Biological molecules Flashcards
1
Q
Draw alpha glucose and beta glucose
A
( use google )
2
Q
Draw ribose and deoxyribose
A
( use google )
3
Q
Draw a condensation reaction between two alpha glucose molecules
A
( use google )
4
Q
What is a glycosidic bond?
A
The bond formed between two alpha glucose molecules in a condensation reaction.
5
Q
Describe the structure and function of cellulose
A
- Long, straight chains of beta glucose strengthened by H bonds
- Structure gives high strength to maintain cell shape and supports
- resists pressure when cells are turgid
- Alternating sequence, rotated 180
- H bond crosslinks between parallel strands form microfibrils which results in high tensile strength
6
Q
Describe the structure and function of amylose
A
- 1-4 glycosidic bonds
- angle of the bond means that this chain twists to form a helix which is stabilised by H bonds
- Makes it compact and less soluble
7
Q
Describe the structure and function of amylopectin
A
- 1-4 glycosidic bonds, 1-6 as well
- causes branching
- More compact and less soluble than amylose
8
Q
Describe the structure and function of glycogen
A
- HIGHLY branched, more compact (less space to be stored)
- Branching means that there are many free ends where glucose molecules can be added or removed (can be converted to energy quickly, good for mobile animals)
- insoluble= no osmotic effect, doesn’t diffuse out of cells
9
Q
What are reducing sugars?
A
Reducing sugars donate electrons to the CU2+ ions in benedicts solution, making a coloured precipitate
10
Q
What are non-reducing sugars?
A
Sugars that do not have availible reducing groups, position of the glycosidic bond prevents donation.
11
Q
What would happen if you heated a starch solution and added iodine to it?
A
Once iodine is added it inserts itself into the helix which causes the black colour.
When heated. H bonds weaken and the helix slightly loses shape which causes the colour to disappear.
12
Q
Draw cholesterol
A
( use google )
13
Q
Draw a triglyceride
A
( use google )
14
Q
Draw a fatty acid; saturated, unsaturated, polyunsaturated
A
( use google )
15
Q
Draw a phospholipid
A
( use google )
16
Q
Draw glycerol
A
( use google )
17
Q
What are the bonds between the glycerol and fatty acid chains known as?
A
Ester bonds. The reaction is called esterification
18
Q
Draw the structure of an amino acid and a dipeptide
A
( use google )
19
Q
What is an R group and what properties can it have?
A
- Any group in which a carbon or hydrogen atom is attached to the rest of the molecule
- Called a ‘random’ group
- Hydrophobic/ philic
- polar/ non-polar
20
Q
Name some roles of lipids
A
- Membrane formation and creation of hydrophobic barrier
- Hormone production
- Electrical insulation
- Waterproofing
21
Q
What do triglycerides stored under the skin provide?
A
- thermal insulation
- cushioning to protect vital organs
- buoyancy
22
Q
What is the primary structure of a protein?
A
- The sequence in which the amino acids are joined
- The amino acid sequence will influence how it folds later on and in turn decides the final shape.
- Involves peptide bonds
23
Q
Describe the secondary structure of a protein
A
- The oxygen, hydrogen, nitrogen atoms of the amino acids interact
- H bonds may form, pulling it into a coil shape called alpha helix
- PP chains can lie parallel to one another, joined by H bonds, forming sheet like structures. Forms a beta pleated sheet.
24
Q
Explain the tertiary structure of a protein
A
- Folding of the protein, often including sections of secondary structure
- the coiling or folding of sections of proteins in the secondary structures bring R groups of other amino acids close enough to interact (further folding)
- May cause disulfide bonds, ionic bonds, H bonds and hydrophobic and hydrophilic interactions
25
What is the quaternary structure of a protein?
1. Results from association of two or more individual proteins called subunits
26
Describe fibrous proteins
- Proteins that are composed of many PP chains in a long, narrow shape
- insoluble in water
- useful for structure and support
- E.g keratin, elastin, collagen
27
What are characteristics of globular proteins?
- Hydrophobic R groups are pointed inwards, hydrophilic outwards= usually water soluble
- Spherical and compact
- involved in metabolic processes
28
How is water important as a metabolite?
Water as a metabolite
- It is a reactant necessary to start metabolic reactions
- Substances can dissolve in it, cytoplasm is mostly water.
- Dissolves substances to be transported in bloodstream
29
Explain the property of water: Cohesion
Cohesion
- water molecules attracted to each other
- Enables flow and transport (xylem, water moves up columns against gravity)
29
Explain the property of water:
latent heat of evaporation
Latent heat capacity
- Most organisms require a specific temp range in order to survive, water has a high LHC so it requires lots of energy to break H bonds to vaporise.
