Biological Molecules 3.1 Flashcards
What are mitochondria?
Oval-shapes structures which are responsible for aerobic respiration.
What are monomers?
Smaller units from which larger molecules are made.
What are polymers?
Molecules made from lots of repeating units joined together.
What is a condensation reaction?
A reaction which joins together two monomers with a covalent bond and includes the removal of a molecule of water.
What is a hydrolysis reaction?
A reaction which breaks down the covalent bond between two monomers, with the use of a water molecule.
What type of reaction joins monosaccharides together?
A condensation reaction.
What are the three key types of monosaccharides?
A triose, pentose and hexose.
What are the two types of glucose?
Alpha and Beta glucose.
What are alpha and beta glucose?
Isomers.
What is meant by the term isomer?
They have the same molecular formulae but different arrangement of atoms.
What do two monosaccharides bond together to form?
A disaccharide.
What type of bond is formed between two monosaccharides?
A glycosidic bond.
What are the three key types of disaccharides?
Maltose, Sucrose and Lactose.
What two monosaccharides make up maltose?
Two glucose monosaccharides.
What two monosaccharides make up sucrose?
Glucose and Fructose.
What two monosaccharides make up Lactose?
Galactose and Glucose.
What is the role of maltose?
It is formed from the breakdown of starch in germinating seeds and it is used to provide energy for the growing embryo.
What is the role of sucrose?
It is the form in which sugars are transported in the phloem in plants.
What is the role of Lactose?
It is the sugar found in milk and is the energy source for suckling mammals.
What molecule is released during a condensation reaction between two monosaccharides?
A water molecule.
What do reducing sugars act as?
Reducing agents in chemical reactions.
What are examples of Reducing sugars?
All monosaccharides and some disaccharides.
What are examples of non-reducing sugars?
Most disaccharides and simple polysaccharides.
What are the two steps for testing for a non-reducing sugar?
- Add dilute hydrochloric acid and then neutralise with sodium hydrogencarbonate.
- Heat and observe colour change.
What are polysaccharides?
Polymers which contain many monosaccharides linked together by glycosidic bonds.
What are polysaccharides mainly used for?
Energy stores and structural components of cells.
What is starch?
The major carbohydrate storage molecule in plants.
What is starch usually stored as?
Intracellular starch grains.
What is starch produced from?
The glucose made during photosynthesis.
Why is starch broken down during respiration?
To provide energy and it is also a source of carbon for producing other molecules.
What type of glucose is starch made up from?
Alpha glucose.
What are the two polysaccharides starch is made up from?
Amylose and amylopectin.
What is amylose?
A long unbranched chain of glucose, joined by 1:4 glycosidic bonds. These chains form a coiled structure.
What are the advantages of amylose?
It is compact and a good storage molecule, meaning that it can fit into a small space.
What is amylopectin?
It is a long branched chain of alpha glucose which has 1:4 and 1:6 glycosidic bonds.
What are the advantages of amylopectin?
It’s branches increases its surface area which allows for enzymes to hydrolyse glycosidic bonds which means that glucose can be released quickly.
How do animals store carbohydrates?
As glycogen.
How is glycogen stored?
As small granules, mostly in the muscles and liver.
What is the structure of glycogen like?
It is branched due to it’s 1:6 glycosdic bonds.
What indicates the higher metabolic requirements of animals compared to plants?
Glycogen is broken down a lot more quickly than starch as there are more branches.
What is cellulose?
Unbranched chains made up of beta-glucose.
What are the glycosidic bonds in cellulose?
1:4
What makes the microfibrils in cellulose very strong?
The hydrogen bonds.
What is a major structural component in the cell wall of plants?
Cellulose.
How does cellulose work as a cell wall?
It provides support and allows for cells to become turgid.
What are the main characteristics of lipids?
- They contain C, H and O.
- They are non polar.
- Insoluble in water.
- Usually hydrophobic.
- Made up of fatty acids and glycerol.
What is meant by the term saturated fats?
When there are no double carbon bonds in a hydrocarbon chain.
What is meant by the term unsaturated fats?
There is at least one double carbon bond in the hydrocarbon tail.
What is meant by mono-unsaturated?
A single double carbon bond
What is meant by poly-unsaturated?
Multiple double carbon bonds.
What are the two main groups of lipids?
- Triglycerides
- Phospholipids
What is the test for lipids?
The emulsion test.
What are the steps of the emulsion test for lipids?
- Add ethanol to the substance and shake for around a minute.
- Add water to the mixture.
- If lipids are present then there will be a white, milky emulsion.
What makes up a triglyceride?
A glycerol molecule and three fatty acids.
How are the glycerol and fatty acids in triglycerides joined together?
By a condensation reaction.
What is meant by hydrophillic?
