It’s A Cellular World

Atoms

Simple molecules

Monomers (sugars, amino acids, nucleotides)

Polymers (starch, glycogen, proteins, DNA, RNA)

Macromolecular assemblies (ribosomes, lipoproteins, membranes)

Cells & Unicellular Organisms

Multicellular Organisms

The Beginning

The primordial soup…

what was in it?

Chemical Elements

6 protons

6 neutrons

Carbon

- -

-

- -

- 6 electrons

Some Key Elements For Organic Molecules

Carbon

- -

-

- -

- 6 electrons

Hydrogen

1 electron

- -

- 7 electrons

Oxygen

8 electrons

-

-

- -

-

- -

- -

-

FYI

6 protons

6 neutrons

1 proton

Nitrogen

-

- -

7 protons

7 neutrons 8 protons

8 neutrons

Natural forces (oxidation, lightning, volcanic activity) create

simple molecules from elements at earth’s surface. Carbon, oxygen,

nitrogen, sulfur, & hydrogen combine to form molecules, e.g.,

carbon dioxide, ammonia, nitrate, acetate, sulfate, phosphate, etc.

In The Beginning

Atoms Bond To Form Simple Molecules

- -

Hydrogen gas (H2)

H-H

A single covalent bond

(sharing 1 pair of electrons)

Oxygen gas (O2)

O=O

A double covalent bond

(sharing 2 pairs of electrons)

Water Is Made With 2 Single Bonds

Water (H2O)

O

H H

Some Molecules Are Polar

(Electrical Charge Distribution Is Uneven)

Electrons are have a negative charge, and

electrons spend more time with the larger oxygen

atom. Therefore, water molecules are polar.

Oxygen

H H

-

- -

-

- - -

- -

-

+

A Molecule of Glucose (a sugar) Is

Made of Carbon, Hydrogen, and

Oxygen Bonded Together In A Ring

C6H12O6

Shorthand Notation

C6H12O6

OH

|

H C H

|

O H

Ionic Bonds

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Crystal Lattice of NaCl (table salt)

Salt Dissolves in Water

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

Na+ Cl-

+ - + - + -

+ - + - + -

+

- +

-

+

- +

-

+

- +

- +

-

+

- +

-

+

- +

-

+

-

+ - + - + -

+ - + - + -

Life Consists of Simple Molecules Combined

to Form Increasingly Complex Molecules

Example: Sugars combine to make disaccharides, starches and glycogen.

• Biological molecules are made from chains &

rings of carbon.

• Single units of biological molecules (monomers)

can join to form increasingly complex molecules

(polymers) with complex shapes.

Simple Sugars Bond to

Form a Disaccharide

+

condensation

hydrolysis (disaccharides)

sucrose

(disaccharide)

The process of splitting a compound into fragments with the

addition of water; a kind of reaction that is used to break down

polymers into simpler units, e.g. starch into glucose.

Hydrolysis

Carbohydrates: Starch, Glycogen, &

Cellulose Are Chains of Sugar Molecules

Proteins, Lipids, & DNA Are Also Polymers

Made From Smaller Building Blocks

• Sugars combine to make disaccharides,

starches, and glycogen.

• Fatty acids make triglycerides, fats, &

phospholipids.

• Strings of nucleotides make RNA & DNA.

• Proteins are chains of amino acids.

Lipids

Fatty substances

Fatty acids

Triglycerides (fat)

Cholesterol

Fatty Acids

• Covalently-linked chains of carbon atoms

• Saturated (all single bonds) & unsaturated (one or more double bonds)

• Monounsaturated fatty acids have 1 double bond

• Polyunsaturated fatty acids have 2-6 double bonds

A Molecule of Fat: A Triglyceride

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

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C

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H O

O H

H

C

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H O

O H

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H O

O H

3 Fatty Acids

Glycerol

backbone

H-

RNA & DNA

Chains of Nucleotides

U

Sugar-phosphate

backbone

Sugar-phosphate

backbone

Nucleotide

Unit

Ribose

(sugar)

Deoxyribose

(sugar)

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Proteins Are Chains of Amino Acids

Cells Are the Units of Life

From Bacteria to Man

Let’s Build a Cell

Some Molecules Are Polar

(Electrical Charge Distribution Is Uneven)

e.g., Water molecules are polar.

