Molecules, Transport & Health Flashcards
1
Q
What state is water at normal temperatures?
A
Liquid
2
Q
Describe hydrogen bonding in terms of water.
A
A water molecule contains two
hydrogen atoms and one oxygen atom held together by hydrogen bonds.
3
Q
Describe water as a solvent and its significance.
A
Water is an effective solvent because of it’s polarity and so can form electrostatic interactions with other polar molecules and ions.
Thus it is a transport
medium and reagent for metabolic and other reactions in plant/animal cells.
4
Q
Describe water’s high surface tension and cohesion.
A
Cohesion refers to the attraction of one water molecule to each other.
Water molecules have strong, cohesive forces due to hydrogen bonds, thus having high surface tension
5
Q
Describe water’s high specific heat capacity and its significance
A
The amount of heat energy required to raise the temperature of 1 kg of water by 1 °C. Water has high SPC due to its hydrogen bonds.
The temperature within organisms remains constant compared to external temperature, and water bodies also have a slow change in temperature, providing stable aquatic habitats.
6
Q
Describe water’s high latent heat of vaporisation and its significance.
A
A measure of the heat energy needed to vaporise a liquid. Water has a high LHV due to its high SPC as H bonds need to be broken before water can be vapourised, cooling the surrounding environment. Sweating is a good cooling mechanism.
7
Q
Describe water’s density and freezing properties and their signicance.
A
Ice is less dense than water and floats on it, insulating water and preventing it from freezing, preserving aquatic life underneath it.
Changes in the density of water with temperature causes currents, which helps to maintain the circulation of nutrients in the oceans.
8
Q
What are monosaccharides made of?
A
Carbon
Hydrogen
Oxygen
9
Q
What is the general formula for monosaccharides?
A
Cn(H2O)n where “n” represents the number of carbon atoms.
10
Q
State one structural advantage of monosaccharides.
A
They are able to be broken down quickly by living organisms to produce ATP energy.
11
Q
State 4 properties of monosaccharides.
A
Sweet
Soluble in water
They have an osmotic effect
Crystalline in nature
12
Q
Give 3 examples of monosaccharides.
A
Alpha-glucose
Fructose
Galactose
13
Q
How do disaccharides form?
A
When two monosaccharides join in a condensation reaction, releasing a water molecule.
14
Q
What is the name of the bond formed between two monosaccharides?
A
Glycosidic bond
15
Q
How is maltose formed?
A
Alpha-glucose + alpha-glucose
16
Q
How is sucrose formed?
A
Alpha-glucose + fructose
17
Q
How is lactose formed?
A
Alpha-glucsoe + galactose
18
Q
Descrobe maltose.
A
Broken down by Maltase enzyme
Contains 1,4 glycosidic bond
19
Q
Describe sucrose.
A
Broken down by Sucrase enzyme
Contains 1,2 glycosidic bond
20
Q
Describe lactose.
A
Broken down by Lactase enzyme
Contains 1,4 glycosidic bond
21
Q
How can disaccharides be broken down?
A
In a hydrolysis reaction using a water molecule.
22
Q
What are polysaccharides?
A
Made up of monomers joined together by glycosidic bonds.
23
Q
State 5 properties of polysaccharides.
A
They are macromolecules with a large molecular mass
Formed from a large number of monomers
Contains Glycosidic bonds between monomers
No sweet taste
No Osmotic effect/insoluble in water
24
Q
What is starch?
A
A polysaccharide that is found in plant cells and is made up of two components, amylose and amylopectin.
25
What are amylose and amylopectin made of?
Alpha-glucose and contain glycosidic bonds.
26
Describe 2 features of starch.
Highly compact
| Stores energy
27
Describe structure and shape of amylose.
1,4 glycosidic bonds
| Helical and more compact
28
Describe structure and shape of amylopectin.
1,4 and 1,6 glycosidic bonds, giving it’s branched structure.
Branched
29
What is glycogen?
A polysaccharide that is used for the storage of energy is animal cells and is also made from a glucose molecules.
30
Describe the structure of glycogen.
The structure of glycogen is very similar to that of amylopectin. However, it is much more branched, allowing it to be hydrolysed rapidly.
31
How do triglycerides form?
Forms by the condensation of 3 fatty acid chains and one glycerol molecule, forming ester bonds.
32
What are fatty acid chains?
Long hydrocarbon chains with a
| carboxylic head.
33
What is glycerol?
An alcohol-containing 3 OH groups.
34
Describe unstaturated fatty acids.
