NUTRITION

WHAT IS NUTRITION?
The process that organisms obtain energy from food, for growth, maintenance and repair of damage tissue

TYPES OF NUTRITION

1) Autotrophs (self, feed)

• Photosynthesis (Green plants)
• Chemosynthesis (Bacteria synthesis organic compounds by oxidising inorganic compounds - ammonia)

2) Heterotrophs (cannot synthesise their own food)

• Holozoic (Herbivours, Carnivours & Omnivours)
• Saprophytic (Organisms fed on dead / decaying matter
• Parasitic (Organisms obtains nutrient by living on/ in the body of other living organisms

BALANCE DIET

• Balance diet: a diet which contains the right amounts of carbohydrate, proteins, fat, vitamins, mineral, water and fibers.
• Healthy diet: should provide the body with all the substances necessary to maintain growth, to keep good health and repair damage tissue.

WHAT ARE THE FACTORS THAT EFFECTING THE DAILY ENERGY REQUIREMENT?
Climate!
Colder place need more energy to maintain body temp. because of the lost of energy to the surrounding.

FACTORS EFFECTING DAILY ENERGY REQUIREMENT

• Body size - The smaller person have a larger surface per unit volume compare to a larger person, the rate of heat loss is higher, they need more energy.
• Gender - Male need more energy because they are more active & the metabolic rate is higher then female.
• Growing children have higher metabolic rate than older people. They need more energy.
• Occupation - Person does heavy work needs more energy than a person who is only moderately active.

NUTRIENTS IN FOOD

• Carbohydrates: (rice, noodles, potatoes)
  
  • Source of energy for motion and growth
  • Used to form supporting structures in plants (cell wall)
  • Effective methods for food storage (starch/glycogen)
  • Part of nucleus (DNA)
  • Lack of it : become very weak

• Proteins : (meat, fish, cheese, eggs)
  
  • Make new cells for growing
  • Repair & Replace damaged cells/tissues
  • Make enzymes, antibodies & hormones
  • Lack of it: kwashiorkor, very weak, muscle are poorly developed

• Fat : ( oils, butter, milk, nuts)
  
  • Supply energy
  • Part of cell membrane
  • Help absorb certain vitamins (ADEK)
  • Too much: excess fat stored under the skin (obese)
  • Too little: vitamins won’t be absorbed, cell membrane won’t be formed normally

• Vitamins:
  
  • To protect health.
  • Biological catalyst for chemical reaction in the body.
  • 2 categories:
    i) Fat soluble vitamins
    
    • A,D,E,K
    • Stored in the body fat
    • No need to consume everyday (stored in the body)
    ii) Water soluble vitamins
    
    • C and B (8 types)
    • Dissolved easily in water, easily lost
    • Cannot be stored in the body, need to be consumed everyday.
      
      
      • Vitamin A
      Source: Milk, green leaf, butter, tomatoes, cod liver, egg.
      Function: Normal growth, healthy eyes & skin.
      Deficiency disease: Night blindness.
      
      
      • Vitamin B1
      Source: Milk, peas, cereals, green leaf.
      Function: Growth & development.
      Deficiency disease: Beriberi (disease affects the nervous system).
      
      
      • Vitamin B2
      Source: Peas, yeast, egg, meat.
      Function: Healthy skin growth.
      Deficiency disease: Skin disease, retarded growth.
      
      
      • Vitamin B4
      Source: Whole cereals, potatoes, tomatoes, meat, fish.
      Function: Healthy skin, digestive & nervous system.
      Deficiency disease: Pellagra (disease affect the skin, alimentary canal & nervous system).
      
      
      • Vitamin C
      Source: Tomatoes, green leaf, vegetables, fruits.
      Function: Healthy growth, strong blood vessels.
      Deficiency disease: Scurvy (gums easily bleed).
      
      
      • Vitamin D
      Source: Sunlight, milk, butter.
      Function: Strong bones & teeth.
      Deficiency disease: Rickets ( Soft bones & deformed on children).
      
      
      • Vitamin E
      Source: Vegetables, oils, milk, butter.
      Function: Protect the cell membrane.
      Deficiency disease: Affect fertility.
      
      
      • Vitamin K
      Source: Green vegetables, Soya bean oils.
      Function: Help in clotting the blood.
      Deficiency disease: Excessive bleeding from wound.

