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Chemistry of Life


Title: Chemistry of Life Author: Tracey Magrann Last modified by: tmagrann Created Date: 8/1/2007 4:42:18 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Chemistry of Life

Chemistry of Life
Chemistry of Life
  • Flowers emit a chemical perfume that attracts
    butterflies, but the plant also makes a noxious
    chemical in its leaves which discourages the
    butterfly from laying her eggs there.
  • Insects interact via chemical messages that range
    from stay away to come mate with me.

Rattlebox Moth
  • Secrete a noxious chemical for defense,
    particularly against spiders.
  • This moth is a native of Central Florida.
  • Its name comes from the rattlebox plant, the
    source of the moths defensive chemical.
  • This chemical also has an important role in its
    mating strategy.
  • While the moth was a caterpillar, it ate the
    leaves from the rattlebox plant and stored this
    chemical in its body.

Rattlebox Moth
  • While both male and female caterpillars contain
    this chemical, the female moth receives an extra
    dose at mating.
  • During the eight hour copulation, the male passes
    a large mass of sperm, nutrients, and this
    chemical to the female, supplying additional
    protection for her and for their offspring.
  • Only a human bridegroom would buy life insurance
    for his bride.
  • This classy moth gives a gift she can really
    use-- a life insurance policy that pays off every
    time her life is in danger.

  • Natures Chemical Language
  • The rattlebox moth
  • Produces chemicals important for mating and

Rattlebox Moth
  • During the courtship dance, the male moth release
    is into the air puffs of this chemical the
    female, sensing it, can assess how much of this
    chemical he has.
  •  There are some kinds of chemical signaling in
    humans as well. For instance, chemicals in the
    armpit of a male can apparently regularize a
    female companions ovulatory cycle.
  •  Chemicals play many more roles in life than
    signaling. Chemicals make up our bodies as well
    as the bodies of other organisms, and they also
    make up the physical environment. To understand
    biology, we should first look at where it all
    begins chemistry.

An element is an atom with a certain number of
electrons (electrical charges) circling around it
in an orbit.
  • 96 of the human body is composed of just four
  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • The other 4 of elements in our body
  • Calcium, phosphorus, potassium, sulfur, sodium,
    chlorine, and magnesium.
  • These elements are involved in important
    functions such as bone formation, nerve
    signaling, and DNA synthesis.

Trace Elements
  • Iron
  • Needed by all forms of life for transporting the
    oxygen in the blood.
  • Iodine
  • only required by certain species it is an
    ingredient of a hormone produced by the thyroid
    gland. Iodine is commonly added to table salt to
    prevent the formation of goiters.
  • Fluorine
  • added to water in some communities to reduce
    tooth decay
  • Zinc
  • Manganese

Vitamin-Fortified Foods
  • Chemicals are added to food to help preserve it,
    make it more nutritious, or simply to make it
    look better.
  • Iron, for example, is a trace element that is
    commonly added to foods.
  • You can actually see the iron that has been added
    to a fortified cereal by crushing the cereal and
    then stirring a magnet through it.
  • Vitamins are also frequently added to cereal.
  • A vitamin consists of more than one element and
    is an example of a compound, which we will
    consider next Elements combine to larger units
    called compounds.

  • Trace elements
  • are essential to
  • human health and
  • may be added to
  • food or water

  • Two or more elements
  • Compounds are much more common than pure
  • In fact, few elements exist in a pure state in
    nature. Many compounds consist of only two
    elements for instance table salt (sodium
    chloride) has equal parts of the elements sodium
    and chlorine.
  • Pure sodium is a metal and pure chlorine is a
    poisonous gas. Chemically combined, however,
    they form a common seasoning.
  • This example shows the emergence of novel
    properties with a higher level of structural
    organization. We will see this in biology too,
    as we study the adaptations of organisms as they

  • Elements can combine to form compounds

  • Hydrogen (H) and Oxygen (O) H2O
  • Sodium (Na) and Chlorine (Cl) NaCl
  • Demonstrates new properties with a higher level
    of structural organization
  • Carbon, hydrogen, oxygen, and nitrogen form most
    of the compounds in living organisms

  • Sodium and chloride ions
  • Bond to form sodium chloride, common table salt

  • Most of the compounds in living organisms contain
    at least three or four different elements, mainly
    carbon, hydrogen, oxygen, and nitrogen.
  • Vitamin K, for example, is formed of just carbon,
    hydrogen, and oxygen.
  • Proteins are compounds containing carbon,
    hydrogen, oxygen, nitrogen, and a small amount of
  • Different arrangements of the elements determine
    unique properties for each compound.
  • There are two groups of compounds in our bodies
    organic and inorganic.

