Biomolecules Flashcards
_____are large or small molecules from pure or synthetic substances that are not living organisms per se but which contribute a
lot to the living or metabolic states of cells.
Biomolecules
A _______ is a long molecule consisting of
many similar building blocks
polymer
small building-block molecules
monomer
What are the three organic polymers?
carbohydrates, protein, nucleic acids
______ occurs when two monomers bond together through the loss of a water molecule
dehydration reaction
______ are macromolecules that speed up
the dehydration process
enzymes
Polymers are disassembled to monomers by _________, a reaction that is essentially the reverse of the dehydration reaction
hydrolysis
______ include sugars and the
polymers of sugars
carbohydrates
The simplest carbohydrates are
__________, or single sugars
monosaccharides
Carbohydrate macromolecules are
__________, polymers composed of many sugar building blocks
polysaccharides
Monosaccharides have molecular formulas that are usually multiples of ________
CH2O
What is the most common monosaccharide?
glucose
2 classifications of monosaccharides
location of the carbonyl group, number of carbons in the carbon skeleton
The location of the carbonyl group is classified as _____ or _______
aldose, ketose
True or False: Though often drawn as linear skeletons, in aqueous solutions many sugars form rings
True
What is the function of monosaccharides?
serve as a major fuel for cells and as raw material for building molecules
A ________is formed when a dehydration reaction joins two monosaccharides
disaccharide
What is the covalent bond in carbohydrates?
glycosidic linkage
Give three monosaccharides
glucose, fructose, galactose
Glucose + Glucose = ?
maltose
Glucose + Fructose = ?
sucrose
What is the function of Polysaccharides?
storage and structural roles
What determines the structure and function of a polysaccharide?
sugar monomers, positions of glycosidic linkages
_______, a storage polysaccharide of plants, consists entirely of glucose monomers
starch
Plants store surplus _____ as granules within chloroplasts and other plastids
starch
______ is a storage polysaccharide in
animals
glycogen
starch:plants
glycogen:____
animals
Humans and other vertebrates store glycogen mainly in _________
liver and muscle cells
The polysaccharide ______ is a major component of the tough wall of plant cells
cellulose
Difference between starch and cellulose
starch - glucose alpha
cellulose - glucose beta
Polymers with a (alpha) glucose are _____
helical
Polymers with b (beta) glucose are _______
straight
In __________, H atoms on one
strand can bond with OH groups on other strands
straight structures
___________ molecules held togetherthis way are grouped into microfibrils, which form strong building materials for plants
parallel cellulose
True or False: Enzymes that digest starch by hydrolyzing a linkages can also hydrolyze b linkages in cellulose
False - Enzymes that digest starch by hydrolyzing a linkages CAN’T hydrolyze b linkages in cellulose
_______ in human food passes through the digestive tract as insoluble fiber
cellulose
True or False: Some microbes use water to digest cellulose
False - Some microbes use ENZYMES to digest cellulose
______, another structural polysaccharide, is found in the exoskeleton of arthropods
chitin
_____ provides structural support for the cell walls of many fungi
chitin
________ are the one class of large biological molecules that do not form polymers
lipids
They have little or no affinity for water (hydrophobic)
lipids
Lipids are hydrophobic because they consist mostly of ________, which form nonpolar covalent bonds
hydrocarbons
What are the most biologically important lipids?
fats, phospholipids, and steroids
Fats are composed of ____ and _____
glycerol and fatty acids
______ is a three-carbon alcohol with a hydroxyl group attached to each carbon
Glycerol
True or False: Fats separate from water because
water molecules form hydrogen bonds with each other and exclude the fats
True
In a fat, three fatty acids are joined to
glycerol by an ester linkage, creating a
__________
triacylglycerol, or triglyceride
Fatty acids vary in _____ and in the ______
length (number of carbons), number and locations of double
bonds
___________ have the maximum number of hydrogen atoms possible and no double bonds
saturated fatty acids
_______ have one or more double bonds
unsaturated fatty acids
Which is healthy, saturated or unsaturated fats?
unsaturated
True or False: A diet rich in unsaturated fats may contribute to cardiovascular disease through plaque deposits
False - A diet rich in SATURATED fats may contribute to cardiovascular disease through plaque deposits
Unsaturated fats can be converted into saturated fats through what process?
hydrogenation
True or False: Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds
True
True or False: Trans fats may contribute more than saturated fats to cardiovascular disease
True
In a phospholipid, _____ and a _____ are attached to glycerol
two fatty acids, phosphate group
The two fatty acid tails are ________, but the phosphate group and its attachments form a ________ head
hydrophobic, hydrophilic
True or False: When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the exterior
False - When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the INTERIOR
The structure of phospholipids results in a bilayer arrangement found in _______
cell membranes
______ are lipids characterized by a carbon skeleton consisting of four fused rings
steroids
________, an important steroid, is a
component in animal cell membranes
cholesterol
True or False: Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease
True
Polypeptides are polymers built from the same set of _____
20 amino acids
A _____ consists of one or more polypeptides
protein
_____ are organic molecules with carboxyl and amino groups
amino acids
What are the monomers of proteins?
amino acids
Amino acids differ in their properties due to differing side chains, called
R groups
Amino acids consists of:
amino group, carboxyl group, carbon, and R group
What are the three types of amino acids?
