DNA As The Genetic Material

Question 1

What are the three main Mendelian laws of inheritance?
He looked at peas (1866)

Answer 1

1. Segregation: genes come in pairs, and individuals only pass one to offspring
2. Independent assortment: different genes are passed on separately from each other
3. Dominance: an individual with two alleles will express the dominant form

Question 2

What did scientists come up with after mendels laws/ theories?

Answer 2

There must be some sort of physical genetic material that is passing on from the peas or anything else he was experimenting on

Question 3

What were the key observations made by Sutton and Boveri in their chromosomal studies?

Answer 3

Observed chromosomes in grasshoppers and Ascaris worms

Question 4

What was Sutton observations in grasshoppers and Boveris observations in acaris worms?

Answer 4

-Noted grouping in pairs and separation
-Found reduction in chromosome number in gametes
-Discovered that destroying chromosomes stopped normal development
-Observed their findings matched Mendel’s laws

Question 5

What is the transforming principle? What was his question?
Frederick Griffith in 1928

Answer 5

Streptococcus pneumoniae (a bacteria) can cause pneumonia in humans and mice
HOWEVER, only some strains can cause infection and illness

Question 6

What were the two types of Streptococcus pneumoniae strains in Griffith’s experiment?

Answer 6

S strain- smooth bacteria
R strain- rough bacteria

Question 7

What are the differences between S and R strains?

Answer 7

S strain- smooth bacteria, have a polysaccharide coat, pathogenic
R strain- Rough bacteria, don’t have a polysaccharide coat, non-pathogenic

*pathogenic- can cause disease

Question 8

What is the function of polysaccharide coat?

Answer 8

Form a capsule that protects some strains from the host immune system

Question 9

What are the three main points of the Sutton-Boveri chromosome theory of inheritance?

Answer 9

1. Chromosomes are required for embryonic development
2. Chromosomes carry Mendel’s “factors” (genes)
3. Chromosomes are linear structures with genes along them

Question 10

What was the key finding of Griffith’s transformation experiment?

Answer 10

When dead S bacteria were injected with live R bacteria, the R bacteria were transformed into pathogenic bacteria with polysaccharide coats, suggesting hereditary material passed between bacteria.

Question 11

What was the main question Avery, MacLeod, and McCarthy investigated?

Answer 11

Which molecules were responsible for the transformation that Griffith observed?

Question 12

How did they determine which molecule was the transforming principle?

Answer 12

They systematically destroyed each component of the S strain extract using specific enzymes, then tested if the modified extracts could still transform R bacteria.

Question 13

How did Hershey and Chase label DNA and protein in their experiment?

Answer 13

DNA was labelled with radioactive phosphorus (³²P)
Proteins were labelled with radioactive sulphur (³⁵S)

Question 14

What were the results of the Hershey-Chase experiment?

Answer 14

When DNA was labelled, radioactivity was found in bacteria

When protein was labelled, radioactivity remained in phage ghosts
This proved DNA, not protein, was the genetic material being injected into bacteria

Question 15

What are the main steps in the bacteriophage T2 life cycle?

Answer 15

1. DNA genome enters and destroys host cell’s chromosome
2. Transcription and translation of viral genes and replication of viral genome
3. Assembly of new virus particles from DNA + protein subunits

Question 16

what are bacteriophages? where would they be found?

Answer 16

A type of virus that eats or destroys bacterium
Found outside the virus