G

A T

A

G C

A T

A T

T A

Base

pair

T

Figure 3.16C

RNA, by contrast is a single-stranded

polynucleotide

RNA, when compared to DNA, is: Shorter

Single stranded

Has a U base (uracil) instead of a T base (thymine)

Has MANY more types/jobs, ex: messenger, transfer, ribosomal etc

ATP – Adenosine Triphosphate

Produced by cellular

respiration

Glucose + oxygen -

Carbon dioxide +

water + ATP

ATP – needed for

active transport

Notice – 2 high

energy bonds

Synthesis of –

ADP + Pi → ATP + H2O

Nucleic Acids Comparison

Molecule ATP DNA RNA

Structure Nucleotide Double

stranded

molecule

Single

Stranded

molecule

Sugar Ribose Deoxyribose Ribose

BASES A A,C,T,G A. C, U,G

Uses Energy Information Information,

many others