1
Q
Functions of water molecules
A
- High SHC - can absorb large amount of energy before changing temp - buffers the heat change, helps with temp regulation to prevent enzymes denaturing
- Large latent heat of vaporisation - energy lost during evaporation - absorbs large amount of energy to evaporate - temp regulation - sweating/transpiration for cooling
- Cohesion - mass flow - transpiration for cooling, surface tension allows small animals to live on it
- Universal solvent (for polar compounds) - when they dissolve, the oppositely charged particles get attracted either to H+ or O-2, hence separating the ionic compounds - transportation of substances, reaction medium
- Involved in metabolite - hydrolysis = digestion of large molecules, condensation = synthesis of molecules
2
Q
Bonding in water molecule
A
- covalent bonding
- polar -nelectrons not evenly distributed - hydrogen = positive, oxygen = negative —> uneven separation of charge is called dipole
- attraction between those forms hydrogen bonds (IMF)
3
Q
K+ ion function
A
very soluble, nerves and muscles, osmotically active (reduce water potential)
4
Q
Na+ / Cl- ions function
A
nerve impulses, sweating, secretory systems
5
Q
H+ ions function
A
cellular respiration + photosynthesis, pH balance, pumps system
6
Q
Ca+2 ions functions
A
insoluble + structurally imp, bone and teeth, calcium pectate - glue for sticking plant cell walls, flow of Ca+2 = functioning muscles
7
Q
Mg+2 ions function
A
porphyria ring in chlorophyll, bones and teeth
8
Q
Fe+2 ions function
A
porphyria ring in haemoglobin, cytochrome involving in electron transport chain in respiration
9
Q
H2CO3 ion function
A
pH buffering systems in blood
10
Q
NO3- ions function
A
AA and nucleotides, nitrogen = porphyria rings for chlorophyll/ haemoglobin
11
Q
PO4 -3 ions function
A
nucleic acids, bones + teeth, cell membranes
12
Q
Monosaccharides
A
sweet tasting
soluble -> easily to transport in blood
small -> can be easily moved in and out of the cells
less reactive -> need to be catalyzed by enzymes (controlled reaction)
(CH2O)n where n is 1-7
13
Q
Glycogen (draw + question)
A
Made of alpha glucose
fungi and animals store carbohydrates as this
fructose/maltose/sucrose absorbed -> converted into glucose -> good source of instant energy release, NOT storage -> converted to glycogen
has 1-4 glycosidic bonds and 1-6 glycosidic bonds
highly branches, very compact
insoluble, can be easily broken down
14
Q
Starch (draw + question)
A
Made of alpha glucose
insoluble
compact
can be broken down rapidly to release glucose
composed of a mix of amylose + amylopectin
stored in amyloplasts
15
Q
Amylose (draw + question)
A
Made of alpha glucose
plants use to store carbohydrates as this
has 1 - 4 glycosidic bonds
unbranches, compact
insoluble, releases energy slowly keeping you go for longer
as the chain lengthens, the molecule spirals -> coiling = makes compact, doesn’t disturb movement in the around the cell
16
Q
Amylopectin (draw + question)
A
plants store carbohydrates as this
has 1-4 glycosidic bonds and 1-6 glycosidic bonds
highly branches, very compact
many terminal glucose units that can be broken off rapidly
insoluble, can be easily broken down = releases energy rapidly
17
Q
Draw alpha and beta glucose monomers
A
check with the diagram
18
Q
Disaccharides pairs
A
Glucose + Glucose —> Maltose (stored in germinating seeds for energy)
Glucose + Fructose —> Sucrose (transported in the phloem for respiration)
Glucose + Galactose —> Lactose (mammalian milk for energy)
19
Q
How do disaccharides join together? (draw + question)
A
Condensation reaction, removal of 1 water molecule, glycosidic bonds
20
Q
How are disaccharides broken up? (draw + question)
A
Hydrolysis reaction, addition of water; takes place during digestion in the gut, muscle and liver cells when the carbohydrate stores are broken down to release sugars for respiration
21
Q
Polysaccharides
A
repeated chains of many monosaccharides joined by glycosidic bonds in a condensation reaction
ideal energy stores
very compact
physically and chemically inactive = don’t interfere with other cell functions
not very soluble = no effect on water potential
22
Q
Test with Benedict’s Solution for reducing and non-reducing sugars
