23. THE GENETIC CODE

Question 1

1. What is the Central Dogma of flow of genetic information?

Answer 1

• the genetic information originates from the DNA
• the DNA is transcribed to the RNA
• the RNA is translated to Proteins

Question 2

2. Who first proposed the Central Dogma?

Answer 2

• this was first proposed in 1959
• it was proposed by Francis Crick
• he is responsible for the discovery of the structure of
  DNA

Question 3

3. What is a Central Dogma?

Answer 3

• this is a process by which the instructions in DNA are
  converted into a functional product

Question 4

4. Where is DNA information stored?

Answer 4

• DNA information is stored in the Nucleotide sequence

Question 5

5. What directs the Synthesis of Proteins?

Answer 5

• the DNA sequence of an organism (genotype)
• leads to specific traits (phenotype)
• it does this by directing the synthesis of proteins

Question 6

6. What is the Phenotype a result of?

Answer 6

• protein production
• proteins from the links between the genotype and the
  phenotype

Question 7

7. What is Gene expression?

Answer 7

• it is a DNA directed protein synthesis

Question 8

8. What two stages does Gene expression have?

Answer 8

1. Transcription
   
   • produces RNA from DNA
2. Translation
   
   • produces proteins from RNA

NB:
- the genes will specify the proteins through these
processes

Question 9

9. What is a Genotype?

Answer 9

• genetic make-up of an organism
• it is defined by the genes on the DNA

Question 10

10. What is a Phenotype?

Answer 10

• the physical appearance of an organism
• the organism’s traits and characters

Question 11

11. What is RNA?

Answer 11

• this is the intermediate
• between genes and the proteins that they code

Question 12

12. What is Transcription?

Answer 12

• this is the synthesis of RNA
• it is directed by the DNA
• it produces messenger RNA (mRNA)

Question 13

13. What is Translation?

Answer 13

• this is the synthesis of polypeptides
• it is directed by the messenger RNA (mRNA)
• it happens on the Ribosomes

Question 14

14. What do viruses have the capacity to do with regards to DNA?

Answer 14

• they have the capacity to convert RNA to DNA
• they can do this using Reverse Transcriptase

Question 15

15. List 3 facts about Translation and Transcription in Prokaryotes?

Answer 15

1. THERE IS NO NUCLEAR ENVELOPE
   
   • to separate transcription from translation
2. THE MRNA PRODUCED BY TRANSCRIPTION
   
   • is immediately translated
   • it is not processed further
   • this means that there is no RNA processing
3. TRANSLATION CAN START
   
   • before the end of Transcription

Question 16

16. List 4 factors about Translation and Transcription in Eukaryotes?

Answer 16

1. THERE IS A NUCLEAR ENVELOPE
   
   • that separates transcription from translation
2. TRANSCRIPTION
   
   • will take place in the nucleus
3. RNA PROCESSING
   
   • the eukaryotic RNA is modified
   • this is done to yield RNA
   • this is done in the nucleus
4. TRANSLATION:
   
   • takes place in the cytoplasm

Question 17

17. Provide the labels for 1-3 in this diagram.

Answer 17

1. DNA
2. Nucleus
3. Precursor mRNA
   (pre-mRNA)

Question 18

18. Provide the labels for 4-7 in this diagram.

Answer 18

4. Processing
   (5’ cap)
   (3’ poly (A) intron removal)
5. mRNA
6. Polypeptide being synthesised
7. Cytoplasm

Question 19

19. Draw a flow diagram for Gene expression in Prokaryotes?

Answer 19

DNA
⬇
mRNA
⬇
Ribosomes
⬇
Polypeptides

Question 20

20. Draw a flow diagram for Gene expression in Eukaryotes?

Answer 20

DNA
⬇
Pre-mRNA
- this is known as the Primary Transcript
- it is the initial RNA transcription
⬇
mRNA
⬇
Ribosomes
⬇
Polypeptides