Transcript E L E M E N T S

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 2
Basic Chemistry
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Biochemistry
Is the specialized area of chemistry that
deals with living organisms and life
processes.
Matter vs. Energy
Matter – anything that has mass & volume
(occupies space)
Energy – ability to put matter into motion
Potential – stored energy
Kinetic – energy in motion
Energy conversions:
Law of conservation
Inefficient – makes us warm blooded
Elements
Elements are said to be “pure”, it cannot be
broken down or decomposed
11 major elements in the human body with 4
elements making up 96% of the body
Carbon
Hydrogen
Oxygen
Nitrogen
15 elements are considered trace elements
Know the major function of each – p.37 Table
2-1
E
L
E
M
E
N
T
S
inyour
C. HOPKINS Ca Fe
A Mighty good place to eat
(Take it with a grain of Na Cl)
BODY
Atomic structure
Central nucleus – protons (positive)
neutrons (neutral)
Electron cloud – electrons (negative)
Atomic number – number of protons in
the nucleus
Atomic weight – refers to the mass of the
atom. Number of protons and neutrons
Energy levels
Hold only a certain number of electrons,
the number and arrangement of electrons
are important because they determine
whether the atom is chemically active.
Octet rule -
Isotopes
Versions of elements
Same # protons & electrons so chemical
properties are exactly the same but;
Different # of neutrons so may be radioactive
Radioisotopes
Used in diagnostics & treatments due to
radioactive properties
Chosen based on
• Target tissue
• Shortest half life
Medical Imaging
Read Medical Imaging: Illuminating
the Body
Study:
• How each image is different?
• Why that is an advantage?
• What are the disadvantages to each?
• What is each type better at visualizing?
Compounds
When atoms combine, they form
Molecules/Compounds
Type of bond formed is determined by
• Atoms involved in bond
• # of bonding electrons
Polarity of bond formed is determined by
• Atoms involved in bond
• How atoms share/transfer electrons
Bonds
Ionic Bonds – transferring of electrons
Covalent Bonds – sharing of one or more
pairs of electrons between the outer
energy levels of two atoms
Hydrogen bonds
Intermolecular bond
between polar
molecules
Hydrogen has partial
positive charge
Attracted to an
electronegative atom
on another molecule
“sticks” molecules
together
Responsible for 3-D
shape of important
molecules
Hydrogen Bonding
Strongest of intermolecular forces
Extremely important in determining the
properties of water and biological molecules such
as proteins
Allows blood (mostly H2O) to absorb and
transport a large amount of nutrients
DNA’s alpha helix shape is due to hydrogen
bonds between strands
Snowflakes are hexagonal due to hydrogen
bonding
Hydrogen Bonding
Hydrogen
Bonding
Surface
Tension
Polarity of Molecules
Nonpolar molecules
Share electrons
equally
Electrically balanced
Symmetrical geometry
Polar molecules
Share electrons
unequally
Asymmetrical
Has + and – charged
poles
Mixtures
Heterogeneous vs. Homogeneous
Solutions = homogeneous mixture
Suspensions & colloids
Different characteristics of different types
mixtures cause useful properties within the
body
See examples in book
Chemical Reactions
Synthesis reactions
A + B  AB
Decomposition reactions
AB  A + B + energy
Exchange reactions
AB + CD  AD + CB
Chemical Reactions
Reversibility
Indicated by double
arrows
Length of each arrow
indicates major
direction of reaction
Determined by
molecules involved,
amount of energy
required, etc.
Chemical Reactions
Will reach chemical
equilibrium when
both reactions occur
at the same rate
Many biological
reactions are
irreversible under
normal body
conditions
Requirements for
reversibility
Must have energy to
either absorb or
release
• Ex. Energy in cells is
used by cell so not
available
Must have product to
take part in reverse
reaction
• Ex. CO2 removed by
lungs so not available
Factors influencing rate of
reaction
Collision Theory: In
order to react,
molecules must:
Collide
With enough force
With the correct
geometric
orientation
Influenced by:
Particle size
Temperature
Concentration
Catalysts
(Enzymes)
Know how these
affect reaction
rates
Biochemistry: Essentials for Life
Organic compounds
Contain carbon and hydrogen
Most are covalently bonded & complex
Example: C6H12O6 (glucose)
Inorganic compounds
Do not contain carbon with hydrogen
Tend to be simpler compounds
Example: H2O (water)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.21
Functional groups
are used to describe specialized
arrangements of atoms attached to the
carbon core of many organic molecules.