A
—> reducing sugars = blue to red,
—> non-reducing = no change
- Heat non-reducing sugars with a few drops of HCl
- Allow it to cool
- Neutralise the solution with NaHCO3 to hydrolyse the glycosidic bonds
=> this produces monosaccharides = positive results
23
Q
Lipids overview
A
when oxidized in respiration, the bonds are broken -> can be used to drive the production of much ATP
good source of water for metabolic reactions
store more energy than carbohydrates for the same mass
animal fat = saturated fatty acids = packed closely = strong IMFoA => solid atp
longer chains = solid atp
plant fat = unsaturated fatty acids = push each other away = weaken the IMFoA => liquid atp
large + non-polar => insoluble - doesn’t affect the osmotic balance
thermal insulation
protecting internal organs
less dense = help aquatic animals to float
24
Q
Forming lipid molecule (draw + question)
A
made of fatty acids + glycerol (propane-1,2,3-triol - C3H8O3) = triglyceride
-> All fatty acids have a folded backbone of C-atoms with hydrogen atoms attached and a carboxyl group.
condensation reaction between carboxyl and hydroxyl groups = esterification
3 water molecules removed
combined by ester bonds
25
26
Saturated vs Unsaturated
saturated = single carbon to carbon bonds only
unsaturated = at least 1 double carbon to carbon bond
Monounsaturated - only 1 double bond
Polyunsaturated - more than 1 double bonds
27
AA structure (draw and question)
amino group (-NH2)
carboxyl group (-COOH)
alpha carbon
hydrogen atom
R group doesn’t affect the joining of AA
R group does affect the interactions of AA
28
Formation of polypeptide
formed by condensation reaction between 2 AA -> carboxyl and amine groups
join in ribosomes, under enzyme control
peptide bond is formed => dipeptide
polypeptide forms a protein after the structure of chain is coiled/shaped or joining another polypeptide
29
Hydrogen bonding in proteins
negative charge on O of the carboxyl group
positive charge on H of amine group
important for folding and coiling polypeptide
break easily
reform if pH/temp changes
30
Disulfide bonding in protein
happens when 2 cysteine (contain S) are close in polypeptide
oxidation reaction between 2 sulfur-containing groups
strong covalent bonds
imp for holding the folded protein chains in place
broken by reducing agents
31
Hydrophobic interactions between R groups
between non-polar R groups (no charge)
weakest out of all
32
Ionic bonding in protein
between positive and negative AA side chains
affected by pH
33
How keratin, blow-drying, hair curling and perming work?
Keratin -> some methods of styling hair involves changing the bonds in protein
Blow-drying -> breaks the hydrogen bonds and temporarily reforms them
Hair curling -> until the hydrogen bonds reform
Perming -> breaks the disulfide bonds between protein chains and reforms them differently permanently
34
Primary protein structure
sequence of AA that make up a polypeptide, held by peptide bonds
35
Secondary protein structure
arrangement of polypeptides into regular, repeating 3D, held together by hydrogen bonds (weak negatively charged nitrogen and oxygen atoms interact with weakly positively charged hydrogen)
-> a-helix = spiral coil with peptide bonds forming the backbone + R group protruding in all directions (between 1st and 4th AA - oxygen of carboxylate group on the 1st AA and hydrogen on 4th AA of the amine group)
-> b-pleated sheet = polypeptide chain folds into regular pleats making them parallel between parallels, held together by hydrogen bonds between amino and carboxyl ends of AA (between polypeptide strands)
-> sometimes, they form random coils
36
Tertiary structure
arrangement of a-helixes and b-pleated sheets are into further complicated shapes, hydrogen/disulfide (cysteine AA)/weak hydrophobic interactions between non-polar R groups/ ionic bonds between the R-group of nearby AA hold this 3D shapes in place
37
Quarternery structure
2 or more polypeptide chains fit together in 3D (eg enzymes/haemoglobin)
38
Globular Proteins
Specific 3D shape -> metabolically active
complex 3ry and 4ry => nature of R group determines the formation of global protein -> R group are hydrophobic (inside)/ R group which are hydrophilic (outside)
