unit 1 Flashcards
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Monomer
The smaller units from which larger
molecules are made
Disaccharide
formed by the condensation of two
monosaccharides
held together by a glycosidic bond
Polymer
Molecules made from a large
number of monomers joined
together
Polysaccharide
Formed by the condensation of
many glucose units
held by glycosidic bonds
Monosaccharide
The monomers from which larger
carbohydrates are made
Glycogen
Polysaccharide in animals
formed by the condensation of
α-glucose
Cellulose
Polysaccharide in plant cell walls
formed by the condensation of
β-gl
Starch
Polysaccharide in plants
formed by the condensation of
α-glucose
contains two polymers - amylose
and amylopectin
Glycosidic bond
C–O–C link
between two sugar molecules
formed by a condensation reaction
it is a covalent bond
Amylopectin
Polysaccharide in starch
made of α-glucose
joined by 1,4 and 1,6-glycosidic
bonds
branched structure
Amylose
Polysaccharide in starch
made of α-glucose
joined by 1,4-glycosidic bonds
coils to form a helix
Condensation
reaction
A reaction that joins two molecules
together
with the formation of a chemical
bond
involves the elimination of a
molecule of water
Hydrolysis
reaction
A reaction that breaks a chemical
bond
between two molecules
involves the use of a water molecule
Fibrils
Long, straight chains of β-glucose
glucose
held together by many hydrogen
bonds
Triglyceride
Formed by the condensation of one
molecule of glycerol and three
molecules of fatty acids
forming 3 ester bonds
Phospholipid
Formed by the condensation of one
molecule of glycerol and two
molecules of fatty acid
held by two ester bonds
a phosphate group is attached to
the glycerol
Induced-fit
model
The enzyme active site is not
initially complementary to the
substrate
the active site moulds around the
substrate
this puts tension on bonds
lowers the activation energy
Competitive
inhibitor
A molecule that is the same/similar
shape as the substrate
binds to the active site
prevents enzyme-substrate
complexes from forming
Non-competitive
inhibitor
A molecule that binds to an enzyme
at the allosteric site
causing the active site to change
shape
preventing enzyme-substrate
complexes from forming
Primary
structure
The sequence of amino acids on a
polypeptide chain
Secondary
structure
The folding or coiling
to create a β pleated sheet or an
α helix
held in place by hydrogen bonds
Tertiary
structure
The further folding
to create a unique 3D shape
held in place by hydrogen, ionic and
sometimes disulfide bonds
What is the effect of
temperature on enzymecontrolled reaction
At low temperatures, there is not
enough kinetic energy for
successful collisions between the
enzyme and substrate.
At too high a temperature,
enzymes denature, the active site
changes shape and enzymesubstrate complexes cannot form.
Quaternary
structure
More than one polypeptide chain in
a protein
Peptide bond
Covalent bond joining amino acids
together in proteins
C–N link between two amino acid
molecules
formed by a condensation reaction
What is the effect of pH
on enzyme-controlled
reaction
too high or too low a pH will
interfere with the charges in the
amino acids in the active site.
This breaks the ionic and hydrogen
bonds holding the tertiary
structure in place
therefore the active site changes
shape and the enzyme denatures
Different enzymes have a different
optimal pH
What is the effect of
substrate concentration
on enzyme-controlled
reaction
At low substrate concentrations,
there will be fewer collisions
between the enzyme and substrate.
At high substrate concentrations,
the rate plateaus
because all the enzyme active sites
are saturated
What is the effect of
enzyme concentration
on enzyme-controlled
reaction
At low enzyme concentrations,
there will be fewer collisions
between the enzyme and substrate.
At high enzyme concentrations, the
rate plateaus
because there are more enzymes
than the substrate, so many empty
active sites.