Atleast 1 C=C double bond
Contains bent chains(kinks)
Lower H:C ratio
35
Describe saturated fatty acids
No C=C double bond
Straight chain
Higher H:C ratio
36
What do kinks in unsaturated fatty acids cause?
Melting point to decrease due to weaker intermolecular bonds.
37
What are 3 roles of triglycerides?
Better energy reserves than carbohydrates as more CH bonds
Acts as an insulator and provides buoyancy
A metabolic source of water as gives CO2 and H20 on oxidation in respiration
38
What are proteins made of?
Made of amino acids which only differ in the R- groups/ variable side chains and will always contain an amine group (basic), carboxyl group (acidic) and a hydrogen atom attached to the central carbon atom.
39
How is a peptide bond formed?
Formed by condensation between 2
| amino acids, forming a dipeptide. Many amino acids that join together by peptide bonds form a polypeptide.
40
How are peptide bonds broken down?
Broken when hydrolysed into amino acids.
41
Describe the primary structure of proteins.
The sequence of amino acids held
| together by polypeptide bonds in a polypeptide chain.
42
Describe the secondary structure of proteins.
The structure of a protein molecule resulting from the regular coiling or folding of the chain of amino acids.
43
What does alpha-helix refer to?
The polypeptide chain twists into a regular spiral and is maintained by hydrogen bonds between the (-NH) group of one amino acid and the (CO-) group
44
What does beta-pleated sheet refer to?
The chain is not tightly coiled and lies in a looser, straighter shape.
45
Describe the tertiary structure of proteins.
The precise folding and coiling of alpha-helices and beta-pleated sheets of an amino acid chain.
46
Describe how alpha-helices and beta-pleated sheats in an amino acid chain are held together.
- Hydrogen bonds between a wide variety of R- groups
- Disulfide bridges between two cysteine molecules
- Ionic bonds between R groups containing amine and carboxyl groups.
- Hydrophobic interactions between non-polar R groups.
47
Describe the quaternary structure of proteins.
The three-dimensional arrangement of two or more polypeptides, or a polypeptide and a non-protein component such as haem, in a protein molecule. The polypeptide chains
are held together by bonds in the tertiary structure.
48
Describe globular proteins.
Curl up into a spherical shape with
their hydrophobic regions pointing into the centre of the molecule and hydrophilic regions pointing outwards.
They are soluble in water.
49
Give two examples of globular proteins.
Enzymes
| Haemoglobin
50
Describe fibrous proteins.
Form long strands, are insoluble in
| water and have structural roles.
51
Give 3 examples of fibrous proteins.
Collagen
Hair
Nails
52
Describe haemoglobin.
Globular protein that has a quaternary
structure with 4 polypeptide chains, 2 a-globin and 2 ß-globin chains, each connected by disulfide bridges. Each chain has one prosthetic haem group containing an iron atom that reversibly binds to an oxygen molecule. Oxyhemoglobin is bright red when the haem group iscombined with oxygen. Otherwise, it is purplish.
53
What is haemoglobin an example of?
A conjugated protein.
54
Why is diffusion a sufficient way for gaining nutrients and excreting waste in small organisms?
The short distance of diffusion between the deepest part of the organism and the outside
The high SA:V ratio allowing for fast diffusion
Usually, small organisms have a low metabolism.
Therefore, they don't use much oxygen and food
55
Why are larger organisms unable to rely on diffusion?
Low SA:V ratio
56
How do larger organisms overcome these limitations?
They have a transport system that carries substances by mass flow from one part of the body to another.
They increase the surface area of parts of the body involved in an exchange with the environment, e.g. alveoli
57
What are the features of mass transport?
A medium of transport, e.g. blood
A system of vessels
A pump
A way to ensure substances moved in the right direction
58
Describe the mammalian circulatory system.
Closed double circulation. This is because blood passes through the heart twice in one circulation of the body (pulmonary circuit and systemic circuit), contained inside blood vessels.
59
What are the advantages of a double circulatory system?
Maintaining different pressures to the lungs and the rest of the body. The lungs require a low blood pressure to prevent damage to the capillaries in the alveoli, while the rest of the body requires a high blood pressure to provide blood to all tissues.
Maximise the rate of diffusion by sending deoxygenated blood to the lungs and sending oxygenated blood to the rest of the body. This creates a steep concentration gradient which increases the rate of diffusion.
60
What 4 components is blood composed of?
Plasma
Leukocytes(WBC)
Platelets
Erythrocytes(RBC)
61
Describe plasma.
