Biological Molecules Flashcards
Is oxygen delta positive or negative, and why?
Negative, as there is an unequal share of electrons, so electrons lean towards oxygen
What are some important functions of water?
- Solvent. Can dissolve polar substances like glucose and amino acids but not non polar substances
- Medium for chemical reactions
- Transport medium in plasma for animals, and in the xylem and phloem in a plant
- Coolant (sweat) so enzymes don’t denature
- Habitat
What bonds and type of chain are formed when alpha glucose molecules join up?
Two alpha next to each other - 1-4 glycosidic bond. Straight chain
Diagonally placed - 1-6 glycosidic bond. Branched
Describe the alpha glucose structures that make up starch in plants and glycogen in animals
Amylose - 1-4 glycosidic bonds, straight chain
Amylopectin -1-4 and 1-6 glycosidic bonds. Branched structure. One 1-6 every 25 alpha glucose molecules
Glycogen - 1-4 and 1-6 glycosidic bonds. Branched, and more branched than amylopectin
What are the positives of a branched alpha glucose structure?
- Energy storage
- Compact so stable
- Can release glucose from ends by hyrdolysis
Describe the cellulose structure
- All beta glucose molecules
- Alternate beta glucose molecule flips and is inverted, forming 1-4 glycosidic bond through a condensation reaction like usual
- Cellulose chains join to form microfibrils for strong, fibrous structural support in plants
- Hydrogen bonds are formed between the walls
What are the food tests for starch, reducing sugars, non reducing sugars, lipids and proteins?
Starch - Iodine solution. Brown to blue black
Reducing sugar - Benedict’s solution, heat in water bath. Blue to brick red precipitate
Non reducing sugar - Boil with HCl, then reducing sugar test
Lipids - Emulsion test (water and ethanol). White layer formed
Proteins - Biuret solution. Blue to purple
What is the structure of a triglyceride?
- One glycerol and 3 fatty acids
- The glycerol is an alcohol because of the hydroxyl groups at the end of three carbons and five hydrogens.
- Kinks in the fatty acids are carbons
- Condensation reaction releases water and joins up glycerol and fatty acids through an ester bond between carbon and oxygen
What enzyme breaks down triglycerides?
Lipase
What is the difference between a saturated and unsaturated fatty acid?
Saturated - Single carbon to carbon bonds
Unsaturated - A double carbon to carbon bond. Forms a kink. More than one double bond makes it polyunsaturated
What substances can and cannot pass through a phospholipid layer?
Can - Gases, hydrophobic molecules, small, non polar, uncharged
Can’t - Large, polar, charged
Describe cholesterol and its function
- 4 ring structure
- Dual hyrophilic/phobic properties
- Provides stability to plasma membrane
Draw an amino acid
What bond is formed between 2 amino acids?
Peptide bond
What is the difference between a polypeptide and protein?
Polypeptide - Linear chain of amino acids joined by peptide bonds
Protein - Contains one or more polypeptides