Properties of Water
Table 2-2 p.45
Water = 60-80% of your body
High heat capacity
Absorbs large amounts of heat energy
BEFORE changing temperature
Assures body temperature homeostasis
High heat of vaporization
Absorbs large amount of heat energy BEFORE
changing phase and carrying the heat away
Efficient cooling mechanism
Water
Polarity gives
excellent solvent
properties
Hydration layers
Colloid formation
Transport medium
Lubricant
Polarity allow water
to surround and
separate polar
compounds & small
molecules
Water
Water is an important part of many
chemical reactions
Dehydration synthesis
Hydrolysis
Water
The presence of water in fluids & tissues
also plays an important role in protection
through cushioning
Cerebrospinal fluid
Tissue fluid
Electrolytes
Large group of inorganic compounds that
include salts, acids, bases.
These electrolytes break up in solution to
form charged particles called ions.
Positive ions – cations
Negative ions – anions
NaCl – Na+ cations and Cl- anions
Acids & Bases
Acids are compounds that increase the
presence of hydronium ions
HCl, H2SO4, etc
pH is below 7
Bases are compounds that increase the
presence of hydroxide ions (OH-)
NaOH, NH3, etc
pH is above 7
pH – a logarithmic scale
• Measures relative
concentration of hydronium
ions
• Scale runs from 0-14 with
each unit representing a
tenfold change in H+ conc.
• pH 7 = neutral
• pH below 7 = acidic
• pH above 7 = basic
• Acid + base = salt + water
Figure 2.11
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.25
Buffers
Combinations of acids & bases that allow
your body to resist large, abrupt changes in
pH
This allows your body to maintain pH
homeostasis
If this buffer is overloaded, a disease
process will be initiated
Salts
Consists of metal with nonmetal (ionic
compounds)
Easily dissociate into ions in the presence of water
pH can be anything
Vital to many body functions
Function as electrolytes to carry current in the
body
Nerve transmission
Muscle contraction
Organic Macromolecules
Organic means to
describe compounds that
carbon – specifically C-C
or C-H bonds.
4 Types of Macromolecules
Important Organic Compounds
• Carbohydrates
• Contain carbon, hydrogen, and oxygen
• Stores energy
• Include sugars and starches
• 1-2% of body mass
• Classified according to size & solubility
• Larger size = decreased solubility
• Solubility is important for transport &
reactivity
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.26
Carbohydrates
Molecules made of C,H,and O
Monosaccharides = monomer
(simple sugar)
Disaccharide = polymer
(double sugar)
Polysaccharide = macromolecule
(complex sugars)
Monosaccharides
• Monosaccharides – simple sugars
• Small size = greater solubility
• Simple sugars that body uses for immediate
energy
• Glucose, fructose, and galactose
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.26
Glucose Structure
Glucose: Your brain’s favorite
food
Disaccharides
• Disaccharides
• two simple sugars joined by dehydration
synthesis ( H2O molecule enters and splits
the sugar apart)
• Sucrose, maltose, and lactose
• All complex sugars MUST be broken down
into MONOSACCHARIDES for the body to
utilize (glycolysis and cellular respiration)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.26
Making & Breaking of
Polymers
Making of Polymers
Dehydration Synthesis – is an
anabolic process by which two
molecules are chemically joined
through the use of enzymes and
a loss of water
AKA: Polymerization
Dehydration Synthesis Example:
Glucose + Fructose = Sucrose
Making & Breaking of
Polymers
Hydrolysis – is a catabolic
process by which the bonds
between monomers are
broken by the enzyme and
the addition of water.
Hydrolysis Example:
Sucrose = Glucose + Fructose
(just reverse dehydration synthesis)
Dehydration Synthesis &
Hydrolysis
Polysaccharides
Polymers – long chains of monomers
Storage forms of sugars (cellular fuel & some
structural components)
Starch
• Plants
• Cellulose & lignin indigestible by humans
• Used for FIBER (drink lots of water!!)
