Biological Molecules (Chapter 1 & 2) Flashcards
What are monomers?
They are the smaller units from which larger molecules are made
What are polymers?
They are molecules made from a large number of monomers joined together
List 3 examples of monomers
Monosaccharides
Amino acids
Nucleotides
What is a condensation reaction?
It is a reaction which joins two molecules together with the formation of a chemical bond and involves the elimination of a water molecule
What is a hydrolysis reaction?
It breaks down a chemical bond between two molecules and involves the use of a water molecule
What is a monosaccharide?
It is the monomers from which larger carbohydrates are made
Give three examples of a monosaccharide
Glucose
Galactose
Fructose
What is bond formed from a condensation reaction of two monosaccharides?
Glycosidic bond
How are disaccharides formed?
By the condensation of two monosaccharides
How is the disaccharide maltose formed?
Condensation reaction of two glucose molecules
How is the disaccharide sucrose formed?
Condensation reaction of glucose and fructose
How is the disaccharide lactose formed?
Condensation reaction of glucose and galactose
How many isomers of glucose is there?
Two ( alpha and beta glucose)
How do alpha glucose and beta glucose differ?
Alpha glucose has both OH on bottom (if that makes sense lol)
How are polysaccharides made?
By the condensation of manny glucose units
How is the polysaccharide glycogen and starch made?
Condensation of alpha glucose
How is the polysaccharide cellulose formed?
Condensation of beta glucose
What is the main energy store in plants?
Starch
What is starch a mixture of?
A mixture of two polysaccharides of alpha glucose- amylose and amylopectin
What is amylose? (Structure and what is it made of)
Long unbranded chain of alpha glucose
Has a coiled structure which is good for storage
What is amylopectin? (Structure, enzymes and what is it made of)
Long branched chain of alpha glucose
Side branches allow enzymes to get to glycosidic bond easily- glucose can be released quickly
What is the test for starch?
Iodine test
Brown/ orange ———> blue/ black
What is the main energy store in animals?
Glycogen
Describe the structure of glycogen
Like amylopectin but has loads more side branches
Very compact
What is cellulose used for?
Cell walls in plants
Describe the structure and bonding in cellulose
Long unbranded chains of beta glucose
Cellulose chains linked by hydrogen bonds to form microfibrils (for structural support)
What is the test for sugars? and the colour change
Benedict’s test
Blue —> green —> yellow —> orange —> brick red
How to test for non reducing sugars
Add hydrochloric acid and bring to boil
Add sodium hydrogen-carbonate to neutralise
And then carry out Benedict’s test
What is a reducing sugar?
All monosaccharides
Some disaccharides ie maltose and lactose
How are triglycerides formed?
Via condensation reaction of one glycerol and three fatty acids
What bond is formed between glycerol and fatty acid?
Ester bond
Is the r group of a fatty acid saturated or unsaturated?
It can be either
What are phospholipids made of?
One glycerol, 2 fatty acids and a phosphate containing group
What do phospholipids make up?
The bilayer of a cell membrane
How are phospholipids catered for their function?
Heads are hydrophilic
Tails are hydrophobic
What are triglycerides mainly used for?
Energy storage molecule
Why are triglycerides catered for their role?
Long hydrocarbon tails contain lots of chemical energy- lipids contain about twice as much energy per gram as carbohydrates
They are insoluble so don’t effect water potential
Do triglycerides clump together?
Yes
They clump together as insoluble droplets in cells because tails are hydrophobic
What is the test for lipids?
Emulsion test
Turns milky
Describe how to undertake an emulsion test
Shake the test substance with ethanol for a minuet
Pour the solution into water
What is the monomers for proteins?
Amino acids
List the three groups in an amino acid
Amine group NH2
Carboxyl group COOH
R group (R) (side chain)
How many amino acids are there and how do they differ?
20
R groups are different
What bond is formed between the condensation of two amino acids?
Peptide bond
How are dipeptides formed?
Condensation of two amino acids
How are polypeptides formed?
Condensation of many amino acids
What may functional proteins contain?
One or more polypeptides
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain
What is the secondary structure of a protein?
Hydrogen bonds form between amino acids in the chain
This cause it to COIL into an alpha helix or FOLD into a beta pleated sheet
What is the tertiary structure of a protein?
More bonds form between different parts of the polypeptide chain including hydrogen, ionic and disulphide bridges.
For amino acids made from a single polypeptide chain the tertiary structure is there final 3D structure
What is the quaternary structure of a protein?
The way polypeptide chains are assembled together
For proteins made from more than one polypeptide chain the quaternary structure is there final 3D structure
List the 4 functions of different proteins
Enzymes- eg. Digestive enzymes
Antibodies- variable regions
Transport proteins- in cell membrane
Structural proteins- eg keratin, collagen
What is the test for proteins?
Biuret test
Blue —> purple
List the steps to carry out a biuret test
Add sodium hydroxide to turn solution alkaline
Add copper (ll) sulphate
What do enzymes do?
Lower activation energy of the reaction it catalyses
What is the induced fit model of enzyme action?
