Chapter 13 DNA Flashcards
Transformation
Process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria
Bacteriophage
Kind of virus that infects bacteria
3 Roles of DNA
Storing Information
Copying Information
Gene Expression
Base pairing
Principle that bonds in DNA can form only between Adenine and Thymine and between Guanine and Cytosine`
Monomer of DNA
Nucleotides
How are Nucleotides bonded?
Covalent bonds
Nucleic Acids
Long slightly acidic molecules built from nucleotides
What are nucleotides composed of?
Nitrogenous base, 5-C sugar, Phosphate group
5-C sugar
Deoxyribose
Nitrogenous bases
Adenine - Thymine
Cytosine - Guanine
What does the Phosphate group act as?
Edge of ladder
Chargaff’s Rule
Adenine must be paired with Thymine and Cytosine must be paired with Guanine
If they aren’t paired there will be an error in the DNA
Double helix structure
Twisted ladder
How are base pairs bonded?
Hydrogen bonds due to their weak velcro like nature
Replication
Process of copying DNA prior to cell division
DNA polymerase
Principle enzyme involved in DNA replication
Telomere
Repetitive DNA at the end of a eukaryotic chromosome
How does DNA replicate?
The strands are separated and the complimentary base pairs are filled in by DNA polymerase forming 2 complete strands of DNA.
DNA Replication type
Semiconservative
DNA proof reader
DNA polymerase
Why do telomeres need to be put in place?
End of DNA is difficult to replicate so cells use telomeres which are repeating DNA sequences. These are done to prevent genes near the end of chromosomes being damaged or lost during replication.
Prokaryotic DNA Replication
Regulatory proteins bind at single starting point on chromosome which triggers S phase. DNA polymerase go opposite and go in two directions until entire chromosome is copied.
Eukaryotic DNA Replication
Many starting points of DNA replication on the molecule. Many proteins to regulate and ensure correct duplication before and after.
Odds of wrong DNA copy
1 in 100 milion
Who discovered Transformation?
British - Fredrick Griffith
How did Fredrick Griffith conduct his experiment
Heat killed harmful bacteria (S type)
Kept harmless bacteria alive (R type)
Infected mix of dead harmful and alive harmless - harmless took on traits of harmful and became harmful.
What did Hershey and Chase’s experiment confirm from Avery’s experiment.
DNA was the genetic material that contained information.
How is DNA read?
5’ to 3’
Pointy side to flat side
How are nucleotides joined?
Covalent bonds
Why are base pairs held by hydrogen bonds?
To take advantage of their weak Velcro like bond.
Franklins most famous photo?
Photo 51
What structure did Franklin discover
The helical structure of DNA
The thefts
American - James Watson
British - Francis Crick
Antiparallel strands
Two strands of DNA run in opposite direction
The “weasel”
English - Wilkins
Karyotype
Laboratory-produced image of a person’s chromosomes isolated from an individual cell and arranged in numerical order
Franklins Death
1958 - died of cancer
What year did Griffith conduct his experiments?
1928
Who discovered transformation?
British - Frederick Griffith
Who continued research on transformation?
Canadian - Oswald Avery
How did Avery conduct his research?
Broke down each component of a cell to narrow down what causes transformation.
Once he broke down DNA transformation did not occur.
Who confirmed importance of DNA
Americans - Alfred Hershey and Martha Chase
How was importance of DNA confirmed?
Radioactive tracers put on proteins and DNA of bacteriophages to see what carries the information when the Bacteriophage injects it to infected cell
DNA with radioactive tracer found in infected cell
How are nucleotides joined?
Covalent bonds between sugar of one nucleotide and the phosphate group of the next.
What is Chargaff’s rule?
A=T
G=C
How did Franklin take her pictures?
X-ray diffraction
Advantage of anti parallel pattern
Enables nitrogenous bases on both strands to come into contact neared the center of the molecule
What forms telomeres?
Telomerase
Telomeres are found in only what type of chromosomes?
Eukaryotic
