Option B: Human Biochemistry

HideShow resource information
How is energy made available?
Respiration - oxidation reactions
1 of 138
What is energy provided by?
Fats, carbohydrates + proteins - converted into glucose + intermediates
2 of 138
What is the function of proteins?
Structure of body (hair, fingernails, tendons, contractile structures in muscles) + tools (catalysts, enzymes, hormones)
3 of 138
What is the structure of proteins?
Polymers - monomers are amino acids
4 of 138
What are some of the properties of proteins?
Exist as zwitterions (dipolar ions), amphoteric (contain acidic and basic group), buffers (important in maintaining pH levels in cells)
5 of 138
How do amino acids link?
Condensation reactions, releasing water, forming peptide bonds
6 of 138
What is name of a chain of amino acids?
Two = dipeptide / Chain = polypeptide
7 of 138
What is the primary structure of proteins?
Sequence of amino acids in chain - covalent backbone of molecule
8 of 138
What is the secondary structure of proteins?
Regular hydrogen bonding between peptide groups (C=O and N-H), resulting in folding of polypeptide chain
9 of 138
What is the alpha-helix structure like?
regular, coiled configuration - hydrogen bonds form 4 amino acid units apart - flexible + elastic, as hydrogen bonds break easily and reform
10 of 138
What is a beta-pleated sheet like?
'side by side' polypeptides - pelted sheets, cross-linked by inter-chain hydrogen bonds - flexible - inelastic
11 of 138
What are proteins with well-defined secondary structures called?
Fibrous proteins - physically tough + insoluble in water
12 of 138
What is the tertiary structure of proteins like?
Result of interactions between R groups / side chains - causes further twisting, folding + coiling
13 of 138
What is the conformation of a protein?
The most stable arrangement of the protein
14 of 138
What happens when the protein loses its specific tertiary structure?
Denatured - upset by temperature or pH
15 of 138
What is the quaternary structure of proteins like?
Where there is an association between different polypeptides (e.g. collagen + haemoglobin)
16 of 138
How are proteins analysed?
First chemically separate amino acids through hydrolysis reactions using acid - then mixture separated through chromatography or electrophoresis
17 of 138
What is chromatography useful for?
Coloured mixtures - amino acids = colourless in solution, but take on colour when treated with locating agent (ninhydrin)
18 of 138
How is the position of an amino acid expressed?
Rf Value / Retention Factor = distance moved by amino acid, divided by the distance moved by the solvent
19 of 138
What is electrophoresis based on?
movement of charged particles in electric field - amino acids placed in buffered solution - they carry different charges depending on pH
20 of 138
What is the medium used in electrophoresis?
Polyacrylamide gel
21 of 138
What are carbohydrates?
Composed of carbon, hydrogen + oxygen
22 of 138
What are the two types of carbohydrates?
Simple sugars = monosaccharides (eg. glucose, fructose) + condensation polymers = polysaccharides
23 of 138
What are the qualities of monosaccharides?
Readily soluble in water (taken up by cells rapidly), release energy in respiration, are precursors in metabolic reactions (eg. synthesis of fats, nucleic acids + amino acids)
24 of 138
What are the qualities of polysaccharides?
Insoluble, used in storage - mostly as glycogen in liver + muscles, cellulose in plants, dietary fibre
25 of 138
What is the structure of monosaccharides?
Empirical formula = CH2O - Contain carbonyl group (C=O) + at least two -OH groups - exist in chain forms, which in aqueous solution undergo internal reactions to make ring structure
26 of 138
What is the structure of disaccharides?
Two monosaccharides linked together through glycosidic linkage (carbon 1-4) - -OH group eliminated by each sugar in condensation reaction
27 of 138
What is lactose made from?
Beta-glucose + beta-galactose (milk)
28 of 138
Whats is maltose made from?
alpha-glucose + alpha-glucose (product from starch digestion)
29 of 138
What is sucrose made from?
alpha-glucose + beta-fructose (cane sugar)
30 of 138
What are the three common glucose-based polysaccharides?
Starch, glycogen + cellulose
31 of 138
What are the two types of starch?
Amylose + amylopectin
32 of 138
