Chapter 5 - Macromolecules Flashcards
what are the four biological molecules all living things are made up of?
- lipids
- carbohydrates
- proteins
- nucleic acids
what are macromolecules?
are large molecules composed of thousands of covalently connected atoms
what is a polymer?
a long molecule consisting of many similar building blocks (only three of the four building block molecules are polymers)
- Carbohydrates
- Proteins
- Nucleic acids
what is a condensation reaction (dehydration reaction)?
occur when two monomers bond together through the loss of a water molecule
what are enzymes?
enzymes are macromolecules that speed up the dehydration process
what is hydrolysis?
a reaction which occurs when two monomers are split apart by the addition of water. the reverse of a dehydration reaction
what is the key for monomers to form different polymers?
the key is the ARRANGEMENT of monomers to form polymers
what are carbohydrates?
- carbohydrates include sugars and the polymers of sugars
- the simplest carbohydrates are, monosaccharides or simple sugars
- polysaccharides are polymers composed of many sugar building blocks
what are sugars?
monosaccharides have molecular formulas that are usually multiples of CH2O
-classified by the location of the carbonyl group and the number of carbons in the carbon skeleton
in aqueous solutions many sugars form?
in aqueous solutions many sugars form rings
what is a disaccharide?
is formed when two monosaccharides (monomers) join together via dehydration reaction
- used as a readily available energy source
- this covalent bond is called a GLYCOSIDIC LINKAGE
what are glycosidic linkages?
they form between hydroxyl groups and because every monosaccharide contains at least TWO HYDROXYL groups, the location and geometry of glycosidic linkages can vary widely among polysaccharides
what are the two most common glycosidic linkages?
alpha α - 1,4-glycosidic linkages
beta β - 1,4-glycosidic linkages
what are oligosaccharides?
are found bound to cells surface proteins and lipids, and may be used for cell recognition
what are polysaccharides?
the polymer of sugars, have storage and structural roles
- the structure and function of a polysaccharide is determined by its sugar monomers and the position of glycosidic linkages
- also very unstable
what is starch?
a storage polysaccharide of plants, consists entirely of glucose monomers (stored energy)
what are the two types of starch (storage polysaccharides)?
- Amylose - straight line, 1,4 linkages, the angle of the linkage is helical
- Amylopectin - branched, with 1-6, linkages at the branches
what is glycogen?
a branched amylopectin, is a storage polysaccharide in animals
- hydrolysis of glycogen, releases glucose (energy)
what is cellulose?
is a major component of of the tough wall plant cells
- like starch cellulose is a polymer of glucose, but the glycosidic linkages differ
polymers with α glucose are?
helical
polymers with β glucose are?
straight
- enzymes that digest starch by hydrolyzing α linkages cant hydrolyze β linkages in cellulose
what is chitin?
another structural polysaccharide that is found in the exoskeleton of arthropods
what are glycoproteins?
proteins joined to carbohydrates by covalent bonds
- key molecules in cell-cell signalling and recognition
who was the first biochemist to synthesize sucrose?
Raymond Lemieux was the first scientist to synthesize sucrose, then went on to synthesize larger sugars
what is TAS1R3?
we have taste receptors for sweetness, this tells us a food is high in energy
what is a common sweetener?
glucose-fructose (also called high fructose corn syrup) is found in processed foods
what are lipids?
lipids are the one class of large biological molecules that do not form polymers
- lipids have little or no water affinity
- they are hydrophobic because they consist mostly of hydrocarbons, which form non-polar covalent bonds
what are the most biologically important lipids?
- fats
- phospholipids
- steroids
what are fats?
fats are constructed from two types of smaller molecules: glycerol and fatty acids
- glycerol: is a 3 carbon alcohol with hydroxyl group attached to each carbon
- fatty acid: consists of carboxyl group attached to a long carbon skeleton (16 to 18 carbons)
what is a triglyceride or triacylglycerol?
in a fat three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol or triglyceride
what is a saturated fatty acids?
have the maximum number of hydrogen atoms possible and no double bonds
what are unsaturated fatty acids?
have one or more double bonds
what are phospholipids?
two fatty acids and a phosphate group are attached to glycerol
- the tails are hydrophobic
- the head is hydrophilic
- when in water they self-assemble into a bilayer with the hydrophobic tails pointing towards the interior
what are steroids?
are lipids characterized by a carbon skeleton consisting of four fused rings; different attachments to the rings would give rise to different steroids
what is cholesterol?
an important steroid, is a component in animal cell membranes
-it is also the precursor for steroids
what are proteins functions?
structural support, storage, transport, cellular communications, movement and defense against foreign substances
what are enzymes?
are a type of protein that acts as a biological catalyst to speed up chemical reactions
what are polypeptides?
are polymers built from the same set of 20 amino acids
- a protein consists of one or more polypeptides
what are amino acids?
are organic molecules with carboxyl and amino groups
- amino acids differ in their properties due to differing side chains, called R groups
R groups can be…?
- R groups may be polar charged
- R groups may be polar uncharged
- R groups may be nonpolar
- Unique or “special” (Cysteine)
peptide bonds form between?
between the alpha-carbonyl and alpha-amino of participating amino acids
amino acids are linked by?
peptide bonds
a functional protein consists of?
one or more polypeptides twisted, folded, and coiled into a unique shape
- a polypeptide is NOT a protein. A couple of polypeptides together, twisted makes a protein
What is some significant information about proteins?
- The sequence of amino acids determines a proteins 3-D structure
- A protein’s structure determines its function
- its function depends on its ability to recognize and bind to some other molecules
what is the primary structure of a protein?
is its unique sequence of amino acids
- the sequence of amino acids is like the order of letters in a long word
- determined by inherited genetic information
what is the secondary structure of a protein?
found in most proteins, consists of coils and folds in the polypeptide chain
what is the tertiary structure of a protein?
is determined by interactions among various side chains (R groups)
what is the quaternary structure of a protein?
quaternary structure results when a protein consists of multiple polypeptide chains
what is denaturation?
this loss of proteins native structure is denaturation
- a denatured protein is biologically inactive
what are chaperonins?
are protein molecules that assist the proper folding of other proteins
what are prions?
are improperly folded forms of normal proteins that are present in healthy individuals
- prions can induce normal protein molecules to change their shape to the altered form
- amino acid sequence does not differ from a normal protein, but shape is radically different
what is X-ray crystallography?
scientist use this to determine a proteins structure
what are the two types of nucleic acids?
- deoxyribonucleic acid (DNA)
2. ribonucleic acid (RNA)
what is DNA?
DNA provides directions for its own replication
DNA directs synthesis of messenger RNA and through mRNA controls protein synthesis
- protein synthesis occurs in ribosomes
what are nucleic acids?
are polymers specialized for the storage, transmission, ad use of genetic information
- polymers of nucleic acids are called Polynucleotides
- monomers are called nucleotides
what is a nucleoside?
nucleoside = nitrogenous base + sugar
what are the two families of the nitrogenous bases?
- Pyrimidines : (cytosine, thymine and uracil) have a single six-membered ring
- Purines: (adenine and guanine) have a six-membered ring fused to a five-membered ring
what is a nucleotide?
nucleoside + phosphate group = nucleotide
what are phosphodiester linkages?
the backbone of RNA and DNA is a chain of sugars and phosphate groups by phosphodiester linkages
- the phosphate groups link carbon 3’ in one sugar to carbon 5’ in another sugar
- this is why the two DNA strands run in opposite directions (antiparallel)