Glycogen
• Skeletal muscle and liver cells in animals
• Carbohydrate loading:
• Glycogen use: stored energy that is quickly
available
Glycogen Storage
Using Glycogen
If your blood sugar (glucose) gets too high:
Your body stores it in your liver and skeletal
muscles as glycogen
If your blood sugar gets too low:
Your body breaks down the glycogen and
releases glucose to your blood
Functions of Carbohydrates
Cellular fuel = monosaccharides &
disaccharides
Energy storage & some structural
components = polysaccharides
LIPIDS
Or fat fat fat fat fat
Important Organic Compounds
• Lipids
• Non Polar organic compound
• Contain carbon, hydrogen, and oxygen
• There is a greater C to H ratio – that is
what makes them different from carbs
• There are 3 main types of fats
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.29
Lipids
KNOW THIS FACT:
Lipids are not soluble in water. This is because
water is polar and most lipids are nonpoloar.
Why are nonpolar substances unable to
dissolve in a polar substance such as water?
(can’t form hydrogen bonds)
Neutral Fats
Aka. - Triglycerides
Most concentrated source of usable
energy/fuel (9 kcal/gram)
• Carbs only have 4 kcal/gram)
Found primarily in subcutaneous fat
Saturated Fats vs.
Unsaturated
Saturated Fats –
SINGLE BONDS, straight, pack closely
together
SOLID at room temp.
ANIMAL FATS
Saturated Fats vs.
Unsaturated
Unsaturated Fats –
DOUBLE BONDS, Bent, can’t pack closely
together
LIQUID at room temp
PLANT FATS
Saturated Fats vs.
Unsaturated
Saturated Fats - all SINGLE C-C bonds
Unsaturated Fats - have one or more double
C=C bond
The double bonds cut down on the # of H atoms
that can be attached. This causes the molecule
to bend at each of the double bond sites.
Saturated vs. Unsaturated
Bonds
http://biology.clc.uc.edu/courses/bio104/lipids.htm
ADD:Function of Neutral Fats
INSULATION (subcutaneous fat)
ENERGY STORAGE
Very energy dense
Fat: 9 kcal of energy per gram
• Carbs & proteins 4 kcal of energy per gram
CUSHIONING FOR INTERNAL ORGANS
ABSORPTION OF FAT SOLUBLE VITAMINS:
ADEK
THESE VITAMINS CANNOT BE ABSORBED UNLESS
THEY ARE DISSOLVED IN FAT
FYI: CIS vs. TRANS ISOMERS
Latin: cis means on the same side , trans means across
http://biology.clc.uc.edu/courses/bio104/lipids.htm
FYI: Trans Fats
Produced when cis vegetable oils are
heated.
Multiple heatings, such as a fast food fryer,
converts large quantities of cis to trans
bonds
Concern: trans fatty acids are carcinogenic
Phospholipids
Complex
lipids
Phospho
portion is
polar
Lipid
portion is
non polar
Use of Phospholipids
Important
for cell
membrane
repair and
construction
Also a
component
of nervous
tissue
Phospholipid Bilayer
Myelin Sheath: Insulates
Nerve
Steroids
Hydrocarbon ring structures
Vital to homeostasis
Cholesterol, cortisol, and aldosterone
Steroid structure
Steroids
Steroid based hormones
Lipid soluble
Diffuse easily into target cells
Pages 41 & 180
Steroids
Cholesterol is found in all ANIMAL tissue.
Plants do NOT contain cholesterol
Cholesterol is the MOST IMPORTANT steroid since
it is essential for the manufacture of ALL other
steroids
It also helps to STABILIZE your cell membranes.
FYI:
HDL
vs.
LDL
LIPOPROTEINS are molecules that help transport
lipids in the blood (since lipids are NOT water
soluble, they cannot circulate by themselves)
HIGH DENSITY LIPOPROTEINS
Transport excess cholesterol to liver for breakdown
LOW DENSITY LIPOPROTEINS
Transport excess cholesterol to cells for storage (can clog
artery walls, etc.)