What is the structure of amylose like?
Carbon 1-4 linkages, soluble in water, polymer of alpha-glucose
33 of 138
What is the structure of amylopectin like?
Branched polymer, carbon 1-4 and 1-6 linkages, polymer of alpha-glucose
34 of 138
What is the structure of glycogen like?
Polymer of alpha-glucose, similar to amylopectin but more 1-6 branches, 'animal starch' main storage carbohydrate in animals
35 of 138
What is the structure of cellulose like?
Linear polymer of beta-glucose, structural material in plant cell walls, alternate monomers 'upside down' with respect to each other - hydroxyl groups form hydrogen bonds with parallel cellulose molecules - forms cables = microfibrils
36 of 138
Digestion of polysaccharides
Insoluble so cannot be transported by blood, broken down through hydrolysis reactions controlled by enzymes, producing soluble monosaccharides
37 of 138
Dietary fibre
substances that cannot be digested (e.g. cellulose - enzyme cellulase not found in human body)
38 of 138
Why is cellulose beneficial to the health of the large intestine?
Fibrils abrade wall of digestive tract + stimulate lining to produce mucus = smooth passage of undigested food - prevents constipation, haemorrhoids, irritable bowel syndrome
39 of 138
What are lipids?
Made of carbon, hydrogen + oxygen - hydrophobic / insoluble in water - soluble in non-polar solvents - (e.g. fats, phospholipids, steroids, oils)
40 of 138
Properties of lipids
Contain stored energy - 1 gram of lipid releases almost twice as much energy as 1 gram of carbohydrate - but, lipids not as readily available due to insolubility and more reactions required for breakdown
41 of 138
Functions of lipids
Ideal storage molecules (fat stores = adipose tissue), hormones (lipids in form of steroids = testosterone + oestrogen), bile acids
42 of 138
What are the functions of phospholipids?
major component in membrane of cells, nerve cells, cholesterol (important in plasma membrane structure), essential fatty acids, help absorb fat-soluble vitamins
43 of 138
What are the negative effects of lipids?
Due to low solubility of lipids - some deposited in walls of main blood vessels (restrict blood flow), obesity (converting excess fats into adipose tissue for storage), cholesterol (cardiovascular disease)
44 of 138
What are triglycerides?
Fats + oils - esters made through condensation reactions between glycerol + 3 fatty acids
45 of 138
Fatty acids
In most natural oils and fats 3 fatty acids not same - differ in length of hydrocarbon chain, number + position of of C-C double bonds in hydrocarbon chain
46 of 138
What does the number of C-C double bonds do to the saturation of fatty acids
No double bonds = saturated, One double bond = mono-saturates, several double bonds = polyunsaturated
47 of 138
What does the nature of fatty acids affect in triglycerides?
Melting point
48 of 138
Saturated fatty acids
Tetrahedral bond angles (109.5) - molecules pack close together - significant Van der Waal's forces - form saturated trilycerides = solid at room temperature (high M.P.) - FATS
49 of 138
Unsaturated fatty acids
120 bond angles - kinks in chains - make it difficult to pack molecules close together - form unsaturated triglycerides - weaker intermolecular forces - liquids at room temperature (low M.P) - OILS
50 of 138
Essential fatty acids
linoleic acid / omega-6-fatty acid + linolenic acid / omega-3-fatty acid
51 of 138
Where are 'omega fatty acids' obtained from
plants + fish
52 of 138
Why are some fatty acids essential?
Involved in synthesis of prostaglandins (lipids) - involved in lower blood pressure - lower LDL cholesterol, protecting against heart disease
53 of 138
How is the degree of unsaturation in a fat determined?
Using iodine - unsaturated fatty acids undergo addition reactions with iodine - 1 mole of iodine will react with each mole of double bonds in fat
54 of 138
Iodine number
Number of grams of iodine which reacts with 100g of fat
55 of 138
'Partially hydrogenated fat'
Oils which have been chemically modified by addition reactions, using hydrogen to add across double bonds + decrease degree of unsaturation
56 of 138
What is the outcome of 'partially hydrogenated fat'?
Fat is more saturated, with higher melting point - solid/semi-solid - breaks down less easily under conditions of high temperatures
57 of 138
