Name___________________________________________________
Per. ______
PreAP Biology Notes
Protein Synthesis/ Gene Mutations/ Gene regulation
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RNA (12-3)
Contains the sugar ______________ instead of deoxyribose.
_____________-stranded instead of double stranded.
Contains ________________ in place of _____________.
 Three Main Types of RNA
1. _____________RNA (mRNA) - Carries _____________ of instructions, for the
assembly of amino acids into _____________, from DNA to the
_____________ (serve as “messenger”)
* Made in the nucleus
2. ______________RNA (rRNA) – Makes up the major part of _____________, which is where proteins are
made.
* made in the nucleolus
3. Transfer RNA (tRNA) – Transfers (carries) amino acids to ribosomes as specified by codons in the mRNA
 Proteins
 Proteins are made up of a chain of
____________________________.
 2 Steps to Make a Protein
1. _______________________
 DNA → RNA
2. _______________________
 RNA → Protein (Chain of amino acids)
 Step 1: Transcription
 _________________ - Process in which part of the nucleotide sequence of ________ is copied into a
complementary sequence in ________.
 RNA polymerase- _ ____________that separates the
DNA _____________.
 RNA polymerase then uses one strand of DNA as a
_____________ from which nucleotides are
_____________ into a strand of RNA
 How does RNA Polymerase know where to start and stop
making an RNA copy of DNA?
 RNA Polymerase will only _________ to regions of DNA known as ________________, which
have specific base _____________.
 Promoters are “_____________” in DNA that tell the enzyme _____________ to bind, to start
transcription.
 Similar signals cause transcription to _____________.
 Editing mRNA (pre-mRNA)
 Many _______ molecules require a bit of _____________ before they are ready to go into action.
 The DNA of eukaryotic genes contains sequences of nucleotides, called _____________ (intruders),
that are ________ involved in coding for _____________.
 The DNA sequences that code for proteins are called _____________.
 They are “_____________” in the synthesis of proteins.
 Editing mRNA:
1. When _______ molecules are formed, ________ the introns and the exons
are _____________ from the DNA.
2. The introns are _______ ______of RNA molecules.
3. The remaining exons are then _____________ back together to form the final
___________. (the exons can be spliced together in diff sequences to
produce diff mRNA’s = diff proteins)
After Transcription
 The __________ (already edited) leaves the _____________ and travels to the _____________ in the
cytoplasm.
1. How the code is read:
a. Every 3 _____________on mRNA is called a _____________.
b. Every codon codes for an _____________
______________(building block of protein)
c. Amino acids are abbreviated most times by using the first 3
letters of the amino acid’s name.
 Met = methonine
 Leu = leucine
 Regulation of Protein Synthesis
 _____________ codons: found at the _____________ of a protein
 Only one - AUG (methionine)
 _____________ codons: found at the __________ of a protein (end of a polypeptide chain)
 Three stop codons that do not code for any amino acid therefore making the process stop : UAA,
UAG,UGA
 Reading the Codon Chart
 Step 2: Translation
 Translation - Decoding of a ___________ message into a _____________ (amino acid chain)
 Takes place on _____________ in cytoplasm
1. Begins when an _____________ molecule in the cytoplasm _____________ to a ribosome.
2. As each _____________ of the mRNA molecule moves through the _____________, the proper amino
acid is brought into the ribosome by _____________.
 Each tRNA contains:
1. An _____________________
2. Three unpaired _____________.
 tRNA - Anticodon
 Each tRNA molecule has _____ unpaired bases called the ______________, which are ______________
to one mRNA _____________.
3. The ribosome forms a ______________ _________between the first and second amino acids.
4. The _______________ chain continues to grow until the ribosome reaches a ________ codon on the
__________ molecule and a _______________has been made.
Roles of RNA and DNA
 The cell _______ the vital _____ “master plan” to prepare RNA “blueprints.”
 The ______ molecule remains within the safety of the ____________, while
______ molecules go to the protein-building sites in the cytoplasm—the
________________.
 Mutations (12-4)
 Mutation – ____________ in the genetic material (like ____________ in copying or transcribing)
 Types of Mutations
Chromosomal Mutations - Involve changes in the ____________ or ____________ of chromosomes.
__________ Mutations - Mutations that produce changes in a ____________ __________ .
Types of Gene Mutations:
1. ____________ Mutations - affect a ____________ nucleotide, or point
in the ________ sequence, usually by
substituting one nucleotide for another.
 Examples include:
Substitution – one base is ____________ to another
Original: AUGUAC → Met – Tyr
Mutated: AUGUAG → Met – Stop
(In this case, causes the amino acid chain to stop protein production early)
2. __________________ Mutations - Mutation that shifts the “reading” frame of the genetic message
by inserting
or deleting a nucleotide.
 Examples include:
– Insertions – A base is ____________ into the DNA sequence.
– Deletions - A base is ____________ from the DNA sequence.
Original:
The fat cat ate the wee rat.
Frame Shift: The fat caa tet hew eer at.
The faa tca tat eth ewe era t.
(Frame shift mutations affect ________________________________________________!)
 Significance of Mutations
 Many mutations have ____________ or ____ effect on the expression of genes.
 Mutations may be ____________ and may be the ____________ of many genetic ____________ and
cancer.
 Source of genetic ___________________ in a species (may be highly ___________________).
 Beneficial Mutations
 ____________mutations may produce proteins with new or ____________ activities that can be
____________ to organisms in different or changing __________________________.
 Plant and animal ____________often take advantage of such beneficial ____________.
 The condition in which an organism has ____________ sets of chromosomes is called
_______________.
 Often ____________ and stronger than diploid ____________.
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 Gene Regulation (12-5)
Only a fraction of the ____________ in a cell are “____________” at any given time
(An “expressed” gene = ____________= genes that are actually transcribed into ________)
How does the cell determine which gene will be expressed and which will remain ‘silent’?
 ____________ allow RNA polymerase to ________ to begin transcription.
____________ prevent RNA polymerase from binding to go through ____________.
 Other DNA ____________ (regulatory sites) act to turn ____________a gene
Eukaryotic Gene Regulation
 The expression of genes can also be influenced by ______________________such as temperature,
light, chemicals, etc.
Development and Differentiation
 Regulation of gene ____________ is important in shaping the way an organism ____________, shaping
the way cells undergo differentiation.
 A series of genes call _______ Genes control the differentiation of cells in the ____________.
 A ____________ in one of these genes can completely change that organism’s ___________________.
 Ex- A mutation in the Hox genes of a fruit fly can replace antennae with legs growing on its
head.