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 planty