What is the issue with 'partially hydrogenated fat'?
Chemical modifications involve heat + pressure - affects positions of groups around double bonds - -cis to -trans - LDL increased + HDL decreased
58 of 138
Digestion of fats
fats + oils = insoluble - broken down in gut through hydrolysis reactions into fatty acids + glycerol
59 of 138
Phospholipids
Similar to triglycerides, but only 2 fatty acids condensed onto glycerol molecule - (e.g. lecithin)
60 of 138
What does the structure of phospholipids look like?
Have polar hydrophilic 'head' + two non-polar hydrophobic 'tails'
61 of 138
What do phospholipids do?
Spontaneously form phospholipid bilayer - maximises interactions between polar groups and water, while creating non-polar hydrophobic interior - provides basis of membrane structure
62 of 138
Steroids
Have 4 fused rings - (eg. cholesterol - used in body in synthesis of other steroids like sex hormones)
63 of 138
Nutrients
Molecules required in diet for absorption + use in body
64 of 138
How do we classify nutrients?
According to amounts in which they are needed / recommended daily intake
65 of 138
Micronutrients
Needed in extremely small amounts - enable body to produce enzymes + hormones - (e.g. vitamins + trace minerals)
66 of 138
Macronutrients
Needed in relatively large amounts - provide energy, build + maintain structure of body - (e.g. macromolecules = carbohydrates, proteins, lipids - other minerals)
67 of 138
Vitamins
Organic micronutrients not synthesised in body
68 of 138
Water-soluble vitamins
Transported directly in blood - excess filtered out by kidneys + excreted - polar bonds
69 of 138
Fat-soluble vitamins
Slower to be absorbed - excess stored in fat tissues - can produce serious side effects - non-polar - long hydrocarbon chains / rings
70 of 138
Vitamin A / Retinol
Fat soluble - hydrocarbon chain + ring = non-polar - involved in visual cycle in eye + important for vision at low intensity
71 of 138
Vitamin C / Ascorbic acid
Water soluble - OH groups enable hydrogen bonds - cofactor in some enzymic reactions - important in tissue - helps give resistance to some diseases
72 of 138
Vitamin D / Calciferol
Fat soluble - chemically similar to cholesterol - stimulates uptake of calcium ions by cells, so important in health of bones + teeth
73 of 138
Malnutrition
Result of deficiencies or imbalance in diet
74 of 138
Iodine Deficiency
needed to synthesise hormone thyroxine (regulates metabolic rate) - present in seafood + some vegetables - lack = swelling of thyroid gland / goitre - in children deficiency considered largest cause of mental retardation
75 of 138
What is the way of controlling iodine deficiency?
Adding it to salt
76 of 138
Vitamin A deficiency
needed for healthy skin, good eyesight + protection against some damaging effects of toxins - orange / yellow fruits and vegetables, spinach + egg yolks - deficiency = xerophthalmia (dry eyes + night blindness)
77 of 138
What is the way of controlling Vitamin A deficiency?
Adding it to margarine via 'Vitamin A fortification' or possibly using rice as a vehicle
78 of 138
Iron Deficiency
essential part of haemoglobin - deficiency = anaemia (fatigue, brittle nails, poor endurance, lowered immunity) - found in read meats, green leafy vegetables, nuts + seeds
79 of 138
What is the way of controlling iron deficiency?
Iron fortification with Vitamin C to cereal flours + milk products
80 of 138
Vitamin B3 / Niacin Deficiency
pellagra = dermatitis, diarrhoea + dementia
81 of 138
Vitamin B1 / Thiamin Deficiency
beriberi = weight loss, fatigue + swelling
82 of 138
Vitamin C / Ascorbic acid
scurvy = bleeding gums, lowered resistance to infection + dark spots on skin
83 of 138
Vitamin D / Calciferol
rickets = softened + deformed bones
84 of 138
Selenium Deficiency
Kashin-Beck disease = atrophy + degeneration of cartilage
85 of 138
Protein deficiency
life threatening - marasmus = failure to gain weight, weight loss + emaciation - kwashiorkor = affects young children whose diet in high in starch + low in protein
86 of 138
What are some of the causes of malnutrition?
lack of distribution of global resources, depletion of nutrients in soil + water cultures, lack of education about importance of balanced diet, over-processing of food, chemical treatments in food production
87 of 138
Hormones
chemical messengers - endocrine system
88 of 138
