DNA structure and replication Flashcards
what is the name of cell division in prokaryotic cells?
Binary fission: one parent cell divides into to identical daughter cells
what is the name of cell division in eukaryotic cells and what are the stages?
Mitosis:
1. interphase: DNA in chromosomes copies itself
2. prophase: DNA and their copies condenses to become more visible
3. metaphase: chromosomes and their copies line up along the middle of the cell
4. anaphase: chromosomes and their copies are pulled to different ends of the cell
5. telophase: new membrane forms around the chromosomes at each end of the cell
6. cytokinesis: cell membrane pinches and eventually divides into two non-identical daughter cells
How was the discovery of mitosis made?
Hershey-chase experiment:
- using viruses (Simple constructs of nucleic acid and proteins)
-one of the DNA capsules was labelled with radioactive phosphorus and another capsule was labelled with radioactive sulphur
-they were agitated in the blended and centrifuged
-sulphur was detected in supernatant, phosphorus is found in cells
-results: clear correlation between DNA and genetic information
What are the names of the 4 bases in DNA?
Thymine, Adenine, Cytosine, Guanine
Which DNA bases like to pari together?
A=T
C=G
What are the two main parts of DNA replication?
translation and transcription
What enzyme untwists the double helix?
helicases
what is the purpose of topoisomerase?
it corrects the overwinding ahead of replication
What are the features of DNA that help replication?
-it is antiparallel (DNA polymerases add nucleotides to the free 3’ end therefore a new DNA strand elongates only in the 5’ direction)
-the lagging strand is synthesised in a series of segments called Okazaki fragments joined together by DNA ligase
