topic 1 alevel bio - biological molecules

Monomer of carbohydrates

Glucose

Monosaccharides

Polymer of carbohydrates

Starch

Polysaccharides

Monomer of lipids

Fatty acids

Glycerol

Nucleic acids monomer

Nucleotides

Polymer of nucleic acids

DNA & Rna

Dipole

Molecule with positive and negative end

What do carbon molecules in straight chains make

Fatty acids

What do carbon molecule make in branched chains

Amino acids

What do carbon molecules make in ring structures

Benezenek

Products of photosynthesis for transport

Sucrose (disaccharide)

Products of photosynthesis for metabolism

Glucose (monosaccharides)

Monosaccharides properties

Small with low molecular mass

Sweet tasting

Crystalline

Readily soluble in H2o

Examples of monosaccharides

Pentoses: ribose

Hexoses: glucose

What are hexoses used for

Energy source

What are pentoses used for

Nucleic acids

Properties of disaccharides

Small with low molecular mass

Sweet tasting

Crystalline Readily soluble

Less soluble in H2o than monosaccharides

Examples of disaccharides

Sucrose

Maltose

Lactose

Properties of polysaccharides

Large molecules - high molecular mass

Not sweet

Not crystalline

Insoluble or not readily soluble in h2o

Examples of polysaccharides

Glycogen, starch, cellulose

Properties of water

Density

Cohesiveness and surface tension

High specific heat capacity, high latent heat, high heat of vaporisation

Description of water density

Water has the highest density at 4°c this means that there is always liquid water under ice

Benefits/uses pf water density

Aquatic organisms have cold but liquid water to live in during the winter

Description of water cohesiveness and surface tension

Water molecules are attracted together by their dipolar nature

Water will move together due to these forces of attraction h bonds

Benefits/uses of water cohesiveness and surface tension

Water can be drawn upwards against gravity (trees)

Description of water high sh lh lhov

Water can be absorb a very high level of energy before either the temp changes or water changes from liquid to gas

Water is thermally stable

Benefits/uses of shc lh lhov

Maintains body temp over a very narrow range (homeostasis)

What is a ribose

Pentose sugar with 5 carbon atoms

What are glucose and fructose

Hexose sugars with 6 carbon atoms

What is an isomer

Same formula different shape

Three uses of alpha glucose

Respiration

Two molecules join to form maltose

Polymerised to form starch or glycogen

What is formed when two molecules of alpha glucose join

Maltose

What is beta glucose used for

Respiration

Polymerises to form cellulose

What is formed when alpha glucose polymerises

Glycogen

What is formed when beta glucose polymerises

Cellulose

What is ribose sugar used for

Found in RNA

What is deoxyribose sugar used for

Found in DNA

What does fructose combine with to form sucrose

Alpha glucose

What is formed when alpha glucose and fructose combine

Sucrose

What combines with galactose to from lactose

Alpha glucose

What forms when alpha glucose and galactose combine

Lactose

Types of pentose sugars

Ribose

Deoxyribose

Types of hexose sugars

Alpha glucose

Beta glucose

Fructose

Galactose

What kind of reaction is the formation of disaccharides

Condensation

What is the type of bond formed when disaccharides are formed

Glycosidic bond

What is the minimum amount of monosaccharides to form polymers

10

What does alpha glucose do when bonded

Used for energy

What does beta glucose do when bonded

Structural - cellulose

What % of starch is amylose usually

30%

How many glucose molecules in helix arrangement in amylose - unbranched chains

>300

How many monomers per turn does amylose have

6

How much of starch does amylopectin make up

70%

When does amylopectin branch

Every 20-30 residues - (monosaccharides)

Glycogen

Very similar to amylopectin but branch points are every 8-12 monomers

Results in very compact molecule

Found in liver and muscle cells - used as energy cell

similar characteristics to starch - well suited to its function

Many terminal ends for easy release of glucose via hydrolysis

Properties of starch and glycogen as storage molecules

Compact - dosent take up much space

Insoluble - cant move out of cells where it is stored

No osmotic effects

Dosent become involved in chemical reactions in cells

Easily hydrolysed to simpler sugars (enzyme action) when required for respiration

Cellulose structure - in terms of glucose

OH groups need to be next to each other

Every second B-glucose molecules is turned upside down

This allows 1,4 glycosidic bonds to form

Cellulose structure

Polymer of beta glucose joined by glycosidic bonds in a straight unbranched chain

Each chain is formed from 100s of monomers

H-bonding develops between hydroxyl groups On each chain

Up to 200 chains form a microfibril long with high tensile strength

What holds microfibrils together in cellulose

Matrix

What is matrix made off

Pectins

Hemicelluloses

Properties of cell walls

Tensile strength

Indigestible

Permeable

Not just cellulose

Why does the cell wall have tensile strength

B glucose monomers form unbranched straight structures

Multiple lengths of B glucose monomers form microfibrils

Microfibrils are oriented in multiple directions

Why are cell walls indigestible

Most organisms cannot produce cellulase enzyme

A few species of bacteria are able to make cellulase

Ruminant herbivores have a symbiotic relationship with bacteria which live in part of their digestive tract called the rumen

Why are cell walls permeable

Water can move through the cell wall and can be transported over long distances without entering any cells

What else is found in the cell wall than cellulose

Pectins and hemicellulose (both carbohydrates) are found in the cell wall

Lipids (fats and oils) Characteristics

Fats and oils contain carbon, hydrogen, and oxygen

Insoluble in water but soluble in organic solvents (acetone and ether)

Relatively small molecules but tend to join together and form globules

Naturally occurring lipids are esters formed by condensation reactions between glycerol and fatty acids

Lipid molecular structure

Glycerol (C3H8O3) has three HYDROXYL groups (OH) which can all take part in condensation reactions with fatty acids

Fatty acid molecules are much larger than glycerol molecules

Fatty acids have long non-polar hydrocarbon chains with a polar carboxyl group (COOH) at one end

3 categories of fatty acids

Saturated

Monounsaturated

Polyunsaturated

Saturated fatty acid

Only single bonds in the hydrocarbon chains

Monounsaturated fatty acid

One double bond in hydrocarbon

Polyunsaturated fatty acids

More than one double bond in hydrocarbons

How does a double bond effect a fatty acid

Causes a kink