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Molecules of Life. Chapter 3. 3.1 Molecules of Life. Molecules of life are synthesized by living cells Carbohydrates Lipids Proteins Nucleic acids. Structure to Function. Molecules of life differ in three-dimensional structure and function Carbon backbone Attached functional groups

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3 1 molecules of life
3.1 Molecules of Life
  • Molecules of life are synthesized by living cells
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic acids
structure to function
Structure to Function
  • Molecules of life differ in three-dimensional structure and function
    • Carbon backbone
    • Attached functional groups
  • Structures give clues to how they function
organic compounds
Organic Compounds
  • Consist primarily of carbon and hydrogen atoms
    • Carbon atoms bond covalently with up to four other atoms, often in long chains or rings
  • Functional groups attach to a carbon backbone
    • Influence organic compound’s properties
slide7

In alcohols (e.g.,

sugars, amino acids);

water soluble

hydroxyl

methyl

In fatty acid chains;

insoluble in water

carbonyl

In sugars, amino acids,

nucleotides; water

soluble. An aldehyde

if at end of a carbon

backbone; a ketone if

attached to an interior

carbon of backbone

(aldehyde)

(ketone)

carboxyl

In amino acids, fatty

acids, carbohydrates;

water soluble. Highly

polar; acts as an acid

(releases H+)

(non-ionized)

(ionized)

Fig. 3.3, p. 36

slide8

amino

In amino acids and

certain nucleotide

bases; water soluble,

acts as a weak base

(accepts H+)

(non-ionized)

(ionized)

phosphate

In nucleotides (e.g.,

ATP), also in DNA,

RNA, many proteins,

phospholipids; water

soluble, acidic

icon

Fig. 3.3, p. 36

slide10

one of the estrogens

testosterone

Fig. 3.4, p. 37

animation functional group
Animation: Functional group

CLICK HERE TO PLAY

processes of metabolism
Processes of Metabolism
  • Cells use energy to grow and maintain themselves
  • Enzyme-driven reactions build, rearrange, and split organic molecules
building organic compounds
Building Organic Compounds
  • Cells form complex organic molecules
    • Simple sugars → carbohydrates
    • Fatty acids → lipids
    • Amino acids → proteins
    • Nucleotides → nucleic acids
  • Condensation combines monomers to form polymers
slide16

enzyme action at functional groups

enzyme action at functional groups

Condensation

Hydrolysis

Fig. 3.5, p. 37

key concepts structure dictates function
Key Concepts:STRUCTURE DICTATES FUNCTION
  • We define cells partly by their capacity to build complex carbohydrates and lipids, proteins, and nucleic acids
  • The main building blocks are simple sugars, fatty acids, amino acids, and nucleotides
  • These organic compounds have a backbone of carbon atoms with functional groups attached
3 2 carbohydrates the most abundant ones
3.2 Carbohydrates – The Most Abundant Ones
  • Three main types of carbohydrates
    • Monosaccharides (simple sugars)
    • Oligosaccharides (short chains)
    • Polysaccharides (complex carbohydrates)
  • Carbohydrate functions
    • Instant energy sources
    • Transportable or storable forms of energy
    • Structural materials
slide22

glucose

fructose

sucrose

c Formation of a sucrose molecule

Fig. 3.6, p. 38

slide26

c Glycogen. In animals, this

polysaccharide is a storage form for excess glucose. It is especially abundant in the liver and muscles of highly active animals, including fishes and people.

Structure of cellulose

Fig. 3.8, p. 39

key concepts carbohydrates
Key Concepts:CARBOHYDRATES
  • Carbohydrates are the most abundant biological molecules
  • Simple sugars function as transportable forms of energy or as quick energy sources
  • Complex carbohydrates are structural materials or energy reservoirs
3 3 greasy oily must be lipids
3.3 Greasy, Oily – Must Be Lipids
  • Lipids
    • Fats, phospholipids, waxes, and sterols
    • Don’t dissolve in water
    • Dissolve in nonpolar substances (other lipids)
  • Lipid functions
    • Major sources of energy
    • Structural materials
    • Used in cell membranes
slide31
Fats
  • Lipids with one, two, or three fatty acid tails
    • Saturated
    • Unsaturated (cis and trans)
  • Triglycerides (neutral fats )
    • Three fatty acid tails
    • Most abundant animal fat (body fat)
    • Major energy reserves
animation fatty acids
Animation: Fatty acids

