Biological Molecules Flashcards
What are monomers, what are they called and what is their general formula ?
- Called monosaccharides
- Simplest ‘simple sugar’
- General formula (CH2O) N , where N is a number between 3 and 7
What reaction forms two carbohydrate a-glucose monosaccharides and what bond holds them together
Condensation reaction
Held together by a glycosidic bond
What is an isomer?
A molecule with the same formula but a different structural formula (variation)
What is the general formula for the group of sugars which include glucose, fructose and galactose?
(CH2O)n
What are the polymers formed from a-glucose and b-glucose and what is their role in living organisms?
A-glucose = starch , used as an energy store
B-glucose = cellulose, used in the cell wall of plants
What kind of sugar is found in genetic material?
Penrose sugar
What are the polysaccharide energy stores in plants and animals?
Animals - glycogen
Plant- Amylose and amylopectin
What makes polysaccharides good energy stores?
Contains glycogen which is compact meaning it doesn’t take up much space
Holds glucose molecules in chains meaning that they can be ‘snipped off’ for a fast energy source
Why are polysaccharides used as energy stores and not monosaccharides?
Polysaccharides are less soluble in water than monosaccharides
If many glucose molecules dissolved in the cytoplasm, the water potential would reduce and excess water would diffuse in, disrupting the cell
Give two similarities and two differences between plant and animal polysaccharide energy stores
Similarities -
• glycogen has 1-4 glycosidic bonds like amylopectin and amylose
• glycogen has glycosidic bonds 1-6 like amylopectin
Differences -
• amylose and amylopectin coil into a spiral shape whereas glycogen doesn’t as it’s bounded chains are smaller
Which enzymes are used to break the polysaccharide chains/branches?
Amylase (breaks 1-4 glycosidic linkages) and glucosidase (breaks 1-6 glycosidic linkages)
Explain how disaccharides and split into monosaccharides
Though hydrolysis
Hydrolysis provides the hydroxyl group
(-OH) and the hydrogen which help the glycosidic bond to break
Describe the basic structure of amylose
Long chain of a-glucose molecules
Glycosidic bonds between carbon 1-4
Describe the basic structure of amylopectin
1-4 glycosidic bonds
Also had 1-6 glycosidic bonds in its branches
Describe the structure of glycogen
1-4 glycosidic bonds
Branches formed by 1-6 glycosidic bonds
Name the covalent bond between two adjacent amino acids in a chain of amino acids
Peptide bond
Name the type of reaction which breaks a peptide bond and describe what happens
Hydrolysis
Water is added
Explain why glycogen makes a good storage molecule
Insoluble
Does not affect water potential
Can be broken down quickly
Lots of branches for enzymes to attach
Compact
What is the food test for starch and what is it’s process
To test for starch add iodine
A positive result will go from orange to blue/black
What is the test for reducing sugars and it’s process
Add Benedict’s and heat
Solution will turn from blue to green to yellow to orange or brick red
What is the test for non-reducing sugars and it’s process
Carry out a reducing sugar test first, if it is negative then carry on with non reducing test
Add acid and boil
Cool solution and add alkali to neutralise
Add Benedict’s and heat
Solution will turn from blue to green to yellow to orange or brick red
What are the reducing sugars
Glucose
Fructose
Galactose
Lactose
Maltose
What is the non reducing sugar
Sucrose
What is the test for proteins what is the process?
Add buiret
Positive result :
Colour change from blue to purple
What is the test for lipids and what is the process?
Dissolve sample on ethanol
Add distilled water
Positive result :
Cloudy white emulsion