  • Contain NO carbon atoms
  • Found in body fluids and is needed for muscle
    contraction and nerve conduction.
  • The body is 70 water.
  • It keeps the body from overheating
  • It also prevents drastic changes in temperature.

  • If you have ever burned your finger on a metal
    pot while waiting for the water in it to boil,
    you know that water heats up much more slowly
    than metal.
  • Water has a better ability to resist temperature
    change than most other substances.
  • Earth's giant water supply moderates
    temperatures, keeping them within limits that
    permit life.

  • A large body of water can store a huge amount of
    heat from the sun during warm periods.
  • At cooler times, heat given off from the
    gradually cooling water can warm the air.
  • That's why coastal areas generally have milder
    climates than inland regions.
  • Water's resistance to temperature change also
    stabilizes ocean temperatures, creating a
    favorable environment for marine life.
  • And at 70 of your body weight, water helps
    moderate your internal temperature.

  • Liquids vaporize into a gas when some of their
    molecules move fast enough.
  • When heat is applied to a liquid, it makes the
    molecules move faster and bump into each other,
    causing the hydrogen bonds break, allowing
    vaporization to occur.

  • Water Molecule

  • Water molecules form weak bonds between each
    other called hydrogen bonds

  • Ice is less dense than liquid water
  • Hydrogen bonds hold molecules in ice farther
    apart than in liquid water

  • Insects can walk on water due to surface tension

  • Another way water moderates temperatures is by
    evaporative cooling.
  • When a substance evaporates, the surface of the
    liquid remaining behind cools down as the hottest
    molecules leave.
  • Evaporative cooling helps prevent land-dwelling
    organisms from overheating.
  • Evaporation from a plants leaves keeps them from
    becoming too warm in the sun, just as sweating
    helps to dissipate our excess body heat.
  • On a much larger scale, the evaporation of
    surface waters cools tropical seas.

How do land organisms keep from overheating?
  • Evaporative cooling
  • Plants leaves
  • Human sweating
  • Evaporation of surface waters cools tropical seas.

Water is the solvent of life
  • Solution a liquid consisting of a uniform
    mixture of two or more substances.
  • Solvent the dissolving agent
  • Solute the substance that is dissolved
  • Water is the solvent inside all cells, in blood,
    and in plants, and it dissolves an enormous
    variety of solutes necessary for life.

The chemistry of life
  • The chemistry of life is sensitive to acidic and
    basic conditions
  • In water solutions, a very small percentage of
    the water molecules actually break apart into
  • The ions formed are called hydrogen ions (H) and
    hydroxide ions (OH-).
  • The proper balance of these ions is very critical
    for the proper functioning of an organism.

Acids and Bases
  • Some water molecules break apart into ions.
  • Hydrogen ions (H)
  • Hydroxide ions (OH-)
  • Acid excess hydrogen ions (H)
  • hydrochloric acid in your stomach
  • Base excess hydroxide ions (OH-)
  • Ammonia is a base

Acids and Bases
  • We use the pH scale to describe how acidic or
    basic a solution is.
  • The scale ranges from 0 (most acidic) to 14 (most
  • Pure water and other solutions that are neither
    acidic nor basic are said to be neutral they
    have a pH of 7.
  • The pH of the solution inside most living cells
    is close to 7.
  • Even a slight change in pH can be harmful.

pH scale
  • Neutral pH 7
  • Acid pH lt 7
  • Base pH gt 7

Acid Rain
  • Imagine arriving for a long awaited vacation at a
    mountain lake only to discover that since your
    last visit a few years ago, all fish and other
    forms of life in the lake have perished because
    of increased acidity of the water.
  • Over the past quarter-century, thousands of lakes
    in North America, Europe, and Asia have suffered
    that fate. This problem is due to acid rain.

