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Ch. 5 Food and Energy
mode of nutrition - Heterotrophic nutrition - taking in organic substances. (Heterotrophs - the organism)
Functions of food : - maintain (维持) life.
- supply energy (by carbohydrates(碳水化合物), fats, proteins)
(energy value (能量值) ratio of carbohydrates : fats : proteins = 1 : 2 : 1)
(energy content determined by burning the food to heat up fix amount of water)
- provide materials for growth and repair (修补) ( by proteins)
Types of food: carbohydrates, fats (for energy),
proteins (body building),
vitamins, minerals (maintain health),
dietary fibre (roughage) (gut peristalsis),
water (maintain life).
Carbohydrates- elements (元素): C, H, O ( in ratio (比例) of H : O = 2 : 1 )
- 3 types: - monosaccharides (单糖类):
- molecular formula (公式) : C6H12O6
eg. glucose (葡萄糖), fructose (果糖), galactose (半乳糖).
- disaccharides (双糖类): (2 monosaccharides combine together with one water molecule lost)
molecular formula : C12H22O11 (2 C6H12O6 - H2O ( C12H22O11 )(condensation)
(C12H22O11 + H2O 2 C6H12O6 )(hydrolysis)(a digestion process in our body)
eg. maltose (麦芽糖) ( 2 glucose molecules )
eg. sucrose (蔗糖) ( non-reducing sugar )
eg. lactose (乳糖)
all monosaccharides and disaccharides are reducing sugars (还原糖) except sucrose.
- polysaccharides (多糖): (NOT sugar)
store energy.
eg. starch (store energy in plants)
eg. glycogen (糖原)(肝糖) (store energy in animals)
eg. cellulose (纤维素) (component (成分) of cell wall)
excess (多馀的) carbohydrates - stored as glycogen in liver & muscles
- stored as fats under skin (subcutaneous fats)
Lipids ( fats & oils ) - elements : C, H, O
- basic components (成分)( building blocks): glycerol (甘油) & fatty acids (脂肪酸)
- functions - give energy
- form fatty tissues under skin - to keep warm
- to store energy
- transport fat-soluble (油溶性) vitamins (A, D, E, K)
Proteins - elements: C, H, O, N some with S, P
- basic components: amino acids (氨基酸).
- Amino acids combine (结合) together to form dipeptides (双氨基酸组) & polypeptides (poly=多)
- cannot be stored - excess amino acids (from proteins) are deaminated (deamination [n])(de=去除) by liver
- a part of the product is changed to urea (尿素) which will be
excreted (排泄) away by kidney
- another part (the carbon skeleton) is changed to carbohydrates (glycogen)
which will be stored in liver and muscle cells.
(so, excess amino acids are not "no use", the carbon skeleton can further provides energy as it is
transformed (转化) into carbohydrates and fats.)
- essential amino acids: must be intake from food.
non-essential amino acids: can be produced by our body (by transforming from other amino acids).
- functions - provides materials for growth and repair of the body.
(acts as structural (结构的)components of cells )
- produce hormones (荷尔蒙) and enzymes (酵素)
- give energy (only by protein in food, NOT by structural (结构) protein in tissue cells)
Vitamins - water soluble (水溶性) vitamins (B, C)
- fat soluble (油溶性) vitamins (A, D, E, K) - take in excess (过多) amount will cause harm to our body.
Dietary fibres (纤维) (roughage)(cellulose) - stimulate peristalsis (蠕动) of gut (alimentary canal)
Deficiency Diseases (vitamins, minerals & dietary fibre):
Vitamins
Deficiency Diseases
A
night blindness
C
scurvy (坏血病) (bleeding gum)
D
rickets (软骨病) (weaken bones)
calcium
rickets
iron
anaemia (贫血) (low haemoglobin level )
dietary fibre
constipation (便秘)
Notes: - rickets (NOT: ricket)
Food Tests
Substance
Tests
Original Colour
Positive Results
reducing sugar (eg.glucose)
Benedict's test
blue
orange precipitate (沈淀物)
starch
iodine test
brown
blue-black
protein
biuret test
blue
violet solution
fats/oils
spot test
translucent spot (半透明小滴)
fats/oils
emulsion test
clear
milky emulsion (乳剂) (oil droplets)
vitamin C
DCPIP test
blue
colourless solution (decolorize)
Notes: - Benedict's test requires heating (There is a Benedict's solution).