This is the liquid part of the blood. It is a dilute solution of salts, glucose, amino acids, vitamins, urea, protein, and fats.
62
Describe leukocytes.
Involved in the immune system.
63
Describe platelets.
Involved in blood clotting.
64
Describe erythrocytes.
Involved in carrying oxygen and carbon dioxide.
65
Give 3 adaptations of RBCs.
Biconcave, allowing for a greater surface area to volume ratio to carry oxygen.
No nucleus or mitochondrion, allowing more space for haemoglobin.
Small diameter to allow it to squeeze through capillaries.
66
Describe haemoglobin.
Is a red oxygen-carrying pigment (found in RBCs and is a globular protein. It is made of 4 polypeptide chains each containing an iron ion.
67
Describe what happens in respiring tissues.
-The pCO2 is high, and the pOis
low.
-CO2, from the cells diffuses into the plasma.
-CO2, combines with Hb to form
carbaminohaemoglobin (10% carried this way)
-Most CO2 combines with water (catalysed by carbonic anhydrase) to form carbonic acid, which then dissociates into H+ and HCO3- ions.
-H+ ions combine with Hb to form Haemoglobinic acid(HHb)
68
Describe what happens in the lungs.
- pO2 is high and pCO2 low
- CO2, in plasma diffuses from the blood into the alveoli, and oxygen diffuses into the blood from the alveoli.
- Carbaminohaemoglobin dissociates to form CO2, and Hb
- Hb then picks up O2, and HHb (haemoglobinic acid) dissociates to form H+ and Hb.
- The H+ ions combine with HCO3 to form carbonic acid, which dissociates to form CO2, and water (catalysed by carbonic anhydrase).
- CO2, diffuses into alveoli.
69
Describe the Bohr effect.
The presence of a high pCO2 causes Hb to release oxygen. High pCO2, are
found in actively respiring tissues that need oxygen. This causes Hb to release oxygen even more readily than it would otherwise.
70
Describe fetal haemoglobin.
It is present in the blood of a developing fetus. It has a higher affinity to oxygen compared to adult haemoglobin. Allowing it to ‘absorb' oxygen from the mother's blood, ensuring proper growth
71
Describe the blood clotting mechanism.
- Upon injury, the platelets break!
- This releases several chemicals that aid in the blood clotting process, causing a cascade of reactions.
- Seretonin
- Thromboplastin
- Prothrombin and Thrombin
- Thrombin to Fibrinogen to Fibrin
- Fibrin
72
What is the role of Serotonin?
Is a chemical that causes smooth muscles to contract, narrowing blood vessels.
73
What is the role of thromboplastin?
Is a globular protein that catalyses the reaction of prothrombin to thrombin in the presence of Ca2+ ions
74
Describe prothrombin and thrombin.
Are both soluble globular proteins in the blood. Prothrombin is present in the plasma.
75
What is the role of thrombin?
Catalyses the reaction of Fibrinogen to Fibrin
76
What is the difference between fibrinogen and fibrin?
Fibrinogen is a soluble globular protein, while Fibrin is an insoluble protein.
77
What is the role of fibrin?
Forms a mesh-like structure that traps red blood cells allowing the clot to dry up and form a scab.
78
State 2 benefits of blood clotting.
Preventing excess blood loss
| Preventing the entry of pathogens
79
Give 2 vessel adaptations.
- Tough collagen fibre wall prevents it from bursting
| - Elastic fibres allow it to stretch and recoil, maintaining blood pressure
80
Give 4 artery adaptations.
-Smooth endothelium lining reducing
resistance
-Small lumen aids to maintain high pressure
-Smooth muscles constrict and dilate to keep the blood at a high pressure
-Large lumens to carry more blood
81
Give 2 vein adaptations.
-Thins walls allowing skeletal muscles to
compress and pump blood towards the heart
-Valves to prevent backflow of blood
82
Give 4 adaptations of capillaries.
-Narrow allowing it to reach tight places
-Forms a dense network increasing the surface area
-Pores allowing substances to move in and out of tissue fluid
-Thin wall making it permeable to small
substances
83
Describe the external structure of the mammalian heart.
-Blood vessels that leave the heart
are the Aorta and pulmonary artery. -Blood vessels that enter the heart are the superior vena cava, the inferior vena cava, and the pulmonary vein. The septum separates the left and right sides of the heart.
84
Describe the internal structure of the mammalian heart.
- The human heart has four chambers.
- 2 upper chambers are known as atria.
