(Bio)Chemistry and Cytology
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Transcript of (Bio)Chemistry and Cytology
(Bio)Chemistry and Cytology
BIOL241Introduction or Recap of Cell
Structure & chemistry
INTERCONNECTEDNESS
• Matter and Energy• Atoms, molecules, and chemical bonds• Importance of organic and inorganic nutrients
and metabolites• Structure and function of carbohydrates,
lipids, proteins, and nucleic acids• Enzymes and ATP help run the metabolic
reactions of the body
Energy• The capacity to do work (put matter into
motion)• Types of energy
– Kinetic – energy in action– Potential – energy of position; stored
(inactive) energy: chemical energy• Energy is easily converted from one form
to another• During conversion, some energy is “lost”
as heat
Chemistry• Chemistry is the science that deals with
matter• Matter is anything that takes up space and
has mass• Smallest stable units of mass are atoms
But I thought this was biology?
• Mathematics (the language of science)• Physics (the structure of matter & energy)• Chemistry (organic and inorganic structure)• Biology: uses them all to understand Life.
Atoms, Elements, Molecules
• Elements are atoms of one particular type (see the periodic table)
• Molecules are groups of atoms that (usually) contain more than one element
Biologically significant elements
• 13 principal elements– Carbon (C)– Oxygen (O)– Hydrogen (H)– Nitrogen (N)– Calcium (Ca), phosphorus (P), potassium (K),
Sulphur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)
• 13 trace elements – (e.g. zinc, manganese)
Atoms with unfilled electron shells are reactive
• Octet Rule• To become stable they form chemical bonds.• Three main types of chemical bonds
– Intramolecular:• Ionic bonds (charged atoms resulting from the gain
or loss of electrons)• Covalent bonds (electrons are shared)
– Intermolecular• Hydrogen bonds
Covalent & Ionic Bonds• Molecules: atoms held together by
covalent bonds• Salts: molecules held together by ionic
bondsQ: What are the strongest type of bonds?
H2O
The body is mostly water (~2/3rd of total body weight) so all chemical reactions in the body occur in water
Covalent bonds are much stronger than ionic bonds in water
H2O – “Special” Properties
• Water can dissolve organic and inorganic molecules making a solution
• Water is needed for chemical reactions• Water absorbs and retains heat• Water is an effective lubricant
H2O
• What is it about water that makes it so special?
• Water has all these amazing properties due to its molecule’s ability to form hydrogen bonds
H-bonds b/t + & - charges
Mixtures and Solutions• Mixtures – two or more components physically
intermixed (not chemically bonded)– Solutions – homogeneous mixtures of components– Colloids (emulsions) – heterogeneous mixtures
whose solutes do not settle out– Suspensions – heterogeneous mixtures with visible
solutes that tend to settle out
Essential Molecules
• Nutrients: – essential molecules obtained from food (you
have to eat them to get them)• Metabolites:
– molecules made or broken down in the body
Organic vs. inorganicOrganic molecules:• Always contain carbon with hydrogen, and
sometimes oxygen• Often soluble in waterInorganic: Electrolytes, minerals, and compounds that
do not contain carbon with hydrogen. • Important examples: oxygen, carbon dioxide, water,
inorganic acids and bases, salts
Vitamins and Minerals• Vitamins and minerals are essential nutrients
that are required in very small amounts for healthy growth and development.
Examples? • They cannot be synthesized by the body and
are essential components of the diet.
Vitamins• Organic substances necessary for metabolism • There are 13 known vitamins (e.g. A, B1, D, K) • Some are fat soluble while others are water
soluble• Are Coenzymes that help carry out the
reactions of metabolism
Minerals• Inorganic compound (often salts or elements)
necessary for proper body function• Can be bulk or trace minerals• Are Cofactors in metabolic reactions
Electrolytes
• Inorganic ions (usually minerals) that conduct electricity in solution
• Electrolyte balance is maintained in all body fluids; imbalance seriously disturbs vital body functions
Electrolytes
Table 2–3
Biological Macromolecules
• Life depends on four types of organic macromolecules:1. Carbohydrates2. Lipids3. Proteins4. Nucleic acids
Can you think of an example of each?
