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Levels of Organizations - the building blocks of living organisms.
- organs >
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- sharing of electrons between atoms; strong bonds:
- Nonpolar: equal sharing of electrons (eg C-C)
- Polar: unequal sharing of electrons (eg H2O)
complete transfer of electrons, relatively weak bond (through crystals are strong). These bonds break in water yielding ions (charged particles).
weak but significant attractive forces between a H atom in one molecule and an O or an N atom in another molecule. Very weak but important bonds.
positively charged ion
a negatively charged ion.
The dissociated in water to form electrolytes in solution. Examples are Na+, K+, Cl-, Ca2+, OH-, Mg2+, HCO3- and H2PO3-.
atoms or groups of atoms joined together by chemical bonds.
do not contain chains of carbon (H2O, NH3, H2CO3). Water (H2O) is the most important inorganic molecule.
contain a central carbon or chains of carbon (CH4, C6H12O6).
Water is a very important inorganic molecule. Water (H2O) accounts for 60 to 70% of total body mass in humans. It is a molecule that exhibits many unique qualities stemming from its polar structure. The important properties of water are discussed below. Here is a diagrammatic drawing of some water molecules. Describe the molecule and how it interacts with itself.
Solvency (of water)
water is able to dissolve a wide range of chemical substances but particularly polar molecules. Also, many substances dissolve in water. That is why it is often described as the universal solvent.
Cohesion (of H2O)
H2O molecules have a high affinity for each other (due to H-bonds) and cling together. H2O molecules on a surface tend to pull one another from below and inward - this creates the 'beading' appearance of water on surfaces and creates surface tension at the fluid to gas interface, giving the surface an elastic surface layer (enough tension for small insects to walk on). Water is also able to adhere to many other surfaces other than water, a term called adhesion.
Thermostability (of H2O)
the temperature of water remains fairly stable despite changes in the surrounding temperature. This means that water has a high heat capacity - the ability to absorb heat energy with only moderate changes in temperature. This special quality of water is used to measure energy in metabolic processes. A calorie is the amount of heat energy required to raise 1g of water 1o C (from 14oC to 15oC). Water also has a high heat of vaporization, in that it requires a large amount of energy to go from the liquid to the gaseous phase. This is the reason why when sweat is blown off in vapor form, it is enormously effective in cooling us down, as so much heat energy leaves with it.
Reactivity (of H2O)
Water molecules not only dissolve substances but can also actively participate in chemical reactions with many different molecules. Some of the most fundamental reactions require water as a reactant or liberate water as a product. For example: Hydrolysis involves breaking chemical bonds using water. Dehydration Synthesis involves removing water in order to synthesize a larger, more complex molecule.
- these are inorganic elements from soil or plants that account for about 4% of body mass. The following minerals are typically found in appreciable quantities within the body: Calcium, Phosphorus, Potassium, Sulfur, Chlorine, Sodium, Magnesium, Iron, Manganese, Silicon, Copper, and Iodine.
- Other minerals are sometimes referred to as "trace minerals" because of the minute amounts present in the body, such as Zinc, Selenium and Chromium. All of these minerals play important roles in metabolic, regulatory and enzymatic pathways in the human body.
- Highly acidic = 1 HCl
- Nuetral = 7 distilled H2O
- Highly Basic = 14 NaOH
Organic Molecules: (examples)
Carbohydrates, Lipids, Proteins, and Nucleic Acids.
The Carbon atom has 6 protons, 6 electrons and most commonly 6 neutrons. Carbon (C) has 4 outer shell or valence electrons. Thus, it can make 4 covalent bonds, giving it versatile qualities. The general term monomer is used to describe the smallest type, or building blocks, of these organic molecules. The general term polymer describes the larger, more complex molecules
- C + H2O (hydrated carbons) usually have a 2:1 (H:O) ratio.
- The primary function of carbohydrates is as an energy (E) source; also some E storage; also as a supply of C for cell components and structural elements of some cells.
- simple sugars (monomers). Here are three common examples:
- 1. Glucose – the most commonly used molecule as a source of E in the human body.
- 2. Fructose – a simple sugar found in fruits (fruit sugar).
- 3. Galactose – a component of milk sugar.
- 2 monosaccharides joined together by a glycocydic bond.
- Important examples:
- 1. Sucrose (table sugar) = glucose +
- 2. Lactose (milk sugar) = glucose + galactose.
- 3. Maltose (grain sugar) = glucose + glucose
- common examples of complex carbohydrates – all are polymers of glucose.
- 1. Glycogen - energy storage molecule for glucose in animal cells, found in liver
- and skeletal muscle.
- 2. Starch - energy storage molecule for glucose in plant cells, e.g., potatoes!
- 3. Cellulose - structural component of cell wall in plant cells, e.g., dietary fiber!
