1: Biological Molecules Flashcards
What’s a monomer and a polymer?
monomer- one of many small molecules combining to form a larger one (polymer)
polymer- large molecules made up of small repeating units (monomers)
What are prefixes of different polymers?
1: mono-
2: di-
3: tri-
4: tetra-
5: penta-
6: hexa-
many: poly-
What is a biological molecule?
an organic molecule including carbohydrates, proteins, lipids and nucleic acids (e.g. DNA and RNA)
What are examples of biological molecules?
- carbohydrates- store and supply energy, can be structural
- proteins- transport and structure, basic component of enzymes, hormones and more
- lipids- part of cell membranes, insulators and protection
- water- formation of molecules and metabolic reaction
- nucleic acid- made of nucleotides to form RNA and DNA
- enzymes- made of proteins, act as biological catalysts by lowering activation energy
What bonds form between all biological molecules?
carbohydrates- glycosidic
proteins- peptide
lipids- ester
water- hydrogen
nucleic acids- phospohodiester
What bonds are present in polymers?
- covalent- share electrons (e.g. carbon froms 2 covalent bonds- C2)
- ionic- 2 oppositely charged ions, lose and gain electrons
- hydrogen- slightly positive and negative charges, more hydrogen bonds, stronger attraction
What monomers and polymers make up biological molecules?
carbohydrates, proteins, nucleic acid, lipids
carbohydrates- monosaccharides –> polysaccharides
proteins- amino acids –> proteins/ polypeptides
nucleic acid- nucleotides –> DNA/RNA
lipids- fatty acids/ glycerol –> triglycerides
What monosaccharides make up carbohydrates?
monosaccharide- single sugar/ carbonhydrate
carbohydrates–> sugars/ polysaccharides
sugars:
- single- glucose, fructose, galactose
- double- sucrose, maltose, lactose
polysaccharides:
- glucose/ starch are carbohydrates for storage
- cellulose and chitin are important for structural carbohydrates
What’s the difference between alpha and beta glucose?
C6H12O6
alpha- H,OH
beta- OH, H
CH2OH top left, O top right
What are different disaccharides made up of?
maltose, sucrose, lactose
maltose- 2 alpha glucose
sucrose- 1 glucose, 1 fructose
lactose- 1 glucose, 1 galactose
How do polysaccharides form?
- a condensation reaction between 2 monosaccharides forms a disaccharise through a glycosidic bond and a water molecule being produced
- if these condensation reactions continue to occur, then a long chain called a polysaccharide will form, held together by multiple glycosidic bonds
What are different adaptations of carbohydrates?
- energy source allow for cellular respiration
- building blocks (structural carbohydrates)
- small monosaccharides can easily transport in and out of the cell
- polar molecule, soluble in water, easy to transport
- only breaks down to release energy when catalysed by the enzyme, can be controlled (as it’s unreactive)
starch: structure, function and properties
STRUCTURE:
- (C6H12O6)n
- most basic form is linear polymer amylose
- alpha 1-4 glycosidic bonds
FUNCTION:
- help plants to store energy
- source of sugar, mainly in plants
- broken down by enzyme amylaase
PROPERTIES:
- turns inky black with iodine
- insoluble, good for storage
- branched,can easily be broken for energy
glycogen: structure, function and properties
STRUCTURE:
- highly branched glucose polymer
- made of long chains of monosaccharides (simple sugars)
- connected by alpha 1-4 glycosidic bond and an alpha 1-6 glycosidic bond
FUNCTION:
- backup supply of energy reserve for body
- made when insulin converts excess glucose to glycogen
- important in blood glucose homeostatis
PROPERTIES:
- has many side branches to release energy quickly, enzymes can act on many branches at once
- highly soluble, easily broken down, compact
cellulose: structure, function and properties
STRUCTURE:
- connected by beta 1-4 glycosidic bonds
- unbranched long, straight chain (linear)
FUNCTION:
- strengthen the cell wall, making it turgid and rigid
- help plants remain stff and upright
- can’t be digested, kept for fibre
PROPERTIES:
- linear, arranged parallel
- joined by hydrogen bonds
- long chaing can combine with other cellulose molecules to provide support
What is a protein and what’s it made up of?
- made of monomer of amino acids
- 20 different amino acids
- soluble all with the same basic structure
basic amino group- NH2
acidic carbpxyl group- COOH
r group- side/ variable group (e.g. H)
NH2-HCR-COOH
How do proteins form?
PROTEINSYNTHESIS
- amino acids join in a condensation reaction between amino group and carboxyl group of 2 different amino acids
- dipeptides are formed by condensation of 2 amino acids (breaking of bonds uses water)
- polypeptides form during the condensation of many amino acids
What is the primary structure of proteins?
- sequence of amino acid bases
- makes up polypeptide chains
- structure coded for by cell DNA
What is the secondary structure of proteins?
- form when polypeptide chain takes up a particular shape (in folding)
- most common shapes are alpha helix (like half DNA) of a beta pleated sheet (zig zag)
- these are stable structures maintaines by hydrogen bonds between different amino acid groups
What is the tertiary structure of proteins?
- forms when secondary structure folds more to form a complex shape
- irregular folding results from formation of different bonds between amino acids
- all globular proteins and amino acids are tertiary from secondary and are essential for functon
e.g. myoglobin, WHERE ACTIVE SITE/ ENZME FORMS
How do R groups affect the structure of amino acids?
- vary (20 different)
- make amino acids different
- affect the way amino acids bond with other amino acids
- play vital roles in determining and maintaining specific protien shapes due to different charges and attractions
BONDS: disulphde, ionc, hydrophillic/ hydrophobic, hydrogen
e.g. glycine- simplest amino acid (just H)
What bonds form between proteins?
- disulphide bridges- R groups of 2 amino acids with sulfurs
- hydrogen- electronegative oxygen (of COOH) and electronpositive hydrogen (ofNH2) of another amino acid
- ionic- oppositely charged groups form
What is the quaternary structure of proteins?
- proteins of more than one polypepide chain folded of the same or a different polypeptide
- attatch to form haem groups
-e.g. iron found (Fe2+) to attract oxygen to attatch polypeptide to polypeptide
e.g. haemglobin/ collagen (stretchy/ fold protein)
What is the biochemical test for reducing sugars?
benedicts
- place sample in clean test tube, if sample is solid, prepare a test solution by crushing the food and adding a moderate amount of distilled water
- add an equal volume of Benedict’s reagent (copper (II) sulfate) is added
- the solution is heated in a water bath for 3-5 minutes
- if reducting sugars are present, they will reduce the Cu2+ ions to Cu+ ions, forming the orange-red precipitate copper (I) oxide.
blue–> orange/red based on initial concentration
What is the biochemical test for non-reducing sugars?
benedicts
- add hydrochloric acid to sample
- test tube is heated in water bath for 3-5 mins resulting in the hydrolysis of non-reducing disaccharide into 2 monosaccharides (there are reducing sugars)
- sample is neutralised with sodium hydrogen carbonate solution
- sample is tested with benedicts
- if colour change now occurs, non-reducing sugars were present in the original sample
blue –> orange/red
What is the biochemical test for starch?
iodine
- place sample in a clean test tube
- potassium iodide solution is added to the test tube
- gently shake tube
- if starch is present, solution chnages yellow –> inky black
yellow/brown –> inky black
What is the biochemical test for proteins?
biuret
- sample placed in clean test tube
- biuret a (sodium hydroxide) is added to the test tube
- add a few drops of biuret b (copper (II) sulfate) are added and the solution is mixed
- if protein’s are present, colour change blue –> violet
blue–>purple/ violet