- 2 lower chambers are known as ventricles.
85
Describe the atria.
They are thin-walled and receive blood at low pressure.
86
Describe the ventricles.
They are thick-walled, receive blood from atria, and pump it out through arteries.
87
State one difference between the left and right ventricle.
The left ventricle has a thicker muscular wall, as it has to pump blood into the systemic circuit, which has a higher resistance to blood flow than the pulmonary circuit.
88
Give 2 benefits of blood clotting.
- Preventing excess blood loss
| - Preventing the entry of pathogens
89
What 3 three layers of tissues make up arteries and veins?
Tunica intima, tunica media, and tunica adventitie
90
Describe the tunica intima.
Endothelium, smooth lining allowing
| the easiest possible blood flow
91
Describe the tunica media.
Containing mainly smooth muscle and
| elastic fibres with some collagen
92
Describe the tunica adventitia.
Containing, mostly collagen, with
| some elastictibres.
93
Describe the features of arteries.
These blood vessels transport oxygenated blood swiftly to the tissues at high pressures. They have thick walls to withstand this high pressure. The exception to this is the pulmonary artery, carrying deoxygenated blood to the lungs. As arteries reach tissues, they branch into smaller vessels called arterioles.
94
Describe the features of veins.
Many capillaries join to form venules, which then join to form veins. These blood vessels carry deoxygenated blood back to the heart. The exception is the pulmonary vein, carrying oxygenated blood from the lungs to the heart.
95
Give 4 differences between veins and arteries.
- Tunica media is thinner in veins when compared to arteries, as the blood in veins is at a lower pressure.
- Valves are also present to prevent the backflow of blood.
- To keep blood flowing upwards from legs, veins are usually near muscles, so the pressure is increased when muscles contract.
- Veins also have a much larger lumen than arteries.
96
Describe the features of capillaries.
Arterioles continue to branch into capillaries. These are the smallest blood vessels and they take the blood as close as possible to the cells. This allows for rapid transfer of substances between cells and the blood. Due to the very small diameter of these blood vessels, blood travels very slowly. This increases the opportunity for diffusion to occur.
97
Give one adaptation of capillaries.
Walls of capillaries are made of a single layer of endothelial cells with pores between individual cells present to allow some components of blood to pass
through into the cells and tissues of the body.
98
Describe the tissue fluid.
It has almost the same components as
plasma but lacks large plasma proteins that are too large to diffuse through pores in capillaries. Osmotic pressure causes tissue fluid to move into and out of capillaries
99
State the 3 stages of the cardiac cycle.
Atrial systole
Ventricular systole
Diastole
100
Describe atrial systole.
This occurs when muscles in the atria
contract and blood passes on to the ventricles. 70% of the blood flows passively down to the ventricles. The
bicuspid and tricuspid valves open while the semilunar valves are closed.
101
Describe ventricular systole.
After Atrial Systole, the ventricles
contract increasing the blood pressure and pushing it out of the heart. The blood passes through the Aorta and pulmonary arteries. The semilunar valves open and the bicuspid and tricuspid valves are closed.
102
Describe diastole.
All muscles of the heart relax, and the
pressure inside ventricles becomes lower than the atria. When this happens, most of the blood starts to flow from the atria to the ventricles even though the atria is not contracting. However, the atria contracts towards the end to push out the last bit of blood into the ventricles, and the cycle begins all over again.
103
What is atherosclerosis?
It is a disease in which artery walls are
| caused to harden. It could eventually lead to coronary heart disease (CHD).
104
Describe the process leading to atherosclerosis.
- Endothelium lining is damaged due to several reasons like high blood pressure and smoking
- The damage to the endothelium lining causes an inflammatory response
- This causes a buildup of cholesterol and calcium salt,forming plaque after hardening
- Plaque causes the narrowing of the lumen, which restricts blood flow. Causing an increase in blood pressure
- Reduced blood flow causes decreased oxygen supply to tissues, resulting in anaerobic respiration
105
Give 2 examples of cardiovascular diseases.
Hypertension
| Coronary thrombosis
106
Define hypertension.
A rise in blood pressure caused by the
| formation of plaque in arteries
107
Define coronary thrombosis
Platelets could stick to a damaged artery wall, causing it to release Thromboplastin, which starts a cascade of reaction, forming a blood clot
108
What is epidemiology?
The study of disease patterns to find a
| correlation between a disease and certain risk factors.
109
What is meant by ‘risk’?
The probability of damage occuring
110
What is meant by ‘actual risk’?
