METABOLIC REACTIONS, BIOMOLECULES & ENERGY PRODUCTION

Question 1

what are ions?

Answer 1

electrically charged particles

Question 2

positive / negative charge

Answer 2

cations / anions

Question 3

molecules / compounds

Answer 3

containing 2 or more elements / molecule made of different elements

Question 4

acids

Answer 4

more H+ / liberates H+ when mixed with water

Question 5

bases

Answer 5

less H+ / takes up H+ ion released from acid

Question 6

synthesis / anabolism

Answer 6

chemical reactions where molecules are added together to form new molecules

Question 7

catabolism

Answer 7

when one molecule is broken down into smaller molecules

Question 8

metabolism

Answer 8

sum of biochemical process which produce/consume energy

Question 9

energy

Answer 9

transferred to ATP which is storage form of energy

Question 10

molecules of life

Answer 10

proteins, lipids/fats, carbs

Question 11

biomolecule

Answer 11

any molecule made within an organism

Question 12

carbs

Answer 12

general formula CHO (1:2:1)

provides glucose, raw energy needed for energy production

smaller in size the more soluble

approx 1-2% cell mass

Question 13

types of carbs

Answer 13

monosaccharides -> smallest
e.g. glucose, fructose, galactose, deoxyribose & ribose
combine to form disaccharides

disaccharides -> 2 mono are joined & water molecule removed
e.g. maltose, sucrose, lactose
too large to pass through cell membrane
digested via hydrolosis (add water molecule to break bond & release mono)

polysaccharide -> chains of simple sugars linked by dehydration synthesis
e.g. starch, glycogen, cellulose
used as storage products e.g. glycogen stored in muscle/liver and released when needed

Question 14

fats / lipids

Answer 14

insoluble organic molecules

e.g. triglycerides, phospholipids, cholesterol

Question 15

types of fats/lipids

Answer 15

triglycerides (neutral fats) -> protect internal organs, stores energy fuel, insulates, building blocks are 3 fatty acid chains attached to glycerol molecule

phospholipids -> modified triglycerides whihc one fatty acid chain replaced by phosphate group
also known as phosphoglycerides - non polar fatty chain & phosphate polar portion
form cell membrane

cholesterol -> most important steroid molecule - ingested in animal products
structure consists of 4 interconnected carbon rings
plays role in stabilisation of cell membranes
synthesise steroid hormones e.g. sex hormones, vit D, bile

Question 16

proteins

Answer 16

prime importance
10-30% cell mass
response for multiple physiological functions
e.g. enzymes, antibodies, blood proteins
formed from 20 different amino acid building blocks

Question 17

structure of proteins

Answer 17

primary -> determined by the sequence of amino acids connected by peptide bonds to from a polypeptide chain

secondary -> depending on the sequence of the amino acids the protein may use hydrogen bonds to form a secondary structure consisting of coils or pleats

tertiary -> final dimensional shape determined by variety of bonding interactions between ‘side chains’ on amino acids
bonds can be stronger than the hydrogen bonds & this the protein will bend, fold & loop
the 4 types of bonding interactions between “side chains” include:
hydrogen bonding, disulphide bonds, salt bridges, & non-polar hydrophobic interactions

quaternary -> combination of 2 or more chains to form complete unit
interactions between the chains are not different from those in tertiary structure, but a distinguished only by being interchain rather than intrachain
e.g. haemoglobin

Question 18

what are proteins vulnerable to?

Answer 18

high temps, change in pH, various chemicals, radiation

Question 19

examples of polypeptides in body

Answer 19

body’s natural painkillers
e.g. encephalins & endorphins
polypeptides bind to receptors in brain to provide temporary relief
endorphins may produce sedative effect by prevention of release of substance P which transmits pain signals to brain
pituitary gland produces nonapeptides vasopressin & oxytocin

Question 20

examples of enzymes

Answer 20

unique 3D shape that binds with a small group of reacting molecules (substrates)
much larger than substrates
affected by changes in pH, temp & some chemicals

Question 21

vitamins & coenzymes

Answer 21

water/fat soluble
water soluble vit not stored in body
water soluble vits are required by many enzymes as co-factors to carry out catalytic reactions

Question 22

catabolic reactions

Answer 22

stage 1 -> digestion where enzymes break down large molecules into smaller ones
polysaccharides -> glucose
fats -> fatty acids & glycerol
proteins -> amino acids
digested products then diffuse across bloodstream

stage 2 -> newly delivered nutrients are either:
built into lipids, protein & glycogen by anabolic pathways
or broken down by catabolic pathways to pyruvic acids & acetyl CoA into cell cytoplasm

digestion products are further broken down to yield 2 to 3 carbon compounds
e.g. pyruvate & acetyl CoA

stage 3 -> major production of energy happens in mitochondria
2 carbon acetyl group is oxidised in the citric acid cycle, which produces coenzymes NADH & FADH2
as long as the cells have an adequate supply of oxygen, electrons & hydrogen ions from the reduced coenzymes are transferred to the electron transport chain to phosphorylate ADP to ATP