- glucose can also be tested by Clinistix paper: colour changes: ( red ( purple )
protein can also be tested by Albustix paper: colour changes: ( yellow ( green )
- Biuret's test: addition of sodium hydroxide (NaOH) solution, then add little copper sulphate solution.
(There isn't a Biuret's solution.)
- emulsion test: addition of absolute alcohol first, shake well to get a clear solution, add little water and
shake well to get a milky emulsion.
- Vitamin C should be dropped onto DCPIP solution (dichlorophenol indophenol) drop by drop.(NOT reverse)
- iodine is not for testing starch, but iodine solution. (iodine solution is iodine dissolved in potassium iodide)
- a positive Benedict's test does not imply the present of glucose, it only indicates reducing sugar.
- spot test should be futher proved by dissolving the oily spot in organic solvents (eg. alcohol).
- absolute alcohol (ethanol) is highly flammable (易燃的). DCPIP is toxic and corrosive.
(Design an experiment to compare the amount of vitamin C in different fruits and vegetables.)
The balanced diet - have enough food to supply enough:
1. energy (carbohydrates, fats, proteins)
2. body building material (protein)
3. substances to maintain (维持) health (vitamins, minerals)
- not balanced diets for long time : malnutrition (营养不良) (mal = 不正常)
eg. anorexia nervosa & anorexia bulimia (神经性厌食症与贪食症)
Food pyramid: sugar, oil, salts (smallest amount)
dairy products (1-3 cups of milk), meat (200-280g), eggs (less amount)
vegetables & fruits (about 300-500g per day)
cereals (谷类), bread, rice (suitable/larger amount)
(Discuss the way in which eating disorder, eg. anorexia nervosa, can affect health)[Small project]
Factors affecting energy requirement - sex
- age
- occupation (职业)
- activities (活力)
- stage of individual ( eg. pregnancy (怀孕), breast-feeding (授乳)
(Discuss the importance of water in our body.)
Concepts for Food & Diets
1. Mother's milk is an ideal food for baby: (1) it contains most nutrients (NOT all, lacking vitamin C, D and iron) required for the growth of the baby; (2) it is easy taken (NOT: easy digested); (3) contains antibody, to help body defence of the baby. [母乳是一种理想的婴儿食物: (1) 含有大部分(不是全部)必需的营养(缺乏维生素C,D和铁质); (2) 容易进食(不是容易消化); (3) 含有抗体, 以帮助婴儿身体防卫.
2. (a) Vitamin C is easily destroyed by heating (therefore not to cook vegetables for too long). However we discovered that boiled orange juice contains more vitamin C than that of unboiled one. This is because the test we applied is only to test for the present of some characters of vitamin C and the amount of substance causing this character will be increased after destruction. [维生素C很容易被加热所破坏(因此烹调蔬菜时, 不要把蔬菜煮得太久); 但我们发现煮沸了的橙内含有的维生素C比鲜橙还多; 这是由於我们用的方法实际上只是测试维生素C内的某些成分, 而它被破坏後这些成分反而增加了]. (b) Vitamin C will also loss by prolong storage. [维生素C亦会在长时间贮藏时失去].
