Biochemistry- Outcome 1.2, lipids

• What is the biological importance of lipids

  Lipids provide energy, they act as hormones, provides layer of insulation in many animals, are components of biological membranes
• Draw the structure of glycerol

  
• Draw the structure of a fatty acid

  Where R is the long hydrocarbon chain

  
• Draw the structure of a triglyceride

  +3H2O

  
• Name the lipid which makes up biological membranes

  Phospholipids
• What are glycolipids?

  Glycolipids are lipids with carbohydrate groups attached
• What is the biological role of cholesterol?

  Apart from its role as a stabilising component of cell membranes, cholesterol is also the precursor for the synthesis of many important steroid hormones.
• Define hydrophobic and hydrophilic

  Hydrophobic= water insoluble , doesn't mix with water

  Hydrophilic= water insoluble, mix with water well
• Why are oils (e.g fish oil) in a liquid state?

  The large number of double bonds in oils accounts for their liquid state
• Are fats soluble in water

  No they are not
• Name a steroid sex hormone

  Testosterone
• Draw and label the structure of an amino acid


  .

  
• Name and draw the bond which links amino acids

  together

  .

  
• How many amino acids are naturally occuring?

  20
• When many amino acids bond together, the

  resulting molecule is referred to as

  polypeptide
• What is the primary sequence of a protein

  It’s a sequence of amino acids in polypeptide e.g. Lys-Asp-Gly-

  Met
• What shapes make up the secondary structure of a

  protein?

  Coils – α helix

  Sheets – β pleated
• What type of bonding helps to stabilise the

  secondary structure?

  Hydrogen bonding
• What makes up the tertiary structure of a protein

  folding of the polypeptide
• What are the bonds which help stabilize the

  tertiary and quaternary structure of a protein

  Van der Waals forces, Hydrogen bonds, hydrophobic interactions,

  disulphate bonds, ionic interaction
• Name a protein which is involved in transport

  of molecules across the membrane

  Integral membrane proteins
• Define the term “active transport

  As the name suggests

  active transport

  requires

  chemical energy

  to transport molecules across the membrane. In active transport

  molecules are carried

  against their concentration gradients

  so

  energy is needed.
• Name the amino acid involved in forming

  disulphide bridges

  Cycteine
• Define hydrophobic interactions

  intra-polypeptide interactions occur in an environment within proteins

  from which water is excluded, exclusion occurs because

  hydrophobic R groups cluster. Clustering occurs because water

  molecules are freer to H bond with one another. In globular

  (water-soluble) proteins hydrophobic R groups are inside so

  secondary and tertiary interactions can occur without water and

  hydrophilic R groups outside and so H bonding occurs between

  water to make it soluble
• Name the following bonds on this nucleotide


  .

  
• What are the four bases in DNA

  Adenine, Thymine, Guanine, Cytosine
• What is the name of the covalent bond which links

  nucleotides?

  Phosphodiester bond
• Name the type of bond which holds the two

  polynucleotide DNA strands together

  weak hydrogen bonds
• Name the base found in RNA but not DNA

  Uracil
• Name the three types of RNA involved in protein production

  mRNA, tRNA, rRNA
• Name a role for each RNA molecule involved in

  protein production

  mRNA –

  Acts as a template for protein synthesis. Conveys

  genetic information from DNA to the ribosome for translation.

  •

  Transfer RNA (tRNA):

  RNA consisting of folded molecules which

  transport amino acids from the cytoplasm of a cell to a ribosome.

  •

  Ribosomal RNA (rRNA): Ribosomal RNA makes up the ribosom
• Name two secondary structures which RNA can

  form

  Stem loop structures and a secondary structure known as

  pseudoknots
• Name the sugars found in DNA and RNA

  Deoxyribose sugar and ribose sugar
• Name two purines and two pyrimidines

  Purine bases – adenine and guanine

  Pyrimidine bases –

  thymine and cytosine
• Describe two similarities between DNA and RNA

  Contain the bases adenine, guanine and cytosin
• Describe two differences between DNA and RNA

  DNA – double stranded, RNA – single stranded

  DNA – Deoxyribose sugar, RNA – ribose sugar

  DNA – Thymine, RNA - Uracil
• How are carbohydrates classified?

  Carbohydrates are classified into sugars, which include monosaccharides, disaccharides, and polysaccharides.
• What are the two types of polysaccharides mentioned?

  Storage polysaccharides include starch and glycogen, while structural polysaccharides include cellulose.
• What is the general formula of carbohydrates?

  The general formula of carbohydrates is Cx(H2O)y.
• What is the difference between α-glucose and β-glucose?

  • α-glucose: OH on Carbon 1 below the plane of the ring
  • β-glucose: OH on Carbon 1 above the plane of the ring