Biological molecules Flashcards
Carbohydrates
What is a polymer?
Made from lots of monomers bonded together
What is a monomer?
smaller units which can create larger molecules
What are polymers of glucose and nucleotides?
Glucose - starch, glycogen and cellulose are its polymers
Nucleotides - DNA and RNA are its polymers
What are monosaccharides, disaccharides and polysaccharides?
Monosaccharides - carbohydrates which are monomers (eg. glucose, fructose and galactose)
Disaccharides - carbohydrates which consist of two monomers - (eg sucrose, lactose, maltose)
Polysaccharides - carbohydrates which are polymers (eg. starch, glycogen, cellulose)
What are the two isomers of glucose?
Alpha glucose and beta glucose
What are features of disaccharides? and how are they formed?
Made from two monosaccharides and joined together by glycosidic bond. They are formed via condensation reactions
What are examples of disaccharide formations?
Glucose + glucose -> maltose + water
Glucose + galactose -> lactose + water
Glucose + fructose -> sucrose + water
How is starch formed?
Formed via condensation reactions between many glucose monomers (amylose and amylopectin)
Where is starch found and what is its function?
- Found in plant cells
- Insoluble store of glucose
What bond is formed when amylose undergoes condensation reaction?
1-4 glycosidic bond
How is glycogen formed? And where is it found?
Glycogen forms by many condensation reactions between alpha glucose. It is found in muscle and liver cells
What is function of glycogen?
It is an insoluble source of glucose.
How is cellulose formed?
By many condensation reactions between beta glucose via 1-4 glycosidic bonds
What is the function of cellulose and where is it found?
Cellulose provides strength to plant cell walls and is found in cell walls of plants
What are fibrils?
Long straight chains which lie parallel and are held together by hydrogen bonds
How does structure of starch help function?
Helix is compact to fit a lot of glucose in small spaces; Branched structure increases surface area allowing for rapid hydrolysis back to glucose; Insoluble so doesn’t affect water potential
How does structure of glycogen help function?
Branched structure increases surface area allowing for rapid hydrolysis back to glucose. Insoluble so doesn’t affect water potential
How does structure of cellulose help function?
Insoluble in water so does not affect water potential
Many hydrogen bonds provide strength
What are the two types of lipids and what do they consist of?
Triglycerides - consist of 3 fatty acid molecules and 1 glycerol molecule; Phospholipids - consist of one glycerol molecule, 2 fatty acid molecules and a phosphate group - attached to the glycerol
What happens when the two fatty acid molecules bond to a glycerol molecule (phospholipid)?
Two fatty acids bond to glycerol molecule via condensation reaction leading to two ester bonds
How are triglycerides formed?
Formed via condensation reaction between molecules, forming an ester bond
What is emulsion test for lipids?
- Take sample and dissolve in ethanol
- Add distilled water
- If lipid is present a white emulsion forms
What are properties of triglycerides?
- Large ratio between number of carbon-hydrogen bonds to the number of carbon atoms, so a lot of energy is stored. 2. High ratio of hydrogen to oxygen atoms, so triglycerides can be a metabolic water source and release water when oxidised. 3. Triglycerides are insoluble so do not affect water potential. 4. Triglycerides have a low mass meaning they do not affect mass and prevent movement.
What are properties of phospholipids?
- Hydrophilic head of a phospholipid can attract water as it is charged - repels fats. 2. Hydrophilic tail (fatty acid chain) is not charged and mixes with fats but repels lipids. 3. Form phospholipid bilayer membrane structure which makes up plasma membrane around cells