polar, non polar, electrically charged
Amino acids are linked by _________
peptide bonds
What is the polymer of amino acids?
polypeptide
True or False: Each polypeptide has a unique linear sequence of amino acids
True
True or False: A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape
True
The sequence of amino acids determines a protein’s _______
three-dimensional structure
A protein’s structure determines its _______
function
The _______ of a protein is its unique sequence of amino acids
primary structure
________, found in most proteins, consists of coils and folds in the polypeptide chain
secondary structure
______ is determined by interactions among various side chains (R groups)
tertiary structure
_______ results when a protein consists of multiple polypeptide chains
quaternary structure
True or False: A slight change in primary structure can affect a protein’s structure and ability to function
True
____________, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin
sickle-cell disease
Nucleic acids are polymers called
___________
polynucleotides
What are the monomers of polynucleotides?
nucleotides
Nucleotide consists of:
a nitrogenous base, a pentose sugar, and a phosphate group
The portion of a nucleotide without the phosphate group is called a ________
nucleoside
nitrogenous base + sugar = ?
nucleoside
What are the two families of nitrogenous bases?
pyramidines and purines
_______ (cytosine, thymine, and uracil)
have a single six-membered ring
pyrimidines
______ (adenine and guanine) have a six-membered ring fused to a five-membered ring
purines
The sugar for DNA is ______, while the sugar for RNA is _______
deoxyribose, ribose
nucleoside + phosphate group = ?
nucleotide
Adjacent nucleotides are joined by covalent bonds that form between the ____ group on the 3’ carbon of one nucleotide and the phosphate
on the 5’ carbon on the next
-OH
True or False: The sequence of bases along a DNA or mRNA polymer is the same for each gene
False - The sequence of bases along a DNA or mRNA polymer is unique for each gene
A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a __________
double helix
In the DNA double helix, the two backbones run in opposite 5’ → 3’ directions from each other, an arrangement referred to as _______
antiparallel
True or False: One DNA molecule includes many genes
True
In DNA…
Adenine:______
Guanine:______
thymine, cytosine
True or False: The linear sequences of nucleotides in DNA molecules are passed from parents to offspring
True
True or False: Two closely related species are more similar in DNA than are more distantly related species
True
Molecular biology can be used to assess __________
evolutionary kinship
A _____ is a chemical agent that speeds up a reaction
without being consumed by the reaction
catalyst
An ______ is a catalytic protein
enzyme
True or False: Hydrolysis of sucrose by the enzyme sucrase is an
example of an enzyme-catalyzed reaction
True
The initial energy needed to start a chemical reaction is
called the ________________
free energy of activation / activation energy (EA)
What supplies activation energy?
heat
How do enzymes catalyze reactions?
by lowering the activation energy barrier
True or False: Enzymes affect free energy
False - Enzymes do not affect the change in free energy (∆G);
instead, they hasten reactions that would occur
eventually
The reactant that an enzyme acts on is called the enzyme’s ______
substrate
What is formed when an enzyme binds to its substrate?
enzyme-substrate complex
The _______ is the region on the enzyme where the
substrate binds
active site
________ of a substrate brings chemical groups of the
active site into positions that enhance their ability to
catalyze the reaction
induced fit
How can the active site lower the Ea barrier?
orienting substrates correctly, straining substrate bonds, providing favorable microenvironment, covalently bonding to the substrate
An enzyme’s activity can be affected by
temperature and pH, chemicals that specifically influence the enzyme
Each enzyme has an optimal ________in which it can function
temperature and pH
______ are nonprotein enzyme helpers
cofactors
An organic cofactor is called a _________
coenzyme
An example of coenzymes
vitamins
_______ bind to the active site of an enzyme, competing with the substrate
competitive inhibitors
________ bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
noncompetitive inhibitors
examples of inhibitors include _____________
toxins, poisons,
pesticides, and antibiotics
True or False: Chemical chaos would result if a cell’s metabolic pathways were not tightly regulated
True
A cell does this by switching on or off the genes that encode specific enzymes or by regulating the activity of enzymes
regulation of enzyme activity
______ may either inhibit or stimulate an enzyme’s activity
allosteric regulation
__________ occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site
allosteric regulation
Inhibition of proteolytic enzymes called caspases may help management of inappropriate __________
inflammatory
responses
True or False: Allosteric regulators are attractive drug candidates for enzyme regulation
True
ATP powers cellular work by coupling
__________________________________
exergonic reactions to endergonic reactions
3 main kinds of work that a cell does
chemical, transport, mechanical
To do work, cells manage energy resources by ___________, the use of an exergonic process to drive an endergonic one
energy coupling
Most energy coupling in cells is mediated by
ATP
Cell’s energy shuttle
ATP (adenosine triphosphate)
ATP is composed of:
ribose (a sugar), adenine (a
nitrogenous base), and three phosphate groups
The bonds between the phosphate groups of ATP’s tail can be broken by __________
hydrolysis
_______ is released from ATP when the terminal
phosphate bond is broke
energy
True or False: This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves
True
The coupled reactions are _________
exergonic
ATP drives endergonic reactions by __________, transferring a phosphate group to some other molecule, such as a reactant
phosphorylation
