biological molecules Flashcards
what are the biological molecules?
disaccharides, polysaccharides, starch, cellulose, glycogen, lipids, ATP, nucleotides, DNA, RNA, proteins
what are disaccharides and polysaccharides made from?
monosaccharides
what are starch and glycogen made from?
a- glucose molecules
what is cellulose made from?
B- glucose molecules
what are lipids made from?
triglycerides: 3 fatty acids and 1 glycerol molecule
what is ATP made from?
adenine, ribose and 3 phosphate groups
what are nucleotides made from?
a pentose sugar, a phosphate group and a nitrogen containing organic base
what is DNA made from?
mononucleotides made of a phosphate group, deoxyribose and an organic base
what is RNA made from?
mononucleotides made of a phosphate group, ribose and an organic base
what are proteins made from?
amino acids
what type of bonds are formed for disaccharides, polysaccharides, starch, cellulose and glycogen?
glycosidic bonds
what type of bonds are formed for lipids?
ester bonds
what type of bonds are formed for DNA and RNA?
between 2 nucleotides= phosphodiester bond
between base pairs= hydrogen bonds
what type of bonds are formed for proteins?
primary structure= peptide bonds between amino acids
secondary structure= hydrogen bonds
tertiary structure= hydrogen bonds, ionic bonds and disulphide bonds
what’s the reaction to form the molecules disaccharides, polysaccharides, starch, cellulose, glycogen, lipids, ATP, nucleotides and proteins?
condensation
what’s the reaction to form the molecule DNA?
condensation between the deoxyribose and the phosphate
what’s the reaction to form the molecule RNA?
condensation between the ribose, phosphate group and organic base to make the RNA nucleotide
what’s the reaction to break down all the biological molecules?
hydrolysis
what’s the enzyme needed to form the molecule ATP?
ATP synthase
what’s the enzyme needed to form the molecule DNA?
DNA polymerase which joins nucleotides together
what’s the enzyme needed to form the molecule RNA?
RNA polymerase
what’s the enzyme needed to break down the molecule ATP?
ATP hydrolase
what’s the enzyme needed to break the molecule DNA?
DNA helicase which breaks down hydrogen bonds linking base pairs
what’s the enzyme needed to break down the molecule RNA?
RNA helicase
how do you make a protein? (detailed)
primary=sequence of many amino acids joined together in a process called polymerisation. Resulting chain of many amino acids is called a polypeptide.
secondary= the folding of the protein into alpha glucose helixes and beta pleated sheets using hydrogen bonds. Hydrogen bonds formed by the two groups (amine and carboxyl)
tertiary= further folding of the secondary structure, bonds formed may include hydrogen bonds (easily broken), ionic bonds (easily broken by changes in pH) and disulphide bonds (not easily broken)
quaternary= multiple polypeptides joined together to form the final position of protein
how many amino acids make up a protein?
20
what happens to the R group when the amino acid changes?
-the residual changes dependant on what type of amino acid
-glycine= H
-alanine= CH2
what are the structures of triglycerides that are related to their properties?
-insoluble in water so doesn’t affect osmosis in cells
-high ratio of energy storing carbon: hydrogen bonds: carbon atoms, so good source of energy
-low mass: energy ratio, making them good storage molecules
how do you form triglycerides/lipids?
-glycerol joins a fatty acid through condensation reactions, forming water
-the bond between glycerol and fatty acid is called an ester bond
what are the roles of lipids?
-source of energy
-water proofing
-insulation
-protection of internal organs
what are saturated fatty acids?
-single bonds
-solid at room temperature
what are unsaturated fatty acids?
-double bonds
-liquid at room temperature
what is a phospholipid and what is it made up of?
-type of lipid formed from the monomer glycerol and fatty acids
-there are only two fatty acids bonded to a glycerol molecule in a phospholipid as one has been replaced by a phosphate group
how are phospholipids able to form cell membranes?
-the phosphate group head is hydrophilic (water-loving)
-the fatty acid tails are hydrophobic (water-hating)
-has a lipid bilayer that forms the main part of the cell membrane
what is the food test for starch?