3. Our daily energy required is mainly supplied by carbohydrates. (The main diet in Chinese is rice). (Fats and protein can also supply energy). Protein can no longer being oxidized to supply energy after being converted to structural protein of tissue cells. (In starvation, these structural proteins (i.e. tissue cells) can also be oxidized to release energy, but this is very dangerous). [我们每天需要的能量, 大部分是由碳水化合物(中国人的主粮是米或麦)所提供, (脂肪和蛋白质也会提供能量). 蛋白质能够供应能量(食物中的蛋白质), 但当转化成正常的人体组织後, 就不再被氧化而释放能量. (在挨饿时, 这些身体组织仍然能够被氧化而放出能量, 但这是十分危险的)
(不要以为: "只有碳水化合物和脂肪提供能量")
4. (a) NOT to say, "to avoid obesity, we should take in less fat but more carbohydrate", since excess carbohydrate will be converted to fat to be stored under skin. This will cause obese.
[不要以为: "要避免变得太肥胖, 我们要进食较少脂肪, 但更多碳水化合物"; 因为体内过剩的碳水化合物也会被转化成脂肪, 而被贮藏成为皮下脂肪组织, 这样也会变肥].
A person gains weight (becomes fat) as he takes in more energy from food than his body needs. (The reverse, for lose weight, is also true.) (NOT because he takes in too much fatty food.) [当人获得的能量比他所需的更多, 他就会增加重量(变得肥胖); (相反, 在变轻时, 也是相同道理).(不接受: 由於吃下太多脂肪)]
(b) 市面上太多所谓纤体方法, 有些还强调不用做运动, 而其实有些可能只是减去你体内的水分, 因而导致体重下降; 如果真是这样, 就会对你的身体造成不良的影响.
5. Our body will not store sugar, since it is soluble and will lowers the water potential of the body fluid. This will alter the osmosis of the cells. Only starch (in plant) and glycogen (in animal) are suitable for storage due to their insolubility.
[身体不能贮藏糖, 由於它们是水溶性的; 这样(糖溶於水)会降低细胞的水势而改变细胞的渗透能力; 只有淀粉 (在植物)及糖原 (在动物), 由於它们是不溶的, 是最适合用作贮藏的].
6. Vegetarian diet is not suitable for children and teenagers. They are actively growing and some essential amino acids may not be provided in sufficient amount. [一个素食者的膳食是不适合给小孩和青少年的, 因为他们正活跃地生长, 而某些必需的氨基酸不能够全由植物中充分地供应他们生长所需].
7. Diet in cool area contains lots of fats, because:
(a) fats can release much more energy (double) than that of carbohydrates and proteins. This can compensate for the great heat loss. (b) excess fats is stored under skin for insulation/ to reduce heat loss.
居住在寒冷环境的人民, 其膳食中含有大量的脂肪, 由於: (a) 脂肪比碳水化合物及蛋白质能够释放更多量(双倍), 这样可补偿他们的巨大散热量; (b) 过剩的脂肪能够被贮藏在皮肤下, 用作隔热, 使身体散热量减低.
8. Besides the skin to produce vitamin D under sunlight/UV ray, the bacteria in the large intestine can also produce vitamin K. Therefore not to say that human cannot produce vitamin. [除了我们的皮肤能够制造维生素D之外, 大肠的细菌(大肠杆菌)也会为我们制造维生素K.因此不要以为人体不能够制造维生素].
9. Patient with night-blindness cannot see things clearly in dim light (NOT at night/without light/dark condition). If there is really no light, nobody can "see" things. [患了夜盲症的人不能够在暗光之下看清楚东西; (不是: 在夜间或没有光时); 没有光就任何人也看不见东西的了]. (而夜间也不一定是暗光的)
10. Balanced diet includes correct amount and type of food in correct ratio (i.e. not too much/little)(NOT accept: take in all type of food in a diet).
[均衡膳食是包含正确份量及各种食物成分的正确比例 (不要太多或太少) (不接受: 在一餐吃下各种食物)]
(即是说: 膳食中要包含所有必需的食物种类[type of food], 而每种要有适当的份量[suitable amount of food substances]; 亦要有适当的能量数量[amount of energy]).
11. Eat more sugar will probably cause tooth decay, NOT diabetes. [吃得太多糖会引致蛀牙, 却不是 "形成糖尿病"].
P. of 3 ch. 5
·上一篇：醣类(碳水化合物)mode of nutrition - Heterotrophic nutrition - taking in organic substances. (Heterotrophs - the organism)
Functions of food : - maintain (维持) life.