Ester bond
–COO– chemical bond
formed between glycerol and fatty
acids
Hydrophilic
The ability to mix, interact or
attract water
Glucose
Monosaccharide that exists as two
isomers
β glucose and α glucose
Hydrophobic
The tendency to repel and not mix
with water
Sucrose
Disaccharide
formed by the condensation
of a glucose molecule and a
fructose molecule
Fructose
An example of a monosaccharide
that forms sucrose
Amino acid
The monomer of a protein
formed from C,H,O,N
contains a carboxyl group, amine
group and an R group
Galactose
An example of a monosaccharide
that forms lactose
Isomer
Molecules with the same molecular
formula
but the atoms are arranged
differently
Maltose
Disaccharide
formed by the condensation
of two glucose molecules
Lactose
Disaccharide
formed by the condensation
of a glucose molecule and a
galactose molecule
Polypeptide
Polymer chain of a protein
made up of amino acids
bonded together by peptide bonds
following condensation reactions
Carboxyl group
COOH group
made up of a C with hydroxyl (OH)
and carbonyl (double-bonded O)
group bonded to it
found in amino acids and fatty
acids
R group on
amino acids
The variable group
the part of each of the 20 amino
acids that is different
Amine group
NH group found on amino acids
β pleated sheet
A secondary structure in proteins
a folded, pleated shape
held in place by hydrogen bonds
α helix
A secondary structure in proteins
a coiled shape held in place by
hydrogen bonds
Hydrogen bonds
Weak bond
forms between H and O
in many biological molecules e.g.
proteins, water, DNA, tRNA
Disulfide bonds
A strong covalent bond
between two sulfur atoms in the R
groups of different amino acids
in the tertiary structure of proteins
Active site
Unique-shaped part of an enzyme
that the substrate binds to
Ionic bonds
Ionic bonds
Enzyme-substrate
complex
forms when an enzyme and
substrate collide and bind
resulting in a lowered activation
energy
Activation
energy
The minimum amount of energy
required for a reaction to occur
Denature
When the active site changes shape
so the substrate can no longer bind
Enzyme-inhibitor
complex
The structure that forms when an
enzyme and inhibitor collide and
bind
prevents enzyme-substrate
complexes from forming
Saturated
fatty acid
A long hydrocarbon chain with a
carboxyl group at one end
only single bonds between carbon
atoms
Polar molecule
A molecule that has an uneven
distribution of charge
Unsaturated
fatty acid
A long hydrocarbon chain with a
carboxyl group at one end
at least one double bond between
carbon atoms
Phospholipid
bilayer
Phospholipids have two charged
regions
in water, they are positioned so
that the heads are exposed to
water and the tails are not
Plasma
membrane
Phospholipid bilayer
cell surface membranes and
organelle membranes
Test for
reducing sugar
Add Benedict’s reagent
heat
observe green/yellow/orange/brick
red precipitate
Reducing sugar
sugars that can reduce Cu ions in
Benedict’s reagent to Cu ions in the
form of copper (I) oxide
which forms a brick-red precipitate
How does the structure
of a triglyceride relate
to it’s function?
large ratio of energy-storing
carbon-hydrogen bonds compared
to the number of carbon atoms; a
lot of energy is stored in the
molecule
high ratio of hydrogen to oxygen
atoms they act as a metabolic
water source
do not affect water potentials and
osmosis
have a relatively low mass
How does the
structure of a
triglyceride and
phospholipid differ?
A phospholipid has one fewer fatty
acid chain
which is replaced by a phosphate
group
What is the difference
between saturated and
unsaturated fatty
acid?
A saturated fatty acid has no
double bonds between carbon
atoms
where as unsaturated fatty acids
had at least one double bond
between carbon atoms
How does the structure of
a phospholipid relate to
it’s function?
Phospholipids have two charged
regions, so they are polar
In water, they are positioned so
that the heads are exposed to
water and the tails are not.
This forms a phospholipid bilayer
which makes up the plasma
membrane around cells.
