Chapter 2
what are the most abundant type of biomolecule?
- *carbohydrates* - monosaccharides, disaccharides, polysaccharides
secondary structure
- as polypeptide forms it takes on this structure, which is a spatial arrangement or shape. -stablized by hydrogen bonding between different parts of the molecule. The three most common shapes for polypeptide chains are a spiral called the *helix*, B-strand whose bond angles create a zigzag shape rather than a spiral, and *U-shaped* B turns. In a polypeptide, B-strands often assemble into side-by-side pleated sheets.
Primary Roles of Electrons in physiology.
- formation of covalent bonds -fomation of ions -the capture and transfer of energy -formation of destructive free radicals
high energy electrons
- in certain atoms can capture energy from their environment and transfer it to other atoms, so that the energy can be used for synthesis, movement, and other life processes. The released energy may also be emitted as radiation
what do monosaccharides have?
- most common monosaccharides are the building blocks of complex carbohydrates and have either five carbons, like *ribose*, or six carbons, like glucose (also known as dextrose).The major disaccharides are formed when glucose combines with another monosaccharide.You can recognize most mono- and disaccharides by the -ose end- ing on their names.
how are lipids and phospholipids similar?
- most similar in structure - Both groups contain a simple 3-carbon molecule known as *glycerol* plus long molecules known as *fatty acids*. Phospholipids also include a phosphate group+H( 2PO4).
primary structure
- sequence of amino acids in a peptide or protein chain - genetically determined and is essential to proper function. For
polar molecules
- uneven sharing -When the electrons are shared unevenly, the atom with the stronger attraction for electrons develops a slight negative charge (indicated by ,+), and the atom with the weaker attraction for electrons develops a slight positive charge( ,*). Molecules that develop these regions of partial positive and negative charge -*hydrophilic*
Protein Interactions
-*enzymes* -*membrane Transporters* proteins in cell membranes help move substances between intra and extracellular compartments. -*signal molecules* act as hormones and other signal molecules -*receptors* bind signal molecules and initiate cellular responses -*binding proteins* mostly in extracellular fluid bind and transport molecules throughout body -*regulatory proteins* turn cell processes on and off/up and down. Transcription bind to DNA and alter gene expression and protein synthesis -*immunoglobulins* antibodies
What two large groups are proteins assembled into?
-*fibrous proteins*are found as pleated sheets or in long chains of helices -insoluble in water and form important structural components of cells and tissues. Examples include collagen, a fibrous protein found in many types of connective tissue, and keratin, a fibrous protein found in hair and nails.
what are the most structurally diverse biomolecules.
-*lipids* or fats made up of carbon, hydrogen, and oxygen. contain less oxygen than carbs. -not very soluble in water -solid at room temperature.
How are covalent bonds formed?
-Covalent Bonds Are Formed When Adjacent Atoms Share Electrons -strong bonds that result when two atoms share a pair of electrons, one electron from each atom -*double bond* share adjacent atoms rather than just one pair.
Globular Proteins
-amino acid chains that fold back on themselves to create a complex tertiary structure containing pockets, channels, or protruding knobs. The tertiary structure of globular proteins arises partly from the angles of covalent bonds between amino acids, and partly from hydrogen bonds, van der Waals forces, and ionic bonds that stabilize the tertiary structure -amino acid cysteine also plays an important role in globular protein shape.Cysteine contains sulfur as part of a sulfhydryl group. -soluble in water act as carriers for water insoluble lipids in blood -enzymes that increase the rate of chemical reactions
ions
-charged atoms -gains or looses an electron an atom becomes an ion -*Cations* positively charged - loss of electrons -*anions*- negatively charged (-)
shells
-electrons move around the nucleus in a series of energy levels. -lowest energy level is closest to nucleus. -arrangement of electrons in the outer shell of an atom determines its ability to bind with other atoms.
list of essential elements
-oxygen, carbon and hydrogen. -nitrogen, phosphorus, sodium, potassium, calcium, magnesium, sulfur, and chlorine)
quaternary structure
-several protein chains associate with one another to form a functional protein
nonpolar molecule
-shared electrons are distributed so evenly that there are no regions of partial positive or negative charge -*hydrophobic*
atomic mass
-total mass of the protons and neutrons in the atom, expressed in atomic mass units, where 1 amu , 1.6605 - 10+27 kg.
