Chapter 12 NOTES – SECTION 12.3 AND 12.4 – Molecular Genetics
RNA, Transcription & Translation
RIBONUCLEIC ACID (RNA)…
 organic compound (contains C+H) and polymer
 composed of many monomers called nucleotides
 composed of a SINGLE STRAND of nucleotides
 carries out protein synthesis (the making of proteins)
 3 types of RNA: _____________________, ______________________, _____________________
RNA nucleotide:
1. ___________________________________________________________
has 3 parts
2. ___________________________________________________________
3. ___________________________________________________________
4 kinds of nitrogenous/nitrogen bases in RNA ______________________
 in RNA – uracil (pyrimidine) takes the place of thymine
 in RNA: A pairs with U AND C pairs with G
RNA differs from DNA in 3 ways:
1. ______________________________________________________________________________
2. ______________________________________________________________________________
3. ______________________________________________________________________________
TRANSCRIPTION…the of making RNA from DNA – RNA must be made BEFORE a protein can be made
2
steps:
1. ____________________________________________________________________
2. ___________________________________________________________________
3 products:
____________________________________________________________________
messenger RNA (mRNA)
transfer RNA (tRNA)
ribosomal RNA (rRNA)
IMPORTANCE OF PROTEIN…
Your body uses the __________________________________ (the amino acids you ingest) to make
specialized proteins that have specific jobs!!! Like… _________________________________________
_______________________________________________________________and many, many, more…
TRANSLATION… the making of ALL TYPES of proteins from the information encoded in DNA
 amino acids (20+kinds)  polypeptide chain (100+ amino acids)  protein (2+ polypeptides)
 occurs at a ribosome (site of protein synthesis) – uses all 3 types of RNA
 process begins with a start (AUG) codon and ends with a stop codon (UGA, UAG, ….)
all 3 types of RNA are used in translation…
o mRNA carries the instructions for a protein
o tRNA transfers the amino acids to the ribosome
o rRNA assists in the binding of mRNA and tRNA in the assembly of a protein
STEPS IN TRANSLATION:
1.
2.
3.
4.
5.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
RNA EDITING – RNA molecules require a bit of editing before they are ready to go into action
Introns - ______________________________________________________________________
Exons - _______________________________________________________________________
THE GENETIC CODE… is read _____ letters at a time
 each sequence of 3 letters “___________________” for a specific ______________________
 as amino acids are put into a specific order they _________________________________________
MUTATION - a change in the DNA (or more specifically stated, a change in the DNA nucleotide sequence)
 REMEMBER…mutations may be helpful, harmful or have no effect at all!
 REMEMBER…mutagens are substances which cause mutations…like chemicals, asbestos, UV radiation,…
 REMEMBER…BODY CELL mutations and SEX CELL mutations have different consequences
2 MAIN TYPES OF MUTATIONS ARE GENE MUTATIONS AND CHROMOSOME MUTATIONS
GENE MUTATIONS
– a mutation in a single gene – it may involve 1 or several nucleotides
GENE = REGION/SEGMENT OF DNA THAT CODES FOR A PARTICULAR TRAIT
Point Mutations – ____________________________________________________________________
o include substitution, insertion (addition) and deletion
Frame Shift Mutations – ______________________________________________________________
____________________________________________________________________________
o results in a shift of the “frame of reference” in the N base sequence
CHROMOSOME MUTATIONS

GENE



– involve segments of chromosomes or whole chromosomes
types of chromosome mutations include:
Deletion, Inversion, Translocation, Nondisjunction
REGULATION – the ability to control (regulate) which genes are transcribed (“turned on”)
different genes may be transcribed (“turned on”) at different times during an organism’s life
a gene is expressed or “turned on” only if __________________________________ occurs
genome = the complete set of genetic material contained in an individual’s DNA
OPERON – _______________________________________________________________________
OPERATOR – ______________________________________________________________________
SPECIAL GENES
Hox Genes Oncogenes Tumor Suppressor Genes –
ONCOGENES AND TUMOR SUPRESSOR GENES ARE THOUGHT TO BE IN A PERPETURAL TUG-OF-WAR
Remember, a gene is not “turned on” until it goes through transcription