DNA structure and function

Define antiparallel

the two strands of the double helix run in opposite directions

Define base

A nitrogen-containing rings  

• Purine or pyrimidine 

• Chemically/physically distinguishable 

• CuT = pyrimidine 

• Au:Gold = purines 

Define base pair

• Purines CANNOT bind to other purines because of chemical structure 

• Keto group of one base binds to amino group of another 

Define complementarity

one strand complements the other 

• Necessary because of base pairing requirements (hydrogen bond formation)

Define double helix

a pair of antiparallel helices intertwined about a common axis, especially that in the structure of the DNA molecule.

Define template

A pair of parallel helices intertwined about a common axis, especially that in the structure of the DNA molecule.

• A DNA mold that codes for other DNA or proteins

Define intron

part of a sequence that is not used to make a protein structure 

• “unused” - but does have some unknown function 

Define exon

part of a sequence that is used/transcribed into mRNA or eventually proteins 

• Spliced together to form a functional gene 

What type of bond exists between bases/across DNA

Hydrogen bonds

• contribute to double helix stability

What type of bonds are between sugar and phosphate in DNA backbone?

Covalent bonds

• strong chemical bond with a sharing of electron pairs with a balance of attractive and repulsive forces

How many hydrogens bonds are between C-G and A-T

3 and 2

What makes up a nucleotide

nitrogenous base, five carbon sugar, and phosphate group 

• Sugar and phosphate form DNA back bone with covalent bonds 

Where are phosphodiester bonds found

between the sugar and phosphate group in backbone

• nucleotides are joined by the PO4 of one nucleotide attaching to the 3’ carbon of the next nucleotide to form a polynucleotide 

Identify the boxes and the bonds

See the image

What is the function of DNA in the overall physiology of the body

Purpose of DNA = to archive information 

• Not functional without it forming RNA 

• Is the blueprint for everything else  

  Protected in the nuclear membrane so it doesn’t get transported out or damaged 

• Only 1% of human genome is protein coding