Acid Rain
  • Acid rain pH well below 7
  • Results from sulfur and nitrogen in the air.
  • These elements react with water vapor in the air
    to form sulfuric acid and nitric acid, which fall
    to the earth in rain or snow.
  • Acid rain with a pH of 1.7 (almost as acetic as
    the digestive juices in the human stomach) has
    been recorded in Los Angeles.

Acid Rain
  • Sulfur and nitrogen in the air comes from the
    burning of fossil fuels such as coal, oil, and
  • Electrical power plants that burn coal produce
    more of these pollutants than any other single

Sulfur and nitrogen in the air comes from the
burning of fossil fuels
The Effect of Acid Rain
  • Lakes
  • most pronounced in the spring
  • Kills eggs and young fish
  • Forests
  • Ions bind with essential minerals needed for
    plant growth
  • Leaves behind toxic levels of aluminum
  • Cities
  • corrosion of buildings and statues

Acid Rain in Lakes
  • The surface snow melts first, drains down, and
    sends much of the acid that has accumulated over
    the winter into lakes and streams all at once.

Most pronounced in the spring Kills eggs and
young fish
Acid Rain in Forests
  • Acid rain has also taken a toll on forests. When
    acid precipitation falls on land, it washes away
    mineral ions, such as calcium and magnesium,
    which are essential nutrients for plant growth.
  • At the same time, minerals such as aluminum reach
    toxic concentrations.
  • In cities, acid precipitation causes a great deal
    of corrosion of buildings and statues.
  • That is why laws were enacted that require
    reductions in emissions to help alleviate the

Ions bind with essential minerals needed for
plant growth Leaves behind toxic levels of
Corrosion of buildings and statues
Chemistry of Life
  • Every organism has a delicate biochemistry that
    needs to be maintained.
  • One spring, a baby finch collapsed with
    exhaustion on my patio.
  • Since it was exhausted, it probably wasnt good
    at finding food and water yet.
  • That means it was dehydrated and hungry.
  • I knew to get an eyedropper and give it water
    with sugar in it because those are the two main
    things it needs right away.
  • We discussed water, now lets get to sugars.

  • Always contain carbon
  • Carbohydrates
  • Lipids
  • Proteins

  • Store energy for a short time
  • Simple (sugars)
  • Complex (starches)
  • Cellulose (fiber) is in plants only

  • Known as sugars
  • Quick source of energy
  • Burned off fast
  • Glucose
  • Sucrose
  • Fructose
  • Lactose (some people are lactose intolerant)

Lactose Intolerance
  • Got milk? Most of the world's people cannot
    easily digest milk-based foods.
  • Milk and other dairy products have long been
    recognized as highly nutritious foods, rich and
    proteins and minerals necessary for good teeth
    and strong bones.
  • But for millions of people, those health benefits
    come with digestive discomfort.
  • Such people suffer from lactose intolerance, or
    the inability to properly break down lactose, the
    main sugar found in milk.

Lactose intolerance is common world-wide
Lactose Intolerance
  • For those with lactose intolerance, the problem
    starts once lactose passes through the stomach
    and enters the small intestine.
  • To absorb this sugar, digestive cells need to
    secrete an enzyme called lactase, which is
    necessary to break down lactose.
  • An enzyme is a protein that breaks down larger
    molecules into smaller ones.
  • Those with lactose intolerance produce
    insufficient amounts of the enzyme and the
    lactose cannot be properly digested.
  • This leads to symptoms of nausea, cramps,
    diarrhea, and gas.
  • .

Lactose Intolerance
  • At birth, nearly everyone produces enough lactase
  • Therefore, milk provides excellent nourishment
    for infants.
  • But after the age of two, lactase levels start to
    decline in most of the worlds populations. In
    the United States, 75 of African Americans and
    Native Americans and 90 of Asian-Americans are
    lactase deficient once they reach their teenage
  • People of European descent are the only group
    that does not suffer much from lactose

  • Present in bottled salad dressings, lunchmeat,
    prescription drugs.