• Mineral salts:
  
  • Major trace mineral- required in large amount
  • Minor trace mineral- required in small amount
• Iron - Formation of heamoglobin
• Calcium - Strong bones & teeth, muscle contractions, clotting blood
• Phosphorus - Strong bones
• Potassium - Growth & osmotic balance
• Sodium - Osmotic balance, proper functioning of nervous system
• Iodine - Body metabolism, development of brain
• Roughage/ fiber
  
  • Higher water holding capacity
  • Help peristalsis / bowel movement
  • Prevent from constipation
  • Lower the cholesterol
  • Reduce the risk of heart disease

• Water:
  
  • Medium for biochemical reactions
  • Medium for transportation of respiratory gases
  • Regulates body temp.
  • Removes excretory waste
  • Maintain osmotic pressure
  • Aids peristaltic movement
  • Hydrolyse some food substances
  • Dissolve most chemical substances

SPECIAL DIET

• Pregnant lady
  Need more nutrient to provide more energy to meet the need of my growing fetus
  
  • Folate – brain development
  • Iron – prevent from anemic
  • Calcium - growth of baby’s bone & teeth

• Baby
  Need mother’s milk to provide me with energy & nutrient.

• Children
  They are active & love to play. They need carbohydrates to give us energy and protein to develop new tissue.

• Vegetarian
  They need supplement in order to complete their need.

• Diabetic
  Low sugar.

• Teenagers
  
  • Carbohydrates – provides energy (they’re active)
  • Protein – still growing
  • Iron – menstruation (girl)

• Athletes
  Carbohydrates – they need more energy.

MALNUTRITION

• Starvation – insufficient amount of food
• Eating disorder:
  
  • Anorexia Nervosa – Girls believe themselves to be fat (they’re extremlely thin), don’t want to eat.
  • Bulimia – Overconcern with body weight, eat a lot and then force themselves to vomit.

• Overweight/ Obesity - high risk of diabetes,hypertension, heart attack
• Over consumption of cholesterol & saturated fat:
  
  • Can cause arthrosclerosis (build up fatty deposits in the coronary arteries/ blood vessels.

• Constipation: lack of dietary fiber.

Class Of Chemicals

Cells need various types of organic and inorganic compounds to enable them to carry out their functions, as well as build their cellular components. While organic compounds contain the element carbon, inorganic compounds do not.

Below is the classified descriptions of chemical compound.

Carbohydrate

• Starch made up of long chain of glucose
• The ratio of C:H:O in it is 1:2:1
• Cellulose that strengthens the cell walls of plants
• Maltose can be converted into glucose by hydrolysis
• Its glucose molecules can be converted into glycogen

Lipid

• Cholesterol is an example of it
• Fats have the triglyceride molecules in them
• Fatty acids can be saturated and unsaturated
• The hormone testosterone is an example of it

Nucleic Acid

• An example is the DNA found in the nucleus of a cell
• Genetic material that directs protein synthesis
• Contain pentose sugars and phosphate groups

Protein

• Amino acids are its building blocks
• Nearly all enzymes are examples of it
• The haemoglobin molecules in the red blood cells
• Builds muscles and aids growth

Water

• An inorganic compound with no carbon in it
• A polar molecule with two H atoms and one O atom
• A universal solvent
• Acts as a medium for reactions in one's body

Proteins

Proteins play an important role in the formation of cellular components, cells and tissues in the human body.

They are also needed for growth and development. Without them, we will not grow or be able to repair damaged tissues in our body.

Among the substances made up of proteins in the human body are haemoglobins, antibodies, enzymes, certain hormones, muscle tissues and part of the cell membrane.

• The basic building block of proteins is the amino acid.
  
• There are 20 types of amino acids.
  
• Of these, the essential amino acids are the ones that cannot be synthesised by the body and must be obtained from the food we eat.
  
• Five example of amino acids are leucine, tryptophan, glutamic acid, valine and serine.
  
• If amino acids are known as monomers, proteins are polymers.
  
• When two amino acids are joined together, a dipeptide is formed.
  
• The bond between two amino acids is called a peptide bond.
  
• The process in which polypeptides are formed from amino acids is known as condensation.
  
• Protein can be broken down to amino acids in a process called hydrolysis.
  
• A molecule that is a protein in nature can be used to speed up the process mentioned above. This molecule is an enzyme.

Battery Biohazard

Throwing your batteries in the dustbin can harm the environment.