Where are hormones produced?
Endocrine glands - secrete hormone directly into blood - circulate until reach target cells, with correct receptors
89 of 138
Pituitary gland
Anti-diuretic hormone (ADH) - short peptide - kidney tubules - increases uptake of water, raising concentration of urine
90 of 138
Thyroid gland
thyroxine - modified amino acid - all cells - regulation of basal metabolic rate, growth + development
91 of 138
Adrenal cortex
Aldosterone - steroid - kidney tubules - increases uptake of Na+ and K+ ratios in fluids, raises blood pressure
92 of 138
Adrenal medulla
Adrenaline - modified amino acid - muscles, brain, circulatory + digestive systems - raises blood glucose levels, increases rate of heartbeat + increases blood supply to heart and skeletal muscles
93 of 138
Pancreas
Insulin - protein - all cells - decreases blood glucose level by increasing uptake + utilisation by cells - increases glucose to glycogen conversion in liver
94 of 138
Ovary
oestrogen + progesterone - steroids - uterus lining - development of secondary female characteristics, control of menstrual cycle, growth + development of placenta + fetus
95 of 138
Testes
Testosterone - steroid - many parts of body - development of male secondary sexual characteristics
96 of 138
Steroid-based hormones
All have common structure (eg. sex hormones) - testosterone, oestrogen / estradiol, progesterone
97 of 138
Oral contraceptives
Prevents ovulation (release of unfertilised ovum) - contains progesterone + oestrogen - suppress secretion of other hormones
98 of 138
Female steroid hormones
Uses = contraceptive pill, medications prescribed to women at menopause (HRT - hormone replacement therapy)
99 of 138
Male steroid hormones
Androgens - testosterone = treatment of testes + breast cancer - promote tissue growth of muscles - synthetic forms used to help gain weight after debilitating diseases / Anabolic steroids = build up muscles + endurance in athletes
100 of 138
Effects of anabolic steroids
can cause many changes in secondary sexual characteristics from systemic hormone imbalances - changes in hair distribution, sexual desire + fertility - hormones are toxic to liver = liver cancer
101 of 138
Enzymes
Proteins - tertiary structure / globular - some have quaternary structure - soluble in water (exists in solution in cytoplasm of cells) - some require binding of non-protein molecules for activity (co-factors / coenzymes if organic)
102 of 138
What do enzymes do?
Are biological catalysts (reactant catalysed in reaction = substrate) - control all biochemical reactions - lower activation energy
103 of 138
How do enzymes work?
Able to form temporary binding to substrate - weak forces of attraction, forming enzyme substrate complex - occurs in active site (pocket/groove on surface of protein) - enzymes highly specific for reactions they catalyse
104 of 138
Enzyme substrate complex
Formation of complex depends on 'chemical fit' between substrate + R groups of amino acids at active site - involves hydrophobic interactions, dipole-dipole, hydrogen bonds + ionic reactions
105 of 138
What happens when the substrate has reacted?
Product no longer hits in active site, so detaches - enzyme released unchanged, so able to catalyse further reaction
106 of 138
What effects enzyme activity?
Temperature, pH + presence of heavy-metal ions
107 of 138
How does temperature effect enzyme activity?
rise in temp. = increased rate of reaction - BUT up to certain temp. (+/- 40C) - enzyme becomes denatured - increase in kinetic energy changes conformation of protein, disrupting bonds + forces - enzyme no longer able to bind to substrate
108 of 138
Denaturation
NOT digestion - irreversible - why maintaining body temperature is so important
109 of 138
How does pH affect enzyme activity?
Effects equilibrium of ionisation reactions - change in ionic charge alters attractive forces in molecule - changes shape + ability to bind to substrate - optimum pH depends on pKa + pKb values of R groups of amino acids in enzyme
110 of 138
How do heavy-metal ions affect enzyme activity?
eg. lead, copper, mercury, silver - poisonous - react with sulfhydryl (-SH) groups in side chains of cysteine residues in protein - form covalent bond w/ sulphur atom, displacing H atom - disrupts folding of protein, changing shape of active site
111 of 138