Factors increasing the probability of getting a disease
111
What is meant by percieved risk?
- Overestimating the risk of something happening due to the unfamiliarity of the risk
- Underestimating the risk of something happening due to it being in the far-future
112
What are multifactorial diseases?
A disease caused by interactions of multiple factors.
113
What is causation?
When a change in 1 variable is responsible for a change in another variable.
114
What is correlation?
When a change in 1 variable is reflected by a change in another variable.
115
What 2 factors need to be checked when evaluating studies?
Validity
| Reliability
116
Describe validity.
Weather the experiment fulfils the intended question.
- Peer-review makes a study valid
- Randomly selecting samples to avoid bias
117
Describe reliability.
Similar results come back when the
experiment is repeated. You can increase reliability by:
-Having a large sample size
-Repeating the experiment under the same conditions
118
Give 6 risk factors of CVDs.
- Genetic factors
- Age
- Gender
- Smoking
- Inactivity
- Hypertension
119
Describe gentic factors in terms of risk factors for CVDs.
```
When there is a trend in the family to
develop CVD. Some reasons include:
- Problems in balancing cholesterol
- Tends to develop hypertension
- Easily damaged endothelium lining in the artery
```
120
Describe age in terms of risk factors for CVDs
The older a person gets, the less elastic their arteries become. Therefore, there is a higher chance of them getting damaged, leading to CVD.
121
Describe gender in terms of risk factors for CVDs
Oestrogen in females lowers the levels of cholesterol in the blood, reducing the buildup of plaque. This is why females have a lower risk of experiencing CVDs compared to males.
122
Describe smoking in terms of risk factors for CVDs
Nicotine present in smoke causes the
narrowing of arteries, which raises the blood pressure leading to damaged endothelium lining. Free radicals formed by smoking increase the activation of platelets, increasing the risk of blood clots.
123
Describe inactivity in terms of risk factors for CVDs
When the energy input is greater than the energy output, it causes the body to convert the extra energy to fat, eventually leading to obesity. Regular
exercise strengthens the heart muscles, which decreases blood pressure.
124
Describe hypertension in terms of risk factors for CVDs
If a person has a blood pressure higher
than 120mmHg/80mmHg regularly, it's a sign of atherosclerosis. When the artery's lumen decreases by the formation of plaque, it increases the blood pressure.
125
What is the role of obesity indicators?
Help raise awareness to individuals
| that might be at a high risk of CVDs
126
What is body mass index(BMI)?
A conventional scale that determines if you have a healthy weight by comparing your weight and height. BMI doesn't differentiate between muscle and fat; therefore,it can be misleading
127
What is the waist-to-hip ratio?
It is a scale that's showing active
association with the increased risk of CVDs. It is the waist circumference measured in cm divided by the hip
circumference also measured in cm.
128
Describe diuretics(antihyperintensives).
Increase the volume of urine produced, causing the blood volume to decrease therefore the blood pressure falls
129
Describe beta-blockers(antihyperintensives).
Blocks hormones like adrenaline to prevent strong contractions.
130
What are the side effects of antihyperintensives?
Dizziness, nausea, impotence
131
Describe statins.
They work by inhibiting the function of the enzyme in the liver responsible for producing LDLs
132
What are the side effects of statins?
Liver damage, kidney failure, nausea
133
Describe anticoagulants(warfarin).
Prevents blood clot formation in the artery.
134
What are the side effects of anticoagulants(warfarin)?
Could result in uncontrolled bleeding if dosage is not monitored
135
Describe platelet inhibitory drugs(aspirin).
They work by reducing the stickiness of platelets, which reduces the chance of blood clot formation.
136
What are the side effects of platelet inhibitory drugs(aspirin)?
Rashes, diarrhoea
137
Describe High-Density Lipoproteins(HDLs).
They are considered good cholesterol, must be maintained in high proportions
Formed from unsaturated fats, protein, and cholesterol
They have a higher percentage of protein compared to LDLS
138
Describe Low-Density Lipoproteins(LDLs).
- They are considered bad cholesterol, must be maintained in low proportions
- Formed from saturated fats, protein, and cholesterol
- An increase in intake of saturated fats causes an increase in blood cholesterol, due to the rise in LDLs produced. Therefore, there is a causal link between LDL levels and the risk of CVD.
139
Describe dietary antioxidants.
They help reduce the risk of CVDs by oxidising free radicals formed by oxidative stress.
Vitamin C, an antioxidant, ensures a firm attachment of the endothelium lining.
