Week 1 Textbook Reading Flashcards
polymer
long molecule made by covalently linking multiple identical or similar subunits (monomers).
subunit
A monomer that forms part of a larger molecule, such as an amino acid in a protein or a nucleotide in a nucleic acid
Can also refer to a complete molecule that forms part of a larger molecule
Many proteins, for example, are composed of multiple polypeptide chains, each of which is called a protein subunit.
how do neutrons affect cells?
-contribute to the structural stability of the nucleus
-change in neutrons can cause the nucleus to disintegrate by radioactive decay
-neutrons don’t alter the chemical properties of atom
what does an element’s chemical reactivity depend on?
the degree that its outer electron shell is filled
electronegativity
tendency of an atom to attract electrons
bond strength
measured by the amount of energy that must be supplied to break the bond
hydrogen bond
-H attracted to N, O, F
-weaker than covalent bonds
-hydrophilic- water loving
-hydrophobic- water fearing
why is water a liquid at room temp?
interlocking hydrogen bonds allows water to be a liquid at room temp and gives it a high BP and surface tension
electrostatic attraction
ionic bonds that hold together the ions in a salt crystal
-strongest when atoms involved are fully charged
van der Waals
These weak attractions occur in all types of molecules and are nonpolar and can’t form ionic or hydrogen bonds
buffer
Buffer→ mixtures of weak acids and bases that maintain proton concentrations at about pH 7 by releasing protons (acids) or taking them up (bases) whenever the pH changes
polymers of sugars
Polysaccharides and oligosaccharides
polymers of fatty acids
fats and membrane lipids
polymers of nucleotides
nucleic acids
Oligosaccharides:
contain a smaller number of sugar subunits (e.g. disaccharides only have 2)
Polysaccharides:
e.g. glycogen and starch can have 1000s of sugar monomers
how are sugars energy sources and subunits of polysaccharides
Monosaccharides are the simplest sugars with the general formula (CH2O)n
Because of this formula, sugars and the larger molecules made from them are called carbohydrates
describe monosaccharides and the bonds they can form
Monosaccharides can be linked by covalent bonds—called glycosidic bonds—to form larger carbohydrates.
2 monosaccharides linked together make a disaccharide, such as sucrose, which is composed of a glucose and a fructose unit.
Larger sugar polymers range from the oligosaccharides, which typically contain 2 to 10 monosaccharide subunits (monomers), all the way up to giant polysaccharides, which can contain hundreds or thousands of subunits
isomers
Sets of molecules with the same chemical formula but different structures are called isomers
condensation rxn
Condensation reaction is when a bond is formed between an -OH group on one sugar and an -OH group on another
**(reverse of hydrolysis)
difference between hydrolysis and condensation rxn
The bonds created by condensation rxns can be broken by the reverse process of hydrolysis, in which a molecule of water is consumed
condensation is the opp of hydrolysis rxns
why are hydrolysis rxns energetically favourable
break down larger molecules into smaller subunits
why are condensation rxns energetically unfavourable
synthesize large molecules from smaller subunits
glycogen
Cells use simpler polys. composed of only glucose units (glycogen) in animals and starch in plants as long term stores of glucose, held in reserve for energy production
glycoproteins
Smaller polys. can be linked to proteins to form glycoproteins or to lipids to form glycolipids
structure of a fatty acid molecule
Fatty acid chains are components of cell membranes
Fatty acid molecule, has 2 distinct regions
One is long hydrocarbon chain, which’s hydrophobic and not very reactive chemically
Other is a carboxyl (COOH) group, which behaves as an acid (carboxylic acid)
In aq solution, it’s ionized(-COO^-) extremely hydrophilic and chemically reactive
amphipathic
Molecules that are both hydrophobic and hydrophilic are amphipathic
saturated tail
Some fatty acids have saturated tails→ containing the max possible number of hydrogens and therefore has no double bonds between its carbon atoms
unsaturated tail
Others have unsaturated tails → with one or more double bonds along their length
how are fatty acids stored
