Module 2: Biological Molecules Flashcards
Name the 4 functions of carbohydrates
Energy source e.g. glucose in respiration
Energy store e.g. starch
Structural support e.g. cellulose
Forms part of larger molecules e.g. nucleic acids or glycoproteins
Elements in a carbohydrate
C, H and O
General formula of a carbohydrate
Cn(H20)n
What is the difference between mono-, di-, and polysaccharides?
Mono- = single sugar unit (monomer) Di- = 2 monomer units bonded Poly- = multiple units bonded in a long chain forming a molecule
Characteristics of monosaccharides
Monomer carbohydrates 3-6 carbon atoms Soulble in water Form crystals Sweet tasting and white
Triose
3 carbons
Glyceraldehyde
C3H6O3
Pentose
5 carbons
Ribose
C5H10O5
Hexose
6 carbons
Glucose
C6h1206
Difference between alpha and beta glucose
Alpha has the hydroxyl group on the bottom on carbon , whereas beta has the hydroxyl group on the top of carbon 1
Define condenstaion reaction
Forming a larger molecule from a smaller one, by removing a molecule of water in order to form a new bond
Define hydrolysis
Forming a smaller molecule from a larger molecule, through the addition of a water molceule, hence breaking a bond.
What bond is formed and broken in condenstion and hydrolysis of a carbohydrate?
Glycosidic bond
Rules when drawing the formation of a glycosidic bond for a carbohydrate
Cirlce the groups involved
Show water is released
Cirlce and label the bond formed (1,4-glycosidic bond)
Formation of maltose
2 alpha glucose
Formaton of lactose
Gluocse and beta galactose
Formation of sucrose
Alpha glucose and frutose
Describe starch
Plants only
Granules in chloroplasts, seeds and storage organs
Alpha glucose
Insoluble to prevent lowering of water potential which would cause lysis
Compact
Main energy store/source
Name the two types of starch
Amylose and amylopectin
Describe amylose
Unbranched helical structure
Compact as a result so takes up less space and more can be stored
Only 1,4-glycosidic bonds
Describe amylopectin
Branched
More free ends so faster glucose release is possible
Both 1,4- and 1,6- glyosidic bonds
Describe glycogen
Animal cells and fungi Granules in muscle and liver cells Alpha glucose Branched structure (more than amylpectin due to higher metabolic demands) 1,4- and 1,6- glycosidic bonds
Function of glycogen
Main energy source
Energy store
Compavt
Insoluble
Describe cellulose
Plants only Microfibrels to macrofibrels to fibres Beta glucose 1,4-glycosidic bonds Every other monomer is inverted 180 degrees Unbranched H bonds cross link between chains
Function of cellulose
Provides sructural support for the cell High tensile strength Fully permeable Rigidity in plants Lignin sometimes between fibres
Define the primary structure of a protein
The order and sequence of amino acids in the polypeptide chain.
Repsonsible fo the final 3D shape of the protein. Chainging one amino acid alters the final protein
Define the secondary structure of a protein
How the polypeptide chain starts to fold or the regular arrangement of the polypetide chains stabilised by hydrogen.
Neame two types of secondary protein structure
Alpha helix
Beta pleated sheets
Structure are held together by hydrogen bond
Define the tertiary structure of protein
How the secondary structures present in the polypeptide chain start to fold even further to produce a precise 3D shape
Which bonds are involved in the tertiary structure?
H bonds
Ionic bonds
Disulphide bridges
Hydrophobic interactions
Describe disulphde bridges
Forms between 2 cysteine amino acids
Can be broken by reducing agents
Describe ionic bonds
Form between R groups with opposite charges
Can be broken by pH changes
Describe hydrophobic interactions
Occurs between non-polar side chains (R groups)
Describe hydrogen bonds
Forms between strongly polar groups ( H with N, O and F)
Can be broken by high temperatures and pH
Define quaternary structure of a protein
Association of 2 or more polypeptide chains, held together by 4 types of bonding (same as tertiary)
Highly folded
What are globular proteins? Give and example
Quarternary structure, spherical shape made of 4 polypeptide chains (2 alpha and 2 beta held together by h bonds).
E.g. haemoglobin
Each polypeptide chain contains a haem group containing an iron ion.
What is a prostheitc group? Example
A group part of the protein structure but not composed of amino acids.
Hb iron ion
What is heamoglobin also known as?
Conjugated protein
Properties of heamoglobin
1 molecule of O2 can bind reversibly with the Fe in the haem group
Each molecule of haemoglobin carry 4 O2 molecules
What are fibrous proteins? Give an example
Quarternary protein which has structural roles, forming regular and repetitive sequences
Ususally form fibres and are insoluble in water
E.g. collagen found in cartilage and keratin
Form long, parallel chains
What elements make up lipids?
C, H and O
What’s the difference between fat and oil?
Fats are solid at room temperature and include many staurated lipids.
Oils are liquid at room termperature and include many unsaturated lipids.
Functions of lipids and examples
Energy store - in adipose tissue
Insulator - blubber in whales to reduce heat loss and electrical insulation of nerves
Biological memebranes - phospholipids and cholesterol
Protection - waxy lipid layer on leaves against dessication
Buoyancy - uropygial gland on tail of ducks provides water resistant oil to be lightweight
Steroid hormones - cholesterol
Meatbolic source of water - respired to release water
Structure of a triglyceride
3 fatty acids
1 gylcerol
How are the bonds in a triglyceride joined?
