lecture 7

Question 1

what are lipids?

Answer 1

• class of large biological molecules (don’t form polymers)
• little to no affinity for water (hydrophobic, non-polar covalent bonds)
• fats, phospholipids, steriods

Question 2

what are fats?

Answer 2

• constructed from glycerol and fatty acid
• glycerol is three-carbon alcohol with hydroxyl group on each carbon
• fatty acid is carboxyl group attatched to long carbon skeleton
• three fatty acids joined to glycerol by ester linkage (triglyceride)
• ester linkage (bond between hydroxyl and carboxyl)
• three fatty acids can be same/different
  saturated fatty acids have maximum number of hydrogen atoms possible (no dbl bonds)
• unsaturated (one/more dbl bonds)
• fats store energy
• store fat in adipose cells (tissue cushions vital organs and insulates body)

Question 3

what are phospholipids?

Answer 3

• two fatty acids and a phosphate group attached to glycerol
• fatty acid tails hydrophobic (phosphate group and attachments form hydrophillic head)
• assemble bilayer in water (tails to interior)
• found in cell membranes

Question 4

what are steroids?

Answer 4

• lipids characterised by carbon skeleton with four fused rings
• cholesterol most important (component in animal cell membranes)
• high levels contribute to cardiovascular disease

Question 5

what are proteins?

Answer 5

• structural support
• storage
• transport
• cellular signalling
• movement
• defence against forein substances

Question 6

what type of proteins are there?

Answer 6

• enzymatic (acceleration of chemical reactions)
• structural (support)
• storage (storae of amino acids)
• transport (transport of other substances)
• hormonal (coordinate organs activities)
• receptor (response of cell to chemical stimuli)
• contractile/motor (movement)
• defensive (protection against disease)

Question 7

what are polypeptides?

Answer 7

• proteins have complex 3-D shape
• polymers of proteins called polypeptides
• all polymers made of same 20 amino acid monomers
• protein consists of one of more polypeptides folded/coiled into specific conformation

Question 8

what are amino acids?

Answer 8

• monomers from which proteins are constructed
• organic molecules with both carboxyl and amino groups
• centre is asymmetric carbon atom (alpha carbon)
• different R groups characterise 20 different amino acids

Question 9

what type of groups of amino acids are there?

Answer 9

• nonpolar R groups
• polar R groups
• charged (ionised) at cellular pH
• some acidic R groups (negative charges due to presence of carboxyl group)
• basic R groups have amino groups with positive charge