Water loving.
What is meant by hydrophobic?
Water hating.
What are the three main groups of an amino acid?
- Variable Group
- Amine Group
- Carboxyl Group
How many different amino acids are there?
Twenty.
What do two amino acids join together to form?
A dipeptide.
What is the test for proteins?
The biuret test.
What are the four stages of the protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What is the primary structure of a protein?
It is the sequence of a chain of amino acids.
What is the secondary structure of a protein?
This is where the chain folds into an alpha helix or a beta pleated sheet, it is held together by hydrogen bonds.
What is the tertiary structure of a protein?
This is where the r groups of different amino acids interact.
What is the quaternary structure of a protein?
This is where many polypeptide chains can interact with each other.
Why will enzymes show a positive result with the biuret test?
This is because enzymes are proteins.
Where can enzymes work?
Both intracellular and extracellular.
What ate enzymes?
Biological catalysts which means that they are formed inside cells of living organisms and catalyse reactions.
What is an active site?
A specific 3D shape that is complimentary to a substrate.
Why are enzymes soluble proteins?
They dissolve in water due to the presence of many hydrophilic side groups on their constituent amino acids. This also means that they dissolve in cytoplasm.
What are the key factors that impact enzyme activity?
Temperature
pH
Enzyme Concentration
Substrate Concentration
What are the two types of enzyme inhibitors?
Competitive and non-competitive.
What does a competitive inhibitor do?
They compete with the substrate to bind to an enzymes active site as they have a similar shape. This blocks the active site meaning that substrates cannot bind and no enzyme substrate complexes can be formed.
What does a non-competitive inhibitor do?
It binds to the allosteric site of the enzyme which causes the active site of the enzyme to change shape so that it is no longer complementary to its substrate and prevents any enzyme substrate complexes from being formed.
Who are the two key scientists who discovered the structure of DNA?
James Watson and Francis Crick.
What is a nucleotide?
It is the monomer that joins together to make the polymer of DNA.
What are the three key parts of a nucleotide?
The phosphate group, the sugar and the base.
What is the bond between the sugar and phosphate in a nucleotide?
An ester bond.
What is the bond between the sugar and the base?
A glycosidic bond.
What are the two phosphate backbone strands in DNA held together by?
Chemicals called bases.
What are the four nitrogen containing organic bases?
Adenine, Thymine, Guanine and Cytosine.
What does adenine always bind with?
Thymine.
What does Guanine always bind with?
Cytosine.
What does Thymine always bind with?
Adenine.
What does cytosine always bind with?
Guanine.
What are purines?
Double ringed structures.
What are pyrimidines?
Single ringed structures.
What type of bond is between two nucleotides?
A phosphodiester bond.
What base is different in RNA compared to DNA?
There is uracil instead of thymine.
What type of sugar is the sugar in DNA?
Deoxyribose.
What type of sugar is the sugar in RNA?
Ribose.
What are the three key types of RNA?
mRNA, tRNA and rRNA.
What is the role of mRNA?
It is messenger RNA, which carries DNA code from the nucleus to the ribosomes.
What is the role of tRNA?
It is transfer RNA which carries amino acids across the cytoplasm.
What is the role of rRNA?
It is ribosomal RNA which makes up ribosomes.
What are the roles of DNA?
It stores genetic information, it contains instructions to grow from a fertilised egg to a fully grown adult and it codes for polypeptides.
What are the roles of RNA?
It transfers generic information from DNA to the ribosomes and the ribosomes read the RNA to make polypeptides through translation.
When does DNA replicate?
In cell division.
Why do we need DNA to replicate?
So that each cell has the correct amount of DNA in the nucleus.
How does the structure of DNA help replication?
It is double stranded which means that it can be split into two and each side can be copied and used as a template.
What is the most respected replication of DNA theory?
Semi conservative replication.
What is semi conservative replication?
This is where half of each new double helix is a strand that has come from the double helix of the original DNA molecule.
What end of the template strand is DNA polymerase only complementary to?
The 3’ end.
What are the three key groups in the amino acid structure?
- Amine Group
- Carboxyl Group
- Variable Group
What are the two theories of DNA replication?
Conservative and semi-conservative.
What does the conservative hypothesis of DNA replicaton suggest?
That the parent DNA molecule acts as a template for the daughter strand, which is completely made up of new nucleotides leaving the parent DNA molecule unchanged.
What is the role of DNA polymerase?
To join nucleotides together in condensation reactions.
How does the cell get energy?
The energy released from glucose via respiration is used to create ATP.
Where does ATP store its energy?
In it’s high energy bonds between the phosphate groups.
How does ATP release energy?
By being hydrolysd to break the high energy bonds which releases a large amount of energy.
What enzyme catalyses the hydrolysis of ATP to ADP?