- vaporisation used to cool down.
30
Explain the property of water: Surface tensions
Surface tension
- supports small insects like pondskaters
31
Explain the property of water: SHC
SHC
- A lot of energy needed to change the temp of water, good for aquatic creatures
32
Explain the property of water: Density
Density
- When water freezes into ice it becomes less dense.
- H bonds fix the positions of the polar molecules slightly further apart, this produces an open rigid structure with an O2 molecule at the centre of a tetrahedral arrangement of H atoms.
- Ice floats
- Layer of insulation
33
Why is incompressibility of water important for organisms?
- provides turgidity to plant cells
- provides hydrostatic skeleton for some small animals like earthworms
34
Why is the density of ice important?
- it insulates water in arctic climates so aquatic organisms can survives
- water acts as a habitat
- prevents enzymes from stopping working/ denaturing due to freezing temps
35
Why is high surface tension of water important?
- slows water loss due to transpiration
- water rises high in narrow tubes, reducing demand on root pressure
- some insects can skin across the surface of water
36
Why is water an important solvent?
- Polar universal solvent dissolves and transports charged particles involved in intra+extracellular reactions
37
Why are the high SHC and LHE important?
- acts as a temperature buffer which enables endotherms to resist fluctuations in core temp
- in turn optimises enzyme activity
- has a cooling effect when water evaporates from skin
38
Name the elements found in carbohydrates, lipids, proteins and nucleic acids.
Carbs and lipids= C, H, O
Proteins= C, H, O, N, S
Nucleic acids= C, H, O, N, P
39
Describe the properties of alpha glucose.
- small and water soluble
- Complementary shape to antiport for co-transport for absorption in gut
- complementary shape to enzymes for glycolysis (respiratory substrate)
40
Describe the structure and functions of starch.
- Storage polymer of alpha glucose in plant cells
- insoluble= no osmotic effect
- large= doesnt diffuse out
- made from amylose (1,4 GC bonds), compact
- made from amylopectin (1,4 and 1,6 GC bonds), many terminal ends for hydrolysis into glucose
41
Compare saturated and unsaturated fatty acids
Saturated= single bonds, higher melting point means solid at room temp, found in animal fats, straight chain mols have many contact points
Unsaturated= C=C double bonds, kinked molecules have fewer contact points, lower MP means liquid at room temp, found in plant oils
42
Relate the structure of triglycerides to their function.
- High energy: mass= high calorific value, energy storage
- insoluble HC chain= no effect on WP, used for waterproofing
- Slow conductor of heat means it provides thermal insulation (e.g adipose tissue)
- Less dense than water
43
Describe the structure and function of phospholipids
- Glycerol backbone attached to 2 hphobic FA tails and 1 hphilic polar phosphate head
- amphipathic
- forms PL bilayers
- tails splay outwards, waterproofing
44
Describe structure and function of cholesterol
- steroid structure of 4 HC rings
- HC tail on one side, hydroxyl (-OH) on other side
- adds stability to PL bilayer by connecting mols and reducing fluidity
- acts as temp buffer
45
Describe the structure of haemoglobin
- globular conjugated protein with prosthetic group
- 2A chains 2B chains 4 haem groups
- FE2+ forms bond with O2
- tertiary structure changes so it is easier for O2 to binds (cooperative binding)
46
Describe how to test for reducing sugars.
1. Add equal vol of benedict's reagent to a sample
2. heat in water bath at 100C for 5 mins
3. Positive= blue to orange, brick red precipitate
47
Describe the test for non-reducing sugars
1. Neg result= remains blue
2. Hydrolyse non reducing sugars (sucrose into monomers) by adding 1cm^3 of HCl.
3. Heat in a boiling water bath for 5 mins
4. Neutralise mixture using sodium carbonate solution
5. Proceed with benedict's test
48
State role and symbol of: nitrates and ammonium
NO3= makes dna, amino acids
NH4+= converted to NO3- during nitrogen cycle, produced by deamination in the liver
49
State role and symbol of: hydroxide and phosphate ions
OH-= affect pH and interact with bonds in protein structure (denature)
PO43-= component of ATP
50
State role and symbol of: sodium, potassium and chloride ions
NA and K= maintenance of resting potential of neurons, NA is involved in co-transport mechanisms
CL-= involved in inhibitory synapses to cause hyperpolarisation
51
State role and symbol of: hydrogen and hydrogencarbonate ions
H and HCO3 forms when CO2 dissolves in water
H+= regulates pH, H+ pump is involved in chemiosmosis and active loading in translocation
52
State role and symbol of: calcium ions
CA2+= calcium pectate adds stability to lamella of plant cell walls, regulates exocytosis
