Chemistry of Life

Chapter 2

Elements

Simplest form of matter

Made of atoms of one type

Cannot be chemically broken down into

simpler substances

About 117 known elements

The Periodic Table of Elements

Each element has unique properties

>90% of the Human

Body

Carbon

Nitrogen

Oxygen

hydrogen

Elements/Atoms

Atoms

Smallest unit of an element

Still has chemical properties of that

element

Examples

Element oxygen – oxygen atoms

Element carbon – carbon atoms

Subatomic Particles

Subatomic

particle

Position/

Charge

Details

PROTONS NUCLEUS/

+

Atomic # = # of protons

# protons = # electrons (neutral element)

Atomic mass= # protons + # neutrons

Stay in clouds

-charge attracted to + charge of protons

Outermost shell electrons---chemical

rxns.

Inner shell electrons---held tightly

NEUTRONS NUCLEUS/

none

ELECTRONS CLOUD/

-

IONS

Elements with a + or – charge

Unequal # of protons and electrons

Lost electrons------- (+) charge

Ca +2

Gained electrons------ (-) charge

Cl –2

Isotopes

Elements with

same # of protons and electrons

Diff # of neutrons

Radioisotopes

Unstable nuclei break down

Release radiation

Uses:

Medical tagging/tracing

Fossil dating

What are isotopes used

for in medicine

Thyroid Scan

-radioactive iodine

Cancerous portion-failure to uptake iodine

PET

radioactive medicine is tagged to a natural

chemical (glucose)

As tracer is broken down positrons are

made

Scan detects different levels of positrons

PET Scans

Used for

• epilepsy (what part of the brain is being

affected)

• Alzheimer’s disease

• Cancer

• Heart disease

A Thyroid scan is a nuclear

medicine examination that uses the

emissions of gamma rays from

radioactive iodine to help

determine whether a patient has

thyroid problems, including

hyperthyroidism, cancer, or other

growths.

The scanner detects the location

and intensity of the gamma rays

emitted

Positron emission tomography (PET) scan of a person on cocaine

Cocaine has other actions in the brain in addition to activating reward. Scientists have the ability

to see how cocaine actually affects brain function in people. The PET scan allows one to see how

the brain uses glucose; glucose provides energy to each neuron so it can perform work. The scans

show where the cocaine interferes with the brain's use of glucose - or its metabolic activity. The

left scan is taken from a normal, awake person. The red color shows the highest level of glucose

utilization (yellow represents less utilization and blue shows the least). The right scan is taken

from a cocaine abuser on cocaine. It shows that the brain cannot use glucose nearly as effectively

- show the loss of red compared to the left scan. There are many areas of the brain that have

reduced metabolic activity. The continued reduction in the neurons' ability to use glucose

(energy) results in disruption of many brain functions.

Chemical Bonds

Attraction, sharing, or transfer of outer shell electrons

Energy bonds one atom to another

Energy stored in the molecule, energy is released when molecule breaks apart

3 Types:

Ionic

Covalent

Hydrogen

Ionic Bonds

Transfer of electrons

Sodium (Na+) + Chloride (Cl-)

Sodium chloride (NaCl)

Sodium Ion: Electron donated by Sodium

Chloride Ion: Electron accepted by Chloride

Covalent Bonds

Electrons shared

Helps fill electron shells

Examples

H-H (H2) and H-O-H (H2O)

Which of the above is a compound?

Single, double, triple

Polar Covalent: if UNEQUAL SHARING

Hydrogen Bonds

Hydrogen atoms bonded to oxygen or

nitrogen

Example: Strong force between water

molecules

Think about surface tension…

Chemical Reactions in

Living Cells

Help form new molecules for

Cell growth

Cell development

Cell maintenance

Allow storage or release of energy

Acids and Bases

ACIDS-

dissociate in H20

release H+

HClH+ + Cl-

BASES-

Take up H+ ions OR

Release –OH ions

NaOH Na+ + -OH

pH

pH = - [log H+]

pH scale = 0 – 14

Indicates how acidic or basic

High H+ = Very Acidic = LOW pH

Low H+ = Weakly Acidic = HIGH pH

or Very Basic

pH of body fluids

narrow range!

