Topic 1- biomolecules Flashcards
what do carbohydrates contain?
carbon, hydrogen, oxygen
what type of agents do monosaccharides act as?
reducing agents, because they are reducing sugars
what type of results does benedict’s test give?
semi quantative
method for benedicts
- add benedict’s reagent to a test tube
- add sample to test tube
- Heat mixture in a water bath heated to 60c for 5 minutes
- A negative result for reducing sugars is blue
- A positive result for reducing sugars is brick red
are condensation and hydrolysis reactions reversible
yes
By what bonds are monosaccharides joined with other monosaccharides?
glycosidic bonds
what is the polysaccharide found in animals
glycogen
what are the 2 polysaccharides found in plants
Cellulose, starch
What type of reaction are monomers joined together in?
condensation reaction, water molecule is lost
Hydrolysis: Is water added or removed?
A water molecule is removed
what is the opposite of a condensation reaction
hydrolysis
what are carbohydrates made of
carbon, hydrogen, oxygen
what type of bond joins monosaccharides together?
glycosidic bond (remember glyco because its carbs)
how many carbons in a glucose molecules
6
C6H12O6
Draw alpha glucose
check notes for answer
Draw beta glucose
check notes for answer
Monomers of maltose
glucose+glucose
Monomers of lactose
glucose+galactose
Monomers of sucrose
glucose+fructose
what is the monomer in cellulose
beta glucose
what are the monomers in glycogen
alpha glucose
what are the monomers in starch
alpha glucose
what is polymerisation
process of forming polymers
why is glycogen a good storage molecule for animals- 3 reasons
-Large number of side branches so energy can be released quickly as enzymes can act simultaneously on these branches
-Large but compact, maximising amount of energy it can store
-Insoluble, will not affect water potential of cells and cannot diffuse out of cells
What are the two polysaccharides that make up starch?
- amylose
-amylopectin
what polysaccharide is made of amylose and amylopectin
starch
what are the properties of amylose (a polysaccharide in starch)
- unbranched chain of glucose
-coiled and very compact, storing a lot of energy
what are properties of amylopectin
-highly branched
-side branches mean it can be broken down quickly by enzymes to release energy
is amylose straight chained or branched
straight chain
is amylopectin straight chained or branched
highly branched
which of the polysaccharides is made of 2 monosaccharides
starch- made of amylose and amylopectin
where is cellulose found
cell walls of plants, (think cellulose so cell)
what is the structure of cellulose
long, unbranched chains of beta glucose (glycosidic bonding) in the form of microfibrils
strong threads running parallel to one another, joined by hydrogen bonds forming cross linkages
why is starch a good storage molecule, 2 reasons
insoluble in water, wont affect w.p. of cell
compact
why is cellulose important in the cell wall
Stops the cell wall from bursting under osmotic pressure, helps cell to stay turgid
what does it mean that monosaccharides are reducing sugars
act as reducing agents, they can donate electrons to reduce another substance (e.g. benedicts)
why does benedicts change colour in the presence of reducing sugar
the benedict’s will receive electrons from the reducing sugar, thus being reduced
what does a negative result look like in a benedicts test
blue solution
what does green/orange/red benedicts mean
reducing sugar, trace-large amounts
does benedicts solution need to be heated?
yes
60 degree water bath for 5 minutes
what does a positive and negative iodine test for starch look like
blue-black
negative is yellow-brown
is heating necessary for iodine test
no
what would a benedicts test look like for sucrose, or any polysaccharide, and why?
Blue because polysaccharides and sucrose are NOT reducing sugars
how to do a benedicts test on a non reducing sugar
- do a benedicts to check it stays blue
- heat in a boiling water bath with acid
- neutralise with alkali
- heat in boiling water bath WITH benedicts
- positive would still be green/orange/red
what are the 2 types of lipids
-phospholipids
-triglycerides
what is the structure of triglycerides
1 glycerol and 3 fatty acids joined by ester bonds
what is the bond type in lipids
ester bond
where are saturated lipids found
animal fat
what is a saturated lipid
triglyceride that doesn’t contain any carbon=carbon double bonds
e.g. animal fat
what is an unsaturated lipid
triglyceride that contains a carbon carbon double bond, therefore molecule is able to bend and is liquid at room temp. e.g. plant oils
what is a fatty acid chain in a triglyceride
a carbon hydrogen chain
what features of triglycerides make them a good energy store and why (4 things)
-high ratio of (energy storing) carbon-hydrogen bonds to carbon atoms
- low mass to energy ratio, a lot of energy stored in a small volume, beneficial for animals as is less mass to move around
- high ratio of hydrogen-oxygen atoms means triglycerides release water when oxidised, beneficial for animals living in dry environments (e.g. camels)
-large and non polar, doesnt affect W.P. of cell
describe structure of a phospholipid
-head is glycerol and phosphate, tail is 2 fatty acids
-polar head is hydrophillic, tail is hydrophobic and faces inward, so forms micelles in water
how does phospholipid structure relate to its properties? (2 things)
- because of the hydrophillic heads, in an aqueous environment, a bilayer can be formed of two layers of phopsholipids with the heads facing outwards
- their structure allows them to form glycolipids with carbohydrates
how is an emulsion test for lipids carried out?
