Monomers and Polymers and Carbohydrates (Biological Molecules) Flashcards
Define Monomer (and examples)
Smaller units that join together to form larger molecules
* monosaccharides (glucose, fructose, galactose)
* amino acids
* nucelotides
Define Polymer (and examples)
Molecules formed when many monomers bond together to form long chains
* Polysaccharides
* proteins
* DNA/RNA
* Starch
* Cellulose
* Glycogen
What happens in a condensation reaction
A chemical bond forms between 2 molecules and a molecule of water is produced.
Hydroxyl (OH) and Hydrogen from hydroxyl on other molecule. 2 molecules bonded by O
What happens in a Hydrolysis reaction?
A water molecule is used to break a chemical bond between 2 molecules.
Glycosidic bonds are broken through addition of water and O becomes OH on one side of moelecule and HO on other molecule
Name the three hexose monosaccharides
- Glucose
- fructose
- galactose
all have molecular formula C6H1206
Name type of bond formed when monosaccharides react
1,4 or 1,6 glycosidic bond
2 monomers= 1 chemical bond= disaccharide
multiple monomers=many chemical bons= polysaccharide
Name three disaccharides and how they form
condensation reaction forms glycosidic bond between 2 monosaccharides
* maltose: glucose+glucose
* sucrose:glucose+fructose
* lactose: glucose+galactose
all have molecular formula C12H22011
Describe the structure and functions of starch
Starch is a polysaccharide made up of chains of alpha glucose monosaccharides linked by glycosidic bonds that are formed in condensation reactions. Chains can be unbranched or branched. unbranched chain is tightly coiled
* Insoluble no affect on wp no osmosis
* Large doesnt diffuse out of cells
* compact so can be stored in a small place
* when hydrolysed it forms alpha glucose which is easily transported and used in respiration
* branched form has many ends each of which can be acted on by enzymes simultaneously meaning glucose monomers are released rapidly.
found in starch grains inside plant cells (e.g inside chloroplasts) insoluble store of glucose
Amylose: condenstation react 1-4 glycosidic bond. unbranched chain coils up to make a helix.
Amylopectin: condensation reaction 1-6 glycosidic bond creates a branch.
Describe the structure and functions of glycogen
main storage polymer of alpha glucose in animal cells (muscle and liver cells) Function insoluble store of glucose. Shorter chains and highly branched.
- 1,4 and 1,6 glycosidic bonds
- highly branched=many terminal ends for hydrolysis. More ends that can be simultaneously acted on by enzymes. more rapidly broken down to form glucose monomers which are used in respiration. Animals have higher metabolic rate and respiratory rate than plants
- insoluble=no osmotic effect and does not diffuse out of cells
- compact alot can be stored in a small place
Describe the structure and functions of cellulose
Polymer of beta glucose gives rigidity to plant cell walls. Prevents cell from bursting by exerting inward pressure stopping any further influx of water, as a result plant cells are trugid and push against eachother making parts of plant semi rigid. Turgid state provides max surface area for photosynthesis. Provodes structure.
- 1,4 glycosidic bonds (condensation)
- only straight chains unbranched molecule
- alternate glucose molecules are rotated 180
- H-bond crosslinks between parallel strands from microfibrils=high tensile strength
- Straight chains of beta glucose run parallel to eachother and are held in place by many H bonds to form a fibril. further allowing H bonds to form cross links with adjacent chains
- H bonds are weak but due to large number they provide strength.
- Molecules groubed to form microfibrils which in turn are grouped together to form fibres
Describe the Benedict’s test for reducing sugars
- Add an equal volume of Benedict’s reagent to a sample
- Heat the mixture in an electric water bath at 100 degrees for 5 minutes
- positive result: colour change from blue to orange and brick red precipitate forms
reducing sugars: Glucose fructose galactose lactose and maltose. They are able to reduce copper sulphate (blue) in benedicts to copper oxide (brick red)
Describe the Benedict’s test for non reducing sugars
- Negative result: Benedict’s reagent remains blue
- Hydrolyse non reducing sugars e.g sucrose into their monomers by adding 1cm3 of Hydrochloric acid. heat in a boiling water bath for 5 mins
- cool solution. Neutralise the mixture using sodium carbonate solution
- proceed with the benedicts test as usual
- blue to green, yellow orange or brick red.
Non reducing sugar: sucrose. sucrose is hydrolysed (through boiling with acid) and glycosidic bond is broken. the reducing group becomes exposed
Describe test for starch
Add iodine solotuion
positive result is colour change from orange to blue/black
What are monosaccharides disaccharides and polysaccharides
Monosaccharides:(monomers) Soluble substances with genreal formula 6 carbon, 12 hydrogen and 6 oxygen (C6H1206) examples include glucose, fructose and galactose
Disaccharides (Dimers) a pair of monosaccharides e,g sucrose maltose lactose
Polysaccharides: (polymers) Monosaccharides combined forming polysaccharides e,g starch cellulose and glycogen
Describe the structure of alpha glucose
TOP ROW: H H
BOTTOM ROW: OH OH
forming hexagon shape C6H1206
Describe structure of beta glucose
Two isomers of glucose: same molecular formula different structure alpha and beta
TOP ROW: H OH
BOTTOM ROW: OH H
What are disaccharides and how do they form + examples
- Made of two monosaaccharides
- Joined together by glycosidic bond
- formed via condensation reaction
Glucose+glucose=Maltose +water
Glucose+galactose=Lactose +water
Glucose+fructose=sucrose +water
What are condensation reactions and Hydrolysis reactions
Condensation reaction: A condensation reaction is one in which two molecules join together via the formation of a new chemical bond, with a molecule of water being released (removed) in the process
The new chemical bond that forms between two monosaccharides is known as a glycosidic bond.
Hydrolysis reaction: Splitting apart molecules through the addition of water and glycosidic bonds are broken
During which processes are polymers hydrolysed in the body to monomers
What catalyses hydrolysis in the body
Digestion e.g starch is hydrolysed into glucose
Glycogeno lysis stores of glycogen hydrolyed back into glucose when blood sugar levels drop.
Compare Monomers, bonds, function.location, structure and function of glycogen cellulose and starch
Starch
Monomer: alpha glucose
Bonds: 1,4 glycosidic amylose and 1-4 and 1,6 amylopectin.
Function: store of glucose
Location: plant cells (chloroplast)
Structure: Amylose- unbranched helix Amylopectin branched molecule
Function: Helix can compact to fit glucose in a small space. Branched structure increases surface area for hydrolysis back to glucose. INsoluble not affected by osmosis
Cellulose:
Monomer: beta glucose
Bonds 1-4 glycosidic
Function strength for cell wall
Location: plant cell wall
Structure: Long straught chains held in parallel by many h bonds forming fibrils
Function: H bonds provide collective strenght insoluble wont affect water potential
Glycogen:
Monomer: alpha glucose
Bonds: 1-4 and 1-6 glycosidic bonds
Function: store of glucose
location: animals muscle liver cells
Structure: highly branched
Function: Branched structure increases surface area for hydrolysis of glucose insoluble
Describe test for proteins
Add Bieurets regent
positive test from blue to black
Describe test for lipids
Disolve the sample in ethanol
add distilled water
positive test a white emulsion forms
