T1: Biological Molecules Flashcards
What are monomers?
Small molecular units that join to make polymers
Define polymer
A molecule made from long chains of monomers
What is a condensation reaction?
The joining of two monomers together with the release/elimination of a
molecule of water (forming a chemical bond)
What is a hydrolysis reaction?
The breaking of a chemical bond between two molecules involving the use of a water molecule
Two monosaccharides = ?
A disaccharide (joined by a condensation reaction forming a glycosidic bond)
More than two monosaccharides = ?
Polysaccharide (joined together by condensation reactions forming glyosidic bonds)
Name 3 monosaccharides
glucose
galactose
fructose
Name one non reducing sugar?
sucrose
glucose + glucose = ?
maltose
glucose + galactose = ?
lactose
glucose + fructose = ?
sucrose
Name the 2 types of glucose
Name the 2 types of glucose
In alpha glucose the OH is…
below
In beta glucose the OH is…
above
How are glycogen and starch formed?
by the condensation of alpha glucose
How is cellulose formed?
by the condensation of beta glucose
Where is starch located in organisms?
Many parts of plants in the form of small grains + large amounts found in seeds & storage organs
What is the purpose of starch?
Plants store excess glucose as starch
How is starch produced?
Condensation of many α-glucose sub units, which then form hydrogen bonds with molecules in the same chain
Starch is a mixture of…
2 polysaccharides of alpha-glucose
amylose + amylopectin
Describe the structure of amylose
Long, UNbranched chain of α-glucose
Describe how the structure of amylose relates to its function
Angles of the glycosidic bonds = coiled structure → makes it compact = can fit more into a small space (= good for storage)
Describe the structure of amylopectin
Long, BRANCHED chain of α-glucose
Describe how the structure of amylopectin relates to its function
Its side branches allow the enzymes that break down starch to get at the glycosidic bonds easily = glucose can be released quickly
α-glucose molecules are formed by what type of glycosidic bonds?
1,4 & 1,6 glycosidic bonds
How is cellulose formed?
by the condensation of beta glucose
Where is glycogen located in organisms?
Stored as small granules mainly in liver and some in muscles
What is the purpose of glycogen?
In animals: excess glucose is stored as glycogen
Glycogen is a p______…
Polysaccharide of α-glucose
Describe glycogen’s structure
Chain of α-glucose with many side branches coming off it + short chains
Describe how glycogen’s structure relates to its function
- Loads of branches & shorter chains = stored glucose can be released even quicker than in starch → important for energy releases in animals
- Very compact molecule, making it good for storage
Why is starch suited for its role? 3x
- Insoluble in water = doesn’t affect water potential (doesn’t cause water to enter cells by osmosis)
- Compact = lots of it can be stored in small space
- When hydrolysed, alpha glucose can be easily transported & used in respiration
Describe the structure of cellulose
- Long, unbranched chains of beta-glucose
- Straight cellulose chains run parallel to each other in cell walls = allows hydrogen bonds to form cross-linkages between chains
Result: formation of bundles called micro fibrils which then join together to make macro fibrils
What is the purpose of cellulose?
To provide rigidity to plant cells
Describe the test for reducing sugars
Add Benedict’s reagent (blue) to sample & heat it in a boiling water bath (5 mins)
Positive result = orange/red precipitate
Higher the concentration of reducing sugar = further the colour change goes
blue - green - yellow - orange - brick red
Describe the test for non-reducing sugars
Heat a new sample with dilute HCl in a boiling water bath
Neutralise with alkali
Repeat Benedicts test for reducing sugars
Describe the structure of a triglyceride
3 fatty acids attached to a single glycerol
What do fatty acids have?
Have long ‘tails’ made from hydrocarbons
Describe the structure of a phospholipid
2 fatty acids attached to a glycerol + a phosphate group
Name two kinds of fatty acids
saturated
unsaturated
Describe how a triglyceride forms
1) A fatty acid joins to a glycerol molecule
2) When ester bonds are formed a molecule of water is released (condensation)
3) This process repeats twice to form a triglyceride
Why are triglycerides good energy storage molecules?
Long hydrocarbon tails of fatty acids contains lots of chemical energy SO lots of energy is released when they are broken down
Describe how the structure of triglyceride makes them insoluble?
Triglycerides clump together as insoluble droplets in cells due to the fatty acids which are hydrophobic
Tails face inwards shielding themselves from water with their glycerol heads