CLICK HERE TO PLAY

slide36

glycerol

three fatty acid tails

Triglyceride, a neutral fat

Fig. 3.11, p. 40

phospholipids
Phospholipids
  • Main component of cell membranes
    • Hydrophilic head, hydrophobic tails
slide39

hydrophilic head

two hydrophilic tails

b

Fig. 3.13, p. 41

slide40

c Cell membrane section

Fig. 3.13, p. 41

waxes
Waxes
  • Firm, pliable, water repelling, lubricating
sterols cholesterol
Sterols: Cholesterol
  • Membrane components; precursors of other molecules (steroid hormones)
animation cholesterol
Animation: Cholesterol

CLICK HERE TO PLAY

key concepts lipids
Key Concepts:LIPIDS
  • Complex lipids function as energy reservoirs, structural materials of cell membranes, signaling molecules, and waterproofing or lubricating substances
3 4 proteins diversity in structure and function
3.4 Proteins – Diversity in Structure and Function
  • Proteins have many functions
    • Structures
    • Nutrition
    • Enzymes
    • Transportation
    • Communication
    • Defense
protein structure
Protein Structure
  • Built from 20 kinds of amino acids
slide49

amino

group

carboxyl

group

Fig. 3.15, p. 42

slide51

valine

Fig. 3.15, p. 42

four levels of protein structure
Four Levels of Protein Structure

1. Primary structure

  • Amino acids joined by peptide bonds form a linear polypeptide chain

2. Secondary structure

  • Polypeptide chains form sheets and coils

3. Tertiary structure

  • Sheets and coils pack into functional domains
four levels of protein structure1
Four Levels of Protein Structure

4. Quaternary structure

    • Many proteins (e.g. enzymes) consist of two or more chains
  • Other protein structures
    • Glycoproteins
    • Lipoproteins
    • Fibrous proteins
slide58

a Protein primary

structure: Amino

acids bonded in a

polypeptide chain.

Fig. 3.17, p. 43

slide60

b Protein secondary

structure: A coiled

(helical) or sheetlike

array, held in place

by hydrogen bonds

( dotted lines) between

different parts of the

polypeptide chain.

helical coil

sheet

Fig. 3.17, p. 43

slide62

barrel

c Protein tertiary structure: A chain’s coiled parts, sheetlike

arrays, or both have folded and twisted into stable, functional

domains, including clusters, pockets, and barrels.

Fig. 3.17, p. 43

slide64

d Protein quaternary

structure: Many weak

interactions hold two

or more polypeptide

chains together as

a single molecule.

Fig. 3.17, p. 43

3 5 why is protein structure so important
3.5 Why is Protein StructureSo Important?
  • Protein structure dictates function
  • Sometimes a mutation in DNA results in an amino acid substitution that alters a protein’s structure and compromises its function
    • Example: Hemoglobin and sickle-cell anemia
slide71

alpha globin

a Globin. The secondary

structure of this polypeptide

includes several helixes. The

coils fold up to form a pocket

that cradles heme, a functional

group with an iron atom at its

center. The kind of molecular

representation shown here is

called a ribbon model, after its

appearance. Appendix V has

more details about such models.

heme

Fig. 3.18, p. 44

slide73

alpha globin

alpha globin

beta globin

beta globin

b Hemoglobin is one of the proteins with quaternary structure. It

consists of four globin molecules held together by hydrogen bonds.

To help you distinguish among them, the two alpha globin chains

are shown here in green, and the two beta globins are in brown.

Fig. 3.18, p. 44

slide75

PROLINE

GLUTAMATE

GLUTAMATE

THREONINE

VALINE

HISTIDINE

LEUCINE

a Normal amino acid sequence at the start of a beta chain for hemoglobin.

