Download Protein Synthesis

Class Notes
RNA & Protein
Synthesis
Questions/Main Idea:
What are genes?
What is RNA?
In what three ways is
RNA different from
DNA?
What is the major
function of RNA?
What is protein
synthesis?
Describe the three types
of RNA.
What is transcription?
What is translation?
Where does transcription
take place?
What is the promoter
region of a gene?
What is the coding
region of a gene?
Name: _______________________________________
Period:_______________________________________
Date: _______________________________________
Notes:
 The DNA molecule contains all of your hereditary information in
the form of genes.
 Genes are portions of the DNA molecule that code for the
production of specific types of proteins.
 RNA is the nucleic acid that acts as a messenger between DNA and
the ribosomes.
1. The sugar in RNA is ribose whereas the sugar in DNA is
deoxyribose.
2. RNA is single stranded while DNA is double stranded.
3. RNA contains a base called uracil instead of thymine.
RNA molecules have many functions, but in the majority of cells, most
RNA molecules are involved in protein synthesis.
Protein synthesis is the assembly of amino acids into proteins.
1. messenger RNA (mRNA) is responsible for copying one strand of
DNA in the nucleus and carrying that information to the ribosomes in
the cytoplasm.
2. ribosomal RNA (rRNA) makes up a large part of the ribosome and
is responsible for reading and decoding mRNA.
3. transfer RNA (tRNA) carries amino acids to the ribosome where
they are joined to form proteins.
the process where a portion of the DNA sequence is copied into a
complementary RNA sequence.
the decoding of an mRNA message into a polypeptide chain (protein).
Transcription occurs on the DNA in the nucleus.
The region of DNA that turns a gene on and off.
The region of DNA which provides the information for which protein to
produce.
What is the termination
sequence of a gene?
What is mRNA
polymerase?
It signals the end of the gene.
How is the mRNA
formed?

Where does the mRNA
go? Where does
translation take place?
The enzyme responsible for reading the DNA code and building the
mRNA strand.
RNA polymerase reaches the coding region and reads ONE side of the
DNA.
 RNA polymerase reads the DNA’s sequence and brings in the
complimentary nucleotides and binds them together forming the
mRNA strand.
 When the RNA polymerase reaches the termination sequence, the
mRNA folds back on itself ending the transcription of DNA.
It leaves the nucleus and goes to a ribosome in the cytoplasm.
How does the ribosome
read the mRNA?
What is an anticodon?
What is the role of the
tRNA?
How do you use a codon
chart?

The sequence of bases in an mRNA molecule serves as instructions for
the order in which amino acids are joined to produce a polypeptide.
 Ribosomes decode these instructions by using codons, sets of 3 bases
that each code for 1 amino acid.
Each codon is matched to an anticodon, or complementary sequence on
the tRNA to determine the order of the amino acids.
 The tRNA has two ends.
o One end has a specific amino acid.
o The other end has a particular sequence of 3 bases known as
the anticodon.
 The tRNA with the correct anticodon pairs up with the codon on the
mRNA and brings with it the specific amino acid.
 This process continues until the entire message is read and all amino
acids are brought in sequence, forming a polypeptide chain.
The mRNA bases or CODONS are used to find the amino acid.
Example 1:
DNA: TAC GCA TGG AAT
1.
mRNA:
Amino Acids:
Example 2:
DNA: CGT GGA GAT ATT
2.
mRNA:
tRNA:
Amino Acids:
What is a gene mutation?  Sometimes during replication, an error is made that causes subsequent
changes in the DNA and causes changes in the proteins which used
that DNA.
 These errors or changes are called mutations.
Explain the two types of
1. Point mutation:
gene mutations
 changes in only 1 or a few nucleotides of DNA.
 Substitutions, in which one base is changes to another, are a type
of point mutation.
2. Frameshift mutation:
 When one base is deleted (deletion) or added (insertion) into a
DNA sequence.
 This causes the entire sequence of codons to shift over by one base.
What are chromosomal
 Mutations involving a long segment of DNA.
mutations?
 These mutations can involve deletions, insertions, or
inversions of sections of DNA.
 In some cases, deleted sections may attach to other
chromosomes, changing both the chromosomes that lost the
DNA and the one that gained it, also called a chromosomal
rearrangement.
What is the significance
Mutations in DNA cause changes in the sequence of amino acids which
of mutations?
ultimately creates changes in proteins and their functions.
Summary: