Biological molecules

Question 1

cations and their roles

Answer 1

• 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

Question 2

anions and their roles

Answer 2

• 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

Question 3

what is a monomer?

Answer 3

small units which are the components of larger molecules eg. nucleotides, amino acids

Question 4

what is a polymer?

Answer 4

molecules made from monomers joined together.

Question 5

importance of condensation+hydrolysis reactions

Answer 5

• 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

Question 6

elements that make up biological molecules

Answer 6

• carbs/lipids=C, H, O
• proteins=C, H, O, N, S
• nucleic acids=C, H, O, N, P

Question 7

what are monosaccharides?

Answer 7

simple sugars made of a single sugar molecule
very soluble+form sweet solutions
general formula: (CH^2O)n

Question 8

role of monosaccharides in living organisms

Answer 8

• 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

Question 9

what is glycosidic bond?

Answer 9

any bond between sugars

Question 10

condensation+hydrolysis in carbohydrates

Answer 10

• condensation: water molecule released, new covalent bind formed, dimer/polymer formed
• hydrolysis: water molecule used, covalent bond broken, smaller molecules formed

Question 11

how are monosaccharides named?

Answer 11

based on no. of Cs in molecule
trioses=3C, pentoses=5C, hexoses=6C

Question 12

what are disaccharides made of?

Answer 12

• sucrose=alpha glucose+fructose
• maltose=2 alpha glucose
• lactose= alpha glucose+galactose

Question 13

structure of starch

Answer 13

• 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

Question 14

structure of glycogen

Answer 14

• storage polysaccharide
• similar to amylopectin but has more 1,6 bonds=more branches
• glycogen granules=energy stores in liver+muscle cells

Question 15

structure of cellulose

Answer 15

• 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

Question 16

benedict test

Question 17

structure of triglycerides

Answer 17

• 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

Question 18

types of fatty acids

Answer 18

• 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)

Question 19

roles of lipids (triglycerides)

Answer 19

• 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

Question 20

structure of phospholipids

Answer 20

• 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

Question 21

role of phospholipids

Answer 21

• formation of phospholipid bilayer of plasma membranes

Question 22

structure of cholesterol

Answer 22

• made of 4 carbon rings
• very hydrophobic=insoluble in water (but OH-=hydrophillic/polar)

Question 23

roles of cholesterol

Answer 23

• found in membranes and regulates their fluidity ans strength
• used as a precursor for makinf testerone, oestrogen, vitamin D

Question 24

lipids test

Question 25

structure of proteins

Answer 25

• amino acids joined by condensation reaction b/w OH+H=forms peptide bond

Question 26

levels of protein structure

Answer 26

• primary structure
• a list of amino acids in a protein in the right order
• secondary structure
• R groups of ami
• tertiary structure
• quaternary structure