3.1.2.4 Polysaccharides structure and function and the starch test Flashcards
How is the structure of cellulose suited to its function?
- β-Glucose molecules can form long straight chains
- Parallel chains of cellulose form hydrogen bond ‘cross links’ which add strength
- Cellulose is arranged into microfibrils and then fibres, which add yet more strength
Which type of bond forms between adjacent α-glucose molecules in glycogen?
α 1-4 glycosidic bonds
Unbranched starch (amylose) coils into a…
compact helix structure
What test is described below:
Place 2 cm3 of the sample being tested into a test tube
Add 2 drops of iodine solution
A blue black colouration indicates a positive result
The test for starch
Identify the polysaccharide
Starch (amylose)
Identify the polysaccharide
Starch (amylopectin)
What form does starch take within plant cells?
Starch grains
Which type of bond forms between branching α-glucose molecules in glycogen?
α 1-6 glycosidic bonds
Which type of bond forms between unbranched starch (amylose) molecules?
α 1-4 glycosidic bonds
Identify the polysaccharide
Cellulose
How is glycogen different to starch?
Glycogen has many more branches
Identify the polysaccharide
Glycogen (more branches than starch)
Which type of organism contains starch?
Plants
What form does glycogen take in cells?
granules within muscle and liver cells
What type of reaction occurs when monosaccharides join?
Condensation reaction
How would you test for starch?
- Place 2 cm3 of the sample being tested into a test tube
- Add 2 drops of iodine solution
- A blue black colouration indicates a positive result
Cellulose microfibrils are grouped are arranged in parallel groups called…
fibres
Which monosaccharide is cellulose made from?
β-Glucose
How does the structure of glycogen make it suited to its function?
- It is insoluble so does not cause water to move into the cell via osmosis
- It is large so does not diffuse out of animal cells
- It is compact
- It forms α-Glucose when hydrolysed for respiration
- Many more branches than starch allow α-Glucose to be released faster from glycogen
What is the function of glycogen?
an energy store for animal and bacterial cells
The coiled helix structure of unbranched starch (amylose) is held in place by…
hydrogen bonds
What is the function of cellulose?
- Cellulose is a major component of plant cell walls and provides rigidity to plant cells
- Stops plant cells bursting when water enters
How are parallel chains of cellulose held together?
hydrogen bonds
What structure does cellulose take?
Long unbranched chains that run parallel to each other
Which type of bond forms between branched starch (amylopectin) molecules?
α 1-6 glycosidic bonds
Which type of monosaccharide is starch made from?
α-Glucose
Which type of bonds join β-Glucose molecules when they form cellulose?
β 1-4 glycosidic bonds
Cellulose chains are arranged in parallel groups called….
microfibrils
Why does glycogen require more branches than starch?
Animal cells require more energy to function
How does the structure of starch make it suited to its function?
- It is insoluble so does not cause water to move into the cell via osmosis
- It is large so does not diffuse out of plant cells
- It is compact
- It forms α-Glucose when hydrolysed for respiration
- Many branches allow α-Glucose to be released fast
Name the 3 types of polysaccharide
Starch (amylose and amylopectin)
Glycogen
Cellulose
What is the main function of starch?
energy storage in plant cells
Describe the structure of glycogen
POLYMER of alpha glucose
joined by glycosidic bonds
branched structure
How does glycogen act as a source of energy?
branched chains are HYDROLYSED
into glucose
used in respiration
Which type of monosaccharide is glycogen made from?
α-Glucose