  • Currently, lactose intolerance cannot be
    corrected by gene therapy to treat the underlying
  • The symptoms of lactose intolerance can be
    controlled through diet.
  • In many Asian cultures, beverages are made from
    soy or rice instead of milk.
  • Milk-based foods pre-treated with lactase.
  • Lactase in pill form can be taken with food

  • Lactose intolerance, with its interplay between
    genes and milk sugar, illustrates the importance
    of biological molecules to the functioning of
    living cells and to human health.
  • In people who easily digest milk, lactose (a
    sugar), is broken down by lactase (a protein),
    which is produced by a gene made of DNA (a
    nucleic acid).
  • If the gene for lactase production is not active,
    lactase is not present.
  • And the presence of lactase can mean the
    difference between delight and discomfort when
    someone contemplates an ice cream sundae.

Sweet Taste Receptors
  • The taste we describe as sweet has been a beloved
    sensation throughout human history.
  • However, sugars are not the only substances
    perceived as sweet there are other chemicals
    that can trigger the same sensation.
  • We perceive sweetness when molecules of a
    substance attach to the sweet taste receptors
    on our tongue, triggering a message to the brain.
  • Many different kinds of molecules can bind to our
    sweet taste receptors, each causing a similar
    message to be sent.
  • The glucose and fructose in honey taste sweet but
    so does the laboratory-produced compound called
    aspartamine (Equal and NutraSweet).
  • Compared to table sugar (sucrose), fruit sugar
    (fructose) is four times sweeter.

Sweet Taste Receptors
  • We perceive sweetness when molecules of a
    substance attach to the sweet taste receptors
    on our tongue.

Sweet Taste Receptors
  • Aspartamine (Equal and NutraSweet)
  • Compounds that bind more tightly to sweet taste
    receptors send stronger sweet messages to the

Sweet Taste Receptors
  • The chemical shape of a compound determines how
    well it fits into a taste receptor.
  • Compounds that bind more tightly to sweet taste
    receptors send stronger sweet messages to the
  • Some artificial sweeteners are much sweeter than
    sucrose because their molecules fit more snugly
    into our sweet taste receptors than natural
  • Neotame, a new artificial sweetener that received
    FDA approval in 2002, has been rated 8000 times
    sweeter than sucrose. Therefore, smaller
    quantities are needed.
  • However, some sugar substitutes also bind to
    other kinds of taste receptors on the tongue.
    For example, a sweetener may have a bitter
    aftertaste because it also binds to bitter

  • The storage form of glucose in plants
  • When we eat breads, corn, rice, potatoes, and
    cakes, we convert it to glucose.
  • These dont break down to glucose as easily, so
    they tend to get stored and are only broken down
    when there is not enough glucose available.

  • Only found in plant cell walls
  • Our body is unable to break it down, so it passes
    through our digestive tract.
  • That is what is referred to as eating fiber.
  • The fiber portion of is the wall of each plant

Eating fiber helps a person who has constipation.
Foods that are high in fiber are most likely
derived from plants.
  • Fresh fruits, vegetables, and grains are rich in
  • The fiber portion of each of these foods is the
    wall of each cell.
  • The contents of each cell contain the
    carbohydrates which can be digested.
  • This is one reason you should chew your food
    well crushing up the cell walls will release the
  • If you swallow a whole kernel of corn, it will
    pass right through your digestive tract without
    being digested.
  • You may have heard the term cellulite referring
    to fat. However, there is no such thing it is
    just regular fat, which well talk about now.
    Some companies made up the term and said their
    cream can dissolve it Wrong!

  • Lipids dont dissolve in water.
  • Fats are animal lipids
  • Oils are plant lipids

When we ingest (eat) oils, we convert them to
fats. One gram of fat stores more than twice as
much energy as one gram of starch.
  • Long-term energy storage
  • Insulate against heat loss
  • Forms protective cushions around organs
  • 1) SATURATED FATTY ACIDS are solid at
    room temperature, like butter and lard
    (animal fats).
    at room temperature, such as vegetable oils
    (plant fats)

  • Most plant fats are unsaturated oils, whereas
    most animal fats are saturated solids.
  • Diets rich in saturated fats contribute to
    cardiovascular disease by promoting a condition
    called atherosclerosis.
  • In this condition, the lipids deposits called
    plaques build up within the walls of blood
    vessels, reducing blood flow.

