Atom(-bonds)

Question 1

alpha carbon atom

Answer 1

in organic acids the C-atom closest to the carboxyl group (see alpha-amino acids)

Question 2

covalent bond

Answer 2

the strongest bond between two atoms in which electrons are shared on common molecular orbits


Question 3

electronegativity

Answer 3

dimensionless number indicating the affinity of atoms of a given element to the electrons

Question 4

hydrogen-bond

Answer 4

weak interaction between an H-atom bound to a highly electronegative atom (O, N) in a molecule and another highly electronegative atom (O, N) in the same or a different molecule

Question 5

purines

Answer 5

compounds based on a two-ring structure containing five C and four N atoms; adenine and guanine, bases in nucleic acids are purine compounds


Question 6

pyrimidines

Answer 6

compounds based on a ring containing four C and two N atoms; uracil, thymidine and cytosine, bases in nucleic acids are pyrimidine compounds


Question 7

side chain

Answer 7

a group bond to the -carbon atom of amino acids; amino acids are distinguished by the chemical composition of this group


Question 8

van der Waals forces

Answer 8

relatively weak attraction between atoms and molecules with hydrophobic properties due to the random fluctuation of the electron clouds

Question 9

alpha helix

Answer 9

helical secondary structure of proteins stabilized by H-bonds between peptide bonds located above each other


Question 10

beta sheet

Answer 10

two-dimensional secondary structure of proteins stabilized by H-bonds between peptide bonds on chain segments running in opposite directions


Question 11

cis and trans position

Answer 11

on the same or on the opposite side (e.g. the two possibilities for the continuation of the lipid chain at the two ends of a double bond in an unsaturated fatty acid)

Question 12

disulfide linkage

Answer 12

a bond between two sulfide groups (side chains of cystein amino acids) determining the structure of proteins


Question 13

non-covalent bonds or weak forces

Answer 13

supplemental, but important interactions between and within biological molecules: electrostatic (ionic) bond, H-bond, van der Waals interaction


Question 14

peptide bond

Answer 14

covalent bond created by condensation (reaction releasing a water molecule) of the amino and carboxyl group of two amino acids

Question 15

secondary structure of proteins

Answer 15

formation of regular structures (α-helix, β-sheet) in the peptide chain stabilized by H-bonds


Question 16

unsaturated fatty acid

Answer 16

fatty acid containing one or more double bonds

Question 17

strength (energy) of a bond

Answer 17

energy released during the formation of the given bond between atoms – this energy is needed to break apart the atoms