History of Genetics Flashcards
Which scientist came up with the laws of inheritance?
Gregor Mendel
Which two scientists came up with the idea of chromosomes and were able to describe?
Strasburger & Flemming
In 1953, which two scientists proposed a structure for DNA?
Watson and Crick
Which field of biology is rapidly developing?
Genetics
Which year was the human genome sequence completed?
2004
What is the idea of a genome?
It is known to be the whole set of genes an organism caries. It codes for all the proteins and other biological molecules that are used to survive the organisms and function correctly.
What characterises genetic information?
- Contains information about cell structure, function, development and reproduction.
- Accurate replication so collective offspring (progeny) have same genetic information as parental cell.
- Capable of change which is essential for genetic variation, adaptation and evolution.
What is Griffith’s transformation experiment famous for?
- First experimental approach to analyse the phyiscal nature of hereditary material
- 2 strains of streptococcus pneumoniae are used, (causes pneumonia)
Which strain of bacteria is virulent?
The S-type
Can S-type cells mutate into R-type cells?
Yes
How was Griffith’s experiment conducted?
See lecture notes (mice…)
What was concluded from the Griffith’s experiment?
That R-type cells can transform into S-type cells when mixed with them even when they have been heat-killed. Oswald Avery thought this was due to a protein.
Which experiment was carried out to discover the “transforming principle”?
Avery’s transformation experiments
Which component of the S-type cell was determined to be the “transforming principle”?
DNA because transformants were produced when they were mixed with IIR bacteria with the RNase-treated IIIS bacteria.
What are recipient bacteria called in a transformation process?
Transformants
Which two methods can be used to induce transformation artificially?
Heat Shock and electroporation. These methods are used to make the cell membrane more permeable for the Donor DNA to transfer across the cell.
What is T2?
A bacteriophage that is a virus which attacks bacteria.
Why is the replication of bacteriophages known as the lytic cycle?
Viruses are unable to produce by themselves. They make use of the host cell machinery with its own genetic material to produces replicates. The replication of such bacteriophages leads to the lysis of the host cell thus it is known as the lytic cycle.
What can be used to label DNA and protein.
Radioactive Isotopes of Sulphur and Phosphorus.
(32P for DNA)
(35S for protein)
What is the purpose of the Hershey-Chase experiment?
To figure out what is the genetic material in T2 that is passed down to its progeny.
What does the Hershey-Chase tell us?
It is DNA that is injected into the cell, not proteins that are required for the formation of the progeny phages. DNA is therefore assumed to be the genetic material.
Complementary base pairings?
A to T
G to C
What is a purine?
Double ring hydrocarbon. Adenine and Guanine are purines.
What is a pyrimidine?
Single ring hydrocarbon. Cytosine and Thymine.
What is the distance between each base pair according to X-ray diffraction studies?
0.34 nm
How long is one helical turn in a double helix DNA structure?
3.4 nm. Therefore, there is 10 base pairs per each helical turn.
Who discovered the semi-conservative model?
Watson and Crick. It is called semi-conservative because each progeny retains one of the parental strands.