- add sample to test tube
- add ethanol to sample and shake to dissolve
- add distilled water to the test tube
- if a white emulsion forms, lipid is present
- as a control repeat with water to ensure sample remains clear
what are the monomers of proteins
-amino acids
what is the structure of amino acids
-an amino group (NH₂)
-carboxylic acid group (-COOH)
-variable R group in a carbon hydrogen chain
what feature of amino acids determine what amino acid it is
the variable R group, can be one of 20
what is the bonding between amino acids
-peptide bonds
by what reaction are amino acids joined
condensation, water molecule is lost
difference between dipeptide and polypeptide
-dipeptide contains 2 amino acids
-polypeptide contains 3+ amino acids
what is the primary structure of a protein
the order and number of amino acids, determines the final protein function
what is the secondary structure of a protein
the shape that the chain of amino acids makes, weak hydrogen bonds lead to
either alpha helices or beta pleated sheets
what is the tertiary structure of a protein
- the 3d shape the protein forms from further twisting and folding
what are the 3 types of bonding in the tertiary structure of a protein
-Disulfide bridges between the sulfur in the R group of cysteine amino acid, strong and not easily broken
- Ionic, between carboxyl and amino groups. Easily broken by PH
- Hydrogen bonds, numerous and easily broken
what is the method of biuret test for proteins
- add sample to test tube
- add biurets solution to sample and shake to mix
- positive result is from blue to purple
what are the two tertiary shapes proteins can be
fibrous (e.g. keratin or globular (e.g. enzymes of haemoglobin)
how do enzymes increase rate of reaction
lowering the activation energy of the reaction they catalyse
what is the structure of an enzyme
3D tertiary globular protein, shape determined by the primary sequence of amino acids
what is the molecule called that an enzyme acts on
the substrate
what is the active site of an enzyme
area of the enzyme that forms a small depression, made of a few amino acids
what is it called when an enzyme binds to its specific substrate
enzyme-substrate complex, the structure of the enzyme changes so that the enzyme fits around the substrate
what is the induced fit model
when an enzyme is altered so the active site fits around the substrate in an enzyme substrate complex
what factors affect the rate of enzyme controlled reactions
-temp
-ph
-enzyme+substrate concentration
-competitive+non competitive reversible inhibitors concentration
how does temperature affect rate of enzyme controlled reactions?
- rate of reaction increases because kinetic energy of enzymes
-above optimum temp rate of reaction decreases because enzymes get denatured
how does ph affect rate of enzyme controlled reactions?
- ph affects enzymes shape as it can disrupt bonds in the tertiary structure of the enzyme
-optimum ph varies between enzymes, e.g. pepsin is the stomach optimum is 2.5
how does enzyme concentration affect rate of reaction
high enzyme conc. means more active sites for substrates to bind to, but increasing enzyme conc. to more than substrate conc. is pointless because there will be more active sites than substrates
how does substrate concentration affect rate of reaction
As conc. of substrate increases, rate of reaction increases as more enzyme-substrate complexes are formed, only up to certain point
how do competitive reversible inhibitors affect rate of reaction
rate of reaction decreases as active sites are blocked
how do non competitive reversible inhibitors affect rate of reaction
decreases as the shape of the enzyme is altered by the inhibitors
what does RNA do
transfers genetic information from DNA to ribosomes where it is used for proteinsynthesis
what is deoxyribonucleic acid and ribonucleic acid polymers of
nucleotides: a pentose sugar (either ribose or deoxyribose), a phosphate and an organic base/nucleotide
what are the components of a DNA nucleotide
deoxyribose sugar, a phosphate group, and a nitrogen containing organic base: adenine, cytosine, guanine or thymine
what are the components of an RNA nucleotide
ribose sugar, a phosphate group, an a nitrogen containing base: adenine, cytosine, guanine or Uracil
how do nucleotides join together and in what reaction do they join together?
phosphodiester bonds formed in condensation reactions to form di or polynucleotides
what is a dna molecule made of
2 chains of polynucleotides joined by hydrogen bonds between the bases from each chain
why is DNA a stable molecule
-phosphodiester bonds in the phosphate sugar backbone means the nitrogen bases are protected inside the molecule, (because they are chemically reactive)
- C-G bonds have 3 hydrogen bonds, as oppose to A-T bonds which have 1, so a high proportion of C-G makes it more stable
why does semi-conservative replication exist
-Ensures DNA continuity between generations of cells
What are the steps of DNA replication?
- DNA helicase unzips the double helix, breaking the hydrogen bonds between the bases
- One of the strands is used as a template and complementary base pairing will occur with free nucleotides
- Once activated nucleotides are bound to the template, DNA polymerase joins them together by forming phosphodiester bonds
- As a result, 2 new identical strands of dna are formed
what is the structure of adenosine triphosphate
ribose sugar, adenine, 3 phosphate groups
what happens when ATP is hydrolysed to form ADP and a phosphate molecule
large amount of energy is released from the bonds between the phosphates, easy to break
what enzyme catalyses the hydrolysis reaction of ATP–>ADP+phosphate molecule
the reaction is catalysed by atp hydrolase
what happens to the inorganic phosphate after ATP is hydrolysed?
-used to phosphorylate other compounds
why is ATP a good source of energy
energy release is immediate, it is broken down in a single step
is water polar or non polar
polar, it has an uneven distribution of charge throughout the molecule because the hydrogens are more positive than the oxygen
is water a metabolite
yes, it is used in condensation and hydrolysis
does water have a high or low specific heat capacity
-high heat specific capacity, because water molecules stick together with hydrogen bonds so a lot of energy is required to break the bonds
- this helps to minimise temperature fluctuations in living things
does water readily evaporate
no it has a large latent heat of vapourisation, so evaporation of water provides a cooling effect e.g. sweating
is there cohesion between water molecules
yes, allows strong columns to form
What is a monomer? (1)
small repeating unit from which polymers are made