-iodine solution
positive result= blue/black
negative result= orange (no colour change)
what is the food test for protein?
-biuret solution (A= sodium hydroxide, B= copper sulphate)
positive result= purple
negative result= blue (no colour change)
what is the food test for lipids?
-ethanol solution
-shake
positive result= cloudy/milky layer (emulsion)
negative result= clear
what is the food test for reducing sugars?
-benedict’s solution
-heat in water bath for 5 minutes
positive result= green, yellow, orange, red
negative result= blue (no colour change)
what is the food test for non reducing sugars?
-benedict’s solution
-heat in water bath for 5 minutes
-no change
-add hydrochloric acid to the sample and heat in a water bath for 5 minutes
-neutralise the solution with sodium hydrogen carbonate
-carry out benedict’s test as normal
positive result= green, yellow, orange, red
negative result= blue (no colour change)
what are reducing and non reducing sugars?
reducing=
-all monosaccharides and some disaccharides (fructose)
non reducing=
-some disaccharides (sucrose)
-have to be broken down by hydrolysis into a monosaccharide for solution to change colour
what are starch’s structure and related functions?
-compact= lots can be stored in one place
-insoluble= doesn’t affect water potential
-large= does not diffuse out of cells
what are glycogen’s structure and related function?
-insoluble in water= isn’t affected by osmosis and doesn’t diffuse out of cells
-compact= a lot can be stored in a small space
-highly branched= can be acted on by enzymes easier than starch
what is cellulose’s structure and related function?
-straight, unbranched chains, allowing hydrogen bonds to form cross linkages across adjacent chains= strengthens cellulose
what monosaccharides join together to make disaccharides? (examples)
-glucose joins glucose to form maltose
-glucose joins fructose to form sucrose
-glucose joins galactose to form lactose
what is a protein?
-amino acids are the monomers from which proteins are made
-proteins are made of 20 amino acids
-a condensation reaction between 2 amino acids forms a peptide bond
-dipeptide bonds are formed by the condensation of 2 amino acids
-polypeptide bonds are formed by the condensation of many amino acids
what are lipids?
-triglycerides are formed by the condensation of one molecule of glycerol and three molecules of fatty acid
-the condensation between glycerol and a fatty acid (RCOOH) forms an ester bond
-the R group of a fatty acid may be saturated or unsaturated
-in phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate containing group
what is the structure and function of phospholipids?
-
what do enzymes do the activation energy?
-each enzyme lowers the activation energy of the reaction it catalyses
what is the induced fit model of enzyme action?
-active site forms as the enzyme and substrate interact
-the proximity of the substrate leads to a change in the enzyme that forms the functional active site
-the enzyme has a certain general shape that alters in the presence of the substrate
-as it changes its shape, the enzyme puts a strain on a substrate molecule
-this strain distorts a particular bond in the substrate and consequently lowers the activation energy needed to break the bond
what effect does temperature have on enzyme action?
-a rise in temperature increases the kinetic energy of molecules
-the molecules move around more rapidly and collide with each other more often
-this means that the enzyme and substrate molecules come together more often
-more effective collisions resulting in more enzyme-substrate complexes being formed, so the rate of reaction increases
what effect does pH have on enzyme action?
-an increase or decrease in pH reduces the rate of enzyme action
-if the change in pH is extreme and beyond a certain pH, the enzyme becomes denatured
-a change in pH alters the enzyme’s active site, therefore the substrate can no longer from an enzyme substrate complex
-it may cause the bonds maintaining the enzyme’s tertiary structure to break, therefore causing the active site to change shape
what effect does enzyme concentration have on enzyme action?
-an increase in the amount of enzyme leads to a proportionate increase in the rate of reaction
-this is because there are more substrates than the enzyme’s active sites to cope with
-if there is insufficient substrates to supply all the active sites then any increase in enzyme concentration will have no effect on the rate of reaction
what are competitive inhibitors?
-competitive inhibitors have a molecular shape similar to the substrate
-this allows them to occupy the active site, therefore compete with the substrate
-if the substrate concentration is increased, the effect of the inhibitor is reduced
-if the inhibitor concentration is increased, the longer it will take for the substrate molecules to occupy the active sites
what are non competitive inhibitors?