Electrons, which have a negative charge, spend

more time with the larger oxygen atom, so the

oxygen end of the molecule is more negative then

the hydrogen end.

Oxygen

H H

-

- -

-

- - -

- -

-

+

Water Molecules Cling To Each Other

Because + & - Charges Attract

Water is polar.

Hydrogen bonding of water molecules http://biomodel.uah.es/en/water/index.htm

Triglycerides Are Non-Polar

The long hydrocarbon chains are

uncharged and therefore repel water.

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

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C

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C

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C

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C

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C

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C

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C

H

H O

O H

H

C

C

C

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O H

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C

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C

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H

C

H

H

C

H

H O

O H

3 Fatty Acids

Glycerol

backbone

H-

The Fatty Acid Composition of Some

Common Oils (Fats)

Phospholipids Are Amphipathic

Phospholipids are amphipathic; they have both polar & non-polar parts.

H

C

C

C

H

H

H

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C

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O H

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C

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H O

O H

CH3-N-C-C-O-P-

O

-CH

3

-CH

3

O

O

=

-

+

Choline Phosphate

2 Fatty Acids

polar head

group

non-polar

fatty acid tails

Glycerol

Water

The Polar Head Group Is Attracted To Water, But

The Non-polar Fatty Acid Tails Are Repelled

Polar head

group

Non-polar

fatty acid tails

“Amphipathic” = Dual nature

Phospholipid Molecules Self-Assemble in H20

Polar head

group

Non-polar

fatty acid tails

Polar Forces Cause Phospholipids To Form Bilayers

Water

Oily Layer

Water

Phospholipid Bilayers Can Form

Spherical Structures …

…thus,

providing the

basis for cell

structure.

Lipids: Cholesterol

• Plants have sterols, but they do not have cholesterol.

Only animal cells have cholesterol.

• The ring structure provides compact rigidity; its purpose

is to modify the fluidity of animal cell membranes.

-

Non-polar

(oily ; hydrophobic;

“water fearing”)

Polar

(hydrophilic;

“water loving”)

Cholesterol Has A Small Polar

Portion, But Is Mostly Non-polar

-

Water

Water

Lipid Bilayer

(Cell Membrane)

A Double Layer of Phospholipids & Cholesterol

Forms the Basis of the Cell Membrane

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Proteins Are Chains of Amino Acids

Polar (hydrophilic, i.e., “water loving”

Non-polar (hydrophobic, i.e., “water fearing”)

Proteins May Have Hydrophobic (Non-

polar) & Hydrophilic (Polar) Segments

Val Leu Met Met Met Met Phe Leu Asp Asp His Lys Lys His Glu Val Leu Met Phe

Val Leu Met Met Met Met Phe Leu Asp Asp His Lys His Lys Glu Val Leu Met Phe Asp Asp His Lys Lys His Glu Val Leu Met Met Met Met Phe Leu Asp Asp His

Lys

His

Asp Asp His

Lys Glu Val Leu Met Phe Lys Lys His Glu Val Leu Met Phe folding

His Lys Glu Val Leu Met Phe Lys Lys His Glu Val Leu Met Phe

Val Leu Met Met Met Met Phe Leu Asp Asp Asp Asp His

Lys Lys His Glu

The Hydrophobic Segments of

Proteins Influences How They Fold

Water

Water

The Hydrophobic Segments of

Proteins Also Influences Their

Insertion Into Cell Membranes

Protein Structure

“Receptors,” binding

sites that recognize

chemical signals

Proteins Serve Many Functions

Antibodies –

chains (subunits)

with binding sites

for antigens

Signal

molecule

Protein

receptor Cylindrical tubes to

transport large

molecules across

the cell membrane

Hemoglobin to

transport oxygen

Enzymes that

join or split

other molecules

Peptide

hormones

(insulin)

Collagen fibers

for structure

Fibers that

contract

Chains bound together

to form a sheet

Extracellular Water

Intracellular Water

Extracellular Water

Intracellular Water

A Stereotypical Eukaryotic Cell

Source: http://www.daviddarling.info/encyclopedia/E/eukarycell.html

The Type Of Fat In Your Diet

May Affect Cellular Function

Different Types of Triglycerides (Fats & Oils)

EPA DCHA

Solid at room temperature:

Coconut butter is a fat with mostly saturated fatty acids.

