Chapter 8

Biology 9
Unit 8:
Cell Communication/
Created by: Jeff Wolf and Mike Graff
Objectives: After completing this
Learning Quest the student will…
 Describe and label the
parts to a DNA and RNA
 Explain how genetic
information flows from
DNA to RNA to Proteins.
 Explain the concept of the
Genetic Code.
 Give examples of
Follow the instructions in
the Anticipation Guide
found in this PowerPoint
Follow the instructions
and answer all questions
found in the Learning
Follow the instructions in
the Conclusion Guide.
Anticipation Guide (Page 1)
• The following slides will be a
quick review of material
covered in Unit 3: Nutrition and
Biological Molecules.
• The structure of a DNA
molecule can be broken down
into three specific parts. The
first part, the nucleotide (a)
consists of three parts: a sugar, a
phosphate, and a nitrogenous
base. In these simplified
diagrams, the three parts of a
nucleotide are symbolized with
shapes and colors.
Anticipation Guide (Page 2)
• The second part of the
DNA molecule is the
DNA strand (b) is
composed of nucleotides
linked into a backbone,
with attached pieces
consisting of the 4
bases. A strand has a
particular sequence of
four bases abbreviated
A, G, C, and T.
Anticipation Guide (Page 3)
• The third part of the DNA
molecule is the Double helix
(c ). A double helix consists of
two DNA strands bonded
together by strand bases. These
bonds are hydrogen bonds and
are therefore individually weak.
However these bonds zip the
two strands together with a
strength to give the double helix
Anticipation Guide (page 4)
• When doctors talk about
children inheriting certain traits
such as blue eyes, red hair, or
some genetic disorder from
their parents, the genetic
material that these children
received from their parents is
• The directions for these traits
are actually chemically coded
in a “nucleic acid.” This
chemical code needs to be
translated from DNA into
proteins.The cell’s use a
chemical in your body called
RNA to take charge of this
Anticipation Guide (Page 5)
• The chemical code used by DNA
consists of four chemical bases.
• The four chemicals and their
abbreviations are found below.
– Adenine (A).
– Guanine (G).
– Thymine (T).
– Cytosine (C ).
• Genes can be passed along to offspring
because inheritance is based upon the
DNA code. In the core of this double
helix are the bases mentioned above that
bond together to create this DNA
molecule. In this code A can pair only
with T, and G can only pair with C.
To find out more about
the DNA molecule, move
to the next slide.
Learning Guide (Page 1)
• DNA gets its name
because of deoxyribose,
the sugar found within
the DNA nucleotide (a) .
• The full name for DNA
is deoxyribonucleic acid.
“Nucleic” refers to the
DNA’s exact location
within the nucleus of the
• Refer to pages 176 –
190 of you textbook.
Learning Guide (Page 2)
There are three
differences between
DNA and RNA:
The RNA sugar is a
ribose rather than a
The nitrogenous base
Thymine is replaced by
the base Uracil.
DNA is a double helix,
whereas, RNA is a single
stranded structure.
Learning Guide (Page 3)
• Once biologists were sure that
DNA was the genetic material,
understanding how DNA
contributed to a persons inheritance
was the next big discovery.
• This discovery was made by
American James D. Watson and
Englishman Francis Crick.. These
two scientists were the first to
develop a wire model of the DNA
• Watson and Crick determined that
DNA was not only a spiral helix but
that the diameter of the helix was
always the same. The thickness of
the DNA helix suggested that it was
made up of two polynucleotide
strands and therefore was a double
Learning Guide (Page 4)
• The diagrams below show two ways scientists illustrate the DNA
molecule. Diagram (a) shows the sugar-phosphate backbones as blue
ribbons and the complementary bases are shown in shades of green
and orange. Diagram (b) is the detailed structure of the DNA
Learning Guide (Page 5)
• When cells divide or
organisms reproduce,
genetic instructions need
to be passed on from one
generation to the next. To
accomplish this
replication process, the
parent DNA molecule
will unwind and act as a
template to build a new
DNA molecule that will
be an exact copy of the
original parent molecule.
(see the diagram to the
right for a further
Learning Guide (Page 6)
• The new daughter DNA
molecules are formed
by using ½ of the
parent DNA molecules
to match nitrogen
bases. Therefore,
Cytosine (C) from the
parent’s DNA molecule
will connect with
Guanine (G) from the
new daughter’s part of
the DNA molecule to
create a new double
helix DNA molecule .
This process is called
Learning Guide (Page 7)
• In the process of
transcription, genetic
information is transferred
from DNA to an RNA
• In the translation stage,
genetic information from
the RNA molecule is
read and a protein
molecule is assembled
from these instructions.
