The structures of vitamin C and the preservatives 2 - BHA and BHT are shown in figure 17 . Determine any chiral carbon atoms in these three compounds by placing an asterisk, *, beside them on a copy of the figure.

The vitamin C contains two chiral carbon atoms. One is on the ring structure and another present in out of the ring. The other two compounds ( 2 - BHA and BHT ) do not contain any chiral carbon atoms due to the presence of same groups in the carbon atom of the ring as well as out of the ring.

EASY

Diploma

IMPORTANT

Earn 100

Amino acids can exist in $D$ and $L$ forms. Describe how the $D$ form of alanine, $H_{2} NCH ({CH}_{3}) COOH$ , differs in its physical properties from the $L$ form.

Important Questions on Biochemistry

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 1

Explain the

D

and

L

convention for describing amino acids and draw the

D

form of alanine to show clearly its three-dimensional structure.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 2

Explain how the “CORN” rule can be used to identify an enantiomer of alanine as either

D -

L -

alanine.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 3

Identify, by marking with asterisk (*) symbols, all chiral carbon atoms in the molecules of leucine, isoleucine, valine, proline, and threonine (sub-topic B.2, table 1). Remember that some amino acids contain more than one chiral centre.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 4

The reason why only

L -

enantiomers of

2 -

amino acids are found in proteins remains a mystery. It is possible that this selection was made arbitrarily and then fixed firmly in evolutionary history. Discuss the role of random events in evolution.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 4

The reason why only

L -

enantiomers of

2 -

amino acids are found in proteins remains a mystery. It is possible that this selection was made arbitrarily and then fixed firmly in evolutionary history. A photosynthesizing organism based on

D -

amino acids could potentially be created artificially. Discuss possible environmental implications of such an experiment.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 5

The structures of vitamin $C$ and the preservatives $2 - BHA$ and $BHT$ are shown in figure $17$ .

Question Image

Determine any chiral carbon atoms in these three compounds by placing an asterisk, *, beside them on a copy of the figure.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 6

Two stereoisomers with the same molecular formula often have very different biological activities. Explain, with reference to enzymatic catalysis, why only certain stereoisomers can be metabolized by living organisms.

EASY

Diploma

IMPORTANT

Oxford IB Diploma Programme Chemistry Course Companion>Chapter 23 - Biochemistry>Questions>Q 7

Distinguish between the structures of

α -

and

β -

glucose.

Amino acids can exist in D and L forms. Describe how the D form of alanine, H2NCH(CH3)COOH, differs in its physical properties from the L form.

Important Questions on Biochemistry

Learn and Prepare for any exam you want !

Amino acids can exist in $D$ and $L$ forms. Describe how the $D$ form of alanine, $H_{2} NCH ({CH}_{3}) COOH$ , differs in its physical properties from the $L$ form.