IB Bio SL B1.1+B1.2

Organic Compound

A compound that contains carbon and hydrogen and is found in living things

What does carbon form?

Carbon forms four covalent bonds and therefore is the basis of all organic compounds

Variety of structures

Branched or unbranched chains and single or multiple rings

Types of carbon compounds

Carbs, Fatty Acid, Protein, Nucleic Acid

Organic compounds are typically polymers made up of subunits called

Monomers

Monomer of Carbohydrates

Monosaccharides

Monomer of Nucleic acids

Nucleotide

Proteins consist of linked chains of

Amino Acids

Polymers are formed by

Condensation reactions

What type of energy is required to build larger molecules

ATP energy

Polymers are broken down into monomers by

Hydrolysis Reaction

A type of molecule is split and added in this process

Water molecule

The monosaccharide that makes up the polysaccharides cellulose, glycogen and starch

Glucose

unbranched and its monomer is beta-glucose

Cellulose

Starch and glycogen consist of

Alpha-Glucose

Unbranched molecules form

1'-4' linkages

Branched molecules form

1'-4' and 1'-6' linkages

Monosaccharides have

3-7 carbon atoms

Pentoses have

5 carbon atoms

Hexoses have

6 carbon atoms

Both pentoses and hexoses can exist as

straight chains and strings

Glucose is

Soluble, relatively small, easily transported, circulates in blood, dissolved in blood + in plasma

Glucoses function

Chemically stable, food storage, cannot be stored in large amounts because it is osmotically active, so it is stored in the form of starch or glycogen

Glucose releases

Energy when it is broken down (oxidized) in cell respiration

What part of blood does glucose travel in

Plasma

Why can it travel in the blood

Glucose is hydrophilic (dissolvable)

What happens when your blood sugar is low?

Low energy

What happens when your blood sugar is high

Increased risk of heart attack and other medical complications

Both starch (in plants) and glycogen (in animals) are used for

energy storage

Both starch and glycogen consist of

Alpha-Glucose molecules

Amylose (starch)

Unbranched, 1'-4' bonds, because of the bond angle the chain is helical

Amylopectin (starch)

Branched, 1'-4' and 1'-6' glycosidic bonds, it branche at about one in every 20 glucose molecules

Glycogen, similar to amylopectin is also

Branched (1'-4' and 1'-6' glycosidic bonds), branches every 10 glucose molecules

Cellulose

Consists of beta-glucose, unbranched (1'-4' glycosidic bonds), makes up the cell wall

Glycoproteins

Made up of proteins with short carb chains attached (oligosaccharides), Trans-membrane, face outwards

Lipids

Diverse group of substances which encompass fats, oils, waxes and steroids. Hydrophobic as they dissolve in non-polar substances for example oil

Biological "consequences" of the hydrophobic properties of lipids

Waxes prevent water loss from leaves, bird feathers are coated with oil which in turn makes them waterproof, phospholipids from membranes and thus different compartments

Triglycerides

Consist of three fatty acid chains linked to a single glycerol molecule

In phospholipids

One of the fatty acid chains is replaced by a polar phosphate group

Main classes of lipids

Simple lipids

Compound lipids

Derived lipids

Simple lipids

Esters of fatty acids and alohols (waxes and triglycerides)

Compound lipids

Esters of fatty acids and alcohol and additional groups (phospholipids and glycolipids)

Derived lipids

Produced from the hydrolysis of the other compounds (steroids)

Fatty acids consist of

A chain of hydrocarbons (14-20 Carbons long)

Variable parts of a fatty acid

The length, the number and the location of the double bonds

Saturated fatty acids

Straight fatty acids with NO double bonds

Unsaturated fatty acids

Contain double bonds (Monounsaturated = 1 double bond ; Polyunsaturated = More than one double bond) (can be cis or trans)

Cis-unsaturated fatty acids

When the hydrogen atoms on the double bonds are on the same side

Trans-unsaturated fatty acids

When the hydrogen atoms on the double bonds are on opposite sides

Lipid storage

Organisms need fatty acids to stay liquid at their body temperature, but they also want them to be packed as tightly as possible for energy storage

Triglycerides in energy storage and thermal insulation

They are stable so no energy is lost over time

They are hydrophobic so they can be stored without having an osmotic effect on the cell

Contain twice more energy per gram than carbs or proteins

Phospholipids are

Amphipathic, they have both hydrophilic (phosphate group) and hydrophobic (fatty acids) parts

When phospholipids are added to water they

Spontaneously assemble into bilayers with the phosphate head pointing to the watery solutions inside and outside the fatty acids pointing away from the water

Structure of steroids

4 fused carbon rings that are non-polar and lipophilic (fat-loving), they are also hydrophobic

Function of steroids

Steroid hormones function as a signaling molecule in the body

They freely diffuse across the phospholipid bilayer and bind to receptors in the target cell

Steroids are hydrophobic and cannot be freely transported within the bloodstream and must be bound to a carrier protein (ex: albumin)

examples of steroids are estrogen or testosterone