Anatomy and Physiology
thinkerbell
Chapter4..pptxUNIT 1 .CHAPTER 4.
BIOMOLECULES
BIOMOLECULES : Substances that are produced by cells and living organisms.
There are four major types of biomolecules:
Carbohydrates.
Lipids.
Proteins.
Nucleid acids.
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ORGANIC AND INORGANIC COMPOUNDS
Inorganic compounds: few have carbon atoms and none have C–C or C–H bonds
Organic molecules
Have at least one carbon atom and at least one C–C or C–H bond in each molecule
Often have functional groups attached to the carbon-containing core of the molecule (Figure 2-13)
INORGANIC MOLECULES
WATER.
OXYGEN.
CARBON DIOXIDE.
ELECTROLYTES.
ACIDS.
BASES.
SALTS.
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The Principal Functional Chemical Groups
INORGANIC MOLECULES
Water
The body’s most abundant and important compound.
Properties of water (Table 2-2)
Polarity: allows water to act as an effective solvent; ionizes substances in solution (Figure 2-10)
The solvent allows transportation of essential materials throughout the body (; enables the body to maintain a relatively const Figure 2-14)
High specific heat: water can lose and gain large amounts of heat with little change in its own temperature.
High heat of vaporization: water requires the absorption of significant amounts of heat to change it from a liquid to a gas; allows the body to dissipate excess heat.
INORGANIC MOLECULES (cont.)
Oxygen and carbon dioxide: closely related to cellular respiration
Oxygen: required to complete decomposition reactions necessary for the release of energy in the body,
Carbon dioxide: produced as a waste product and helps maintain the appropriate acid-base balance in the body.
INORGANIC MOLECULES: ELECTROLYTES
Electrolytes
Large group of inorganic compounds that includes acids, bases, and salts.
Substances that dissociate in solution to form ions (resulting ions are sometimes called electrolytes)
Positively charged ions are cations; negatively charged ions are anions.
INORGANIC MOLECULES: ELECTROLYTES (cont.)
Acids and bases: common and important chemical substances that are chemical opposites
Acids
Any substance that releases a hydrogen ion (H+) when in solution; “proton donor”
Level of acidity depends on the number of H+ a particular acid will release
Bases
Electrolytes that dissociate to yield hydroxide ions (OH) or other electrolytes that combine with H+
Described as “proton acceptors”
pH scale: assigns a value to measures of acidity and alkalinity (Figure 2-15)
pH indicates the degree of acidity or alkalinity of a solution
pH of 7 indicates neutrality (equal amounts of H+ and OH); a pH less than 7 indicates acidity; a pH higher than 7 indicates alkalinity
The PH Scale.
INORGANIC MOLECULES: ELECTROLYTES (cont.)
Buffers
Maintain the constancy of pH
Minimize changes in the concentrations of H+ and OH
Act as a “reservoir” for hydrogen ions
Salts (Table 2-3)
Compound that results from chemical interaction of an acid and a base
Reaction between an acid and a base to form a salt and water is called a neutralization reaction.
ORGANIC MOLECULES
Organic” describes compounds that contain C–C or C–H bonds
CARBOHYDRATES FUNCTIONS.
The four primary functions of carbohydrates in the body are:
Provide energy.
Store energy.
Build macromolecules such as fat for other uses.
Glucose energy is stored as glycogen, with the majority of it in the muscle and liver.
ORGANIC MOLECULES: CARBOHYDRATES
Carbohydrates: organic compounds containing carbon, hydrogen, and oxygen; commonly called sugars and starches
Monosaccharides: simple sugars with short carbon chains; those with six carbons are hexoses (e.g., glucose); those with five are pentoses (e.g., ribose, deoxyribose) (Figure 2-17)
Disaccharides and polysaccharides: two (di-) or more (poly-) simple sugars bonded together through a synthesis reaction (Figure 2-18)
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Glucose Structure.Example of Monosaccharide.Simple Sugar.
ORGANIC MOLECULES: LIPIDS
Lipids (Table 2-5)
Water-insoluble organic molecules that are critically important biological compounds
Major roles:
Energy source.
Structural role.
Integral parts of cell membranes.
ORGANIC MOLECULES: LIPIDS (cont.)