- supply energy (by carbohydrates(碳水化合物), fats, proteins)
(energy value (能量值) ratio of carbohydrates : fats : proteins = 1 : 2 : 1)
(energy content determined by burning the food to heat up fix amount of water)
- provide materials for growth and repair (修补) ( by proteins)
Types of food: carbohydrates, fats (for energy),
proteins (body building),
vitamins, minerals (maintain health),
dietary fibre (roughage) (gut peristalsis),
water (maintain life).
Carbohydrates- elements (元素): C, H, O ( in ratio (比例) of H : O = 2 : 1 )
- 3 types: - monosaccharides (单糖类):
- molecular formula (公式) : C6H12O6
eg. glucose (葡萄糖), fructose (果糖), galactose (半乳糖).
- disaccharides (双糖类): (2 monosaccharides combine together with one water molecule lost)
molecular formula : C12H22O11 (2 C6H12O6 - H2O ( C12H22O11 )(condensation)
(C12H22O11 + H2O 2 C6H12O6 )(hydrolysis)(a digestion process in our body)
eg. maltose (麦芽糖) ( 2 glucose molecules )
eg. sucrose (蔗糖) ( non-reducing sugar )
eg. lactose (乳糖)
all monosaccharides and disaccharides are reducing sugars (还原糖) except sucrose.
- polysaccharides (多糖): (NOT sugar)
store energy.
eg. starch (store energy in plants)
eg. glycogen (糖原)(肝糖) (store energy in animals)
eg. cellulose (纤维素) (component (成分) of cell wall)
excess (多馀的) carbohydrates - stored as glycogen in liver & muscles
- stored as fats under skin (subcutaneous fats)
Lipids ( fats & oils ) - elements : C, H, O
- basic components (成分)( building blocks): glycerol (甘油) & fatty acids (脂肪酸)
- functions - give energy
- form fatty tissues under skin - to keep warm
- to store energy
- transport fat-soluble (油溶性) vitamins (A, D, E, K)
Proteins - elements: C, H, O, N some with S, P
- basic components: amino acids (氨基酸).
- Amino acids combine (结合) together to form dipeptides (双氨基酸组) & polypeptides (poly=多)
- cannot be stored - excess amino acids (from proteins) are deaminated (deamination [n])(de=去除) by liver
- a part of the product is changed to urea (尿素) which will be
excreted (排泄) away by kidney
- another part (the carbon skeleton) is changed to carbohydrates (glycogen)
which will be stored in liver and muscle cells.
(so, excess amino acids are not "no use", the carbon skeleton can further provides energy as it is
transformed (转化) into carbohydrates and fats.)
- essential amino acids: must be intake from food.
non-essential amino acids: can be produced by our body (by transforming from other amino acids).
- functions - provides materials for growth and repair of the body.
(acts as structural (结构的)components of cells )
- produce hormones (荷尔蒙) and enzymes (酵素)
- give energy (only by protein in food, NOT by structural (结构) protein in tissue cells)
Vitamins - water soluble (水溶性) vitamins (B, C)
- fat soluble (油溶性) vitamins (A, D, E, K) - take in excess (过多) amount will cause harm to our body.
Dietary fibres (纤维) (roughage)(cellulose) - stimulate peristalsis (蠕动) of gut (alimentary canal)
Deficiency Diseases (vitamins, minerals & dietary fibre):
Vitamins
Deficiency Diseases
A
night blindness
C
scurvy (坏血病) (bleeding gum)
D
rickets (软骨病) (weaken bones)
calcium
rickets
iron
anaemia (贫血) (low haemoglobin level )
dietary fibre
constipation (便秘)
Notes: - rickets (NOT: ricket)
Food Tests
Substance
Tests
Original Colour
Positive Results
reducing sugar (eg.glucose)
Benedict's test
blue
orange precipitate (沈淀物)
starch
iodine test
brown
blue-black
protein
biuret test
blue
violet solution
fats/oils
spot test
translucent spot (半透明小滴)
fats/oils
emulsion test
clear
milky emulsion (乳剂) (oil droplets)
vitamin C
DCPIP test
blue
colourless solution (decolorize)
Notes: - Benedict's test requires heating (There is a Benedict's solution).