Lard is animal fat, which is rich in saturated fatty acids.

Liquid at room temperature:

Olive oil is a fat with a high amount of oleic acid (18:1, i.e.,

monounsaturated).

Corn oil is a fat with a high amount of linoleic acid (18:2).

Fish oils are fats with unusually long fatty acids (20 or 22

carbon atoms) with 5 or 6 double bonds.

The Fatty Acid Composition of Some

Common Oils (Fats)

Mozaffarian, D. et al. N Engl J Med 2006;354:1601-1613

Structure of Cis and Trans Fatty Acids

Mozaffarian, D. et al. N Engl J Med 2006;354:1601-1613

Potential Physiological Effects of Trans Fatty Acids

Proteins in the Cell Membrane

Serve a Number of Functions

Protein Binding Sites

Protein folding may create “pockets” with a specific shape that can bind other molecules, like a lock that accepts a specific key. This enables them to serve:

As receptors that recognize signal molecules (e.g. hormones).

A defensive function to recognize foreign molecules.

As enzymes that can bind cellular molecules and then break them down or combine them with other molecules to effect synthesis.

These highly specific binding sites enable proteins to function as:

Receptors that recognize signal molecules (e.g. hormones).

Receptors that trigger defensive responses

Antibodies that tag foreign molecules

Enzymes that can bind cellular molecules and then break them down or combine them with other molecules to effect synthesis.

Almost All The Activities of Cells

Are Controlled By Proteins

• Proteins can change shape & properties when another molecule binds to them, causing things to happen.

• Enzymes & channel proteins, act as little programmed chemical robots.

Simple Sugars Bond to

Form a Disaccharide

+

condensation

hydrolysis (disaccharides)

sucrose

(disaccharide)

The process of splitting a compound into fragments with the

addition of water; a kind of reaction that is used to break down

polymers into simpler units, e.g. starch into glucose.

Hydrolysis

Some Enzymes Break Substrates

Apart & Others Combine Them

Transport of Substances Across the Cell Membrane

The lipid bilayer is

permeable to water and

small, uncharged

molecules (e.g. oxygen

[O2] and carbon dioxide

[CO2]

Simple

diffusion

Facilitated

diffusion

Active

transport

Energy

Transmembrane

proteins create a water-

filled pore through which

ions and small

molecules like glucose

can pass by diffusion.

The lipid bilayer of the cell membrane is not permeable to ions,

water-soluble molecules like glucose, or large molecules like

protein or DNA.

Some transmembrane

proteins use ATP energy

to actively transport ions

and small molecules

against a concentration

gradient.

Muscle Fibers Are Made of Proteins

Cell Membrane – A Fluid Mosaic

Atoms

Simple molecules

Monomers (sugars, amino acids, nucleotides)

Polymers (starch, glycogen, proteins, DNA, RNA)

Macromolecular assemblies (ribosomes, lipoproteins, membranes)

Cells & Unicellular Organisms

Multicellular Organisms

A “Typical” Eukaryotic

Cell and Its Organelles

Mitochondria:

convert sugar,

starch, fat into

cellular energy.

Nucleus: DNA,

RNA synthesis.

Rough endoplasmic

reticulum & ribosomes:

protein synthesis.

Muscle Cells

Endothelial Cells

Intestinal Cells

Pancreatic Cells

Gallbladder Cells

Nerve Cells

White Blood Cells

Bone Cells

On A Scale From 1 To 10,000

1 m 10

m

.1 m .01

m

.001

m

.0001

m

viruses bacteria

History of the Evolution of Life

Levels of Organization

Atoms

Molecules

Macromolecules

Organelle

Cells

Tissues

Organs

Organ

systems

Organism