You've probably got a dozen things that are powered by batteries. Just check your mobile phone, calculator, television remote control, camera and torchlight.

Batteries are incredibly useful but they run on poisonous chemicals and metals like mercury, lead, cadmium and nickel. That is why you mustn't throw old and damaged batteries in the dustbin.

When batteries are thrown into a rubbish heap or a landfill, the chemicals they run on leak into the soil and groundwater. Nobody wants that in their food or water!

If you throw a battery into incinerator, heavy metals like mercury can vapourise and be released into the air. When it rains, they fall back to the earth, poisoning soil, rivers and oceans.

Burning batteries leave ashes with concentrated cadmium and lead. When these are dumped, the poison leaks into the environment.

You can reduce the amount of batteries you use by buying rechargeable products. They cost a little more, but you can use them many times.

You can also buy batteries with fewer dangerous chemicals. Modern alkaline batteries have up to 90% less mercury than those used 20 years ago. Some are completely mercury free. Just read the label!

When your batteries dies, take it to a recycle centre. The recycle centre disposes of any leftover chemicals in such a way that they can't harm the environment.

Animal Cell & Plant Cell

The cell is the basic unit of all organism. It is made up of a cell membrane that encloses the cytoplasm.
Contained within the cytoplasm are not only the nucleus but also organelles, whose specific functions help the cell perform a range of activities.

While plant and animal cells are similar, the plant cell has, in addition to the cell membrane, another boundary that separates it from its external environment. This is called the cell wall.

As most plant cells carry out photosynthesis - the synthesis of organic substances - they contain chloroplasts.

In plant cells, vacuoles also tend to be larger in size and smaller in number than those found in animal cells.
In the laboratory, you have learned how to prepare a microscope slide of human cheek cells as well as the epidermal cells of onions.

a) The differences you can observe between the two types of cells in term of the following:

• Shape
  Onion cells have a regular shape while cheek cells have an irregular shape.
  
• Presence or absence of cell wall
  Onion cells have a cell wall while cheek cells do not.
  
• Presence or absence of vacuoles
  Onion cells have a large vacuole while vacuoles in cheek cells, if present, are small.

b) Can you observe chloroplasts in the epidermal cells of onions? Explain your answer.
No chloroplasts can be observed in the epidermal cells of onions because epidermal cells do not carry out photosynthesis.

Diffusion

Various substances pass through the plasma membrane of a cell. The simplest mode of transport for these substances is by diffusion.
Diffusion is defined as the movement of substances from an area of high concentration to an area of low concentration. When substances move in this manner, we say that they are moving along the concentration gradient.

This movement process is simple and passive, which means that the substances move easily from the region of high concentration to the one whose concentration is lower without requiring any energy.

When water moves from an area of high concentration to an area of low concentration across a semi-permeable membrane, its movement called osmosis.

Therefore, when a cell absorbs water by diffusion through its semi-permeable cell membrane, we say that water has entered the cell through osmosis.

Eg: Roots absorb water through osmosis because the soil solution around the roots has a higher water concentration than the root cells.

Certain substances need help in the diffusion process. These substances move into a cell by diffusion through the membrane but they are brought in by special carrier proteins. Such a diffusion process is known as facilitated diffusion.

An active diffusion takes place when a substance moves from an area of low concentration to an area of high concentration, with the use of energy. This movement goes against the concentration gradient.

An active diffusion process usually involves transporting important ions into and out of a cell, whose plasma membrane may have special protein pumps to engage in it.

Onion Skin Cell & Cheek Squamous Epithelial Cells

Roles That Vary

A number of components or organelles are present within a cell. Each of them has different and specific function within the cell.

The presence or absence of a particular group of organelles tell us what kind of functions the cell can or cannot perform.

For instance, the presence of absence of chloroplasts. The mesophyll cell in the leaves of plants contain chloroplasts. This enables the mesophyll cell to carry out photosynthesis.

Epidermal cells, on the other hand, do not contain chloroplasts. Do you think they can carry out photosynthesis?

The ability of cells to carry out specific function due to the organelles contained in them is known as cellular differentiation.

Different cells carry out different functions because of the varying types of organelles contained in them.

A man's sperm cell, for instance, is packed with organelles known as mitochondria in its neck.

This enables the sperm to produce its own energy for movement.

Thus, a cell's structure determines its function.