Lesson 6 Flashcards
DNA Replication
Deoxyribonucleic acid is made out of:
sugars (deoxyribose)
phosphates
nitrogen bases
Who discovered the DNA structure in 1953?
James Watson and Francis Crick
What is Chargoff’s Rule?
A=T
C=G
What are the four requirements for DNA to be a genetic material?
- Must carry information
- Must replicate
- Must allow for information to change
- Must govern the expression of the phenotype
DNA requirement that is cracking the genetic code
Carrying information
DNA requirement that replicates
DNA replication
DNA requirement for allowing information to change
Mutation
DNA requirement that govern the expression of the phenotype
Gene function
Where does DNA store information?
In the sequence of its bases
Much of DNA’s sequence of information is accessible only when:
The double helix is UNWOUND
When do proteins read the DNA sequence of nucleotides?
As the DNA helix unwinds
Can proteins bind to a DNA sequence or initiate the copying of it?
Both
How are some genetic information accessible even in intact?
In double-stranded molecules
How do some proteins recognize the base sequence of DNA without unwinding it?
with restriction enzymes
Three things that happens when cells divide:
- growth
- repair
- replacement
Before cells divide, what happens to the cell structures, organelles and genetic information?
Double
DNA replication occurs with
great fidelity
Essential for DNA replication:
- Somatic cell DNA stability
- reproductive-cell DNA stability
What does stability have to do with DNA replication?
- ensures identity
- to avoid occurrence of genetic diseases
It is the process of duplication of the entire genome prior to cell division
DNA replication
The significance of DNA replication
Biological Significance
Why is extreme accuracy of DNA replication necessary?
In order to preserve the integrity of the genome in successive generations
When does replication occur in eukaryotes?
S phase
Replication rate in eukaryotes that results in a higher fidelity/accuracy of replication
slower
3 possible models of DNA replication
- Semi-conservative
- Conservative
- Dispersive
Basic rules of DNA replication
- semi-conservative
- starts at the “origin”
- uni/bidirectional
- semi-discontinuous
- RNA primers required
One strand of duplex passed on unchanged to each of the daughter cells
Semi-conservative
Act as a template for the synthesis of a new, complementary strand by the enzyme DNA polymerase
“conserved” strand
Who demonstrated the semi-conservative model of DNA?
Meselson and Stahl
The initiator proteins that identify specific base sequences on DNA
sites of origin
Prokaryotes origin
single
Eukaryotes origin
multiple sites