DNA and Protein Synthesis
Goal: to understand the structure and function of DNA, its
role in protein synthesis and evolution.
Chapter 12 DNA
12.1 Identifying the Substance of Genes
Bacterial Transformation
 Early biologist studying genetics wanted to know the
chemical nature of __________.
Griffiths
 Through _____________ experiment scientists
hypothesized the chemical compound that transformed
the harmless bacteria into disease causing ones was
most probably a gene.
 Griffiths experiment discovered the process called
__________________.
Avery
 Oswald Avery did further experiments to discover the
_____________ _____________ of a gene.
 By exposing the bacteria to ___________ that would
destroy proteins, lipids, carbohydrates and RNA they
discovered that neither of those was responsible for
transformation.
 It wasn’t until they used an enzyme to destroy ______
that they realized that _______ was the transforming
factor.
Bacterial Viruses
Hershey - Chase
 In the Hershey – Chase experiment scientists wanted to
determine if the bacteriophage injected the __________
coat or the ________ core.
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 They tagged the bacteriophage with two types
of _________ _________, phosphorus-32 and sulphur35. Phosphorus is attached to ______ and sulphur is
usually attached to _____________.
 When they allowed the bacteriophage to enter the
bacteria they discovered phosphorus inside the bacterial
cells meaning ________ was genetic material.
The Role of DNA
 DNA is capable of ___________ information in the form
of genes.
 DNA __________ the information stored in genes when
cells divide.
 When cells divide the information stored in genes is
_______________ from one generation to the next.
12.2 The Structure of DNA
The Components of DNA
 DNA is a nucleic acid made up of subunits called
______________.
 A nucleotide is composed of a 5 carbon sugar called
_____________, a ___________ group and a
______________ base.
 There are four types of nitrogen bases; ___________,
__________, __________ and ___________.
 Nucleotides are joined together by ____________ bonds
between the ____________ sugar and the
____________base.
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Make a diagram of Figure 12-5 on page 345.
Solving the Structure of DNA
 Chargaff’s rule states that there are _______
percentages of adenine and thymine and the same rule
applies to __________ and __________.
Complete “Analyzing Data” on page 345 to check your
comprehension.
The Double – Helix Model
 Franklin’s X-ray of DNA enabled Watson and Crick to
build a model that explained the ___________ and
____________ of DNA.
 DNA is shaped in a double helix and looks like a
_________ __________.
 Each side of the ladder or strands of DNA run in opposite
directions making it ____________.
 The two strands of DNA are held together by
____________ bonds between the nitrogen bases.
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 The hydrogen bonds between the nitrogen
bases occur only between complimentary
base pairs; ______ and ______.
Make a diagram of Figure 12-7 Base Pairing
on page 348
12.3 DNA Replication
Copying the Code
 The process of copying the cell’s DNA is known as
_____________.
 Replication occurs during ___________ of the cell cycle
before mitosis.
 Replication is to ensure that each cell has an exact copy
of _________.
 During replication the two strands of DNA ___________
and each side is used as a template for a new strand
 The adenine base bonds with ___________ and guanine
bonds with ___________.
 ____________ (types of proteins) play a role in
replication.
 The helicase enzyme will “unzip” the DNA strands by
breaking the __________ __________.
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 DNA ______________ will join nucleotides
together by producing the sugar phosphate
bonds.
 DNA polymerase will also _________
________ the DNA strands to make sure
there are no copying errors.
Complete the Chapter 12 Assessment on pages 356-357
to check your comprehension
Chapter 13 RNA and Protein Synthesis
The Role of RNA
 DNA has the codes to build a protein but these
instructions must first be copied into ________.
 RNA is similar to DNA in that it is made of
_____________, however there are three important
differences; RNA has a ______ sugar while DNA has a
deoxyribose sugar, RNA has a _________ strand while
DNA is double stranded and RNA contains the nitrogen
base _________ in place of thymine.
 There are __________ types of RNA and each has its
own job to perform.
Make a diagram to match each type of RNA (figure 132)
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
___________ RNA carries the
instruction to build a protein from
the nucleus to the ribosome.
 ___________ RNA helps form the subunits of a
ribosome (where protein synthesis takes place).
