2.2 Biological Molecules Flashcards
What forces occur between water molecules?
- Hydrogen bonds
- Dipole interaction
What are the properties of water?
- High specific heat capacity
- Ice is less dense than water because H bonds hold them apart
- Cohesion and adhesion between molecules
How is water used in life?
- Solvent/transport medium
- act as coolant
- ice can act as insulation
- surface tension due to cohesion
- Stable temperature
Why is waters ability to act as a solvent beneficial for life?
- Less membranes to pass through
- Allows ionic substances to seperate
- Such as blood or glucose
- Dilutes toxic substances
Why does a meniscus occur?
- Adhesion between water molecules cause the molecules to be attracted to the side of the container
Why do oil and water not mix?
- Water is polar and oil is non polar
Why does density increase when salt is added to water?
- More molecules in the same volume
What elements do carbohydrates contain?
- Carbon, Hydrogen and Oxygen
What is the basic formula for carbohydrates?
Cn (H2O)n
What is a monosaccharide?
Monomer of carbohydrate forming a basic repeating unit (can exist on there own)
What are the properties of a carbohydrates?
- Simple sugars
- Soluble so dissolve in cell cytoplasm
- Sweet tasting
- Form crystals
What does the term ‘Pentose’ mean?
- Five carbon ring
What is the difference between alpha and beta glucose?
- The O and OH on carbon 1 are flipped
- Alpha= H
I
OH
How do monosaccharides form disaccharides?
Condensation reaction forms glycosidic bond removing a water molecule
How are monosaccharides formed from disaccharides (polysaccharides)?
- Hydrolysis which breaks glycosidic bond using up a water molecule
What is a disaccharide?
- Two monosaccharides joined together
What is a reducing sugar?
A sugar which when Benedict’s solution is used the Cu 2+ ions are turned into atoms and form a precipitate
What is the test for a non reducing sugar?
- Test with Benedict’s (gives negative result)
- Hydrolyse with boiling acid
- Retest with Benedict’s solution
Why is glucose well suited to its function?
- Soluble in water
- Small so it can be transported across membranes
What bond occurs between monosaccharides?
Glycosidic
What monosaccharide does starch consist of?
- Alpha glucose
What are the two parts to a starch molecule?
- Amylose and Amylopectin
Why is starch insoluble?
Too large a structure
What are the features of amylose?
Alpha glucose joined by 1-4 glycosidic bonds
Helical shape making it compact
- hydrogen bonds within
What are the features of amylopectin?
- Alpha glucose joined by 1-4 and 1-6 glycosidic bonds
- Branched structure
What is glycogen?
An energy storage polysaccharide more branched and compact than starch
How does hydrolysis work with starch/glycogen?
- release glucose for respiration
- Involves carbohydrate enzymes
What is the test for starch?
- Add iodine
Positive- Blue-black
Negative- Brown-orange
What is cellulose?
A structural polysaccharide
What are the features of cellulose?
- Beta glucose polymer
- 1,4 glycosidic bond between beta glucose
- Every alternate glucose is flipped 180
- Straight chain
- Strong and insoluble which gives strength to plants
Why is cellulose a straight chain molecule?
Each glucose is flipped 180 so there is no helical structure
What do cellulose molecules form?
Microfibrils
What do microfibrils form?
Macrofibrils
What do macrofibrils form?
Cellulose fibres
How are macrofibrils held together?
Hydrogen bond
Why do beta glucose flip in a cellulose molecule?
Formation of hydrogen bonds
How would you test enzyme action on a reducing sugar on the change in concentration?
- five testubes of known concentration of sugar
- Add Benedict’s solution
- Waterbath for five minutes
- Filter each solution into curette
- Calibrate colorimeter
- Test for percentage transmission for each concentration making a calibration curve
- Then add Benedict’s to a mix of sugar and enzyme and put in water bath
- Take samples of mixture at regular intervals
- Filter samples then test under colorimeter
What is a macromolecule?
-Large complex molecules
What are the roles of lipids?
- Membranes
- Hormone production
- Electrical insulation
- Waterprrofing
- Thermal insulation
How do you test for lipids?
- Emulsion test
- Add ethanol,add water then shake
Positive = Cloudy emulsion
Negative- No change
What is a triglyceride?
- 1x glycerol molecules with three fatty acids attached
- fatty acids joined in condensation reaction
How are fatty acids joined to glycerol in a triglyceride?
Ester bond
What is the usual purpose of a triglyceride?
For energy storage which can be broken down by lipase enzyme
What forms can fatty acids come in?
Saturated- NO double bonds forming a straight chain
Unsaturated- Double bonds causing kinks so cannot pack as tightly and more likely lquid
What molecule is formed in a condensation reaction?
Water
What is different about a phospholipid compared to other lipids?
- Polar molecules
What is a sterol?
A steroid alcohol
WHat are the features of a sterol?
- 4x carbon ring
- OH group at one end
- Produced by liver and intestines
How do anabolic steroids reach the nucleus?
- Anabolic steroids are non polar so can diffuse through membrane
What are the roles of proteins?
- Enzymes
- Hormones
- Structural
- Antibodies
- proteins in cell surface membranes
What are the monomers of proteins?
Amino acids
What is an amine group?
NH2
What part of an amino acid molecule are involved in a condensation reaction?
-Hydrogen,carboxylic and amine group
What is the test for proteins?
Biuret test which if positive will turn lilac
What is the primary structure of protein?
- Sequence of amino acids in a structure
What is the secondary structure of a protein?
The shape due to interaction of O,H and N forming H bonds
What are the two types of secondary structures?
- Alpha helix- Helical shape
- Beta pleated sheets- folded
What is the tertiary structure of a protein?
- The final 3D shape which is held in place by multiple interactions
What bonds/interactions can be present in a tertiary structure of proteins?
- DIsulfide bridges- Exists between amino acids with Sulfur in their R groups
- Ionic bonds- Exists between charged r groups
- Hydrogen bonds
- Hydrophobic/hydrophylkic R groups which will orientate accordingly
What is the definition of quarternery structure of proteins?
When two or more proteins are joined together
What are the features of globular proteins?
- Spherical in shape
- Compact
- Watersoluble due to lots of hydrophylic r groups
What are the features of the insulin?
- Globular proteins
- Involved in regulation of blood glucose
- Simple proteins
- Unique shape to compliment cell surface receptor
What is a conjugated protein?
Proteins that contain a prosthetic group
What is the structure of haemoglobin?
- 4x polypeptides: 2x alpha and 2xbeta
- Each subunit has a prosthetic haem group attached
- Contains Fe +
What is the structure of catalase?
- 4x polypeptides with 4x prosthetic haem groups
- allows enzyme to be used on H2O2
What is a fibrous protein?
- Long insoluble molecule contains hydrophobic R groups
- Small number of insoluble amino acids in a repetitive sequence
What are the features of keratin?
- Large proportion of cysteine (DIsulfide bridges)
- Strong,inflexible and insoluble
What are the features of Elastin?
- Found in elastic fibres
- Cross linked structure
- Large insoluble molecules
Where is collagen found?
- Skin tendons and ligaments
What is the structure of collagen?
- H bonds between the 3x polypeptide chains
- Every third amino acid is glyceine which is a small amino acid so it packs more tightly together
What are the properties of collagen?
- Flexible
- Doesn’t stretch
- Strong
- Insoluble
What is a tropocollagen?
Collagen joined together forms a left handed spiral
