The amount of A= T The amount of G= C The amount of purines (A+G) = pyrumdines
Who discovered the helix?
Linus Pauling did what for DNA?
Built 3-d models of possible structures
What did watson and Crick do for DNA?
Combined all previous knowledge to make model of DNA
What are the 3 different works of DNA that Watson and Crick combine?
Double Helix (from Franklins work), Antiparallel (from models) and exposure
What are double stranded structure of DNA?
Sugar phosphate backbone on the outsides of the double helix, a sugar of one nucleotide bonded to phosphate of nest with phosphodiester bonds. Complementary base pairing on the inside of the double helix.
Sugar phosphate backbone is comprised of what?
On the outside of the double helix. sugar of one nucleotide bonded to phosphate of the next
What types of bonds bond the nucleotide to the phosphate?
Phosphodiester bonds (covalent)
What are alternatives to the backbone?
Sugar phosphate s p s p
Complementary base pairing are what?
On the inside of the double helix. One base is covalently bonded to each sugar.
In complementary base pairing what type of bond bonds the sugar?
Ghargaff's rule is what?
Each base pair has 1 purine and 1 pryimidine.
A always pairs with what?
T with 2 hydrogen bonding sites
G always pairs with what?
C with 3 hydrogen bonding sites
What is the uniform diameter?
Length of at cg is 2 nanometers
What are antiparalle Stands?
direction determined by sugar phosphate bonds
Phosphate bonds to its nucleotide on what?
5' carbon of sugar
Phosphate bonds to next nucleotide with phosphodiester bond on what?
3' carbon of the next sugar
Ends of the strands differ how?
On one end of strand a 5' phosphate on the other end a 3' hydroxyl
What happens in antiparallel?
2 Bakcbones run in oppostite directions
What is base exposure?
Base pairs exposed in major and minor grooves
What are the functions of DNA.
Storage Mutation Replication Expresssion
What does storage of DNA
Millions of nucleotides per DNA moelcule store genetic information
What does mutation of DNA do?
Change in nucleotide sequence Change in information happens randomly
What does replication do in DNA?
DNA sequence copied to pass information to next generation
What does expresssion of DNA do?
DNA sequence codes for amino acid sequence in proteins that express phenotype
What are the two steps in DNA replication
Double helix is unwound and unzipped 2 New nucleotides added by semiconservative replication
What is the backbone of DNA?
Sugar and Phosphate
What is the origin of replication?
Site on chromosome where replication starts, one chromosome may have several orgins
Replication complex is?
Group of proteins enzymes that carry out replication
What does the helicase do?
Unwinds DNA double helix and unzips two strands
What does the primase do?
Pairs RNA primer to 3' end of template strand
What is DNA polymerase III do?
Adds new bases to template 3' to 5'/
How is the lagging strand replicated?
The helicase unwinds DNA double helix and unzips two strands. The primase adds an RNA primer to template near replication form. The DNA polymerase III adds new bases to template 3' to 5'. DNA polymerase I removes primer and replaces with DNA. DNA ligase connects separate segments.
What does the Helicase do in lagging strand replication?
Unwinds DNA double helix and unzips two strands
What does Primase do in lagging strand replication?
Adds an RNA primer to template near replication fork
What does DNA polymerase III does what in laggin strand replication?
Adds new bases to template on the 3' to 5'
What does DNA polymerase I do in lagging strand replication?
Removed primer and replaces with DNA
What does DNA ligase do in lagging strand replication?
Connects separate segments.
What are telomeres?
Chromosomes ends in useless repetitive sequence
What is telomerase?
Some cells use telomerase to create a new RNA template and replace the telomere.
What are some examples of telomerase?
Stem Cells Gamete Producing Cells Cancer Cells
What are some causes of DNA errors?
During replication, damage to exising DNA and from UV or Chemicals
What are the three repair mechanisms?
Proofreading, Mismatch repair, and excision repair
What does proofreading do?
Recognizes and removes wrong base pair when it is placed
What does mismatch repair do?
Removed wrong base pair missed in proofreading, happens immediately after replication
What does excision repair do?
Repairs damage causes later by environment
PCR stands for what?
Polymerase Chain Reaction
what does PCR do?
Amplifies makes many copies of DNA sequences
What are some uses of PCR?
Research labs medical forensics
what does DNA need?
DNA of interest primer that matches first few bases of each endcorrect pH and salt concentration
Process of PCR?
Heat denatures DNA and seperates into two strands. Then cooled primers attach to reee ends warmed DNA polymerase copies then repeats.