Ester bonds
Process of esterification for triglycerides
3 H2O molecules released in a condensation reaction
Why are triglycerides insoluble in water?
The glycerol molecule in hydrophobic
What is a saturated fatty acid?
Single bonds between carbons so maximum umber of hydrogens attached
What is an unsaturated fatty acid?
One or more double bonds between carbons. Fewer hydrogens can bond
Structure of a fatty acid
Carboxyl group and hydrocarbon chain
Difference between a mono-unsaturated and poly-unsatured fatty acid
Mono- = single carbon carbon bonds Poly- = 2 or more carbon carbon bonds
Explan how C=C bonds change the shape of an unsaturated fatty acid
Cause the chain to kink/bend. Makes the lipid more fluid
Structure and bonds in a phospholipid
Hydrophobic and hydrophilic regions
Elements C, H, O, P
2 fatty acids, glycerol and phosphate group
Phosphate forms an ester bond with glycerol
Function of phospholipids
Structure of plasma membrane forming a partially permeable phospholipid bilayer
What causes the membrane to become more fluid?
Higher proportion of unsaturated fatty acids
Structure and bonds in cholesterol
Hydroxyl group at periphery
Hydrophobic and hydrophilic ends - hydroxyl is hydrophilic and hydrocarbon tail is hydrophobic
4 carbon based rings (hydrophobic)
Function of cholesterol
In phospholipid bilayer to regulate fluidity of the membrane, providing a stable sturture and mechanical strength
What is cholesterol also a type of?
Sterol
Formed in liver and intestine
Used to form steroid hormones :oestrogen and testosterone
Name the 2 types of sugar
Reducing
Non-reducing
How to test for reducing sugars?
Add benedicts reagent to the sample and heat in a water bath
Positive is brick red precipitate
Negative is same colour - blue
E.g. glucose
How to test for non-reducing sugars?
Only if reducing sugar test is negative
Add HCl and heat in a water bath - breaks the glycosidic bonds.
Add NaHCO3 to neutralise
Add bendicts reagent and heat in a water bath
Positive is brick red precipitate
Negative remains blue
How to test for starch?
Add iodine solution
Positive is blue-black
Negative is yellow/orange (remains the same)
How to test for lipids?
Add ethanol to the sample and mix.
Pour liquid into water.
Positive is cloudy white emulsion
Negative is no emulsion
How to test for proteins?
Add biuret reagent (contains sodium hydroxide and copper (II) sulfate)
Do not heat
Positive is lilac/purple
Negative is blue (remains the same)
Function of calcium ions
Nerve impulse transmission
Muscle contraction
Function of sodium ions
Nerve impulse transmission
Kidney function
Function of potassium ions
Nerve impulse transmission
Stomatal opening
Function of hydrogen ions
Catalysis of reactions
pH determination
Function of ammonium ions
Production of nitrate ions by bacteria
Function of nitrate ions
Nitrogen supply to plants for amino acid and protein production
Function of hydrogen carbonate ions
Maintenance of blood pH
Function of chloride ions
Balance positive charge of sodium and potassium ions in cells
Function of phospahte ions
Plasma mambrane formation
Nucleic acid and ATP formation
Bone formation
Function of hydroxide ions
Catalysis of reactions
pH determination
Purpose of a colorimeter
Measures the absorbance or transmission of light by a coloured solution. The more concentrated the solution, the more light will be absorbed, and less light will br transmitted. This calculates the concentration of a reducing sugar. Must calibrate using distilled water first.
Purpose of biosensors
Use biological components to determine the presence and concentration of molecules like glucose.
Molecular recognition - transduction - display
Function of catalase as an enzyme and a protein
Quaternary protein with 4 haem groups. These groups allow catalase to interact with hydrogen peroxide and speed up the breakdown, preventing the build up and any damage to cells.
A type of conjugated protein.
What type of bond is present between amino acids?
Peptide bonds
Insulin as an example of a globular protein
Regulates blood glucose concentration. Hormones are transported in the blood so need to be soluble. Has a precise shape to carry out its specific function
Role of water as a solvent?
Role as a transport medium e.g. glucose in blood, urea transport. For polar molecules and ions. Allows for capillary action
Cohesive properties of water?
Allow movement of unbroken columns of water through the xylem vessel in plants
Water causes non-polar molecules to group together
Allows the formation of a phospholipid bilayer in the plasma membrane
High latent heat of vaporistaion in water?
Large amount of energy required to evaporate water. Sweating as a cooling mechanism in mammals
High surface tension of water?
Provides a habitat for some insects e.g. pond skaters
Ice is less dense that liquid water?
Insulates bottom of ponds which allows inhabitants to survive and provide a habitat for some organisms.
Water is not easily compressed?
Creates turgor pressure to support plant cells. Amniotic fluid supports fetus
Water is transparent?
Allows aquatic plants to photosynthesise
High specific heat capacity of water ?
Large amount of energy required to heat a given mass of water. Acts as a temperature buffer and coolant to maintain a stable environment in lakes/oceans. Organisms are able to survive, due to only being active at a narrow temperature range
Change in density with temperature changes?
Changes in density allow nutrients to circulate in bodies of water - widely available to all organisms
