Biological Molecules Flashcards
What is a monomer?
Small units from which larger units are made from
What is a polymer?
Molecules made from a large number of monomers joined together
What are examples of monomers?
- Monosaccharides
- Amino acids
- Nucleotides
What is a condensation reaction?
A reaction that joins two molecules together with the formation of a chemical bond, and involves the elimination of a water molecule
What is a hydrolysis reaction?
A reaction that breaks a chemical bond between two molecules and involves the use of a water molecule
What are the 4 biological molecules?
- Carbohydrates
- Proteins
- Lipids
- Nucleic acids
What are the 3 types of carbohydrates?
Monosaccharides, disaccharides and polysaccharides
What is a monosaccharide and what are the 3 examples?
A monomer, which joins together to form disaccharides - these are reducing sugars
Glucose, fructose and galactose
What is a disaccharide and what are the 3 examples?
A sugar formed from 2 monosaccharides joined together in a condensation reaction, forming a glycosidic bond
Maltose, sucrose, lactose
What is a polysaccharide?
A polymer formed from many monosaccharides joined by glycosidic bonds in a condensation reaction
What monosaccharides form maltose, sucrose and lactose?
Glucose + glucose —> Maltose
Glucose + fructose —> Sucrose
Glucose + galactose —> Lactose
What are the two forms of glucose?
Alpha glucose and beta glucose
What is formed from alpha and beta glucose?
Alpha glucose forms starch and glycogen
Beta glucose forms cellulose
Whatvis a glycosidic bond?
When the H of one monosaccharide reacts with the OH of the other monosaccharide in a condensation reaction, producing a water molecule
What is the function of starch and it’s adaptations?
Function: Energy storage in plants
- Insoluble - does not affect water potential so does not affect osmosis
- Large - does not diffuse out of cells
- Compact - lots can be stored in a small space
- A - glucose - easily transported and used in respiration
- Branched chains - Many ends can be acted upon by enzymes simultaneously meaning rapid release
What is the function of glycogen and it’s adaptations?
Function: Energy storage in animals
- Insoluble - does not affect water potential so does not affect osmosis
- Large - Does not diffuse out of cells
- Compact - lots can be stored in a small space
- Highly branched - Many ends acted upon simultaneously by enzymes meaning rapid release
Whatbis the function of cellulose and it’s adaptations?
Function: Structural support in cell walls
- B - glucose - forms long straight unbranded chains
- Chains - run parallel, cross linked by hydrogen bonds which add strength
- Microfibrils - chains grouped into microfibrils which are grouped into fibrils adding strength
- Freely permeable fibres - allows water/solutes to leave or reach cell surface membrane
What is the biochemical test for starch and its positive result?
The biochemical test is the iodine test
A positive result indicates a bluish/black colour
What is the test for reducing sugars, what are the steps, and the positive result?
The test is the benedicts test and a positive test indicates a bright red precipitate
- Add benedicts reagent to a sample solution
- Heat in a water bath for a few minutes
- If a reducing sugar is present, a brick red precipitate will form as Cu2+ ions are reduced to Cu+ ions
What is the test for non-reducing sugars?
The test is the benedicts test, result is still a brick red precipitate
- Carry out benedicts test ad normal, negative test remains a blue colour
- Boil the sample with dilute hydrochloric acid
- Neutralise the solution with sodium hydrogencarbonate
- Carry out benedictsbas normal, add reagent and heat in a water bath
- If any reducing sugar are now present, brick red precipitate forms
