B1.1 Carbohydrates and Lipids

Organic

refers to molecules containing carbon and hydrogen

eg. methane (CH4)

Inorganic

refers to molecules without carbon and hydrogen

eg. carbon dioxide (CO2)

There are 4 common functional group carbon can combine with:

1. Hydroxyl group — OH (common in alcohol)

2. Carboxyl group — COOH (found in fatty acids and amino acids)

3. Amine group — NH2 (found in amino acids)

4. Phosphate group — PH^₄2-

(found in ATP and ADP — used to transfer energy between molecules)

Monosaccharide

a single sugar monomer

Pentoses

monosaccharides with 5 carbon atoms

eg. Ribose – found in RNA

• Deoxyribose – found in DNA

Hexoses

monosaccharides with 6 carbon atoms

eg. Glucose – primary energy source for cells

• Fructose – found in fruits

• Galactose – found in milk sugars

Disaccharides

carbohydrates formed when two monosaccharides join together

Polysaccharides

large, complex carbohydrates composed of long chains of more than ten (often hundreds or thousands) monosaccharide units

Glucose

The formula: C6H12O6

forms a hexagonal ring (hexose) — form of sugar that fuels respiration

Characteristics of glucose

1. soluble

2. relatively small molecule

3. easily transported into the blood

4. stable molecule, useful for food storage

5. used for respiration to produce ATP

What if there is a large quantity of glucose..

it is normally converted into starch (plants) or glycogen (animals) to prevent water move into the cell by osmosis therefore it doesn’t affect the osmotic potential of cell

ATP is required for 7 processes of life

Movement

Respiratory

Growth

Reproduction

Excretion

Nutrition

Alpha glucose

the hydroxyl group is downwards

Beta glucose

the hydroxyl group is upwards

How is glucose oxidised during cellular respiration?

Glucose is oxidised when it combines with oxygen in the process of cellular respiration, producing ATP, water, and carbon dioxide. The reaction can be summarized as: Glucose + oxygen —> ATP + water + carbon dioxide

Examples of hexose monosaccharides

Galactose and Fructose

Examples of pentose monosaccharides

Ribose and Deoxyribose

Polymers

chains of subunit (monomers)

Condensation

reactions occurs when molecules are convantly joined together and water is formed as a by-product

In carbohydrates, the bond that is formed is called:

glycosidic linkage

Glycosidic linkage have two types

1-4 and 1-6

Common disaccharides

Maltose, Lactose and Sucrose

hydrolysis

water molecule to break a covalent bond between two subunits (water is added)

What occurs during the hydrolysis of polysaccharides?

During the hydrolysis of polysaccharides, glycosidic bonds are broken, resulting in the formation of monosaccharides.

What occurs during the hydrolysis of polypeptides?

During the hydrolysis of polypeptides, peptide bonds are broken, resulting in the formation of amino acids.

What occurs during the hydrolysis of fats and lipids?

During the hydrolysis of fats and lipids, ester bonds are broken, resulting in the formation of fatty acids and glycerol.

Starch

alpha-glucose, 1-4 glycidic linkage

What is the orientation of glucose molecules in starch, and what are the consequences of this orientation?

All the glucose molecules in starch can be oriented the same way, which causes the starch molecule to be curved rather than straight. Additionally, the size of the molecule is not fixed.

Amylose

the chain of alpha-glucose molecules is unbranched and forms a helix, which is a form of starch and made from repeating glucose units (1-4)

amylopectin

the chain is branched so it has a more globular shape (both 1-4 and 1-6)

Glycoprotein

class of protein with a carbohydrates group attached to them, they are used for cell recognition

Blood type A

will have the A glycogen (antigens) on the surface of Red blood cell

Blood type B

will have the B glycogen (antigen) on the surface of RBC

Blood type AB

will have both A and B type glycoproteins on the surface of their cells

Blood type O

neither A or B glycoprotein on their RBC

lipids made up of monomers called..

triglycerides

triglycerides is made up of..

Glycerol and 3 fatty acids (saturated or unsaturated)

Fatty acids all have the same general structure

H3C - (CH2)n — C = O and — OH

Lipids are polar or non-polar

non-polar

Which type of liquid will lipid dissolve and not dissolve in

It will not dissolve in polar liquids but will dissolve in non-polar solutions such as ethanol

Are fatty acid chains hydrophobic or hydrophllic

hydrophobic

Four classes of lipids

Oils — liquid at room temperature

Fats — solid at room temperature and liquid at body temperature

Waxes — solid at room temperature

Steriods — molecules with 4 ringed structure

formation of triglycerides

3 hydroxyl groups of glycerol and the carboxyl groups of three fatty acids

The bond between the glycerol and the fatty acids is an..

ester linkage

the structure of phospholipids

2 fatty acids chains linked to glycerol with a phosphate group replacing the third fatty acid

Lipid

a group of organic molecules that are insoluable in water but soluable in non-polar organic solvents. common lipids include triglycerids (fats or oils), phospholipid and steroids

Saturated fat

contain no double bonds, straight, high melting point

unsaturated fat

contain double bond but low melting point, a bent

monounsaturated

1 double bond

polyunsaturated

>1 bond

amphipathic

substances such as phospholipids which are part hydrophilic (heads) and part hydrophobic (tails)

The heads of phospholipid polar or non-polar

polar

The stability of the phospholipid can be increased by the presence of…

cholesterol molecule

What barrier do the hydrophobic tails create?

The tails are hydrophobic (water-hating), so they create a barrier that blocks charged or polar molecules from passing through the membrane. Charged molecules cannot cross the hydrophobic core of the bilayer.

Why can't charged molecules pass through the tails?

Charged molecules are polar and attracted to water (hydrophilic). The fatty acid tails in the middle of the bilayer are hydrophobic — the opposite of water-loving — so charged molecules cannot move through this region.

How are individual phospholipids attracted to each other?

The phosphate heads are charged, so neighbouring phospholipids attract each other through these charges. This gives the membrane some stability, keeping the bilayer together as a sheet.

Can phospholipids move, and if so, how?

Yes! Phospholipids can move sideways within their own layer (this plane). They cannot flip to the other layer. This sideways movement is why the membrane is called fluid — as in the fluid mosaic model.

Phospholipid bilayer

the basic structure of the cell membrane made up of two layers of phospholipid molecules!

Non polar steriods all have the basic structure of…

4 rings, fused together, 3 hexagon + 1 pentagon

two examples of non-polar steriods hormones are:

Oestradiol and Testosterome

What type of macromolecule are steroids classified as?

steroids are classified as lipids.

Give three properties that allow steroids to pass through the phospholipid bilayer

1. They are lipids — same nature as the bilayer itself. 2. They are non-polar — so they are not repelled by the hydrophobic fatty acid tails in the middle. 3. They are small — small enough to fit through without needing a transport protein.

Why can steroids pass through the bilayer but charged molecules cannot?

Charged molecules are polar and hydrophilic — they are repelled by the hydrophobic tails in the middle of the bilayer. Steroids are non-polar so they are not repelled — they can move freely through the hydrophobic core.