1.1 Biochemistry Flashcards
What are inorganic ions? What are they also known as?
A molecule or ion that has no more than one carbon atom
Electrolytes or minerals
Why are inorganic ions important to living organisms?
They are essential to many cellular processes: muscle contraction, nervous coordination and maintains water potential in blood and cells.
What are the 2 groups of inorganic ions?
Macronutrients (small concentrations) and micronutrients (minute/trace concentrations)
Macronutrient 1: Magnesium, Mg2+
-important constituent of chlorophyll and therefore photosynthesis
-plants cannot make chlorophyll if no Mg2+ so chlorosis occurs
-mammals need Mg2+ for bones
Macronutrient 2: Iron, Fe2+
-constituent of haemoglobin which transports oxygen in RBC
-Lack of iron in human diet can lead to anaemia
Macronutrient 3: Phosphate ions, PO4 3-
-making nucleotides including ATP
-constituent of phospholipids found in biological membranes
Macronutrient 4: Calcium, Ca2+
-important structural component of bones and teeth in mammals
-component of plant cell walls, providing strength
Why is water important in organisms?
It is a medium for metabolic reactions and an important constituent of cells
Define a dipole
A polar molecule with a +ve and -ve charge separated by a very small distance (alpha+ and alpha-)
Why does water have a range of properties?
The hydrogen bonds are weak but there are so many that the molecules are difficult to separate, allowing any properties
Properties of water: solvent
-organism obtain key elements from the aqueous solution
-water molecules are dipoles so attract ions and polar molecules
-chemical reactions take place in the water
-used as a transport medium ie. Plasma in pants, minerals in the xylem
Properties of water: metabolite
-used in biochemical reactions as a reactant
Metabolite: Hydrolysis
Breaking down of large molecules into smaller molecules by the addition of a water molecule. For example, Maltose + Water = Glucose + Glucose
Metabolite: condensation
2 molecules combine to form a more complex molecule, producing water.
Glucose + Fructose = Sucrose + Water
Properties of water: high specific heat capacity
-the energy required to raise the temperature of 1g of a substance by 1C
-hydrogen bonds restrict movement which resists an increase in KE and therefore temp
-prevents large fluctuations in H2O temp which keeps aquatic environments stable & allows enzymes to work efficiently
Properties of water: high latent heat of vaporisation
-energy needed to convert 1g of a liquid into vapour at the same temperature
-important in temp control of mammals - sweat
Properties of water: cohesion
-molecules attract each other, forming hydrogen bonds
-molecules stick together in a lattice
-allows water to be carried in a column up the xylem
Properties of water: high surface tension
-cohesion of molecules at the surface
-water has highest surface tension of all liquids at ordinary temp
-supports insects and their habitats ie. Pond skaters
Properties of water: high density
-provides support and buoyancy
-max density at 4C
-ice is less dense than water and is a good insulator, preventing heat loss from aquatic habitats
Properties of water: transparent
-allows light to pass through
-enables aquatic plants to photosynthesise
Define a carbohydrate
- organic molecule containing carbon, hydrogen and oxygen
- basic unit is a monosaccharide
Define a monosaccharide
- basic building blocks of larger carbohydrates with the general formula (CH2O)n
What are the isomers of glucose?
Alpha and beta glucose
Where is the OH on an alpha glucose?
Bottom of C1
Where is the OH on a beta glucose?
The top of C1
What are the functions for monosaccharides?
- source of energy in respiration - breaking of C-C and C-H bonds releases ATP
- building blocks of larger molecules
- intermediates in reactions
- constituents of nucleotides
What are disaccharides?
- 2 monosaccharide units bonded together with a glycosidic bond and the elimination of water (condensation reaction)
- alpha 1,4 glycosidic bond
Draw the formation of maltose on whiteboard
Glucose + glucose =
Maltose
Glucose + fructose =
Sucrose
Glucose + galactose =
Lactose
What is a polysaccharide
Large, complex polymers made from many monomers (monosaccharides) joined by condensation reactions involving glycosidic bonds.
What is glucose and how is it relevant to storage?
- main source of energy in cells
- soluble in water and influences osmosis
- converted to starch in plants and glycogen in animal cells
Why are starch and glycogen good storage products?
- insoluble so have no osmotic effect
- cannot diffuse out of the cell
- compact molecules stored in small pace as are coiled
- carry lots of energy in the C-H and C-C bonds
What is starch made of and what are the two types?
- alpha glucose bonded in 2 different ways to form amylose and amylopectin
What is amylose? Draw on whiteboard
- linear, unbranched molecule with alpha- 1,4 glycosidic bonds forming on C1 and C4
- repeated condensation reactions form a chain which coils into a helix
What is amylopectin? Draw on white whiteboard
- chains of glucose molecules joined with alpha- 1,4 glycosidic bonds cross linked with alpha- 1,6 glycosidic bonds to create side branches every 24-30 glucose molecules
What is glycogen?
- similar to amylopectin
- it’s alpha- 1,6 bonds occur every 8-10 glucose molecules
- shorter 1,4 chains so more branched
Where is cellulose found?