Chemical inhibitors
Affect activity of enzymes by binding to them
112 of 138
Competitive inhibitors
Bind reversibly at active site, competing w/ substrate - do not react to form products - increasing concentration of substrate reduces extent of inhibition - Vmax no altered - Km increased
113 of 138
Non-competitive inhibitors
Bind reversibly away from active site - causes conformational change in protein structure, altering active site - increased substrate concentration does not reduce extent of inhibition - Vmax decreases + cannot be restored - Km unchanged
114 of 138
DNA
deoxyribonucleic acid
115 of 138
RNA
ribonucleic acid
116 of 138
What is the role of DNA?
store information that controls genetic characteristics of organism
117 of 138
What is the role of RNA?
enable information to be expressed
118 of 138
What must DNA do?
Be very stable - able to retain precise chemical structure in cell conditions - contain some 'code' that stores genetic info - be able to replicate / produce an exact copy of itself
119 of 138
What is the structure of nucleic acids like?
Polymers = polynucleotides (monomers = nucleotides)
120 of 138
What are nucleotides made up of?
Pentose (DNA = deoxyribose / RNA = ribose) , Phosphate group + organic nitrogenous base (purines + pyridines)
121 of 138
What are the purine bases?
Adenine + Guanine
122 of 138
What are the pyridine bases?
Cytosine, thymine, uracil
123 of 138
What is DNA composed of?
A, G, C, T
124 of 138
What is RNA composed of?
A, G, C, U
125 of 138
How do nucleotides form?
Condensation reactions, releasing water
126 of 138
What is DNA?
Double helix of two polynucleotides - sugar-phospahte backbone on outside - nitrogenous base on inside - held together by hydrogen bonds between bases
127 of 138
How do the bases bond?
A - T + G - C
128 of 138
What are some of the properties of DNA?
Stability achieved by maximising hydrophobic interactions between stacked bases - sequence of bases in strand = digital code - base pairing between strands provides means for replication of code
129 of 138
What is RNA?
Simple-stranded polynucleotide - less stable than DNA - more short-lived in cells - able to cross nuclear membrane
130 of 138
What are the 3 types of RNA?
messenger RNA (mRNA), transfer RNA (tRNA) + ribosomal RNA (rRNA)
131 of 138
How is information in DNA expressed?
Through control of protein synthesis - four letter code of bases in DNA translated into code to account for 20 amino acids found in proteins
132 of 138
What are the two steps in protein synthesis?
Transcription + translation
133 of 138
How does transcription work?
2 strands of DNA separate by breaking H-bonds between paired bases (unzipping) - nucleotides assemble to form mRNA strand using DNA strand as template - mRNA detaches + leaves nucleus for ribosome
134 of 138
How does translation work?
Assembly of protein from code - tRNA molecule recognises specific triplet of bases in mRNA = codon - successive tRNA molecules bring appropriate amino acids into position, linking together by peptide bods to form polypeptide
135 of 138
Genetic code
Specific relationship between bases + amino acids - code = universal in all organisms
136 of 138
DNA replication
Occurs during cell division - molecule of DNA makes exact copy of itself - new molecules contain one strand from original parent molecule + one newly synthesised strand = semi-conservative replicaiton
137 of 138
What can DNA profiling be used for?
identify victims whose bodies are not recovered from scene of accident / crime, forensic cases to identify subject, confirm biological relationships of individuals, determine relationships between populations in study of evolution + ecology
138 of 138

Other cards in this set

Card 2

Front

Fats, carbohydrates + proteins - converted into glucose + intermediates

Back

What is energy provided by?

Card 3

Front

Structure of body (hair, fingernails, tendons, contractile structures in muscles) + tools (catalysts, enzymes, hormones)

Back

Preview of the back of card 3

Card 4

Front

Polymers - monomers are amino acids

Back

Preview of the back of card 4

Card 5

Front

Exist as zwitterions (dipolar ions), amphoteric (contain acidic and basic group), buffers (important in maintaining pH levels in cells)

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Option B: Human Biochemistry resources »