Biologia

Posted on Jun 21, 2023 in Biology

Food is our sorce of nutrients, that are biomolecules our body needs to sustain vital functions. Nutrients are the building blocks and energy sources our cells need to live.

Cells need nutrients to satisfy 3 basic requirements:

  • ENERGETIC: Some nutrients are broken down in our mitochondria to extract energy (movement, temperature, etc..): LIPIDS, GLUCIDS.

  • STRUCTURAL: Some nutrients are building blocks of body structures: membranes, bones, cartilage, etc. PROTEINS, LIPIDS, MINERAL SALTS

  • REGULATORY: Some nutrients are necessary in small quantities to regulate body metabolism: VITAMINS, MINERAL SALTS

Carbohydrates: stores energy; provides structural suport.

  • Biomolecules present in bread, cereals, potatoes, pulses, pasta, fruits, vegetables, sweets, pastry,…

  • Provide energy to cells and some of them have to be consumed in a regular daily basis.

GOOD CARBS: complex, harder to digest, burns calories being digested, keep you feeling fuller longer, natural `sugar´, dosen’t spike blood sugar levels, used for energy, low glycemic, help you lose fat.

BAD CARBS: simple, digest immediately, don’t burn many calories being digested, makes you hungry (sooner), makes you crash, caused sugar cravings, processed+added sugars, spikes blood sugar fast, converts into fat easily, can cause other `good´nutrients to be stored as fat, high glycemic, helps you store fat.



SIMPLE (“SUGARS”): INMEDIATE SOURCE OF ENERGY in Brain and muscle. Sweet taste, small molecules: 

  • 1) MONOSACCHARIDS (Glucose, Fructose) or 

  • 2) DISACCHARIDS (Sucrose in fruits, Lactose in milk). 

  • Are quickly metabolized to release energy.

  • Excess of simple sugars is converted into fat!!.

COMPLEX (“POLYSACCHARIDS”): Big macromolecules made up of many monosaccharids. Sweetless. 

  • 1) GLYCOGEN (animals, stored in the liver)

  • 2) STARCH (plants, stored in leaves, roots, tubers, etc.), 

  • CELLULOSE o “Dietary Fibers” (plants, structural function)

  • CHITINE (skeleton of invertebrates) 

  • 1 & 2: When broken down in digestion, they provide a steady and long-term supply of energy to the cell as simple sugars.

    Made up of monosaccharides joined together

    Stored in the liver as complex GLYCOGEN, which is then broken down into simple sugars 

    They give a slow release of sugar (energy) to cells, preventing uncontrolled rise of sugar in blood

Lipids: stores energy; provides steroids; waterproofs coatings.

Group of very diverse substances with a few things in common: water insolubility and oily appearance

3 TYPES:

  • FATS: Rich in energy, can be SATURATED or INSATURATED: Triglicerids

  • MEMBRANE LIPIDS: Make up cell membranes: (Phospholipids, Cholesterol)

  • REGULATORY LIPIDS: Control metabolic processes VITAMINS (A,D,K,E) and HORMONES,



SATURATED FATS: Animal origin, solid. Contribute to rise “Bad cholesterol” (LDL) levels. Excess is a factor of cardiac disease and brain stroke. 

INSATURATED FATS: Plant origin, and sometimes animal. Liquid (OILS) and easily digestible. Prevent LDL levels to rise.  

“TRANS FATS”: Artificially saturated plant fats with hydrogen to obtain solid, durable and tastier foods. Serious risk of LDL LEVELS RISE

Proteins: transport substances; speeds reactions; provide structural suport; provides hormones.

  • Half of our dry body weight is made up of proteins: They are the most important structure-building molecules in our body: bones, cartilage, conjunctive tissue, muscles, etc..)

  • Proteins are MACROMOLECULES made up by joining numerous smaller molecules called AMINO ACIDS

  • Proteins are made up of a chain of aminoacids (called a PEPTIDE) with a specific 3D structure that brings the protein its function.

Functions:

  • Forming body structures (Bones, teeth, cartilages, ligaments: COLLAGEN, KERATIN……

  • Oxygen transport in blood: HAEMOGLOBIN

  • LIPID transport in blood: Lipoproteins (LDL, HDL)

  • Defense and inmmunity: Antibodies

  • Muscle/Cardiac contraction: ACTIN &  MYOSIN

  • Metabolic regulation: INSULIN



Mineral salts:

  • They are esentially regulators of our vital functions, but some form bones and teeth

  • Fruits, vegetables and dry fruits are rich in salts.

  • The lack of some salts like Fe (Iron), Ca (Calcium or I (Iodine) can cause serious illnesses and deficiencies: (anemia, hipothyroidism)

  • Macrominerals; required in large quantities

  • Microminerals; required only in minor amounts, but always essential

VITAMINS:

  • Needed in very small quantities. Lack of vitamins produces serious illnesses.

  • Regulate a huge number of body functions.

  • Easily destroyed by light, heat or O2 exposure, so they are more abundant in fresh food.

Vitamins classification:

  •  WATER SOLUBLE: Soluble in water. Easily eliminated through urine; do not accumulate. Problems when they are absent or in low levels

  • FAT SOLUBLE: Stored in the liver, when there is excess of these vitamins, there are health problems.

A HEALTHY DIET:

  • A healthy and BALANCED diet prevents many disorders and deficiencies associated with nutrition: OVERWEIGHT, OBESITY, MALNUTRITION, DEFFICIENCIES, …

  • Must contain ALL NUTRIENTS in ADEQUATE AMOUNTS. It should provide with the adequate daily energy needs; according to our age, sex, weight and physical activity.

  • CARBOHYDRATES: 55%

  • FATS: 30%

  • PROTEINS: 15%

The food wheel:

  • Divides foods into 5 major groups based on nutrient content and their function in our body:

  • 1: Fruits and vegetables (Regulatory, fiber, vit)

  • 2: Starchy foods (Energetic, Carbohydrates)

  • 3: Oils, spreads (Energetic, Fats)

  • 4: Dairy products (Energetic, Structural. Prots, Fats)

  • 5: Meat, pulses, eggs, poultry. (Structural, Prots)

  • ¾ of our daily diet have to be based on groups 1 and 2. 1/3 of it on 

  • Try a plant-based diet

Nucleic Acids: stores and communicates genetic information.