-non competitive inhibitors attach themselves to the enzyme at a binding site which is not the active site
-the inhibitor alters the shape of the enzyme and its active site in such a way the substrate can no longer occupy it
-therefore, the enzyme cannot function
-as the substrate and inhibitor are not competing for the same site, an increase in substrate does not decrease the effect of the inhibitor
what is the nucleotide structure?
-made up of three components: a pentose sugar, a phosphate group and a nitrogen containing organic base (cytosine, guanine, thymine, adenine and uracil)
-the pentose sugar, phosphate group and organic base are joined as a result of condensation reactions to form a mononucleotide
-the bond between the deoxyribose sugar of one mononucleotide and the phosphate group of another is called a phosphodiester bond
what is RNA’s structure?
-single, short polynucleotide chain in which the pentose sugar is always ribose and the organic bases are adenine, guanine, cytosine and uracil
-RNA transfers genetic information from DNA to the ribosomes
what is DNA’s structure?
-Watson and Crick worked out the structure of DNA
-the pentose sugar is deoxyribose and the organic bases are adenine, guanine, cytosine and thymine
-made up of 2 strands that are joined together by hydrogen bonds formed between certain bases
-DNA can be thought of a ladder in which the phosphate and the deoxyribose alternate to form the uprights and the organic base pairs form the rungs
what are the base pairing for DNA?
-adenine always pairs with thymine
-guanine always pairs with cytosine
what is the stability of DNA?
-the phosphodiester backbone protects the more chemically reactive organic bases inside the double helix
-hydrogen bonds link the organic base pairs forming rungs between the phosphodiester uprights
what is the function of DNA?
-its two separate strands are joined only with hydrogen bonds, which allow them to separate during DNA replication
-an extremely large molecule, therefore carries an immense amount of genetic information
-base pairing leads to DNA being able to replicate and to transfer information as mRNA
what are the four requirements needed for semi conservative replication?
-the four types of nucleotide, each with their bases of adenine, guanine, cytosine or thymine must be present
-both strands of the DNA molecule act as a template for the attachment of these nucleotides
-the enzyme DNA polymerase
-a source of chemical energy
what is the process of semi conservative replication?
-the enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA
-as a result the double helix separates into its two strands and unwinds
-each exposed polynucleotide strand then acts as a template to which complimentary free nucleotides bind by specific base pairing
-nucleotides are joined together in a condensation reaction by DNA polymerase to form the missing polynucleotide strand on each of the two original strands of DNA
-each of the new DNA molecules contains one of the original DNA strands, half the original DNA has been saved and built into each of the new DNA molecules
what is the structure of ATP?
-adenine= a nitrogen containing organic base
-ribose= a pentose sugar
-phosphates= a chain of three phosphate groups
how does ATP store energy?
-adenosine triphosphate is a nucleotide that has three phosphate groups
-this is the key to how ATP stores energy
-the bonds between these phosphate groups are unstable and so have a low activation energy, which means they are easily broken
-when they do break they release a considerable amount of energy
what is the phosphate hydrolysis equation?
ATP + water -> ADP + Pi + energy
-as water is used to convert ATP to ADP, this is known as a hydrolysis reaction which is catalysed by ATP hydrolyse
what is the synthesis of ATP?
-the conversion of ATP to ADP is a reversible reaction and therefore energy can be used to add an inorganic phosphate to ADP to reform ATP according to the reverse of the equation
-this reaction is catalysed by the enzyme ATP synthase
what is ATP used in?
-metabolic processes
-movement
-active transport
-secretion
-activation of molecules
how is a phosphodiester bond formed?
-condensation reaction between two nucleotides
what are water’s important properties?
-is a metabolite in many metabolic reactions, including condensation and hydrolysis reactions
-is an important solvent in which metabolic reactions occur
-relatively high heat capacity, buffering changes in temperature
-relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation
-strong cohesion between water molecules: supports columns of water in the tube like transport cells of plants and produces surface tension where water meets air