  • Caused by diets rich in saturated fats
  • The lipids deposits (plaques) build up within the
    walls of blood vessels, reducing blood flow.

  • Formed from cholesterol
  • Cholesterol is found in the cell membranes of our
  • Examples of steroids that our body makes are
    estrogen and testosterone.

Anabolic Steroids
  • Synthetic form of the male hormone testosterone
  • Testosterone causes a buildup (anabolism) in
    muscle and bone mass in males during puberty and
    maintains masculine traits throughout life.
  • Because anabolic steroids structurally resemble
    testosterone, they also mimic some of its

Anabolic Steroids
  • As a prescription, steroids are used to treat
    anemia and diseases that destroy body muscle.
  • Overdosing may cause violent moods swings
    (steroid rage) and deep depression.
  • The liver may be damaged, leading to cancer.
  • High blood pressure
  • The body reduces its output of natural male sex
  • Men shrunken testicles, reduced sex drive,
    infertility, and breast enlargement.
  • Women menstrual cycle disruption and development
    of masculine characteristics, including facial
  • Teenagers bones may stop growing, stunting

Steroid Abuse
  • Despite risks associated with steroid use, some
    athletes use steroids to gain a competitive edge.
  • Sports organizations banned their use, implement
    drug testing, and penalize violators.
  • In 2003, the discovery of a new designer steroid
    rocked the sports world.
  • THG is a drug modified to avoid detection in
    ordinary drug testing.
  • The drug was discovered when a track coach mailed
    a syringe containing a sample of it to the US
    Anti-Doping Agency.

Steroid Abuse
  • With that sample, the agency was able to develop
    a test that revealed the substances use among
    track and field athletes and professional
    football players, so the International Olympic
    Committee has begun retesting frozen urine
    samples from the 2002 Winter Games.
  • The US FDA declared THG an illegal steroid.
  • In 2004, a British sprinter became the first
    athlete to be penalized for its use, with a
    permanent exclusion from the Olympics following
    his positive test for THG.

Olympic Drug Testing
  • THG was a new steroid that was not detectable in
    ordinary drug testing before 2003.
  • Performance-enhancing drugs bar an athlete from
    getting a medal.
  • Blood doping blood is removed from an athlete's
    body several weeks before a competition and then
    re-injected into the body right before the event.

Performance-Enhancing Drugs
  • Discussion

  • PROTEINS are compounds that make up most of our
  • Our hair, nails, tissues, ligaments, cartilage,
    bone, tendons, muscles, and organs are made of
  • Other proteins we have are enzymes, which
    function to speed up metabolic reactions and
    break down larger compounds into smaller ones.
  • A protein is made from a string of amino acids.
    Each of our many thousands of different kinds of
    proteins has a unique shape that corresponds to a
    specific function.

  • Other types of proteins include the anti-bodies
    of our immune system, hormones that coordinate
    bodily activities, hemoglobin in red blood cells
    which deliver oxygen to working muscles,
    transport proteins that move sugar molecules into
    cells for energy, storage proteins, the protein
    of egg white, and milk proteins which provide
    amino acids for baby mammals.
  • Plants also have storage proteins for the
    developing embryos in their seeds.
  • Since proteins are made of amino acids, in order
    to understand what a protein is, we have to talk
    about amino acids (AAs).

  • The building blocks of protein
  • They are tiny compounds, made of just a carbon
    atom and a few other atoms.
  • Although there are many thousands of different
    types of proteins, they are all made up of a
    various combination of only 23 amino acids.
  • They are like beads on a necklace. How they are
    arranged on the string determines the type of
    necklace. Each bead is an amino acid, and the
    whole necklace is the protein.
  • A proteins specific shape determines its
    function. A bunch of the same types of necklaces
    (proteins) woven together makes up our tissues.