ATP hydrolase.
How can ATP be formed?
Through a condensation reaction involving ADP and an inorganic phosphate.
What enzyme catalyses the formation or resynthisisation of ATP?
ATP synthase.
What are the key advantages of ATP?
- Instant source of energy in the cells.
- Releases energy as neeeded.
- Soluble and mobile.
- Universal energy carrier.
Why is ATP being soluble and mobile an advantage?
It can travel and transport chemical energy to where it is needed in the cell.
What is a metabolite?
A small molecule which is involved in reactions of metabolism.
What makes water a polar molecule?
The oxygen has a partial negative charge and rhe hydrogens have a partial positive charge.
What is a polar molecule?
A molecule with regions of negative charge and positive charge.
What does water form at room temperature?
A lattice.
What is cohesion in water?
This is where the water molecules are close together and the oppositely charged parts of the molecules attract each other and form hydrogen bonds and stick together.
Why is water a good solvent?
It is a polar molecule meaning that it is atracted to other substances that are also polar. This allows for the positive and negative regions to cluster around the oppositley charged parts of the olute molecules/ions and help them to seperate and stay apart.
What is the value of the latent heat vaporisation of water?
2260 KJ kg-1
What is meant by high latent heat of vaporisation?
The amount of energy required to change one gram of liquid water at 100 degrees celsius to water vapor.
Why does water have a high latent heat of vaporisation?
Due to the hydrogen bonds in the water molecule.
What is meant by specific heat capacity?
The heat needed to raise the temperature of 1kg of water by 1 degree celsius.
Why does water have a high specific heat capacity?
The hydrogen bonds mean that a lot of energy is needed to break the hydrogen bonds and therefore there is less energy to increase the temperature of the water.
What is the specific heat capacity of water?
4200 J kg-1 degrees celsius-1
When does water become more dense?
As it gets colder until 4 degrees celsius.
What point does water reach at 4 degrees celsius?
The freezing point.
What happens at waters freezing point?
The water molecules align themselves into a less dense structure, due to their polar nature.
How does water arrange itself at its freezing point?
The hydrogen bonds cause the polar molecules to move slightly further apart than the average distance in the liquid state and creates a giant, rigid and open structure with each oxygen at the centre of a tertrahedral arrangement of hydrogen atoms.
What is adhesion?
A property of water in which water molecules are attracted ti surfaces such as walls of the cells, vessels or tubes.
What does inorganic mean?
It does not contain carbon.
Where can inorganic ions be found?
In the cytoplasm and body fluids.
What are the four key inorganic ions?
- Sodium ions
- Hydrogen ions
- Irons ions
- Phosphate ions
Why are inorganic sodium ions important to the body?
They are involved in the co-transport of glucose and amino acids across membranes.
Why are ionrganic hydrogen ions important?
They are the determination of the pH level depending on its concentration in its environment in question.
Why are inorganic iron ions important to the body?
They are an important part of haemoglobin and are key to how oxygen is transported around the body by red blood cells.
Why is iron important in haemoglobin?
The oxygen birds to the iron.
Why are inorganic phosphate ions important to the body?
They are an essential part of nucleic acids; DNA and RNA. They also are used to produce ATP which is a key energy storage molecule.
What type of glucose is starch made from?
Alpha glucose.
What are the four factors that affect enzyme activity?
Temperature, pH, enzyme concentration and substrate concentration.
How does temperature impact enzyme activity?
- Temperature increases causing more kinetic energy, which increases rate of reaction. Molecules move faster = more collisions and no. of ES complexes formed.
- Each enzyme has optimum temperature, when gone past increasing temp decreases rate of reaction.
- When too high, enzyme molecules vibrate too much and cause bonds to be broken which maintain the tertiary structure and therefore changes the active site and no more ES complexes can be formed and it is permanently denatured.
How does pH impact enzyme activity?
- All enzymes have an optimum pH.
- Above and below this H+ and OH- ions disrupt the ionic and hydrogen bonds holding the enzymes tertiarty structure in places.
- At extreme pHs they can denature permanently.
How does enzyme concentration impact enzyme activity?
- Increasing the enzyme concentration increases the number of active sites for substrates to collide with.
- More ES complexes can eb formed as enzyme concentration increases.
- The rate of reaction wil increas until the amount of substrate becomes the limiting factor.
- The gradient can be used to determine how fast the rate is changing.
How does substrate concentration impact enzyme acitivity?
- Increasing the substrate concentration will increase the rate of reaction as there are more substrate molecules, so more ES complexes will form.
- The rate of reaction will slow as the enzyme concentration becomes the limiting factor.
- When all of the enzyme active sites are occupied, increasing the substrate concentration will hve no effect on the rate of reaction.