YOU WANT YOUR HDL LEVEL TO BE HIGHER
THAN YOUR LDL LEVEL
Fat Soluble Vitamins
ADEK
Page 41 & 457
Toxicity: easier to OD on these than on
water soluble vitamins
ADEK excesses are stored in your fat cells
Other vitamins are excreted in the water
based urine
Lipolysis
Function of low carbohydrate diets,
diabetes, etc.
Ketosis
http://science.nhmccd.edu/biol/bio1int.ht
m
PROTEINS
In charge of all your body functions
Important Organic Compounds
• Proteins
• Contain carbon, oxygen, hydrogen,
nitrogen, and sometimes sulfur
• 10-30% of body mass
• Wide variety of functions:
•Structural
•enzymes
Proteins
Consists of amino acids connected by
peptide bonds
Unique properties of each protein are
determined by
Type of amino acid
Sequence of amino acid
Protein formation
Dehydration synthesis joins the amino acid
monomers together by use of a peptide
bond
You will sometimes hear proteins called
“polypeptides” for this reason.
Proteins
Levels of structural complexity
Primary
Secondary
Tertiary
quaternary
Functions of Proteins
Proteins have a wide variety of functions.
These functions can be divided into 2
categories:
STRUCTURAL: support and strengthen
FUNCTIONAL: crucial roles in biological processes
Let’s take a look at a few of the examples in your
notes: You do need to memorize these examples.
Proteins are VERY IMPORTANT!!!
Structural Proteins
Keratin: component of hair, nails, and
found in skin – also helps waterproof your
skin
Functional Protein
Hemoglobin –
Carries oxygen
Cell Membrane Proteins
Proteins
Structural
Linear building
proteins
Primary/secondary
structure
Insoluble in water
Very stable/chemically
inactive
Collagen, keratin,
elastin
Functional
Globular action
proteins
Tertiary/quaternary
Soluble in water
Chemically active
Antibodies, hormones,
most enzymes (-ase)
Protein denaturation
Function of proteins depend on their
structure
Structure depends on H bonds
Active site and substrate relationship crucial to
the function
Shape of active site determines enzyme
specificity
Protein denaturation
Caused by excesses in temperature & pH
Disrupts H bonds
Structure/active site is lost
Function is lost
Normal blood pH = 7.35-7.45
Slight change of pH (within a tenth) can
disrupt H bonds but will reform if pH is quickly
restored by buffer system
Enzyme action
Enzymes can act as a catalyst
A molecule that lowers ACTIVATION
ENERGY
This can increase a reaction’s speed (rate) up
to 1010 times!!
The enzyme is not changed at all by the
chemical reaction so can be reused over and
over
Enzymes – read section
Enzyme ensures that substrates collide with
enough force and in the correct geometric
orientation
Highly specific (lactose – lactase)
Cofactor = metallic element (mineral)
Coenzyme = vitamins
Enzyme Specificity
Substrate: the molecule that is affected
by the enzyme
Active site: place on the enzyme where
the reaction occurs
ONE ENZYME ACTS ON ONLY ONE
SUBSTRATE: VERY SPECIFIC !
Amylase breaks down amylose
Lactase breaks down lactose
Enzyme Action
Lock and key fit: active site and
substrate fit exactly
Induced fit: active site can adjust to
“wrap around” substrate to get optimum
fit
Enzymes
Figure 2.16
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.34
Important Organic Compounds
• Deoxyribonucleic
acid (DNA) &
Ribonucleic Acid
(RNA)
• Collectively
provides
instructions to
make every
protein in the body
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 2.17c
Slide 2.36
DNA Structure
DNA and RNA: Copy this
DNA
RNA
Location
Nucleus only
May leave nucleus
Structure
Double helix
Single strand
Bases
A, T, G, C
A, U, G, C
Function
Directs protein
synthesis
Carries out genetic
instr. for protein
synthesis
Complementary
Base Pairing
A-T, G-C
A-U, G-C
ATP
Chemical energy universally usable by all
cells
High energy phosphate bonds
Ruptured by hydrolysis
Energy is in bonds between phosphates
Contain just the right amount of energy for
most biochemical reactions
Reversible reaction - ATP is replenished by
oxidation of food fuels
HELPFUL HINTS
Read the chapter
Study your notes
Study all your worksheets & quizzes
It is VERY helpful to give someone your
notes & quizzes so they can verbally quiz
you & drill you over the information