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Flashcards in Biological Molecules Deck (27)
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What is a condensation rection?

A reaction that joins 2 molecules together and removes a molecule of water


what specific type of bond gives water its unusual properties?

Hydrogen bonds


Why is water being a liquid at RTP usefull to living things?

it is a liquid at RTP so provides an aquatic habitat as well as being able to make up a majority of living tissues


What are the 7 key properties of water?

Liquid at RTP: major component in tissues and provides a habitat

Density: it gets less dense as it freezes

Solvent: good slovent for many solutes found in living things (NaCl or glucose)

Cohesion and Surface Tension: Caused by hydrogen bonding and allows water to move up Xylem

High Specific Heat Capacity: Requires alot of energy to heat or cool so is good at thermoregulation in organisms and provides stable habitat

High Latent Heat: requires large amount of energy to evapourate so allows mammals to sweat to cool down

Reactant: involved in reactions such as photosynthesis and hydrolysis (digestion of starch, lipids and protiens)


What are the three functions of Carbohydrates?

Energy source (Glucose)

Energy Store (Starch and Glycogen)

Structural Units (Cellulose and Chitin)


What are Monosaccharides?

The simplest types of sugars, they are small molecules that are soluble in polar solvents (water)

can exist as staight chains or in cyclic form

some monosaccharides like glucose are the monomers for more complex carbohydrates like disaccharides or polysaccharides.


Are monosaccharides reducing or non reducing sugars?

All monosaccharides are reducing sugars


What are Disaccharides?

Disaccharides are small polar molecules, that are soluble in polar solvents

Formed when 2 monosaccharides join together in a condensation rection.

examples include maltose, sucrose, and lactose


What is the type of bond formed when a disccharide is made

Glycosidic bond


Are dissacharide reducing or non reducing?

Depends, some disaccharides are reducing and some are non reducing.
e.g Maltose and Lactose are reducing but Sucrose is non reducing.


What are polysaccharides

They are polymers of monosaccharides, made of thousands of repeating units


why are polysaccharides good energy stores

because they can be broken down into their monosaccharide monomers (like glucose) which are often used in respiration


What are the 2 main examples of polysaccharides as energy stores

Starch and Glycogen


what are the 4 Properties of starch and glycogen that makes them good energy stores

Compact so don't take up much space and can be stored as large granules

They hold glucose in long chains so can be 'snipped off' when needed

Branched chains (glycogen and amylopectin) are more compact meaning more can be 'snipped off' when lots of energy is needed at once

Polysaccharides are less soluble in water, if they were soluble then it would reduce water potential and disrupt the normal cell workings


Name 1 example of a structural polysaccharide



Which monomer makes up Cellulose

Beta glucose


Which type of reaction forms cellulose



Why don't Beta glucose chains spiral

Because each monomer rotates 180 degrees so the bonds are on opposite sides forming a straight chain


Why is cellulose so strong

Forms 1-4 glyosidic bonds that are very strong

Hydrogen bonds form between chains adding strength

The chains lie parallel like bricks forming microfibrils. which then further bundle to make macrofibrils.

Macrofibrils run in all directions and criss-cross.


Where is cellulose most commonly found?

plant cell walls

Bacteria cell walls

Exoskeletons in insects


Why is cellulose useful in plant cell walls

Plants don't have a skeleton so each cell must be strong in order to provide structure

There are gaps between the macrofibrils so water and mineral ions are able to pass through making the cell wall fully permeable.


What are the 3 main properties of lipids

Insoluble in water (non polar)

soluble in alcohol

NOT polymers, however do consist of components bound together so are called macromolecules.


what are the 3 main types of lipids in living things





What is the structure of a Triglyceride?

Made up of glycerol and fatty acids

3 fatty acids

glycerol is an alcohol with 3 free -OH groups

fatty acids have a carboxyl group (-COOH) which can dissociate its hydrogen to form H+ and COO-


How does and unsaturated fat differ from a saturated fat

Unsaturated fats have 1 or more C=C where as saturated fats have all single bonds.

A C=C causes a kink in the chain which prevent the molecules packing as close together. this is why all plant oils are liquid and animal fats are solid at RTP.


What are the 5 main functions of triglycerides

Energy Source: Can be broken down in respiration, provide much more energy when broken down than a sugar does

Energy Store: Insoluble in water so dont affect the water potential of the cell

Insulation: good thermal insulator, Blubber in whales and penguins

Buoyancy: Fat is less dense than water so keeps aquatic animals afloat

Protection: Fat deposits round vital organs to absorb impacts and prevent damage


Describe the structure of a phospholipid

Same as a triglyceride but