spherical shape, compact
soluble
catalytic enzymes, transport, antibodies, metabolic reaction
39
Colloid
-> suspension of molecules that are not fully dissolved
-> particles of one substance (protein) are suspended throughout another substances -> don’t settle/separate easily, they hold molecule in position in cytoplasm + immune system (antibodies, enzymes, hormones)
40
Haemoglobin
Haemoglobin - arranged in 4 polypeptide chains (2 alpha + 2 beta chains) bonded by disulfide bonding, each polypeptide chain surrounds an iron-containing heme groups (Fe 2+ to Fe 3+ when O2 is loaded) = iron enables haemoglobin to bind/release O2 (arrangement determines how easily the O2 is released/binded)
41
Fibrous Proteins
simple structure => little to no 3ry structure - more stable to changes in pH/ temp
long, parallel chains of polypeptide, occasional cross linkage = fibres
Insoluble in water, very tough
create structures, connecting tissue in tendons and the matrix of bones
42
Collagen
Collagen - fibrous protein that gives strength to tendons, ligaments and skin, often found in fibrils that are held together to form collagen fibres -> combine with bone tissue, giving tensile strength= withstand large pulling force without stretching, connective tissue; stable as the R groups of hydroxyproline and proline repel each other
Its primary structure is a repeating sequence of glycine (with simple H as an R group - hydrogen bonds) with 2 other AA - proline/ hydroxyproline (every 3rd AA is glycine (inside the polypeptide)= arranged tightly)
The 3 peptide a-chains are arranged in triple helix, held together by many hydrogen bonds
covalent bonding forms cross-links between R groups when they’re parallel to each other = FIBRILS (have staggered ends = more strength)
Its quaternary structure has 3 polypeptide chains
43
Conjugated Protein
Prosthetic Group - a molecule incorporated in a conjugated protein
joined with other molecule to serve its function
-> haemoglobin is a protein with iron as a prosthetic group
-> lipoproteins - protein conjugated with lipids
Glycoproteins - help molecules hold loads of water + make it harder for protein-digestive enzymes to break them down (e.g. lubricants in human body = slippery and viscous, reducing friction - mucus in the stomach neutralizes acid)
Lipoprotein - transport of cholesterol in blood, enabling it to combine with lipid
-> low density lipoproteins = less protein
-> high density lipoproteins = more protein (it’s compact hence dense)
44
2 diff circulatory systems?
Pulmonary circulation - all the blood vessels going to lungs
Systemic circulation - the rest of blood vessels, including the head
45
Mass Transport
Mass Transport - bulk transport of substances to all parts of organism using mass flow
Vessels
Transport Medium
Mechanism for maintaining a flow
46
Blood Composition
55% - plasma
45% - red blood cells
1 % - white blood cells + platelets
47
Plasm Function
the liquid part of the blood: helps the blood to flow + allows the substances (such as CO2, digested food and minerals, urea, hormones*, heat energy) being dissolved in it and then transported around the body
transfer heat from the tissue to the skin = temp regulation
buffer to regulate the pH
48
Platelets
the fragments of the megakaryocytes cells: they clump together to form a blood clot to stop blood loss
49
Adaptations of RBC
Biconcave disk shaped -> increase the SA for faster diffusion of oxygen
No nucleus -> more space for carrying the oxygen
Haemoglobin -> globular protein that gives the red colour; binds with iron to hold oxygen into place
50
Transport of oxygen
forms oxyhaemoglobin -> first molecule to bind changes the arrangement of molecule making it easier for the next molecules to bind (reversed: progressively harder to remove oxygen -> due to change in charge (H+) disrupts the ionic bonding hence to release oxygen)
at low oxygen level, the subunits are in a closed formation hence narrow gap (low oxygen binding affinity) hence hard to LOAD the oxygen, once that happens, there’s change in arrangement making the gaps wider hence easier to load oxygen onto heme group (high oxygen binding affinity)
51
Affected by?