 ____________ RNA carries amino acids to the ribosome
to match them to the coded mRNA message.
RNA Synthesis
 _______________ is the process where DNA will serve
as the template to make a strand of RNA.
 The RNA will be made in the nucleus and then go to
_____________ to help make a protein.
 RNA ____________ is an enzyme that will bind to the
DNA strand and cause it to separate.
 One strand of DNA will act as a ___________ to make
the RNA strand.
 ____________ are regions of DNA that signal the RNA
polymerase where to begin making the RNA strand
 mRNA often needs to be edited so the portions cut out
are called _______ and the portions spliced together are
call ________.
13.2 Ribosomes and Protein Synthesis
The Genetic Code
 The code carried in DNA which is then transcribed into
RNA is information to make a ____________.
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 Proteins are made by joining ________ _______
together in long chains called polypeptides.
 The order of amino acids is directly related to the
proteins _________ and __________.
 RNA has four different bases: adenine, cytosine, guanine
and _________ which makes form the base of a
language we call the ________ code.
 The genetic code is read three letters at a time and the
three letters correspond to a specific ________
_______.
 The three letter code on mRNA is called a _________.
 Often amino acids have more than one ________. Lysine
has two _______; AAA and AAG.
 The message to start and stop the process of making a
polypeptide is in the form of “_______” and “________”
codons.
Complete the “Quick Lab” on page 367 to check your
comprehension.
Translation
 The role of a ribosome in the process called translation
is to _________ the mRNA message into a sequence of
amino acids to form a polypeptide and eventually a
____________.
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 The first step in translation is when the ribosome binds
to the strand of ___________.
 As each codon on the mRNA strand passes through the
ribosome, _________ will bring the proper amino acid
into the ribosome.
 tRNA has ___________ (3 unpaired bases) that are
complementary to the mRNA codons.
 The codon for methionine is AUG so the anticodon
would be ________.
 The ribosome will create ________ bonds that will
attach the amino acids together and as the bond
between tRNA and the amino acid break, tRNA will exit
the ____________.
 More tRNA will enter the ribosome bringing in amino
acids specified by the ___________.
 The process continues until the ribosome reaches a
“stop” codon and then the polypeptide is
____________.
Please review the “Visual Summary” on page 368
The Molecular Basis of Heredity
 Most genes contain the instructions to build _________.
 Proteins are microscopic tools designed to build and
operate the cell.
 The central basis of molecular biology is that
information is transferred from ______ to ______ to
protein. The process is known as _______ expression.
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Please review the “Visual
Summary” Gene Expression on
page 371.
13.3 Mutations
Types of Mutations
 Mutations are changes in ___________ information.
 There are two types of genetic mutations; ________ and
______________ mutations.
Gene Mutations
 There are three types of gene mutations; ___________,
____________ and ____________.
 These types of mutation usually only change one or a
few nucleotides and are known as _________
mutations.
 ____________ occurs when on base is changed to
another base. It can change the amino acid or have no
change at all since amino acids have more than one
codon.
 _________ and __________ occur when a base is
inserted or removed. These mutations will cause shift in
the reading of the three letter code and as a result it can
change every amino acid that follows the point of the
mutation.
 Insertion and deletions are also known as “__________
___________” mutations
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Chromosomal Mutations
Chromosomal mutations can change the _________ of
genes on chromosomes or even the __________ of
copies.
There are four types of chromosomal mutations:
__________, __________, _________ and
_____________.
___________ refers to a loss of all or part of a
chromosome.
___________ produces an extra copy of part or all of a
chromosome.
___________ refers to the changing of direction of parts
of a chromosome.
____________ occurs when a part of a chromosome
breaks off and attaches to another.
Effects of Mutations
 Mutations usually occur during cell division and happen
once in every _______ million bases.
 ____________ are agents that alter the genetic code or
cause and increase in copying errors.
 Mutations can be either __________ or beneficial and at
times have no effect at all.
 Harmful mutation can lead to faulty _________ or even
cancer.
 Beneficial mutations alter proteins and allow the
organism survive in a changing environment.
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Complete the Chapter 13 Assessment on pages 386 387
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