Denatured Proteins
  • If a protein becomes denatured, the amino acid
    chain unravels, causing a loss in shape and, as a
    result, function.
  • Things that can denature a protein include salt
    concentration, pH, and excessive heat.
  • You can see an example of protein becoming
    denatured by frying an egg. Heat quickly
    denatures the clear protein surrounding the yoke,
    making them solid, white, and opaque.
  • One of the reasons why extremely high fevers are
    so dangerous is that some proteins in the body
    become denatured and cannot function.

Denatured Proteins
  • Denatured proteins are those whose amino acid
    chains becomes unraveled, and results in loss of
  • Proteins are denatured by
  • salt concentration
  • pH
  • excessive heat

  • Special type of amino acids that make up DNA and
  • DNA makes up our genes
  • Genes
  • store information about how to replicate,
    including how to arrange the amino acids in the
    new cell to form the proper proteins for the

  • DNA
  • The genetic material that organisms inherit from
    their parents consists of DNA.
  • Genes are the specific stretch of a DNA molecule
    that programs the amino acid sequences.
  • RNA
  • Messenger molecules that take a copy of the DNA
    blueprint out of the nucleus and into the cell
    where it is used to make proteins

Nucleic acids are made of nucleotides
  • An architect who spends a lot of time designing
    an original blueprint for a building does not
    take this precious document down to the dusty
    construction site.
  • Instead, he makes a copy and leaves the original
    at home in a safe place.
  • Likewise, DNA in the nucleus does not put its
    genetic information to work directly by leaving
    the nucleus.
  • It works through an intermediary called RNA,
    which can enter the nucleus from the cytoplasm,
    make a copy of the gene and take it outside of
    the nucleus into the cytoplasm, were the protein
    is actually built.

  • To do this, the information in DNA is first
    copied onto a strand of messenger RNA (mRNA),
    which is like stamping an impression in clay.
  • Since the clay impression is not an exact copy of
    the original, but is instead a reverse copy, the
    DNA then needs to be translated before the
    protein is built.
  • This is done by transcription RNA (tRNA).
  • After the protein is built in the cytoplasm, it
    is either used by that cell or transported
    outside of the cell so it can be taken wherever
    else in the organism it is needed.

  • Nucleic acids are made out of a string of
  • There are only four types
  • adenine (A)
  • thymine (T)
  • cytosine (C)
  • guanine (G)
  • A sample protein sequence AATCAGC

  • A sample protein sequence AATCAGC
  • If you were to remove the last letter in that
    sequence, a completely different protein would
  • Likewise, if you were to substitute the last
    letter in that sequence for a different letter,
    you would also get a completely different
  • And of course, if you insert additional letters,
    you would have a new protein.

  • Actually, a DNA string of beads is actually
  • Each of the nucleotides (A,T,C,G) on one strand
    fits like a puzzle piece into the nucleotides on
    the other strand.
  • The nucleotide adenine (A) always pairs up with
    thymine (T), and cytosine (C) always pairs up
    with guanine (G)these are called base pairs.
  • Therefore the two strands of DNA lock together
    like a jigsaw puzzle.
  • The two strands of this DNA string of beads are
    also twisted like a coiled telephone cord. This
    structure is called a double helix.

  • Each of the nucleotides (A,T,C,G) on one strand
    fits like a puzzle piece into the nucleotides on
    the other strand.
  • adenine (A) pairs up with thymine (T)
  • cytosine (C) pairs up with guanine (G)
  • These are called base pairs.

  • The two strands of this DNA are also twisted into
    a double helix

  • Most DNA molecules are very long, with thousands
    or even millions of base pairs.
  • One long DNA molecule may contain many genes,
    each one being a specific series of hundreds or
    thousands of nucleotides.
  • The specific sequence of nucleotides in a gene is
    the information that programs the primary
    structure of a protein.

  • The type of protein that provides all the energy
    to cells.
  • When food is broken down to glucose for energy,
    ATP is what is released, which is the actual
    energy molecule.
  • The more ATP that is produced, the more energy we
  • When we inhale oxygen, it is used in a process
    called respiration, which produces ATP for
    energy. That is why we breathe.
  • Just remember that ATP is an energy molecule.

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