Phospholipids (Figure 2-21)
Fat compounds similar to triglyceride.
One end of the phospholipid is water soluble (hydrophilic); the other end is fat soluble (hydrophobic).
Phospholipids can join two different chemical environments.
Phospholipids may form double layers called bilayers that make up cell membranes.(Figure 2-22)
PHOSPHOLIPID MOLECULE
PHOSPHOLIPID BILAYER MOLECULE
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ORGANIC MOLECULES: LIPIDS (cont.)
Steroids (Figure 2-23)
Main component is steroid nucleus .
Involved in many structural and functional roles.
Prostaglandins (Figure 2-24)
Commonly called tissue hormones; produced by cell membranes throughout the body.
Effects are many and varied; however, they are released in response to a specific stimulus and are then inactivated.
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ORGANIC MOLECULES: PROTEINS
Proteins (Table 2-6)
Most abundant organic compounds
Chainlike polymers
Amino acids: building blocks of proteins (Figures 2-25 to 2-27)
Essential amino acids: eight amino acids that cannot be produced by the human body
Nonessential amino acids: 12 amino acids that can be produced from molecules available in the human body
Amino acids consist of a carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a side chain
Proteins Functions
Two special and common types of proteins are enzymes and hormones.
| Table 1. Protein Types and Functions | ||
| Type | Examples | Functions |
| Digestive Enzymes | Amylase, lipase, pepsin, trypsin | Help in digestion of food by catabolizing nutrients into monomeric units |
| Transport | Hemoglobin, albumin | Carry substances in the blood or lymph throughout the body |
| Structural | Actin, tubulin, keratin | Construct different structures, like the cytoskeleton |
| Hormones | Insulin, thyroxine | Coordinate the activity of different body systems |
| Defense | Immunoglobulins | Protect the body from foreign pathogens |
| Contractile | Actin, myosin | Effect muscle contraction |
| Storage | Legume storage proteins, egg white (albumin) | Provide nourishment in early development of the embryo and the seedling |
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ORGANIC MOLECULES: PROTEINS (cont.)
Levels of protein structure (Figure 2-28)
Protein molecules are highly organized and show a definite relation between structure and function
Protein organization is defined by four levels:
Primary structure: the number, kind, and sequence of amino acids that make up the polypeptide chain
Secondary structure: polypeptide is coiled or bent into pleated sheets stabilized by hydrogen bonds
Tertiary structure: a secondary structure can be further twisted and converted to a globular shape; the coils touch in many places and are “welded” by covalent and hydrogen bonds
Quaternary structure: highest level of organization; occurs when protein contains more than one polypeptide chain
PROTEIN SHAPES
ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES
Nucleic acids and related molecules
DNA (deoxyribonucleic acid)
Composed of deoxyribonucleotides: structural units consist of the pentose sugar (deoxyribose), phosphate group, and nitrogenous base (cytosine, thymine, guanine, or adenine)
DNA molecule consists of two long chains of deoxyribonucleotides coiled into a double-helix shape (Figure 2-31)
Specific sequence of more than 100 million base pairs constitutes one human DNA molecule; all DNA molecules in one individual are identical and different from those of all other individuals
DNA functions as the molecule of heredity
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THE DNA MOLECULE
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ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)
RNA (ribonucleic acid) (Figure 2-32; Table 2-7)
Composed of the pentose sugar (ribose), phosphate group, and a nitrogenous base
Nitrogenous bases for RNA are adenine, uracil, guanine, or cytosine (uracil replaces thymine)
Some RNA molecules are temporary copies of segments (genes) of the DNA code and are involved in synthesizing proteins
Some RNA molecules are regulatory and act as enzymes (ribozymes) or silence gene expression (RNA interference)
TRANSFER RNA
ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)
Nucleotides
Nucleotides have other important roles in the body
Adenosine triphosphate (ATP) (Figure 2-33)
Composed of:
Adenosine
Ribose, a pentose sugar
Adenine, a nitrogen-containing molecule
Three phosphate subunits
High-energy bonds present between phosphate group
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ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)
Adenosine triphosphate (ATP) (cont.)
Energy stored in ATP is used to do the body’s work
ATP often called the energy currency of cells
ATP is split into adenosine diphosphate (ADP) and an inorganic phosphate group by a special enzyme
