Biology - Lesson 3

• Glucose - contains the elements carbon, oxygen, and hydrogen. The only elements occurring in complex sugars and in most fats.
• Nutrient - refers to any substance required for the growth and maintenance of an organism.
• A . AUTOTROPHS - organisms that obtain enegy from sunlight andchemicals to produce

  their ownfood. Example: plants
• B. HETEROTROPHS - organisms that cannot make their own food and obtain their energy from other organisms. Example: fungi
• THE MACRONUTRIENTS - are those nutrients needed by all plants in relatively large amounts.
• Nitrogen - one of the first nutrients to be discovered.

  - A deficiency may produce yellowing of older

  leaves or a general lightening of all the green

  parts of the plant, combined with a stunting of growth.
• B. Potassium - Another early known plant nutrient, is traditionally added to the soil in the form of wood ash.
• Phosphorus - essential for the production of such vital compounds as the nucleic

  acids and ATP.

  It is needed for flowering fruiting, and root

  development.
• Sulfur - an essential component of protein because of its occurrence in the amino

  acids cysteine and methionine.
• Calcium - deficiency results in abnormal growth and cell division, since calcium is an important component of the middle lamella of

  cell walls (along with pectin) .
• Magnesium - is required for the action of many enzymes and is needed also in the synthesis of chlorophyll, which contains it
• Micronutrients - are as vital as macronutrients but are required only in extremely small amounts.
• Iron - is needed in several of the electron tran sport substances of the cell (ferredoxin, cytochromes), and in some other materials (e.g., phytochrome) .
• Boron- The function is unknown. - Deficiency results in abnormally darkfoliage, growth abnormalities, and malformations.
• Zinc - is required for the production ofamino acid tryptophan.

  • In excess, it is poisonous to plants.
• Manganese - is required as a co factor for enzymes in oxidative metabolism and in photosynthetic oxygen production
• Chlorine - probably required for ionic balance and maintenance of cellular membrane potentials, chlorine (in the form ofchloride) is apparently also needed for oxygen production in photosynthesis.
• Molybdenum - is needed as part of the denitrifying and nitrogen fixing enzymes of microorganisms.
• Copper - is a component of some enzymes and cytochromes.
• ROOT HAIRS - slender extensions of specialized epidermal cells that greatly increase the surface area available for absorption
• ROOT NODULES - localized swellings in roots of certain plants where bacterial cells exist symbiotically with the plant.
• MYCORRHIZAE (SINGULAR, MYCORRHIZA) - a symbiotic interaction between a young root and a fungus.
• Symplast route – through plasmodesmata
• Apoplast route – along cell walls
• Nitrogen - is an important macronutrient because it is part of nucleic acids and proteins.
• Hyphae - are long extensions of the fungus, which can grow into small soil pores that allow access to phosphorus otherwise unavailable to the plant.
• Mycorrhizae - function as a physical barrier to pathogens.
• A parasitic plant - depends on its host for survival .
• hemi-parasites - are fully photosynthetic and only

  use the host for water and minerals.
• According to Johnson and Raven, Calorie - is a unit of energy that indicates the amount of energy contained in food.
• Carbohydrates - serve as a major energy source for the cells

  in the body.

  • These are usually obtained from grains, cereals, breads, fruits and vegetables.
• Proteins - can also be used as an energy source but the

  body mainly uses these as building materials

  for cell structures and as enzymes, hormones, parts of muscles,and bones.
• Fats - are used to build cell membranes, steroid hormones, and other cellular structures;also used

  to insulate nervous tissue., and also serve as an

  energy source.
• Essential amino acids - needed for synthesis of proteins and enzymes; among the 20 amino acids, eight

  could not be synthesized by humans:
• Essential fatty acids - used for making special membrane lipids ;an example is linoleic acid in humans
• Vitamins - organic molecules required in small amounts for normal metabolism;examples

  include fat-soluble Vitamin
• PHAGOCYTOSIS - engulfment of organic fragments or big particles, e.g. pseudopodformation in Amoeba
• PINOCYTOSIS - uptake of extracellular fluid by a cell using small vesicles derived from the plasma membrane.
• RECEPTOR-MEDIATED ENDOCYTOSIS - this relies on membrane receptor recognition of specific solutes which are then taken up by the cell via receptor-coated pits.
• Substrate feeders - animals that live in or on their food source. - Examples: earthworms that feed throughthe soil where they live in