Normal blood pH = 7.4 (slightly alkaline)

Acidosis pH < 7.35

Alkalosis pH > 7.45

BUFFERS-maintain pH

[H2CO3] – [HCO3]

carbonic acid- H+ donor

Bicarbonate - H+ acceptor

Body’s pH

pH controls the speed of biochemical

reactions

low pH (too acidic) – body is slowly stewing

in poisonous wastes

Forces body to borrow minerals from vital

organs to neutralize the acid

Electrolytes

Salts, acids, bases

Dissociate in water

Release ions

Electrolyte balance

affects vital organs (heart, brain etc.)

Organic Compounds

Carbon atoms combined with Hydrogen

Usually Oxygen also

May contain Nitrogen, Sulfur, & Phosphorous

Macromolecules

Macromolecule Example Subunit(s)

Carbohydrates Polysaccaride Monosaccharide

Lipids Fat Glycerol + fatty

acids

Proteins Polypeptide Amino acid

Nucleic Acids DNA, RNA Nucleotide

Carbohydrates

Contain Carbon, Hydrogen, & Oxygen

H:O 2:1

Function: Source of Energy

3 Types :

Monosaccharides (1 sugar, simple)

Disaccharides (2 sugars, simple)

Polysaccharides (Multiple sugars, complex)

Monosaccharides

3-7 Carbons

Simplest form: glucose

Disaccharides

Double sugar

Know 3 types:

Sucrose(table sugar)= glucose + fructose

Lactose(milk sugar) = glucose+galactose

Maltose(malt sugar)=glucose + glucose

Polysaccharides

Many glucose molecules

Complex Carbohydrates

Examples

Starch

Glycogen

Cellulose

Pectin

chitin

Lipids

Fats and Oils

Contain carbon, hydrogen, and oxygen

Not in fixed ratio

Fatty acid + glycerolTG(Fat) + H2O

Non-polar (do not dissolve in water)

Functions:

Long-term energy and carbon storage

Parts of cell membrane

Types of Fats

Saturated: Butter and lard, solid at room temp

Single bonds only

Unsaturated: Olive oil, corn oil etc, liquid at room temp

Some double or triple bonds

Phospholipids : form cell membrane

Cholesterol: hormone development, cell membrane

Proteins

Made of Amino Acids

Functions

Structural components of cell

Messengers

Receptors (receive messages)

Defense

Enzymes (help with cellular reactions)

Amino Acids

Contain carbon, hydrogen, oxygen,

nitrogen

Building blocks of proteins

Peptide Bond –

Bond amino acids together to make

protein!

Protein Structure

Primary: Long polypeptide chain

Secondary: folded long polypeptide chain

Tertiary: more complex folding

Globular or spiral structure

Determined by amino acid sequence

Determines function

Quarternary: combined tertiary

Enzymes

Are a type of protein

Speed up chemical reactions (ex:

lactose)

Nucleic Acids

DNA and RNA

Stores genetic info

Contains info to

make protein for the

body.

Nucleic Acid Structure

Made of nucleotides (4 possibilities)

Each nucleotide has 3 parts:

5-carbon sugar (pentose)

A phosphate group

A nitrogen base (more on this…)

Nitrogen Bases

Purines (2 Rings):

Adenine (A)

Guanine (G)

Pyrimidines (1 Ring):

Cytosine (C)

Thymine (T)

replaced in RNA by Uracil (U)

DNA

Deoxyribonucleic acid

Double helix

Each helix/strand is made of:

Nucleotides

Each DNA nucleotide has:

A 5-carbon sugar (deoxyribose)

A phosphate group

A nitrogen base (A, T, G, C)

DNA Base Pairing

Hydrogen bonds

A and T (double bond)

G and C (triple bond)

Bonding b/w nitrogen base

Sugar phosphate backbone

RNA

Ribonucleic acid

Single stranded

Each strand is made of nucleotides

Each nucleotide is made of:

A ribose sugar

A phosphate group

A nitrogen base (A, U, G, C)

ATP

adenosine triphosphate

A nucleic acid that stores energy

contains 3 phosphate groups

Made in the mitochondria of every cell as

it carries out cellular respiration

Cells need energy from ATP to make

carbs/proteins, for muscle contraction

and for nerve impulse conduction