- glucose can also be tested by Clinistix paper: colour changes: ( red ( purple )
protein can also be tested by Albustix paper: colour changes: ( yellow ( green )
- Biuret's test: addition of sodium hydroxide (NaOH) solution, then add little copper sulphate solution.
(There isn't a Biuret's solution.)
- emulsion test: addition of absolute alcohol first, shake well to get a clear solution, add little water and
shake well to get a milky emulsion.
- Vitamin C should be dropped onto DCPIP solution (dichlorophenol indophenol) drop by drop.(NOT reverse)
- iodine is not for testing starch, but iodine solution. (iodine solution is iodine dissolved in potassium iodide)
- a positive Benedict's test does not imply the present of glucose, it only indicates reducing sugar.
- spot test should be futher proved by dissolving the oily spot in organic solvents (eg. alcohol).
- absolute alcohol (ethanol) is highly flammable (易燃的). DCPIP is toxic and corrosive.
(Design an experiment to compare the amount of vitamin C in different fruits and vegetables.)
The balanced diet - have enough food to supply enough:
1. energy (carbohydrates, fats, proteins)
2. body building material (protein)
3. substances to maintain (维持) health (vitamins, minerals)
- not balanced diets for long time : malnutrition (营养不良) (mal = 不正常)
eg. anorexia nervosa & anorexia bulimia (神经性厌食症与贪食症)
Food pyramid: sugar, oil, salts (smallest amount)
dairy products (1-3 cups of milk), meat (200-280g), eggs (less amount)
vegetables & fruits (about 300-500g per day)
cereals (谷类), bread, rice (suitable/larger amount)
(Discuss the way in which eating disorder, eg. anorexia nervosa, can affect health)[Small project]
Factors affecting energy requirement - sex
- age
- occupation (职业)
- activities (活力)
- stage of individual ( eg. pregnancy (怀孕), breast-feeding (授乳)
(Discuss the importance of water in our body.)
Concepts for Food & Diets
1. Mother's milk is an ideal food for baby: (1) it contains most nutrients (NOT all, lacking vitamin C, D and iron) required for the growth of the baby; (2) it is easy taken (NOT: easy digested); (3) contains antibody, to help body defence of the baby. [母乳是一种理想的婴儿食物: (1) 含有大部分(不是全部)必需的营养(缺乏维生素C,D和铁质); (2) 容易进食(不是容易消化); (3) 含有抗体, 以帮助婴儿身体防卫.
2. (a) Vitamin C is easily destroyed by heating (therefore not to cook vegetables for too long). However we discovered that boiled orange juice contains more vitamin C than that of unboiled one. This is because the test we applied is only to test for the present of some characters of vitamin C and the amount of substance causing this character will be increased after destruction. [维生素C很容易被加热所破坏(因此烹调蔬菜时, 不要把蔬菜煮得太久); 但我们发现煮沸了的橙内含有的维生素C比鲜橙还多; 这是由於我们用的方法实际上只是测试维生素C内的某些成分, 而它被破坏後这些成分反而增加了]. (b) Vitamin C will also loss by prolong storage. [维生素C亦会在长时间贮藏时失去].
