Biological Molecules (NF) Flashcards
What are ions in solution called
Electrolytes
What elements are carbohydrates made up of
C, H, O
What elements are lipids made up of
C, H, O
What elements are proteins made up of
C, H, O, N, S
Only 3 amino acids contain S
How many amino acids contain S
3
What elements are nucleic acids made up of
C, H, O, N, P
What are monomers
Atoms or molecules that bond together to form long-chains
What are the monomers for carbohydrates
Saccharides
What are the monomers for proteins
Amino acids
What are polar molecules
Molecules that have regions of positivity and negativity
Water is a liquid at room temperature. Explain why it has a high boiling point
Water molecules continually move around, and as they do, they form hydrogen bonds. These bonds mean that a lot of energy is required to increase the temperature of water and cause it to become gaseous.
Explain why water’s density is important
The density of water provides an ideal habitat for living things. if water was less dense, aquatic organisms would find it very difficult to float. As water cools, it becomes more dense up until 4 degrees, after which it becomes less dense because the water molecules align themselves in a structure less dense than liquid water. This means that:
Aquatic organisms have a stable environment in which to live in
It can be beneficial for the movement of animals, such as polar bears
What does water being cohesive mean
It moves as one mass as the molecules are attracted to each other. This means that:
Plants are able to draw up water through their roots
What does water being adhesive mean
Where water molecules are attracted to other materials. For example, when you wash your hands, your hands become wet, the water doesn’t run off.
Why is water a good solvent
The polar nature of water means that the positive and negative parts of the water molecules cluster around the charged parts of the solute molecules and will help to separate them and keep them apart. This means that:
Molecules and ions can move around and react together in water
Molecules and ions can be transported around living things whilst dissolved in water
Water has a high specific heat capacity. Explain what this means
Water molecules are held together quite tightly by hydrogen bonds. Therefore, you have to put in a lot of heat energy to increase their kinetic energy and temperature. This means that
Living things can survive because they need a stable temperature for enzyme-controlled reactions to happen properly
Aquatic organisms need a stable organisms need a stable environment in which to live
Water has a high latent heat of vaporisation. Explain what this means
When water evaporates, heat energy, known as the latent heat of vaporisation, helps the molecules to break away from each other to become a gas. because the molecules are held together by hydrogen bonds, a relatively large amount of energy is required for water to change state. therefore water can help to cool living things and keep their temperature stable. This means that
Mammals are cooled when sweat evaporates
Plants are cooled when water evaporates from mesophyll cells
What is the name of a carbohydrate polymer
Polysaccharide
How are alpha and beta glucose different
The H on carbon 1 is up on alpha glucose and down on down glucose
What kind of reaction joins glucose molecules together
Condensation reaction
What kind of bond is formed between 2 glucose molecules in a condensation reaction
Glycosidic
What are 5 functions of carbohydrates
Substrate for respiration
Hereditary information
Energy stores
Structure
Recognition of molecules outside of the cell
What are isomers
Molecules that have a different structure to each other but the same chemical formula
What is the difference between ribose and deoxyribose
Deoxyribose doesn’t have an oxygen on carbon 2, whereas ribose does
Where is the ribose sugar present
RNA nucleotides
Where is deoxyribose the sugar present
DNA nucleotides
What do 2 alpha glucose molecules make
Maltose
What does alpha glucose and fructose make
Sucrose
What does alpha glucose and beta galactose make
Lactose
What do 2 beta glucose molecules make
Cellobiose
What is starch made up of
Amylose and amylopectin
What is the monomer of starch
Alpha glucose
What are amylose and amylopectin joined together by in starch
Hydrogen bonds
Why does starch have branches
More glucose can be hydrolised due to a larger SA and more endings
What reaction releases glucose for respiration
Hydrolysis
What is the monomer for cellulose
Beta glucose
What is unique about cellulose in the terms of monomers
Every other beta glucose is flipped 180 degrees so the OH groups can bond together
What kind of bond do the beta glucose molecules form in cellulose
1,4 beta glycosidic bonds
What is glycogen used as in the liver and muscles for animals
A storage molecule
What bonds are formed in the chain of glycogen
1,4 alpha glycosidic bonds
What bonds are formed in the branches of glycogen
1,6 alpha glycosidic bonds
Why do animals use glycogen instead of starch as a storage molecule
The molecule is more compact and more branched (compared to amylopectin). This allows for faster breakdown of the molecule during respiration as there can be more hydrolysis of free ends
Is the chain of cellulose straight or coiled
Straight
Does cellulose have stacked chains
Yes
How are fibres that are used to make cell walls made
Cellulose molecules join together to make microfibrils. The microfibrils then join together to form macrofibrils, which combine to give these fibres
What can reducing sugars do
Donate electrons or reduce another molecules
Which type of molecule are reducing sugars
All monosaccharides and some disaccharides
What test is used for reducing sugars
Benedicts solution
What are the steps to the Benedict’s test for reducing sugars
Place the sample in a boiling tube. If it’s not in liquid form, grind it up
Add an equal volume of Benedict’s reagent
Heat the mixture gently for 5 minutes (at least 60 degrees)
What colour change indicates a positive result for reducing sugars
Blue to green to amber to red
Explain the results behind a positive reducing sugars test
The blue Cu2+ will have electrons added to them, making them brick-red Cu+ ions
What is the test for starch
Iodine solution
What are the steps to the test for starch
Add iodine solution which is dissolved in potassium iodide
What colour change indicates a positive result for starch
Yellow-brown to blue-black
Explain why a colour change is seen in a positive starch test
Iodine (I2) formed a triiodide ion (I3-), which slips into the middle of the amylose helix, causing the colour change and forming an iodine-starch complex
What are the advantages of using reagent strips to test for reducing sugars
With the use of a colour-coded chart, the concentration of glucose can be determined
How to use Benedict’s solution to test for non-reducing sugars
Have to check that it is not a reducing sugar first using Benedict’s solution
Then boil with HCl to separate sample into monosaccharides
Then test again. If a positive result is given then the sample was a non-reducing sugar
Why are lipids not soluble in water
They are non-polar, so the electrons within the bonds more are evenly shared than in polar molecules
How is a triglyceride made
By combining one glycerol molecule with three fatty acids
What kind of bond is formed between glycerol and fatty acids
Ester bonds by esterification
What is a phospholipid made of
A phosphate group, glycerol molecule and 2 fatty acids
Which part of the phospholipid is hydrophilic
The charged heads
Which part of the phospholipid is hydrophobic
The non-polar tails
Why is cholesterol important in a cell membrane
It has an important role in the formation of cell membranes and regulates their fluidity
What are some roles of lipids
Membrane formation
Hormone production
Electrical insulation in nerve transmission
Waterproofing
Buoyancy in animals
What is the test for lipids
Emulsion test
What are the steps in the emulsion test
Mix sample with ethanol
Filter and add solution to water in a test tube
Shake. If a cloudy white emulsion forms then this indicates the presence of a lipid
What is the monomer for proteins
Amino acids
What happens in the levels of protein production
1 - sequencing of amino acids
2 - initial folding into an alpha helix or beta pleated sheet held together by H bonds
3 - folding into a 3D shape, held together by the 4 different kind of bond (hydrogen, ionic, disulphide and hydrophilic and hydrophobic interactions)
4 - multiple tertiary structures joined together
What are the physical qualities of globular proteins
Compact, water soluble and roughly spherical
Why are globular proteins water-soluble
The way that they fold into their tertiary structures means that their hydrophobic R group is kept away from the aqueous environment