• Transcription and
translation will be
discussed in more detail
starting on page 10 of the
Learning Guide.
Learning Guide (Page 8)
• The genetic information
that needs to be decoded
is referred to as codons.
These codons are groups
of three nitrogen bases
located on the
messenger RNA.
• These codons identify
the correct amino acid
that needs be put into
place as the protein are
Learning Guide (Page 9)
• In order to identify the
correct amino acid, the
codon must first be
looked up on a table of
mRNA codons. Note the
table to the left.
• For example, if the codon
UUU is displayed, the
amino acid phenylalanine
(Phe) would be called for.
• Notice there are 64
different codon messages
and 20 common amino
acids displayed to the
Learning Guide (Page 10)
• As mentioned before transcription is the stage in which genetic
information transfers from the DNA molecule to an RNA
molecule. This genetic information is then able to be used
within the cell for the creation of proteins. It is these proteins
that will then determine how that organism or tissue will look
and work.
Learning Guide (Page 11)
• Notice that the table also
contains one start
message/codon and three
stop messages/codons.
These messages are
important because it
signifies, much like
punctuation in a sentence
where the protein
production process should
begin and where it should
Learning Guide (Page 12)
• To transfer the information
from mRNA to make a
protein, a process called
translation must occur. It
begins with the codon being
read and a helper called
transfer RNA assisting in
this stage.tRNA is referred
to as the anticodon.
Transfer RNA pairs up with
the correct 3 base code on
mRNA. As a result transfer
RNA attaches the correct
amino acid called for onto
the growing protein chain.
Learning Guide (Page 13)
• The six step diagram below demonstrates the entire process of creating
new genetic material from DNA to RNA and eventually to protein.
Learning Guide (Page 14)
• When a child is born with a medical condition such as sickle cell
anemia, the disease can be traced back through a difference in one
• This change in a nucleotide sequence of DNA is called a mutation.
• Mutations can involve a large region (diagram A) of a chromosome or
just a single nucleotide pair (diagram B).
Diagram A
Diagram B
Learning Guide (Page 15)
• Mutations can occur in a number of ways.
Mutations can result from errors in DNA
replication or recombination errors are called
spontaneous mutations.
• When the source of mutation come from physical
or chemical agents these sources are called
mutagens. The most common mutagen is high
energy radiation. Others include sunlight and
cigarette smoke.
• These mutagens may lead to cancer. Refer to page
214 – 215.
Learning Guide (Page 16)
• Most mutagens are cancer causing
agents called carcinogens. These
carcinogens bring about changes in
• Potent carcinogens created by X-ray
or radiation can cause leukemia and
brain cancer. Carcinogens created
by ultraviolet (UV) radiation can
cause skin cancer and a deadly type
of skin cancer called melanoma.
• The substance known to cause more
types of cancer than any other single
agent is tobacco. Smoking causes
the mutation of cells and promotes
rapid cell division and therefore the
development of tumors.
Learning Guide (Page 17)
• Please print the
following pages and
then read and
summarize the article
Conclusion Guide (Page 1)
• See your teacher with your article review and then
move on to the next assignment. You may need to
return to your notes, the PowerPoint Learning
Quest, or use the textbook to complete this
Conclusion Guide (Page 2)
• Use the words provided in the list to best
complete the following statements (see next
slide). Use these choices:
nitrogen bases
double helix
frameshift mutation
chromosomal mutation
point mutation
Conclusion Guide (Page 3)
nitrogen bases
double helix
frameshift mutation
chromosomal mutation
point mutation
During the process of transcription, DNA serves as the template for
making ______, which leaves the nucleus and travels to the
A _________ involves the addition or deletion of a single base in a
DNA molecule.
Watson and Crick developed the _________ model of DNA.
Thymine, adenine, guanine, and cytosine are _________________.
Conclusion Guide (Page 4)
nitrogen bases
double helix
frameshift mutation
chromosomal mutation
point mutation
The process by which DNA makes a coy of itself is called _______.
Each set of three nitrogen bases representing an amino acid is
referred to as a _________.
_________ brings amino acids to the ribosomes for assembly of
A change in a single base pair of DNA molecule is called a ______.
Conclusion Guide (Page 5)
nitrogen bases
double helix
frameshift mutation
chromosomal mutation
point mutation
________ is the failure of a par of homologous chromosomes to
separate properly during meiosis.
The process of converting RNA code into an amino acid sequence is
called _____________.
When parts of chromosomes are broken off and lost or reattached
incorrectly during mitosis or meiosis , the result is a _________.
Mutations in DNA can result in cells reproducing rapidly, producing
the disease called ___________________.
Works Cited
After completing the test, move onto Unit #9.
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