- C, H and O but not a 2:1 (H:O) ratio as in carbohydrates, much less O than carbohydrates. In general they are non-polar molecules, not solvent in water. Let’s briefly examine the 4 primary types of lipids in the human body:
- 1) Fatty acids
- 2) Mono-, Di-, & triglycerides
- 3) Phospholipids
- 4) Steroids
1) Fatty acids (Lipids)
4 to 24 C’s long with carboxylic acid and methyl group at either end. Rich source of Energy (E). Compare Saturated and Unsaturated (mono and poly) fatty acids (F.A.’s). Typically, the monomers of lipids are fatty acids and glycerol. Make a quick sketch of a fatty acid and glycerol:
2) Mono-, Di- and Triglycerides (Lipids)
Made from 1 glycerol and 1, 2 or 3 Fatty Acids. In the body, triglycerides are storage molecules for Energy (E), it is the most abundant lipid in body and diet. Rich source of E, has at least 2 x the energy as carbohydrates per g.
3) Phospholipids (Lipids)
Similar to triglycerides: 1 glycerol + 2 F.A.’s + Phosphate group (+ N compounds). An Amphiphilic molecule, it has a polar head and non-polar tail region, thus it can mix in both polar and non-polar solutions. This is the most abundant and important lipid molecule in the plasma membrane of cells. Draw a Generalized Phospholipid:
4) Steroids (Lipid)
A lipid with 17 of its C atoms arranged in 4 rings (3 x 6-C and 1 x 5-C rings). Most abundant steroid in human body is Cholesterol – important structural component of plasma membrane and precursor to many other important steroid lipids – such as sex hormones (progesterone, estrogen, and testosterone), bile, cortisol, Vitamin D.
= C, H, O, N, S. The most versatile and complex of the organic molecules. Largest range of functions. Amino Acids (AA’s) are the building blocks (monomers) of peptides, polypeptides and proteins. How many amino acids does the human body use? Draw a Generalized Amino Acid:
Levels of Structures of Proteins:
Primary, Secondary, Tertiary, Quaternary
Define each of these levels of proteins.
- Primary (1o) – linear sequence of amino
- acids joined together by covalent ‘peptide’ bonds.
- Secondary (2o) – the formation of alpha () helix or beta (b) pleated sheet due to hydrogen bonds.
- Tertiary (3o) – the three dimensional
- folding of protein, due to interactions of functional groups.
- Quaternary (4o) – interactions of several
- polypeptides chains with each other (not all proteins).
Proteins can be. . .
either Globular or Fibrous (based on form or shape)
Some functions: Structural, Catalytic, Transport, Contractile, Regulatory, and Immunological.
What is Energy?
Energy is the capacity to do work
What is Work?
- Work is essentially moving things. There are three basic types of work:
- 1) Chemical Work - making and breaking chemical bonds; exchanging, storing and releasing Energy.
- 2) Transport Work - movement of substances across a concentration gradient (via plasma membrane).
- 3) Mechanical Work - movement of a 'whole'; organelles inside a cell; flagella; muscle fibers
There are many forms of energy, two important forms that we encounter in physiology are:
- Kinetic Energy (KE) - Energy of motion (chemical, transport, mechanical).
- Potential Energy (PE) - Energy that is stored (concentration gradient, chemical bond).
- KE and PE can be converted from one form to the other but it is never a 100% efficient
Work (chemical, transport, mechanical) involves the inter-conversion of these 2 forms of energy.
1st Law of Thermodynamics
Energy can be converted from one form to another but cannot be created or destroyed. Energy (E) in the universe is constant.
2nd Law of Thermodynamics
- 1) In every Energy transfer, some Energy is lost as heat and can no longer do useful work.
- 2) Natural spontaneous processes move from a state of order (non-randomness) to a state of disorder (randomness) known as Entropy (S, the degree of randomness). Entropy in the universe is increasing.
- Fuel (PE) in a car used to move (KE) a car. If $100 of fuel is used, $87 is lost as heat and exhaust and only $17 is used for the movement of the car.
- This means that the machinery is only 17% efficient in converting the fuel (PE) into movement (KE). Only 17% of original investment can be deemed as useful work (2nd Law of Thermodynamics).
The Human Body:
- Food (PE) in a person used to move and operate (KE) the body. If 100 Kcal of food is consumed, about 60 Kcal are lost as heat and about 40 Kcal are used for movement (chemical, transport and mechanical) of the body.
- This means that our machinery is only 40% efficient in converting the fuel (PE) into movement (KE).
- Efficiency of the human body can change depending on the activity of the body. When exercising, for example, at least 70% is lost as heat energy and less than 30% used for muscle contraction.
Chemical reactions in the body are used to. . .
Store, Release, or Transfer Energy
- Sum total of all chemical reactions in body.
- Metabolism = Anabolism + Catabolism
1) Endergonic Reactions -
– Require Energy (E) input
- e.g. A + B + E → C
- (Anabolic Reactions)
- A specific example: The formation of a dipeptide from 2 amino acids.
The removal of water (H2O) to create a larger molecule is called a Dehydration Synthesis reaction.
- Overall, these can be referred to as Anabolic Reactions – they are synthesizing something, building a more complex, larger molecule
- from simpler, smaller molecules and they require input of E.
2) Exergonic Reactions
- – Release Energy (E)
- e.g. C → A + B + E
- (Catabolic Reactions)
- A specific example: The breakdown of a dipeptide into 2 amino acids.
Often in biological systems water (H2O) is used to break chemical bonds, this is called Hydrolysis.
Overall, these can be referred to as Catabolic Reactions – they are breaking chemical bonds. Large molecules are broken down to produce smaller molecules and they release E that can be used for physiological work.