Affected by: oxygen and carbon dioxide partial pressure, blood pH
-> Less CO2 in blood, less dissolved hence less acidic solution hence more alkaline so higher pH value (>8)
52
Transport of CO2
CO2 dissolves in plasma = carbonic acid formed = separates into ions
5% of CO2 in carried in plasma
10-20% combines with haemoglobin to form carbaminohaemoglobin
most is transported in the cytoplasm of RBC as HCO3-
carbonic anhydrase controls the rate of reaction between CO2 and H2O
-> check the textbook diagram
53
Fetal Haemoglobin
If the foetus’ blood would have the same oxygen affinity as mother’s blood ⇒ very little oxygen transfer
-> has a higher oxygen affinity than adult haemoglobin = can remove O2 even when the proportion of O2 is relatively low
54
Lungworm/ llama/ mice/ bird ‘s oxygen affinity
environment (lugworm (wet sand) - Hb has a high oxygen affinity, more lugworm’s Hb is saturated at low ppO2 = sufficient O2 is supplied to cells even at low O2; llama (live at high altitude - little O2 pp) - Hb has a high oxygen affinity, more lugworm’s Hb is saturated at low ppO2 = sufficient O2 is supplied to cells even at low O2)
size (mouse - large SA:V ratio, loses heat really rapidly = high metabolic rate to generate heat to maintain the body temperature => Hb has a lower oxygen affinity, more lugworm’s Hb is saturated at higher ppO2 (quick unloading of O2) = sufficient O2 is supplied to cells even at low O2)
activity (Birds/fish - Hb has a lower oxygen affinity, more lugworm’s Hb is saturated at high ppO2 (quick unloading of O2) = sufficient O2 is supplied to cells even at low O2)
55
Bohr Curve
changes in the oxygen dissociation curve that result as CO2 level changes
Curve, not a straight line because: if it’d be a line, as soon as there’s a slight drop in pressure this would immediately reduce oxygen loading, high affinity to unload where it doesn’t need to (arteriole); curve - in respiring cells = lower affinity to unload O2 faster for faster aerobic respiration
When the proportion of CO2 in the tissues is high, blood pH falls (acidification), the oxygen affinity of haemoglobin is reduced, curve is pushed to the right and down (it needs higher O2 level to become saturated and releases oxygen more freely: high CO2 level = rapid oxygen release) ⇒ CO2 builds-up which affects the pH - affects the protein structure (denatured)
56
Blood Clotting
Serotonin causes a smooth muscle of the blood vessel to contract -> narrows the BV, reduces the blood flow to the damaged area
Thromboplastin is an enzyme that starts a sequence of chemical changes that clot the blood
Vitamin K is important for the production of multiple chemicals, needed for clotting
Thromboplastin catalyses the conversion of prothrombin (inactive, in plasma) into thrombin (soluble, in plasma, active) -> prothrombin is a precursor of thrombin, calcium ions needed
Thrombin acts on fibrinogen (soluble plasma protein) converting it into fibrin (insoluble) ⇒ fibrin forms a mesh of fibres to cover the wound
More platelets and RBC get trapped in a clot
Special proteins in the structure of platelets contract, making the clot tighter and tougher to form a scab
This prevents the blood loss and the entry of pathogens into the body
57
Artery Structure
arteries take oxygenated blood away from the heart (ex. pulmonary + umbilical artery)
thick layer of smooth muscles to create high pressure + withstand the pressure to ensure the blood reaches its destination (receives blood from LV that’s under high pressure)
elastic fibre to withstand high pressure without bursting + recoil to push the blood further
narrow lumen to maintain high pressure
arterioles help with temp regulation, peripheral arteries are before arterioles at a lower pressure
58
Vein structure
veins take deoxygenated blood to the heart (ex. pulmonary + umbilical vein)
thin layer of smooth muscles because no need to withstand high pressure
Semilunar valves to prevent the backflow of blood (made from inner infolding of the vein)
large lumen because no need to maintain high pressure + carry large volume of deoxygenated blood
as the pressure from the heart is lost, the muscles create this pressure by contracting to push the blood up
59
Capillary Structure
penetrate deep into the tissue
can carry 1 RBC at a time
Basement membrane made of endothelium cells is one cell thick -> efficient diffusion
very small lumen
60
Why do humans have double closed circulatory system?