Cell walls of plants
Describe the structure of cellulose
- long chain of beta glucose joined by beta- 1,4 glycosidic bonds
- every 2nd glucose is rotated 180° to enable condensation reactions to take place
- hydrogen bonds form between OH groups on adjacent parallel chains which gives it structural stability
How does cellulose make up cell walls?
Cellulose bonds bundle in rows of 70 to make microfibrils which further bundle to make macrofibrils and then cell walls.
What are some characteristics of cell walls?
- high tensile strength
- freely permeable
- water and solutes penetrate all the way to membrane
What is chitin?
Tough, semi transparent substance found in arthropod exoskeletons and fungal cell walls
Describe the structure of chitin
- long chains of beta-1,4 monomers with added amino acid groups
- rotated 180° too
- N side chain makes acetylglucosamin
Properties of chitin
- strong, waterproof and lightweight
Describe lipids
- carbon, hydrogen and oxygen
- non polar compounds
- insoluble in water but dissolve in organic solvents ie alcohol
Explain the formation of a triglyceride
- form from one glycerol molecule and three fatty acid molecules through a condensation reaction where 3 H2O molecules are removed and ester bonds form.
Draw a condensation and hydrolysis reaction between triglycerides
What is a phospholipid?
- essential components of cell membranes made from glycerol, phosphate and two fatty acids
- phosphate head is hydrophilic (polar) whereas fatty acid tails are hydrophobic (non-polar)
Explain some functions of lipids
- efficient energy storage molecules ( 2x more energy per gram than carbon )
- found in adipose cells under the skin and act as thermal insulators & provide mechanical protection for delicate organs as well as buoyancy for aquatic animals
- waterproof as hydrophobic (repel water)
Explain a saturated fat
- only have 1 bond between carbon atoms so have the max hydrogen atoms
- long chain - fat (solid) at room temp
Explain unsaturated fat
- one or more double bonds between carbon atoms (kink in chain)
- less H molecules
- liquid at room temp - oil
Polyunsaturated fat
- many double carbon bonds so even less H
Impact of high levels of saturated fat on the human body
- low density lipoprotein (LDL) builds up
- atheroma builds up in coronary arteries, reducing blood flow and therefore oxygen to the heart
- can result in angina, myocardial infarction or heart attack
Impact of high levels of unsaturated fat on the human body
- body makes more high density lipoprotein (HDL) which carries fats away to the liver for disposal
- higher ratio of HDL:LDL in a persons blood, the lower their risk of cardiovascular diseases
Describe the structure of AA
central carbon attached to:
-amino group (N-terminal) - NH2
-carboxyl group (C-terminal) - COOH
-hydrogen atom
-R group side chain (varies between each AA)
ALL AMINO ACIDS HAVE C,H,O,N
What bonds join AA via condensation to make a polypeptide (protein)?
Peptide
Amino acids are described as amphoteric. What does this mean?
- acts as both an acid and a base ( donates and accepts protons )
— amino acid end act as a buffer (stop pH change)
What is the primary structure of protein?
- the order of different amino acids joined by repeated condensation reactions forming peptide bonds in a protein chain
— determined by base sequences on strand of DNA molecule
What is the secondary structure of protein?
- the shape a polypeptide forms based on the hydrogen bonding between the O and H groups
- twists chain into 3D shape
- alpha helix or beta pleated
What is the tertiary structure of a protein?
- secondary shapes can be further folded and twisted to give a more complex, compact 3D structure
- caused by interactions with R groups (range of bonding ie, hydrogen, ionic, disulphide, hydrophobic)
- give globular proteins their shape
Explain the quaternary structure of proteins
- some polypeptide chains are non-functional unless they combine with others
- ie insulin has 2 chains
- large complex molecules ie haemoglobin
Food test for reducing sugars (sugars that can donate an electron)
- use Benedict’s test ( works by sugar donating an electron to Cu2+ ions which causes colour change)
- equal vol of Benedict’s and test solution heated strongly to min 70°C
- positive = brick red
Food test for non-reducing sugars
- give -ve results for Benedict’s
- add HCL (break to monosaccharide) and alkali and Benedict’s and heat
- should turn red
Test for fats and oils
- sample mixed kept absolute ethanol and shaken with an equal volume of water
- form an emulsion turning sample cloudy white
Test for proteins
- add a few drops of biurets and when present, solution goes blue to purple
- difficult to see at a low concentration
Globular proteins
- compact and spherical
- soluble in water so many diff functions ie enzymes, antibodies, hormones
- ie haemoglobin: 4 folded polypeptide chains w/ iron containing group at centre (haem)
Fibrous proteins
- long, thin molecules
- insoluble in water so structural functions ie bone
- parallel chains or sheets with cross linkages
- collagen: strength and toughness in tendons, 3 identical chains wrapped around each other like a rope linked by H bonds making it very stable
- keratin
Endopeptideases vs exopeptideases
Endo - hydrolyse bonds in AA in proteins to produce smaller polypeptides
Exo - hydrolyse bonds at end of polypeptide chains producing dipeptides and single AA
