Biological molecules Flashcards
cations and their roles
- Ca+: nerve impluse transmission+muscle contraction
- Na+: nerve impluse transmission+kidney function
- K+: nerve impluse transmission+stomatal opening
- H+: catalysis of reactions+pH determination
- NH4+: production of nitrate ions by bacteria
anions and their roles
- NO3-: nitrogen supply for amino acid and protein formation
- HCO3-: maintanence of blood pH
- Cl-: balance + charges of Na and K ions in cells
- PO4 3-: cell membrane formation+nucleic acid & ATP formation+bone formation
- OH-: catalysis of reactions+pH determination
what is a monomer?
small units which are the components of larger molecules eg. nucleotides, amino acids
what is a polymer?
molecules made from monomers joined together.
importance of condensation+hydrolysis reactions
- condensation: building up large molecules e.g. glucose to glycogen for storage.
- hydrolysis: breakdown of large, insoluble molecules into smaller, soluble molecules e.g. glycogen to glucose for respiration
elements that make up biological molecules
- carbs/lipids=C, H, O
- proteins=C, H, O, N, S
- nucleic acids=C, H, O, N, P
what are monosaccharides?
simple sugars made of a single sugar molecule
very soluble+form sweet solutions
general formula: (CH^2O)n
role of monosaccharides in living organisms
- source of energy in respiration: lots of C-H=give high yield of energy=released when bonds are broken=make ATP from ADP (ATP=key energy molecule in most organisms)
- building blocks to make larger molecules eg. glucose polymerised to make polysaccharides starch, cellulose, glycogen; ribose=makes ATP+RNA; deoxyribose=DNA
what is glycosidic bond?
any bond between sugars
condensation+hydrolysis in carbohydrates
- condensation: water molecule released, new covalent bind formed, dimer/polymer formed
- hydrolysis: water molecule used, covalent bond broken, smaller molecules formed
how are monosaccharides named?
based on no. of Cs in molecule
trioses=3C, pentoses=5C, hexoses=6C
what are disaccharides made of?
- sucrose=alpha glucose+fructose
- maltose=2 alpha glucose
- lactose= alpha glucose+galactose
structure of starch
- mixture of amylose+amylopectin=very large grains=fiund in storage organs+chloroplasts
- amylose=made by lots of alpha glucose molecules ->curved+curled up chain=max. glucose molecules stored in min. space
- amylopectin=shorter main chain of alpha 1, 4 bonds with side chains of 1, 6 bonds
structure of glycogen
- storage polysaccharide
- similar to amylopectin but has more 1,6 bonds=more branches
- glycogen granules=energy stores in liver+muscle cells
structure of cellulose
- structural polysaccharide
- very strong=ideal for reinforcing structures
- polymer of beta glucose
- hydrogen bonds between cellulose fibres=immensely strong tgt
- cellulose fibres linked with other molecules to form bundles=microfibrils which join to form fibril
- cellulose fibres=permeable=allow water+dissolved solutes
- cell wall=resist turgor pressure+support plant
benedict test
structure of triglycerides
- 1 glycerol+3 fatty acids
- join by condensation reactions between hydroxyl groups
- ester bond formed
- insoluble in water=hydrophobic but soluble in organic solvents eg. alcohol
- fatty acids=long chains w even spread of electric charge=hard to mix w eachother
types of fatty acids
- saturated
- straight chain=tightly packed=up mp=solid at room temp
- eg. animal lipids (fats)
- unsaturated
- have C=C double bond=x contain max. no. of hydrogens
- kinks in chains=difficult to slot together=loosely packed=down mp=liquid at room temp
- eg. plant lipids (oils)
roles of lipids (triglycerides)
- energy source+reserve=contain many C-H bonds=higher energy yield than carbs
- insulator against heat loss+electrical insulation around nerves
- provides buoyancy (floating)
- mwtabolic source of water when used in respiration
- protection
structure of phospholipids
- one hydrphillic phosphate head+2 hydrophobic fatty acid tails
- one soluble end and one insoluble end
- when forced underwater form:
- micelle or bilayer sheet=phosphate head touches water, tails dont
role of phospholipids
- formation of phospholipid bilayer of plasma membranes
structure of cholesterol
- made of 4 carbon rings
- very hydrophobic=insoluble in water (but OH-=hydrophillic/polar)
roles of cholesterol
- found in membranes and regulates their fluidity ans strength
- used as a precursor for makinf testerone, oestrogen, vitamin D
lipids test
structure of proteins
- amino acids joined by condensation reaction b/w OH+H=forms peptide bond
levels of protein structure
- primary structure
- a list of amino acids in a protein in the right order
- secondary structure
- R groups of ami
- tertiary structure
- quaternary structure