Fig. 3.19, p. 45

slide77

VALINE

HISTIDINE

LEUCINE

THREONINE

PROLINE

VALINE

GLUTAMATE

b One amino acid substitution results in the

abnormal beta chain in HbS molecules. Instead

of glutamate, valine was added at the sixth

position of the polypeptide chain.

sickle cell

c Glutamate has an overall negative charge; valine has no net charge. At low oxygen levels, this difference gives rise to a water-repellent, sticky patch on HbS molecules. They stick together

because of that patch, forming rodshaped clumps that distort normally rounded red blood cells into sickle shapes. (A sickle is a farm tool that has a crescent-shaped blade.)

normal cell

Fig. 3.19, p. 45

slide79

Clumping of cells in bloodstream

Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys

Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure

Spleen concentrates sickle cells

Spleen enlargement

Immune system compromised

Rapid destruction of sickle cells

d Melba Moore, celebrity spokes-person for sickle-cell anemia organizations. Right, range of symptoms for a person with two mutated genes for hemoglobin’s beta chain.

Anemia, causing weakness,fatigue, impaired development,heart chamber dilation

Impaired brain function, heart failure

Fig. 3.19, p. 45

slide80

Clumping of cells in bloodstream

Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys

Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure

Spleen enlargement

Immune system compromised

d Melba Moore, celebrity spokes-person for sickle-cell anemia organizations. Right, range of symptoms for a person with two mutated genes for hemoglobin’s beta chain.

Anemia, causing weakness,fatigue, impaired development,heart chamber dilation

Impaired brain function, heart failure

Spleen concentrates sickle cells

Rapid destruction of sickle cells

Stepped Art

Fig. 3-19, p. 45

denatured proteins
Denatured Proteins
  • If a protein unfolds and loses its three-dimensional shape (denatures), it also loses its function
  • Caused by shifts in pH or temperature, or exposure to detergent or salts
    • Disrupts hydrogen bonds and other molecular interactions responsible for protein’s shape
key concepts proteins
Key Concepts:PROTEINS
  • Structurally and functionally, proteins are the most diverse molecules of life
  • They include enzymes, structural materials, signaling molecules, and transporters
3 6 nucleotides dna and rnas
3.6 Nucleotides, DNA, and RNAs

Nucleotide structure, 3 parts:

  • Sugar
  • Phosphate group
  • Nitrogen-containing base
slide86

base (blue)

sugar (orange)

three phosphate groups

Fig. 3.20, p. 46

nucleotide functions reproduction metabolism and survival
Nucleotide Functions: Reproduction, Metabolism, and Survival
  • DNA and RNAs are nucleic acids, each composed of four kinds of nucleotide subunits
  • ATP energizes many kinds of molecules by phosphate-group transfers
  • Other nucleotides function as coenzymes or as chemical messengers
slide89

phosphate group

adenine

(A)

base with a double-ring structure

sugar (deoxyribose)

Fig. 3.21, p. 46

slide90

THYMINE

(T)

base with a single-ring structure

Fig. 3.21, p. 46

slide91

GUANINE

(C)

base with a double-ring structure

Fig. 3.21, p. 46

slide92

CYTOSINE

(C)

base with a single-ring structure

Fig. 3.21, p. 46

dna rnas and protein synthesis
DNA, RNAs, and Protein Synthesis
  • DNA (double-stranded)
    • Encodes information about the primary structure of all cell proteins in its nucleotide sequence
  • RNA molecules (usually single stranded)
    • Different kinds interact with DNA and one another during protein synthesis
slide95

covalent

bonding in

carbon

backbone

hydrogen bonding

between bases

Fig. 3.22, p. 47

key concepts nucleotides and nucleic acids
Key Concepts:NUCLEOTIDES AND NUCLEIC ACIDS
  • Nucleotides have major metabolic roles and are building blocks of nucleic acids
  • Two kinds of nucleic acids, DNA and RNA, interact as the cell’s system of storing, retrieving, and translating information about building proteins
animation structure of atp
Animation: Structure of ATP

CLICK HERE TO PLAY