MOLECULAR GENETICS
DNA






DNA – _____________________________________________________
DNA carries our _________________________ information.
Recall where is DNA found? _________________________________________
What is type of macromolecules is DNA an example of? ___________________________
______________________________ are the subunits of nucleic acids
Two types of nucleic acids
- _____________
- _____________
History
 A scientist named Franklin was the ______________ to do
a_____________ model of DNA.
 Watson and __________________ determined that DNA
has a helical structure.
 They were able to determine this with the help of
Franklin’s X-Ray Model.
DNA is _______________stranded and helical (Double helix).
It is composed of ___________________ things:
1) A 5-carbon sugar called ________________________,2) a
nitrogenous _____________,
and 3) a _______________________ group.
 There are four different types of nitrogenous bases
- ___________________ (A)
- Thymine (T)
- ___________________ (C)
- Guanine (G)
Chargaff’s Rule
 Chargaff’s Rule – states that the amount of _____ should equal the amount of _______ and the
amount of ______ should equal the amount of T.
 _______ will bond to T , _______ will bond with C! A-T , G-C
Pyrimidines – Cytosine and ______________________
Purines – Adenine and Guanine
Purines will always ____________ to pyrmidines.
 DNA is like a _________________ where the sides are made up of phosphate and ______________.
The rungs of the ladder are made up of ____________________.
 Phosphate is bonded to ________________. They make up the “backbone” of DNA. Bonded to the
sugar is the base.
 The bases are held together by a _________________________ bond!
How to make a protein
 There are three steps involved in making a ________________________.
 1st – The DNA must be _______________________________.
 2nd – The DNA must be transcribed. This means the DNA must be made into ___________________.
 3rd- The RNA must be translated. This means the RNA must be made into _______________________.
Central Dogma
______________
→
___________
→
_________________
(Transcription)
(Translation)
DNA replication
 To make a protein, first _________ replication will
occur.
 It occurs during the_____________________ of the
cell cycle.
 First the double stranded DNA will ____________
or unwound
-DNA helicase is the _________________
responsible for the unzipping.
 Now with a single strand of DNA , DNA polymerase,
another ________________ will add the
complementary __________________________ to the new DNA strand.
 After replication, the new DNA strand will be complementary to the old DNA strand.
Transcription
 After DNA has been replicated, the DNA must be ____________________.
 Transcription is DNA being converted into _________.
 DNA codes for many messages, but DNA cannot leave the ___________________. It must be made
into RNA to leave the nucleus.
RNA
 RNA – Ribonucleic Acid
 __________________ stranded
 Contains a __________________ sugar, a nitrogenous base, and a phosphate group.
 G-C and A-U There is no _______________ in RNA, Thymine is replaced with Uracil!!!!!
Types of RNA
 mRNA, used to carry the _______________________ from the nucleus to the ribosome.
* Used in transcription (_____-Messenger)
 tRNA, used to carry or transfer amino acids to the _________________________
* Used in translation (_______-Transfer)
 rRNA, used to form the structures of ribosomes (______-Ribosomal)
Transcription
 Occurs in the ________________ of the cell
 RNA polymerase, an enzyme, will ________ the
DNA
 The new__________ strand will be
complementary to the unzip part of the DNA.
 It will follow the base pairing rule! Recall different
for RNA!
 The product from transcription is_____________
 The mRNA will release and go to the cytoplasm
where ribosomes are located.
Translation
 Translation is converting RNA into ____________________.
 What are the subunits of proteins?_____________________________
 There are ________ amino acids.
 _________________ are made on ribosomes; therefore, Translation
will occur on a ribsome.
 Recall – Where can ribsomes be found in a
cell?________________________
Codon
 There are 64 codons
 Only ______ codons actually code for an amino acid
 There is _____ start codon – it also codes for the amino acid methionine
 There are 3 stop codons
 What is the start codon? ________________
 Three base code – can be in DNA or mRNA
 What are the stop codons? ________ _________ _________
Translation
 Occurring on the ribosomes where mRNA made in _______________________ will travel outside to
nucleus to a ribosome.
- During translation, the ___________ will come and attach to the codon regions on the mRNA.
-tRNA has a sequence of bases, called the______________________. tRNA is also carrying the amino acid.
 The anticodon will be complementary to the codon region of _____________.
-Recall again what is the function of tRNA……________________________________________
 tRNA will carry the amino acids to the ribosome to begin translation.
 So, on one end of the tRNA is the anticodon and the other end has the_____________________
attached.
 Once the tRNA anticodon has attached to the mRNA ____________, the appropriate amino acid will be
released.
 Now, the next codon will be read and the tRNA will release appropriate amino acid.
 That amino acid will link with the previous ____________________________.
 Recall- What type of bond holds amino acids together?__________________________
 These chains of amino acids will build a polypeptide chain which will create a specific
_______________.