radioisotopes
-unstable and emit energy called radiation. Radioisotopes emit three types of radiation:alpha,beta,,and gamma. -can have medical uses - nuclear medicine
tertiary structure
3D shape of a protein
eicosanoids
20-carbon fatty acid found in animals - thromboxanes, leukotrienes, and prostaglandins
nucleic acids
DNA and RNA nucleotide polymers -store genetic information within the cell and transmit it to future generations of cells
biomelcules
Organic molecules associated with living organisms -Four major groups: Carbohydrates, lipids, proteins, and nucleotides - *polymers* made up of repeating units - several combinations of atams *functional groups*, occur repeatedly in biological molecules.
what are other required elements called but are needed in smaller quantities?
Trace elements or minor essential elements
buffer
any substance that moderates change in pH -many contain anions
glycolyids
carbs and lipids
glycoproteins
carbs and proteins
solution
combo of solvents and solutes
Atoms
composed of protons, neutrons and electrons. - building blocks of all matter, including the human body were once thought to be the smallest particles of matter [atomos, indivisible].
pH
concentration of H+ in body fluids
compounds
contain more than one element
solubility
degree to which a moleculte is able to dissolve
isotopes
different number of neutrons - equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties
purines
double ring structure -adenine and guanine
Starch
glucose for energy stored in cells for energy in the form of a polysaccharide in plants. - digestable by humans - most abundant organic molecule on earth
Steroids
lipid related molecules -structure: 4 linked carbon rings -Cholesterol source of steroids
solvents
liquids into which solutes dissolve
fatty acids
long chains of carbon atoms bound to hydrogens with a carboxyl group. -*saturated* if there are no double bonds between carbons -*monosaturated* one double bond -*polyunsaturated* two or more double bonds - the more saturated the more likely to be solid at room temp
organic molecules
molecules that contain carbon
Triglycerides
most important form of lipid in the body, more than 90% of our lipids -predictors of artery disease
electrons
negatively charged. -name number as protons -travel around nucleus in orbits
What elements make up more than 90% of the body's mass?
oxygen, carbon and hydrogen.
basic/alkaline
pH greater than 7
Proteins
polymers of smaller building block molecules called *amino acids* -*essential amino acids* 9 that must be obtained from dietary proteins -*peptide bond* two amino acids link together, the amino group of one is joined to the carboxyl group of the other -*oligopeptide*
proton
positively charged -same number as electrons, electrical charge of zero -in nucleus
Conjugated proteins
protein molecules combined with another kind of biomolecule
lipoprotiens
proteins and lipids
ionic bonds
result when an atom has such a strong attraction for electrons that it pulls one or more electrons completely away from another atom.
covalent bonds
shared electrons form strong covalent bond to create molecules
element
simplest type of matter. -listed in periodic table
pyrimidines
single ring -cytosine, thymine and uracil
acid
solutions have a pH less than 7
free radicals
some types of radiation alter the distribution of electrons in atoms, converting the atoms into unstable free radicals. Every free radical has at least one unpaired electron.
glycogen
stored glucose in cells for energy in form of a polysaccharide in animals
solutes
substances that dissolve in liquid
Antioxidants
substances that prevent damage to our cells by giving up electrons without becoming free radicals. Many antioxidants occur naturally in fruits and vegetables. The most common antioxidants promoted in vitamin supplements are vitamins C and E.
atomic number
the number of protons in the nucleus -determines which element the atom is
nucleotides
three-part molecule composed of (1) one or more phosphate groups, (2) a 5-carbon sugar, and (3) a carbon-nitrogen ring structure called a *nitrogenous base* - two possible sugars: ribose or deoxyribose
molecules
two or more atoms link by sharing electrons
neutrons
uncharged -in nucleus
hydrogen bond
weak attractive force between a hydrogen atom and a nearby oxygen, nitrogen, or fluorine atom.
Van der Waals forces
weak, nonspecific attractions between the nucleus of any atom and the electrons of nearby atoms. Two atoms that are weakly attracted to each other by Van der Waals forces move closer together until they are so close that their electrons begin to repel one another. Consequently, van der Waals forces allow atoms to pack closely together and occupy a minimum amount of space.