Establishing DNA as hereditary material Flashcards
What do Darwin’s genetics say?
‘Gemmules’ in cells are inherited.
How is Mendel’s Law of Inheritance named alternatively?
Law of segregation.
What does the Law of segregation say?
Gametes only had one version of allele for each gene.
What did Darwin’s and Mendel’s Laws do?
They overlap.
What is characterised as ‘The missing link’?
Friedrich Miescher’s composition of lymphoid/pus.
What did biochemists do?
They isolated protein.
What does make biology more interesting except DNA isolation?
Other molecules’ isolation.
When did Griffith do his experiment?
In 1928.
What was Griffith’s experiment about?
Streptococcus pneumoniae in mice.
What did Grififth do in his experiment?
Grew bacteria on agar plate.
Why did Griffith experienced bacterial growth on agar plates in mice?
To check if Streptococcus pneumoniae was lethal in mice.
What strains did Griffith use in his experiment with bacteria and mice?
Rough strain.
Smooth strain.
What did Griffith realise as an outcome of his strain experiment in mice?
Only smooth strain killed mice.
What was the characteristic of smooth strains in the experiment?
Smooth colonies were identified in agar plate.
How did smooth strains kill mice?
Produced polysaccharide –> immune response in organism –> does not see it –> kill it.
What did Griffith manage to grow in his experiment?
Live cells.
Dead cells.
Whole cells.
What did Griffith do with mice in his experiment?
Took blood from mice –> in agar –> colonies growth.
What was the control Griffith used in his experiment?
Blood of live cells –> injected in mice –> in agar –> colonies growth.
What happened when killed cells were injected in mice?
Mice killed.
What happened when heat killed cells where injected in mice?
Mice died.
Colonies grew.
What does the ‘Transforming principle’ say?
Smooth cell gradient –> into rough cell –> produce polysaccharide.
What happens when bacteria take DNA from environment?
They produce proteins.
What did Griffith show with his experiment?
Something (DNA) could be transferred –> change phenotype –> genetic information.
What do different enzymes do?
Destroy different molecules: sugars, polysaccharides, DNA, proteins.
What is the advantage of destroyed proteins?
They still work.
What happens when degraded RNA is transferred to a sample?
Smooth cells appear.
How many experiments occurred in biomolecules and genetics for DNA?
A lot.
What happened when material were incubated with DNA?
Mixture did not transform cells in smooth cells.
What was the outcome of the experiments in DNA?
DNA carries the information only not another molecule.
With which factors did Hershey and Chase work their experiment?
E. coli.
T2 (agar plate).
When did the Hershey and Chase experiment take place?
In 1952.
Who was Chase?
One of the most important women in genetics.
What substances did Hershey and Chase used in their experiment?
Radioactive phosphate and sulphur.
How did Hershey and Chase use E. coli in their experiment?
E. coli culture + phage –> mixed –> on agar plate.
What did Hershey and Chase measure when E. coli and phage were added on an agar plate after they mixed?
Bacterial growth.
A hole.
How did Chase and Hershey use an initial virus infection?
Virus’ DNA injected in –> cell –> replication –> maturation –> lysis –> blended food process.
What appears most in DNA? Phosphate or protein?
Phosphate.
How where E. coli and phage mixed?
In a tube.
What happened when DNA was injected in a cell?
Some DNA found in progeny.
Where was DNA transferred from a parent?
In a cell, not in progeny.
What was the outcome of Hershey and Chase experiment?
Only DNA is transferred in generations, not proteins.
What is DNA after these experiments?
Carrier of genetic information.
What we must use to understand something difficult?
A simple system.
Model systems.
Why should we use model systems in biomedicine?
To understand human diseases.
From where can we isolate DNA in an organism?
From any organ.
Why would we isolate DNA from an organism?
To use the information –> make a standard genetic tool –> transfer it in other organisms –> investigate DNA functions.
What is DNA?
Carrier of inherited information.
What was the hypothesis of Darwin?
Cells contain ‘gemmules’.
What where the ‘gemmules’ of cells responsible for?
Inheritance of variation.
Phenotype.
By what were gemmules produced?
By adult tissues.
Where were gemmules incorporated?
In developing eggs.
Sperm.