Double closed circulatory system - mass transport system - double (each RBC enters the heart twice in one circuit = pulmonary system and systemic system) + closed (blood flows inside the blood vessels) —> pressure can be increased to make blood flow faster, flow can be directed more precisely to the organs needed
61
Heart Structure
enclosed by pericardium (tough tissue covering the organ itself)
pericardial liquid is secreted to aid movement
protects the heart from over expansion
has myoglobin in the muscle cells (higher oxygen affinity than fetus haemoglobin - stores oxygen for respiration for the heart)
Heart Walls - made of myocardium (cardiac muscle)
never tires, but cant do anaerobic respiration
only found in the heart
62
Structure of valves/ walls/ arteries/ ventricles/ septum
Outer muscular wall contracts to pump the blood, hence it’s thicker on the left side because it needs a greater pumping force to send the oxygenated blood all around your body + to create a higher pressure
Outer muscular wall is thinner on the right side because it needs to pump to the deoxygenated blood to the lungs, which are nearby hence smaller pumping force is required + the great pressure would damage delicate alveoli
Septum muscle separates the right and left sides of the heart to keep the oxygenated and deoxygenated blood the same
Atria have thinner walls than ventricles because they only need to pump blood into the ventricle (gravity helps)
Tricuspid valve = 3 flaps, bicuspid = 2 flaps, tough tendinous cords make sure the valves don’t turn inside out by pressure exerted when the ventricles contract
63
Pathway of RBC
Interior and superior vena cavas bring deoxygenated blood to the heart. The blood goes into the right atrium from great veins, pressure builds up, the blood moves through the tricuspid valve into the right ventricle and then RA contracts to fill it more. Then RV contacts and the blood comes into the pulmonary artery through the semilunar valve. The blood goes into the lungs, where it gets oxygenated and comes back through the pulmonary vein into the left atrium, then LA contracts and the blood moves into the left ventricle through the bicuspid valve. From there it gets pumped by the LV to enter the aorta through the semilunar valve. Then, the blood moves through other arteries to the organs (e.g. renal artery), where the diffusion of oxygen happens, the deoxygenated blood moves up the veins (e.g. renal vein). Then, it enters the inferior/ superior vena cava.
64
Cardiac Cycle
A series of contractions and relaxations that occur in the heart during 1 heartbeat
Systole - period of contraction
Diastole - period of relaxation
Diastoles: All muscles in relaxation, all valves closed, pressure in arteries >ventricles, pressure in veins > atria => blood flows in via veins (forces AVV to open - flows in passively)
Atrial Systole: Atria in contraction, AV valves open, blood coming into ventricles (pressure is greater in A than in V)
Ventricular Systole: Ventricles in contraction, AV valves close to prevent tha back flow of blood, SL valves open, blood coming into arteries (pressure is greater in V than in A)
65
Why is excessive oxygen supply crucial for heart function?
