Flashcards
Replication of DNA
Cards in this deck (6)
- 1THE CELL CYCLE...What is the Cell Cycle?
DNA replication in Interphase (Semi-conservative replication)
How Science Works: Meselson and Stahl - 2What is the Cell Cycle?The cell cycle is a process by which all body cells from MULTICELLULAR organisms grow and divide. The cell cycle starts when a cell has been PRODUCED by CELL DIVISION. There are two stages of cell division: NUCLEAR DIVISION- process where nucleus of cell divides. Happens either by meiosis or by MITOSIS. After this the whole cell divides in CELL DIVISION and ends with TWO IDENTICAL CELLS.
Before the parent cell divides, it needs to COPY/REPLICATE its DNA so daughter cells have the genetic info. to produce the specific enzymes and other proteins that they need in order to function. Mitosis only occupies a small % of cell division, the main bulk of the cycle is INTERPHASE by where the DNA is copied and checked for errors to prevent mutations in the DNA. - 3DNA replication in Interphase (Semi-conservative replication): RequirementsFor this process to take place, 4 main requirements are needed: 4 nucleotides each with all bases present. Both strands of DNA must act as a template for attachment of these nucleotides. Enzyme POLYMERASE needed to catalyse reaction. Source of chemical energy needed to drive process.
- 4DNA replication in Interphase (Semi-conservative replication)1. DNA HELICASE breaks the hydrogen bonds between the two POLYNUCLEOTIDE DNA strands. The HELIX UNZIPS to form two single strands.
2. Each original single strand acts as TEMPLATE for NEW strand. Free-floating DNA nucleotides JOIN to EXPOSED BASES on each original template strand by CERTAIN BASE PAIRING. Energy is used to ACTIVATE nucleotides.
3. Nucleotides on new strand joined together by enzyme DNA POLYMERASE. Hydrogen bonds FORM between bases on original and new strand.
4. Each new DNA molecules contains ONE strand from ORIGINAL DNA and ONE strand from NEW strand. This type of copying is called SEMI-CONSERVATIVE REPLICATION! - 5How Science Works: Meselson and StahlBefore Meselson and Stahl, scientists were unsure whether DNA replication was CONSERVATIVE- parental DNA remained intact and separate daughter DNA copy was built from new molecules of deoxyribose, phosphate and organic base. New DNA molecules would contain 2 new strands... or SEMI-CONSERVATIVE- produce new DNA molecule containing one original strand and one new strand. The evidence for semi-conservative replication, is Meselson and Stahl's experiment using two isotopes of nitrogen...
- 6Evidence for Meselson and Stahl's experiment...
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- AS/A2 Level Biology Unit 2 Flashcards on Replication of DNA, created by Amar B. on 29/04/2015.
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- Amar B.
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