Fatty acids are stored in the cytoplasm of cells in the form of fat droplets composed of triacylglycerol molecules- compounds made of 3 fatty acid chains covalently joined to a glycerol molecule
Phospholipids→
constructed from fatty acids and glycerol
However glycerol is joined to 2 fatty acid chains, rather than 3 as in triacylglycerols
peptide bond vs. polypeptide
Covalent bond b/w 2 adjacent amino acids in a protein chain is called a peptide bond and the resulting chain of amino acids is a polypeptide
how are peptide bonds formed
Peptide bonds are formed by condensation rxns that link one amino acid to the next
noncovalent bonds
-specify the precise shape of a macromolecule
-allow a macromolecule to bind other selected molecules
-can also stabilize associations b/w any 2 macromolecules, as long as their surfaces match closely
Amines
Amines in water combine with an H+ ion to become positively charged
amides
Amides are formed by combining an acid and an amine
Unlike amines, amides are uncharged in water
ring formation in sugars and fatty acids
In aqueous sol, the aldehyde or ketone group of a sugar molecule tends to react with a hydroxyl group of the same molecule, thereby closing the molecule into a ring
isomers (monosaccharides)
When monosaccharides differ only in the spatial arrangement of atoms
a and B(beta) Links
The hydroxyl group on the carbon that carries the aldehyde or ketone can rapidly change from one position to the other
-2 positions called a and B
Disaccharides
When the carbon that carries the aldehyde or the ketone can react with any hydroxyl group on a second sugar molecule
Oligosaccharides vs. polysaccharides
Oligo→ short chains
Polysacc→ long chains
fatty acids
All have a carboxyl group at one end and a long hydrocarbon tail at the other
triacylglycerols
Fatty acids are stored in cells as an energy reserve (fats and oils) through an ester linkage to glycerol to form triacylglycerols
carboxyl group
If free, the carboxyl group of a fatty acid will be ionized
More often it is linked to other groups to form either esters or amides
how do photosynthetic organisms use sunlight to synthesize organic molecules
Photosynthesis converts the electromagnetic energy in sunlight into chemical bond energy in cells
In the 1st stage, energy from sunlight is captured and temporarily stored as chemical-bond energy in specialized molecules called activated carriers
In the 2nd stage, activated carriers are used to help drive a carbon-fixation process, in which sugars are made from CO2 gas
This way, photosynthesis generates an essential source of stored chemical-bond energy and other organic materials
how do cells get energy
-by the oxidation of organic molecules
-Oxidation→ extraction of chemical energy from food molecules takes place through a process of gradual oxidation
-The complex process by which food molecules are broken down in this way to produce energy is known as cell respiration
oxidation
Oxidation→ the addition of oxygen atoms to a molecule; the removal of electrons from an atom
reduction
Reduction→ the addition of electrons to an atom
how is a polar covalent bond formed?
When a carbon atom becomes covalently bonded to an atom with a strong affinity for electrons, it gives up more than its equal share of electrons to form a polar covalent bond
how does carbon gain partial positive and negative charges
The positive charge of the carbon nucleus now slightly exceeds the negative charge of its electrons→ C atom gains a partial positive charge and is oxidized
When the carbon atom in a C-H bond has more than its share of electrons; it gains a partial negative charge and is reduced
true or false: an individual enzyme can make an energetically unfavorable rxn occur
false
Even though an individual enzyme can accelerate an energetically favourable rxn, it can’t force an energetically unfavourable rxn to occur
activation energy
Activation energy→ when a molecule requires a boost over an energy barrier before it can undergo a chemical rxn that moves it to a lower-energy (more stable) state
what do enzyme-catalyzed rxns depend on?
Enzyme-catalyzed reactions depend on rapid molecular collisions
For 2 molecules to interact, they must first collide
what do noncovalent interactions allow?
Noncovalent interactions allow enzymes to bind specific molecules
1st step is the binding of the substrate
Once this occurs, the substrate must stay bound to the enzyme long enough for the chemistry to occur