The heart muscles need to undergo a large amount of aerobic respiration in order to contract and relax (they can’t do anaerobic) hence they need to have a good supply of oxygen and glucose - these are supplied by coronary arteries. If there’s lack of blood supply, muscle cells don’t respire hence the heart muscle cannot contract => heart attack
66
Plaque Formation
Plaque = Atheroma - fatty deposits (mostly fat, but also cells, amino acids, etc)
Once damage to the endothelium has occurred, the body’s inflammatory response begins and WBC arrive to site
They accumulate the chemicals in the blood, esp cholesterol = form an atheroma on the endothelial lining of the artery
Ca 2+ ions and fibrous tissues also build up around the atheroma = artery wall is less elastic and more narrow
67
Aneurysms
when an area is narrowed, blood tends to collect behind the plaque hence artery budges and the wall is put under more pressure = weakens
may split open, leading to massive internal bleeding (brain, aorta, abdomen = fatal)
68
Raised blood pressure
plaque narrowing the BV leads to raised BP
this exerts more force on the BV walls
can lead to bleeding and incorrect ultrafiltration => stroke
69
CVD: angina
Angina - plaques slowly buildup, reduce blood flow beyond the plaque -> narrowed coronary arteries can’t supply enough oxygen for aerobic respiration = starts anaerobic
-> gripping pain in chest, causes breathlessness during exercise
=> regular exercise, drugs to dilate the arteries, small tube called STENT is inserted into BV to keep it open, STATINS - reduces the cholesterol production in the liver
70
Raised blood pressure
plaque narrowing the BV leads to raised BP
this exerts more force on the BV walls
can lead to bleeding and incorrect ultrafiltration => stroke
71
CVD: myocardial infarction
Myocardial Infarction (Heart Attack) - plaques slowly buildup + artery wall damage = clotting (thrombosis) ⇒ once detached, thrombosis can easily block the artery that’s been narrowed by plaque == blocked BV supplies NO oxygen hence muscles starves
-> severe gripping pain in chest for several hours, no prior symptoms
=> 2 full strength aspirin tablets to stop the blood clotting and to the hospital ASAP
72
Stroke
interruption of normal blood supply to the brain
bleeding from damaged capillaries/ blockage (atheroma/clot)
-> dizziness, confusion, blurred vision, numbness, paralyses
=> go to hospital ASAP, non-clotting drug to stop clotting/ dissolve existing one
73
Define “Risk” and “Risk factors”
Risk - probability that an event will happen (likelihood calculated mathematically)
Risk Factors - factors that affect the risk of an event happening (look at ppl who have the same factors and compare their risk of the disease with an average risk for the whole population)
74
Define “Correlation” and “Causation”
Correlation - a strong tendency for 2 sets of data to change together
Causation - when a factor directly causes a specific effect
75
How do we perceive risks?
Overestimate - drain of medical resources, stress, intake of unnecessary medication, deficiency and malnutrition, misdiagnosis
Underestimate - no change in lifestyle, financial burden, promoting (misinformation), comparison
76
How do we judge risks?
how familiar you are with an activity
how much you enjoy the activity
whether or not you approve of the activity
overestimate the benefits and underestimate the costs
risk applies to an average of the group, not me
ppl who do “bad stuff” but appear health looks more convincing than studies done
77
Longitudinal vs Meta-analysis
Longitudinal Studies - studies that follows the same group of individuals over many years -> the impact of their known lifestyle on their health can be tracked over time
Metadata Analysis - scientists looking at available studies in a subject area and analyse the available data in a massive literature study (more reliable)
78
Stroke
interruption of normal blood supply to the brain
bleeding from damaged capillaries/ blockage (atheroma/clot)
-> dizziness, confusion, blurred vision, numbness, paralyses
=> go to hospital ASAP, non-clotting drug to stop clotting/ dissolve existing one
79
How do we judge risks?
how familiar you are with an activity
how much you enjoy the activity
whether or not you approve of the activity
overestimate the benefits and underestimate the costs
risk applies to an average of the group, not me
ppl who do “bad stuff” but appear health looks more convincing than studies done
80
Evaluating scientific papers
Biased?
Valid (an investigation is well designed to answer the questions being asked)?
Precise (measurements with only slight variation between them)?
Reliable (evidence that can be repeated by diff scientists)?
81
Control group
a group that doesn't modify their lifestyle to use for comparison
a group that takes the placebo (drug with no active ingredient)
82
NMRF for atherosclerosis development: genetics
Genetics -> genetic tendency in some families and ethnic groups to develop CVD (specific alleles) such as arteries that are easily damaged, hypertension causing arterial damage and problems with the cholesterol balance of the body; some alleles are beneficial = higher HDLs level
83
NMRF for atherosclerosis development: age
Age -> as you get older, your blood vessels lose their elasticity and narrow slightly => raised BP
84
NMRF for atherosclerosis development: gender
Gender -> mean are more likely to suffer CVDs => oestrogen which is an imp factor in menstrual cycle, appears to reduce the build-up of plaque, increases the blood flow to muscles + have higher levels of HDLs - this gives women protection against CVs until they reach menopause
85
What is Control group
a group that doesn't modify their lifestyle to use for comparison
a group that takes the placebo (drug with no active ingredient)
Biology AS
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