Nucleic Acid, Replication, Transcription and mRNA processing Part 1 - (Week 5)

Question 1

Genetic Material possesses several key characteristics. True or False?

Answer 1

True.

• contains complex information
• replicate (copy itself) faithfully
• encode all the phenotypes of the organism
• have the capacity to vary

Question 2

What did Frederich Griffith do?

Answer 2

• performed experiments to demonstrate that molecules can transfer genetic material information from one organism to another
• worked with different strains of Streptococcus pneumoniae bacteria
• virulent bacteria strain, able to infect/damage a host

Question 3

What is transformation?

Answer 3

• change in genotype and phenotype due to assimilation of foreign DNA
• technique now commonly used in molecular biology

Question 4

What happens in transformation?

Answer 4

• bacteria acquires genetic information from dead bacteria strain - permanently changes the live bacteria

Question 5

What did Frederick Griffith observe in his experiment?

Answer 5

• virulent bacteria causes mice to get sick
• non-virulent bacteria do not cause mice to get sick
• killed virulent bacteria do not cause mice to get sick
• when mice are mixed, the injected mice got sick and died
• when he isolated bacteria from dead mice, they had the appearance of the virulent strain, though he injected the non-virulent bacteria

Question 6

What is the nature of the genetic material? (Griffith)

Answer 6

• nonvirulent strain of bacteria can be transformed into virulent strain of bacteria by an unknown molecule from the virulent cells
• unknown molecule carries info that causes virulence

Question 7

What is the chemical nature of the “transforming” material?

Answer 7

• 3 hypotheses
• Protein, combining protein of killed virulent bacteria strain with non virulent bacteria to virulent
• DNA, combining DNA of the killed virulent bacteria with nonvirulent to make virulent bacteria
• RNA, combining RNA of the killed virulent strain strain nonvirulent bacteria will transform this into virulent

Question 8

How are we able to conclude the transforming material is DNA?

Answer 8

• removal of lipids + sugars from a solution of heat - killed S cells
• Proteins, RNA, DNA remain
• treat solutions with enzymes to destroy protein, RNA/DNA
• add to culture containing living R cells.
• observe for transformation by testing for the presence of virulent S cells
• DNAse treatment removed the transforming substance, = DNA

Question 9

What is the S (smooth) bacteria?

Answer 9

• virulent bacteria

Question 10

What is the R (rough) bacteria?

Answer 10

• the nonvirulent bacteria

Question 11

What is the relevance of sulphur in the Hershey-Chase experiment?

Answer 11

• component of every protein

- S^35 represents the protein, which makes up the exterior of the phage

Question 12

What is the relevance of phosphorus in the Hershey-Chase experiment?

Answer 12

• P^32 represents the phage’s DNA

- DNA backbone’s = composed of phosphate & deoxyribose

Question 13

You need DNA to pass down genetic material. True or False?

Answer 13

True - Alfred Hershey - Martha Chase