3. Our daily energy required is mainly supplied by carbohydrates. (The main diet in Chinese is rice). (Fats and protein can also supply energy). Protein can no longer being oxidized to supply energy after being converted to structural protein of tissue cells. (In starvation, these structural proteins (i.e. tissue cells) can also be oxidized to release energy, but this is very dangerous). [我们每天需要的能量, 大部分是由碳水化合物(中国人的主粮是米或麦)所提供, (脂肪和蛋白质也会提供能量). 蛋白质能够供应能量(食物中的蛋白质), 但当转化成正常的人体组织後, 就不再被氧化而释放能量. (在挨饿时, 这些身体组织仍然能够被氧化而放出能量, 但这是十分危险的)
(不要以为: "只有碳水化合物和脂肪提供能量")
4. (a) NOT to say, "to avoid obesity, we should take in less fat but more carbohydrate", since excess carbohydrate will be converted to fat to be stored under skin. This will cause obese.
[不要以为: "要避免变得太肥胖, 我们要进食较少脂肪, 但更多碳水化合物"; 因为体内过剩的碳水化合物也会被转化成脂肪, 而被贮藏成为皮下脂肪组织, 这样也会变肥].
A person gains weight (becomes fat) as he takes in more energy from food than his body needs. (The reverse, for lose weight, is also true.) (NOT because he takes in too much fatty food.) [当人获得的能量比他所需的更多, 他就会增加重量(变得肥胖); (相反, 在变轻时, 也是相同道理).(不接受: 由於吃下太多脂肪)]
(b) 市面上太多所谓纤体方法, 有些还强调不用做运动, 而其实有些可能只是减去你体内的水分, 因而导致体重下降; 如果真是这样, 就会对你的身体造成不良的影响.
5. Our body will not store sugar, since it is soluble and will lowers the water potential of the body fluid. This will alter the osmosis of the cells. Only starch (in plant) and glycogen (in animal) are suitable for storage due to their insolubility.
[身体不能贮藏糖, 由於它们是水溶性的; 这样(糖溶於水)会降低细胞的水势而改变细胞的渗透能力; 只有淀粉 (在植物)及糖原 (在动物), 由於它们是不溶的, 是最适合用作贮藏的].
6. Vegetarian diet is not suitable for children and teenagers. They are actively growing and some essential amino acids may not be provided in sufficient amount. [一个素食者的膳食是不适合给小孩和青少年的, 因为他们正活跃地生长, 而某些必需的氨基酸不能够全由植物中充分地供应他们生长所需].
7. Diet in cool area contains lots of fats, because:
(a) fats can release much more energy (double) than that of carbohydrates and proteins. This can compensate for the great heat loss. (b) excess fats is stored under skin for insulation/ to reduce heat loss.
居住在寒冷环境的人民, 其膳食中含有大量的脂肪, 由於: (a) 脂肪比碳水化合物及蛋白质能够释放更多量(双倍), 这样可补偿他们的巨大散热量; (b) 过剩的脂肪能够被贮藏在皮肤下, 用作隔热, 使身体散热量减低.
8. Besides the skin to produce vitamin D under sunlight/UV ray, the bacteria in the large intestine can also produce vitamin K. Therefore not to say that human cannot produce vitamin. [除了我们的皮肤能够制造维生素D之外, 大肠的细菌(大肠杆菌)也会为我们制造维生素K.因此不要以为人体不能够制造维生素].
9. Patient with night-blindness cannot see things clearly in dim light (NOT at night/without light/dark condition). If there is really no light, nobody can "see" things. [患了夜盲症的人不能够在暗光之下看清楚东西; (不是: 在夜间或没有光时); 没有光就任何人也看不见东西的了]. (而夜间也不一定是暗光的)
10. Balanced diet includes correct amount and type of food in correct ratio (i.e. not too much/little)(NOT accept: take in all type of food in a diet).
[均衡膳食是包含正确份量及各种食物成分的正确比例 (不要太多或太少) (不接受: 在一餐吃下各种食物)]
(即是说: 膳食中要包含所有必需的食物种类[type of food], 而每种要有适当的份量[suitable amount of food substances]; 亦要有适当的能量数量[amount of energy]).
11. Eat more sugar will probably cause tooth decay, NOT diabetes. [吃得太多糖会引致蛀牙, 却不是 "形成糖尿病"].
P. of 3 ch. 5
·下一篇：碳水化合物的种类