Non-reducing
sugar
a sugar unable to reduce Cu
the glycosidic bond must be
hydrolysed to expose the reducing
group
e.g. sucrose
Test for starch
Add iodine
turns blue/black
test for non reducing sugar
ollowing a negative Benedict’s test
boil sample in acid and then
neutralise with alkaline
add Benedict’s reagent and heat
observe orange/brick red colour
Test for lipids
Add ethanol and shake
to dissolve
then add water
white emulsion forms
Test for protein
Add biuret
turns purple
Nucleotide
The monomer of DNA and RNA
contains a pentose sugar, a
phosphate group and a nitrogenous
base
Nitrogenous
base
Part of a nucleotide
adenine, guanine, cytosine, thymine
and uracil
DNA nucleotide
the monomer of DNA
contains a deoxyribose sugar, a
phosphate group and a nitrogenous
base
Polynucleotide
DNA polymer
many nucleotides
joined together via
a condensation
reaction
joined by
phosphodiester
bonds
Phosphodiester
bond
Bond joining two nucleotides
together
forms between a phosphate group
and the pentose sugar
Complementary
base pairs
The base pairs that align opposite
each other and form hydrogen
bonds
adenine and thymine/uracil
guanine and cytosine
Ribose
pentose sugar
found in RNA nucleotide and ATP
Uracil
Nitrogenous base
found in RNA instead of thymine
mRNA
a copy of a gene
single-strand polymer of RNA
tRNA
found only in the cytoplasm
single-stranded but folded to
create a shape that looks like a
cloverleaf
held in place by hydrogen bonds
rRNA
rRNA combines with protein to
make ribosomes
DNA template
strand
A DNA strand that is used to make a
new DNA copy from
both DNA strands in the double
helix are used as templates in DNA
replication
Semi-conservative
replication
DNA replication is semiconservative replication
one strand is from the parental
DNA and one strand is newly
synthesised
DNA polymerase
an enzyme in DNA replication
joins together adjacent nucleotides
DNA helicase
Enzyme that breaks hydrogen
bonds between the two chains of
DNA in a double helix
causes the two strands to separate
involved in DNA replication and
transcription
Large latent heat
of vaporisation
a lot of energy is required to convert
water from its liquid state to a
gaseous state
this is due to the hydrogen bonds,
as energy is needed to break these
to turn it into a gas
means water can provide a cooling
effect
High specific
heat capacity
a lot of energy is required to raise
the temperature of the water
because some of the heat energy is
used to break the hydrogen bonds
between water molecules
important so water can act as a
temperature buffer
Metabolite
Water is involved in many reactions
such as photosynthesis, hydrolysis,
and condensation reactions
Solvent
Water is a good solvent
meaning many substances dissolve
in it
polar (charged) molecules dissolve
readily in water due to the fact
water is polar
Strong
cohesion
water molecules ‘stick’ together
due to hydrogen bonds
results in water moving up the
xylem as a continuous column of
water
provides surface tension, creating
a habitat on the surface of the
water for small invertebrates
ATP synthase
Enzyme that catalyses the
synthesis of ATP from ADP + Pi
ATP hydrolase
Enzyme that catalyses the
hydrolysis of ATP into ADP +Pi
Phosphorylation
the addition of a phosphate group
to a molecule
making the molecule more
reactive/it gains energy
structure of water
water is a polar molecule
the oxygen atom is slightly negative
the hydrogen atoms are slightly positive
Dipeptide
Two amino acids bonded together
by a peptide bond
formed by a condensation reaction
RNA nucleotide
monomer of RNA
composed of a phosphate group,
ribose and a nitrogenous base
has the base uracil instead of
thymine
Role of
hydrogen ions
determine the pH
the more hydrogen ions, the more
acidic the conditions are
an important role in chemiosmosis
in respiration and photosynthesis
Role of
iron ions
a compound of haemoglobin
involved in oxygen transport
Role of sodium ions
in co-transport
involved in co-transport for
absorption of glucose and amino
acids in the ileum
Role of
phosphate ions
as a component of DNA, RNA and
ATP
phosphodiester bond in DNA and
RNA forms between the phosphate
group and the pentose sugar
fatty acid structure
carboxyl group and a long hydrocarbon chain
can be saturated or unsaturated
