revision 2 Flashcards
what are peptide bonds?
-join amino acids to form a protein polymer (polypeptide)
-links a C atom to a N atom
-generates a linear polymer with 2 distinctly different ends, a free a-amino group (N-terminus) and a free a-carboxyl group (C-terminus)
what is disulphide bonding?
-may stabilise protein tertiary structure
-involves a covalent link between 2 cysteines
-often occurs in extracellular proteins
what is a b-sheet?
a secondary structure in proteins consisting of b-stands connected by the backbone of hydrogen bonds
link between activation energy and rate of reaction
decreasing the activation energy increases the rate of a spontaneous reaction
what is catabolism?
the process of breaking down large complex molecules into smaller ones
examples of catabolism
-glycolysis: glucose -> pyruvate
-citric acid cycle: pyruvate -> CO2
-fatty acid oxidation: fatty acids -> acetyl-CoA
characteristics of catabolism
-release energy-result in synthesis of ATP
-take place by oxidation of substrates-usually oxidation takes place by transfer of pairs of hydrogen atoms to NAD+
what is phosphofructokinase (PFK)?
-main point of regulation of glycolysis
-an allosteric enzyme that is inhibited by ATP (good energy supply) but activated by ADP or AMP (with signs of low energy supply)
what’s the animal cell cycle order?
G1 phase - cell size checkpoint
S phase - DNA replication
G2 phase
Mitosis: prophase, metaphase, anaphase, telophase
Cytokinesis
what features do mitosis and meiosis share?
-breakdown of nuclear membrane
-chromosome condensation
-alignment of chromosomes on the equatorial plate
what feature does only meiosis have?
chromosome recombination
what does apoptosis do?
help prevent autoimmune disease
what is apoptosis?
programmed cell death
where do multicellular organisms occur?
eukaryotes only
where do unicellular organisms occur?
archaea and bacteria