Substrate binds to active site
The active site slightly changes shape to form enzyme substrate complex
The substrate splits in two and forms the products
Do enzymes properties relate to their tertiary structure?
Yes
Very specific- enzymes can usually only catalyse one reaction
Describe lock and key model
Substrate fits perfectly into active site
Substrate splits in two and makes the products
(Active site dosent change)
What acctually are enzymes tho?
Biological catalysts
How does temperature affect enzyme activity?
A rise in temp causes molecules to vibrate more (kinetic energy)
Molecules move faster which will increase the likelihood a collision will cause a reaction
Although above a certain temp these vibrations will cause bonds to break
Active site changes shape and enzyme substrate complex can not be made (denatured enzyme)
How does pH affect enzyme activity?
Each enzyme has an individual optimum temperature if not working around that pH the enzyme will denature as it can mess up their hydrogen and ionic bonding
How does enzyme concentration affect rate?
More enzyme molecules there is in a solution will increase the likelihood a substrate molecule will collide with it. So increasing enzyme conc will increase the rate
However if substrate conc is limited there comes a point where there is more than enough enzyme molecules to deal with the available substrate. So adding more will have no further effect
How does substrate concentration affect rate of reaction?
Higher substrate concentration the faster the reaction. Only true up to saturation point. After this there are so many substrate molecules that the enzymes have about as much as they can cope with LOL. So adding more will make no further effect.
Describe what competitive inhibitors do
They have similar shape to substrate
Compete with substrate for active site but no reaction takes place
They block the active site so no substrate molecule can fit
Describe what non competitive inhibitors do
Bind to another binding site on the enzyme causing the active site to change shape so substrate cannot bind to the active site anymore LOL.
What does DNA stand for LOL.
Deoxyribonucleic acid
What does RNA stand for?
Ribonucleic acid
What is DNAs role?
Holds genetic info
What is RNAs role?
Transfer genetic info from DNA to ribosomes
What are ribosomes formed of?
RNA and Proteins
What are both DNA and RNA?
Polymers of nucleotides
What is DNA made of?
Phosphate group
Deoxyribose
Nitrogen containing organic base
What is RNA made of?
Ribose
Phosphate group
A nitrogen containing organic base
What bond is formed from the condensation reaction between two nucleotides?
Phosphodiester bond
Describe the structure of DNA
Double helix with two polynucleotide chains
Held together by hydrogen bonding between bases
Which bases in DNA bond together?
A & T
C & G
Which bases in RNA bond together?
C & G
A & U
What did scientists doubt about DNA due to its simplicity?
Whether it carries the genetic code
Describe semi conservative replication of DNA
DNA helicase breaks hydrogen bonds between bases- unwinding the double helix
Each original strand acts as a template- complementary base pairing
Condensation reactions join nucleotides of the new strands together
New hydrogen bonds form between bases
Each new DNA molecule contains one strand from original DNA molecule and one new strand
What did Watson and crick discover?
The structure of DNA
What validated Watson and crick?
Meselson and stahl discovering semi conservative replication
Describe the experiment meselson and stahl used to prove semi conservative replication
Two samples of bacteria grown- one in light nitrogen and one in heavy nitrogen broth. As bacteria replicated they took up nitrogen from the broth to make nucleotides.
A sample of DNA was taken from each batch of bacteria and then spun in a centrifuge. The DNA with heavy nitrogen settles lower down than the light nitrogen.
Then bacteria grown in heavy broth was taken out and put in a light broth. Bacteria left for one round of DNA replication. Another DNA sample taken and then spun in a centrifuge.
It showed DNA had a mixture of heavy and light nitrogen therefore semi conservative LOL.
What does ATP stand foR?
Adenosine triphosphate
What is ATP made up of?
Adenine
Three phosphate molecules
Ribose
What does the hydrolysis of ATP make?
ADP (adenosine diphosphate)
Inorganic phosphate
Which enzyme catalyses the hydrolysis of ATP?
ATP hydrolase
What is inorganic phosphate used for?
Phosphorylate other compounds- often making them more reactive
What is the hydrolysis of ATP used for?
Energy requiring reactions within cells
How is ATP resynthesises?
Condensation of ADP and inorganic phosphate
(Catalysed by ATP synthase during either respiration or photosynthesis)
Is water a metabolite?
Yes
In many metabolic reactions, condensation and hydrolysis reactions
Is water a good solvent?
Yes it is an important solvent in which metabolic reactions occur
What property of water means it is good at buffering changes in temperature.
High heat capacity
Does water have a large latent heat of vaporisation?
Yes
Providing a cooling effect with little loss of water through evaporation
What does strong cohesion between water mean?
It can support columns of water in tube like transport cells of plants and produce surface tension where it meets air.
Where are inorganic ions found?
In cytoplasm and body fluids of organisms
What do hydrogen ions determine?
PH
More H+ ions present the lower the pH
What do iron ions do?
Important part of haemoglobin (carries o2)
What do sodium ions do?
Co transport- help glucose and amino acids across cell membranes
Why are phosphate ions essential?
Important component of ATP and DNA
Is water a polar molecule?
Of course babe