1. Carbohydrates• Contain carbon, hydrogen and oxygen in a
ratio of 1:2:1• Account for less that 1% of body weight• Used as energy source• Called saccharides (sugars, starches)
Glucose is a monosaccharide
DisaccharidesSucrose
Lactose
Polysaccharides
• Starch• Glycogen• CelluloseAll are long strings of glucose moleculesDifference lies in how they are bonded together
Polysaccharides
• Polysaccharides or polymers of simple sugars
Figure 2.14c
PLAY Polysaccharides
Polymers
• A polymer is any molecule made up of several repeating units. Starch is a polymer of glucose.
2. Lipids• Contain carbon, hydrogen, and oxygen but the
ratio of C:H is 1:2 (much less O)• May also contain other elements,
phosphorous, nitrogen, and sulfur• Form essential structures in cells• Are important energy stores
Lipids: Triglycerides (Fats and Oils)
• Consist of 3 fatty acids and glycerol– Insulation– Energy– protection
Q: What’s the difference between saturated and unsaturated?
Lipids: Steroids and Cholesterol
• All consist of a complex ring structure
Lipids: Phospholipids
Amphipathic
3. Proteins
• Consist of chains of amino acids liked together by peptide bonds
• Enzymes are proteins
Protein Structure• Proteins are the most abundant and
important organic molecules• Basic elements:
– carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
• Basic building blocks: – 20 amino acids
Figure 2–20a
Protein Structure – 4 levelsPrimary: amino acid sequenceSecondary: Hydrogen bonds form spirals or
pleats (α-helix, β-sheet)Tertiary: Secondary structure folds into a unique
shapeQuaternary: several tertiary structures together:again: Shape!!
Protein structure
Shape and Function• Protein function is based on shape• Shape is based on sequence of amino acids• Denaturation:
– loss of shape and function (due to heat, pH change or other factors)
Protein Functions
– support: • structural proteins
– movement: • contractile proteins
– transport:• transport proteins
– buffering: regulation of pH
– metabolic regulation:
• enzymes– coordination and
control: • hormones
– defense:• antibodies
Figure 2–7
Activation Energy
• Chemical reactions in cells cannot start without help
• Activation energy gets a reaction started
Characteristics of Enzymes
Figure 2.20
Energy In, Energy Out
• Exergonic reactions: – produce more energy than they use
• Endergonic reactions: – use more energy than they produce
KEY CONCEPT• Most chemical reactions that sustain life
cannot occur unless the right enzymes are present
How Enzymes Work
• Substrates: – reactants in enzymatic reactions
• Active site: – a location on an enzyme that fits a particular
substrate
Figure 2–21
Active siteAmino acids
Enzyme (E)Enzyme-substratecomplex (E-S)
Internal rearrangementsleading to catalysis
Dipeptide product (P)
Free enzyme (E)
Substrates (S)
Peptide bond
H2O
+
How EnzymesWork
4. Nucleic acids
• Contain C, H, O, N, and P
• DNA and RNA are nucleic acids
• Nucleotide consists of– Sugar– Phosphate group– Nitrogenous base
Structure of DNA
Figure 2.22b
A nucleotide: ATP
• Energy storage for cells
• Many enzymes use ATP
• Provides a way to run reactions that are otherwise endergonic (require energy)
Figure 2.24
Solute Solute transported
Contracted smoothmuscle cell
Product made
Relaxed smoothmuscle cell
Reactants
Membraneprotein
P Pi
ATP
PX X
Y
Y
+
(a) Transport work
(b) Mechanical work
(c) Chemical work
Pi
Pi
+ADP
ATP is the energy currency
of the cell
Compounds Important to Physiology
Table 2–8
Summary
• Energy and matter• Atoms, molecules, and chemical bonds• Importance of organic and inorganic
nutrients and metabolites• Structure and function of carbohydrates,
lipids, proteins, and nucleic acids• Enzymes and ATP help run the metabolic
reactions of the body