WK 4 (Macromolecules) Flashcards
What constitutes most of the dry mass in cells?
Proteins
How are amino acids linked to form a protein? (what kind of bond)
Covalent peptide bond
The covalent bond between the carbon atom in the carboxyl group of one amino acid shares electrons with the nitrogen atom of amino group of another amino acid
- Water is released
Can rotation occur between amino acids?
Yes, covalent peptide bonds may allow rotation between amino acids (depending on the amino acids e.g. proline)
Can non covalent bonds form between atoms in polypeptide backbone and side chains?
Yes
Types of non-covalent bonds?
ionic bonds
Hydrogen bonds
Van der Waals attractions
Do bonds significantly affect the three dimensional structure of proteins?
Yes
Do hydrophobic and hydrophilic forces affect the structure of proteins?
yes, folding arrangement is affected
What is the primary structure of a protein?
The sequence of amino acids that make ups a polypeptide chain
What is the secondary structure of a protein?
The secondary structure is the way a polypeptide folds in a repeating arrangement to form α-helices and β-pleated sheets.
This folding is a result of hydrogen bonding between the amine and carboxyl groups of non-adjacent amino acids
Secondary structure provides the polypeptide chain with a level of mechanical stability (due to the presence of hydrogen bonds)
What is the tertiary structure of a protein?
The tertiary structure is the way the polypeptide chain coils and turns to form a complex molecular shape (i.e. the 3D shape)
It is caused by interactions between R groups; including H-bonds, disulfide bridges, ionic bonds and hydrophobic interactions
Relative amino acid positions are important (e.g. non-polar amino acids usually avoid exposure to aqueous solutions)
Tertiary structure may be important for the function of the protein (e.g. specificity of active site in enzymes)
What is the quaternary structure of a protein?
Structure formed by more than one polypeptide
Why is a proteins final conformation consistent?
It is guided by chaperone proteins
Ribosomal subunits are an example of what level of protein structure?
Quaternary structure
True or False
Different parts of proteins can fold differently
TRUE
Protein domains
Any part of a polypeptide chain that can fold independently into a compact stable structure
Usually contains between 50-350 amino acids
Different domains are often assigned to different functions
Fibrous proteins
Arranged in long chains or sheets
Globular proteins
Tightly folded into spherical or globular shapes
Ligand
the molecule to which a protein binds
Is protein binding an irreversible process?
No, overtime proteins and ligands will dissociate
The biological activity of proteins is only possible because of:
a) the number of disulphide bodies present
b) The repeatability of their tertiary structure
c) the glycosylation of proteins
d) none of the above
b)
Function of triacylglycerols
Stores of chemical energy
Most abundant lipid in cells
Triglycerides
Ester
Compound formed between an acid and alcohol reaction
How are triglycerides formed?
Through an ester linkage to glycerol to form triglycerides
Are lipids usually found in membranes?
No
Lipid that contains 3x same fatty acid
Simple triacylglycerols
Lipid that contains 2 or more different fatty acids
Mixed triacylglycerols
What type of reactions will triacylglycerols undergo?
Autoxidation (oxygen will double bonds) in unsaturated fatty acids to form rancid fats
What to adipocytes store?
Triacylglycerols (found in skin, mammary gland, abdomen)
What yields more energy carbohydrates of triacylglycerols?
Triacylglycerols yield 2x more energy than carbohydrates
What type of lipid is a phopholipid?
Polar lipid
What type of lipid is a sphingolipid?
Polar lipid
Micelles are formed by?
Polar lipids
Monolayers are formed by?
Polar lipids
Bilayers are formed by?
Polar lipids
Most abundant form of steroids is?
Sterol
E.g. cholesterol
What is the precursor to all steroid hormones?
Cholesterol
Fat soluble molecules which have 4 fused rings
Steroids
Testosterone is a…
Steroid
Lipoproteins contain
Polar lipids
Triacylglycerols
Sterols
What is on the surface of a lipoprotein?
Hydrophilic polypeptide chains and polar lipids
What is on the inside of a lipoprotein?
Hydrophobic polypeptide chains
Triacylglycerols
Sterols
True or false
Lipoproteins are a method of transporting water insoluble lipids around the body
True
What are the four classes of lipoproteins in blood plasma?
Chylomicrons
Very low density lipoproteins (VLDL)
Low density lipoproteins (LDL)
High density lipoproteins (HDL)
Where are waxes secreted from?
Skin glands
Glycogen is abundant in what location?
Liver and skeletal muscle
Mucopolysaccharides
Glycoproteins where carbohydrate % is much higher than the protein component
Heparin
Inhibitor of blood clotting
Abundant in arterial blood vessels
High Glycaemic Index range
70 or more
Mucopolysaccharides are:
a) Glycoproteins that contain a greater % of carbohydrate
than protein.
b) Glycoproteins that contain a greater % of protein than
carbohydrate.
c) An important form of glucose storage
d) Found only in synovial fluid.
a)
Where does transcription occur?
Nucleus
Where does translation occur?
Cytoplasm
How are polynucleotide chains formed?
by the interlocking of the phosphate and sugar components of the nucleotides (sugar-phosphate backbone)
How dies each DNA strand maintain polarity?
The subunits of the sugar-phosphate backbone align in the same orientation
Why does DNA form a double helix?
The sugar-phosphate group is hydrophilic and the bases
are hydrophobic.
Hence, the formation of a double helix structure with the sugar -phosphate backbone on the exterior of the molecule and the bases in the centre of the molecule.
Is RNA single stranded or double stranded?
Single stranded