Structure and function of globular proteins
-
structure
Proteins curl into a ball shape with hydrophobic R-groups pointing to the centre=soluble=found in many tissue fluid -
function
Have various roles in metabolism eg. Enzymes, carrier molecules
Function of globular proteins
-
Enzymes
globular proteins=shape can be altered appropriately to fit their active sites with high specificity eg. Lipase -
Transport proteins
soluble=function well as transport proteins as they can cross cell membranes eg. Haemoglobin -
Messengers proteins/hormones
Soluble=work well as hormones=regulate body’s metabolic processes eg. Insulin
Haemoglobin: structure+function
Structure
- globular conjugated protein
- quaternary structure=4 polypeptide chains (globin proteins)=2 α+2 β chains=each has a prosthetic haem (Fe 2+) grp (reacts reversible w O2)
- chains held by disulphide bonds+hydrophobic R-groups in=preserves 3D shape & hydrophilic out=maintains solubility
- carries 4 O2 molecules due to 4 haem group
Function
- binds with O2 in lungs+transports it bld
- soluble=carries O2 more efficiently as O2=insoluble in H2O
- haem grp=allow small molecules eg. O2 to bind easier=alter tertiary/quaternary structure=up affinity for other O2 molecules=bind easier
Structure of fibrous proteins
- long, thin strands=long polypeptide chains=twist tgt
- insoluble=hydrophobic parts x folded inward
Function of fibrous proteins
- structural proteins=stable+insoluble=support+protect tissues eg. Keratin (structure to hair+nails), collagen (connective tissue), elastin (elastic connective tissue)
Collagen: structure+function
-
structure
3 polypeptide chains held tightly tgt by H-bonds+covalent bonds in a triple helix=tropocollagen
Each chain=helix shape (NOT α helix) -
function
Cross-links hold collagen molecules tgt=fibrils
Molecules are positioned in fibrils to have staggered ends
Grp of fibrils=collagen fibres=positioned to line up w forces they withstand=provide support+tensile strength - found in skin, muscles, tendons, bones
Proteins test
Paper/thin layer chromatography
Rf values
ATP: function+properties
-
properties
Universal energy currency
Small=lots of it can be stored+move quickly
Water soluble as most reactions occur in cytoplasm+ATP has to be next to them
Bonds bw phosphate grips=unstable, low Ea=easily broken
Releases energy in small quantities=more stable energy lvls
Easily regenerated=readily available
Phosphate can phosphorylate other compounds=makes them more reactive -
function
ATP+H2O —> ADP+Pi
catalysed by ATP hydrolase and releases energy for use in cells
ADP+Pi —> ATP+H2O
Catalysed by ATP synthase & requires energy and traps chemical energy in the bond
Structure of water
- dipolar molecule
The Hs have a delta+ charge, O have a delta- charge=positive and negative poles - water molecules form H-bonds w each other (one O with 2 H)
Roles of water
- solvent=substances dissolve in it
- temp control=buffer sudden temp changes
- cooling mechanism=mammals use evaporation of water in sweat to cool skin
- habitat=organisms survive+reproduce in it
- metabolite=chemical reactions involve it
- transport= use it to move substances
Water as a solvent
- most substances in cells=ionic compounds=split apart when added to H2O=negative ions attracted to H+ and positive ions to O2- = ions surrounded by water=compound dissolves
- useful bc
Biological reactions occur in solution eg. Cytoplasm of eukaryotes/prokaryotes
Dissolved substances can be transported around the body eg ions in plasma
Water as temp buffer
- high SHC=resistant to rapid changes in temp
As many organisms are made up of water=body can maintain a stable temp
Water as a cooling mechanism
- H-bonds bw water molecules=a lot of energy needed to evaporate water due to high LH of vaporisation=lots of energy needed to break H-bonds to go from liquid to gas
- useful bc
Organisms can use evaporation of water as a cooling method w/o losing too much water
Water as a habitat
- high SHC+high LH of vaporisation=x change temp easily=stable environment for organisms to live in
- ice less dense than water as molecules are further apart=ice floats=insulating layer at surface=water below freeze=allowing organisms to survive
Water as metabolite
Involved in many chemical organisms inside organisms eg. Hydrolysis, condensation, photosynthesis
Water as a transport medium
- cohesion=tendency of water molecules to stick tgt
- adhesion=tendency of water to stick to other materials
This allows water to flow through organisms, carrying substances along w it eg. In the xylem of a plant - water molecules create high surface tension when they meet air=forms skin-like structure at water’s surface=string enough to support small organisms eg.pond-skaters
