CHAPTER 3

IS IT POSSIBLE TO SUPPLEMENT YOUR WAY TO BETTER HEALTH?

 

Nutrients - Macronutrients

-         Nutrients: substances in foods that provide structural materials or energy

-         Macronutrients: nutrients that are required in large amounts

-         Water

-       Adults need about 3 liters per day

-       Too little leads to dehydration

-       Maintains blood pressure

-       Involved in all cellular activities

-         Carbohydrates: main energy source

-       Simple sugars (glucose) enter our system quickly

-    Complex carbohydrates (branching chains of simple sugars) are digested more slowly

-    Starch: complex carbohydrate from plants

-    Glycogen: complex carbohydrate from animals

 

-        Processed food

-    Food that has undergo processing that has stripped it of its nutritional value

-        Whole foods

-    Foods that have not been stripped of their nutrition

-    Fiber: indigestible complex carbohydrates

-    Essential for large intestine function
-    Lowers cholesterol and reduces cancer risk

 

-         Proteins

-    Polymers of amino acids

-    Essential amino acids: we cannot make these ourselves; must obtain them from food

-    Complete proteins: contain all the essential amino acids we need

-    Plant proteins can be combined to make them complete.

-         Fats

-    Energy storage molecules

-    Acts as a cushion and insulator

-    Consist of a glycerol attached to fatty acid tails

-    Essential fatty acids: we cannot make these ourselves (e.g., omega-3 and omega-6)

-    Saturated fats: fatty acid carbons are bound to as much hydrogen as possible

-   Lack double bonds

-   Solid at room temperature

-   Most animal fats are saturated

-    Unsaturated fats are not bound to as much hydrogen as possible

-   Contain double bonds which give kinks in the tails

-   Liquid at room temperature

-   Most plant fats (oils) are unsaturated or polyunsaturated

-    Polyunsaturated fats

-   Have many double bonds preventing it from tightly packing

-    Hydrogenation

-   Process that adds hydrogen atoms to unsaturated fats to make it a solid

-    Trans fats are produced by incomplete hydrogenation and not beneficial

-   May be linked to an increased risk of heart disease and diabetes

 

Nutrients - Micronutrients

-         Micronutrients: nutrients that are needed in small quantities

-         Vitamins: Table 3.1 lists the various vitamins

-    organic substances which usually function as coenzymes

-    Vitamin D the only one we can synthesize

-    Water-soluble vitamins

-    Not stored in the body and typically the cause of deficiencies

-    Fat-soluble vitamins

-    Stored in fat and can cause problems in excess

-         Minerals: inorganic substances

-    Do not contain carbon but essential for cell functions

-    Must be supplied through diet and are water soluble

-    Calcium is a very important mineral that plays a role in bones, clotting, muscle contraction and nerve impulses

-    Table 3.2 lists the various minerals and their functions

-         Antioxidants

-    Found in whole foods

-    Protect cells from damage by free radicals

-    Free radicals can damage DNA and cell membranes

-    Table 3.3 describes food sources of antioxidants

 

 

Prokaryote and Eukaryote Organisms

- All cells on Earth are either prokaryotic or eukaryotic.

- Prokaryotic cells are smaller and simpler in structure.

- They probably resemble the earliest cells to arise on Earth.

- Some structures in the Martian meteorite resemble them.

 

Cell Structures

- All cells have the following:

- Plasma membrane surrounding the cell (this is a phospholipid bilayer)

- Cytoplasm (cytosol) inside the membrane; chemical reactions take place here

- Genetic information in the form of DNA

- Ribosomes for the production of proteins, made up of RNA and proteins

 

- All cells are surrounded by a plasma membrane.

- Made of a phospholipids bilayer: hydrophobic tails orient inside the membrane, away from water

- Fluid mosaic: lipids and proteins can move about within the membrane

- Semipermeable: some molecules can cross and some canÕt

 

- Prokaryotes do not have a nucleus (membrane-bound structure that contains the DNA).

 

- Eukaryotic cells are much more complex.

- Have true nuclei surrounded by a membrane

- Also have membrane-bound organelles with specialized jobs

 

- Nucleus: surrounded by a double nuclear membrane which houses DNA

- Ribosomes: protein production function Š made of RNA and protein (NO membrane); can be attached to membranes or free floating

- Cytosol: watery substance that surrounds the nucleus and organelles

- Mitochondria: provide energy for the cell, using oxygen

- Chloroplasts: sites of photosynthesis in plant cells

- Lysosomes: contain digestive enzymes to break down substances

- Rough Endoplasmic reticulum: involved in protein synthesis and has ribosomes attached to its membrane

- Smooth Endoplasmic reticulum: involved in lipid synthesis and lacks ribosomes

- Golgi apparatus: modifies and sorts proteins and packages them into vesicles

- Centrioles: moves genetic material during cell division

- Cytoskeleton: maintains cell shape

- Central vacuole: found in plant cells and stores water, starch and pigments

 

Transport Across Membranes

-         Nutrients have to move across the cell membrane in order to be used by the cell.

-         Plasma membrane is composed of a phospholipid bilayer & is differentially permeable

-         Diffusion: movement of molecules from area of high concentration to low concentration

-         Passive transport: diffusion of small hydrophobic molecules without energy

-         Facilitated diffusion: transport of hydrophilic and charged molecules across the membrane.

-    Uses proteins embedded in the membrane

-    No input of energy required

-         Osmosis: movement of water across a membrane, from high to low concentration.

-    When an animal cell is placed in salt water it will shrivel

-    When an animal cell is placed in distilled water it will swell and burst

-         Active transport

-    Uses proteins to move molecules from low to high concentration

-    Powered by energy from ATP

-         Exocytosis: a membrane-bound vesicle fuses with the membrane and expels the large molecule

-         Endocytosis: a vesicle forms around a large molecule and brings it into the cell

 

3.2 You are what you eat

-         Food is digested into building blocks used by cells for various functions and structures