MUTATION:CHANGES IN
THE GENETIC CODE
for Science Grade 10
Quarter 3 / Week 5
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FOREWORD
This Self Learning Kit is a continuation of the SLK for week
number 4. In this learning kit students will have to utilize their
learning and understanding of the basic structure of the DNA and
its replication in studying the different changes that may occur in
the DNA sequence. The changes that occurs in our DNA
sequence, either due to mistakes when the DNA is copied or as
the result of environmental factors such as UV light and cigarette
smoking all result into mutation.
This kit shall introduce the different types of mutation and
how such mutations my affect the structure and function of
specific proteins. As students go over the readings in this module,
they shall understand the factors that may have caused the
occurrences of such mutations and relate it to common daily
practices.
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OBJECTIVES
At the end of this lesson, students shall be able to:
K: describe the types of mutations that can affect genes;
S: differentiate the different kinds of chromosomal
mutation; and
A: explore the causes and effects of mutation.
LEARNING COMPETENCY
Explain how mutations may cause changes in the structure
and functions of a protein. (SIOLT-IIIe-38)
I. WHAT HAPPENED
PRE-TEST
A. Directions: Match Colum A with Column B. Write the letter of
the correct answer in your notebook.
COLUMN A
COLUMN B
______1. It is the product of recombinant
A. Sex cells
DNA technology.
B. Mutagens
______2. It refers to the factors like radiation,
C. 46
chromosomes chemicals, extremes of temperatures, D. Karyotype
and viral infection that causes mutation.
E.(GMO)
______3. A type of cell where mutation occurs
and are said to be heritable.
______4. The total number of chromosomes in the human body.
______5. It is a test where abnormalities in the chromosome
structure and number can be detected.
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B. Directions: Tell whether the following mutation is HARMFUL or
BENEFICIAL. Write your answers in your notebook.
_____________1. Plants inability to make chlorophyll.
_____________2. Albinism in humans where an albino is sensitive to
the effects of sun exposure.
_____________3. Mutation in blood proteins prevents viruses or
parasites to thrive in host organisms.
_____________4. Mutation in the color of a butterfly species
protects itself from predators.
_____________5. Mutation in certain body cells can cause cancer.
II.WHAT I NEED TO KNOW
DISCUSSION
A change in the genetic code results in the change in
protein structure or level of expression. This may lead to changes in
cellular properties and behavior thus, the organism is affected.
The change in the genetic material of an organism is called
mutation and can be induced by factors called mutagens.
Mutagens can be in the form of radiation, chemicals, extremes of
temperature, and even viral infection.
Mutations may be harmful. In body cells, mutations can
cause cancer, while in sex cells it can cause birth defects. In
plants, mutations may result in their inability to make chlorophyll
that eventually led to plant death. Another harmful mutation is
albinism in humans. Unlike normal persons, an albino cannot
tolerate excessive exposure under the sun.
Mutations can sometimes be beneficial. Example in blood
proteins, it prevents viruses or parasites to thrive in host organisms.
In agriculture, traits of plants and animals could be modified by
targeted or random mutations.
Mutations are said to be heritable if it occurs in sex cells. If
the eggs or sperms are affected, it can produce offspring with
new characteristics. If mutations occur in body or somatic cells, it
is not hereditary. The defects cannot be passed on to the offspring
and is only observed in the individual.
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Mutations may involve a change in the genes or in the
chromosomes. It can be of two types, namely:
1) Gene mutation
There is a permanent change in the DNA sequence that
makes up a gene. It may be caused by high energy
radiation (e.g. X-rays and UV light), chemicals reacting with
DNA, and high temperature.
2) Chromosomal mutation
It occurs at the chromosome level resulting in gene deletion,
duplication, or a change in chromosome structure. It may be
caused by parts of chromosomes breaking off or incorrect
combination.
The normal genetic content of the chromosome may be
affected. Many diseases are caused by the effects of inherited
genes. In most cases, there is only a small difference between the
DNA sequence in the defective gene and a normal one. This
difference is enough to cause serious and often fatal diseases.
Consider what might happen if an incorrect amino acid was
inserted in a growing protein chain during the process of
translation. Do you think this will affect the structure of the entire
molecule? Read the two sentences below. What happens when a
single letter in the first sentence is changed?
THE DOG BIT THE CAT.
THE DOG BIT THE CAR.
Did you see that changing a single letter also changes the
meaning of the sentence? A change in nitrogenous base in a
protein may yield a different amino acid and a corresponding
change in the protein structure and function.
What will happen if a single base is deleted from a DNA
strand? Deletion or insertion of a base may change the reading
frame of the codon leading to a frameshift mutation. Read again
the two sentences below.
THE DOG BIT THE CAT.
THE DOG ITT HEC AT.
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What was deleted? Would the result be the same if these
would be an addition of a single base? You learned that an
mRNA corresponds to a DNA sequence translated by ribosomes
into proteins. If the new sequence with a deleted base was
transcribed, then every codon after the deleted base would be
different.
Figure. 1. Deletion of a region in
a chromosome
Source: Learners Manual
Mutations in chromosomes may occur in a variety of ways.
Sometimes parts of chromosomes are broken off and last during
mitosis or meiosis.
Here are the kinds of chromosomal mutations.
1) Translocation occurs when a piece of chromosome breaks
off and attaches to another chromosome.
Figure 2. Translocation of a
region in between two
chromosomes
Source: Learners Manual
2) Deletion refers to the loss of a segment of DNA or
chromosome.
3) Inversion involves the breakage of a chromosome in two
places in which the resulting piece of DNA is reversed and reinserted into the chromosome.
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LET’S APPLY!
Complete the following table by filling in the needed
information for each type of chromosomal mutation. Write your
answers in your notebook.
Changes that affect the structure of chromosomes can cause
problems with growth, development, and function of the body’s
systems. These changes can affect many genes along the
chromosome and disrupt the proteins made from those genes.
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Gain or loss of chromosome material results in chromosomal
mutations or aberrations. Human examples of genetic disorders
are the following:
 Down’s syndrome is usually caused by an extra copy of
chromosome 21 (trisomy 21)
 Edward’s syndrome in trisomy of chromosome 18. The
second most common trisomy after Down’s syndrome.
Source: thinglink.com
 Klinefelter’s syndrome (XXY). Men with this condition are
usually sterile and tend to have longer arms and legs and to
be taller than their peers. They are often shy and quiet and
have a higher incidence of speech delay.
 Turner’s syndrome. Female sexual characteristics are present
but underdeveloped. They often have a short stature, low
hairline, abnormal eye features, and bone development,
and a “caved-in” appearance to the chest.
 “Cri du chat” is caused by the
deletion of part of the short arm of
chromosome 5. The condition is so
named because affected babies
make high-pitched cries that
sound like a cat. Affected
individuals haul wide-set eyes, a
small
head
and
jaw,
are
moderately to severely mentally
retarded, and very short.
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Human Karyotyping
It is estimated that one in 156 live births has some kind of
chromosomal abnormality. Some of the abnormalities associated
with
chromosome
structure and number
can be detected by
a
test
called
karyotype.
A
karyotype is an image
of the full set of
chromosomes of an
individual
that
displays the normal
number, size, and
shape.
To produce a
karyotype, chromosomes
commonly derived from actively dividing white blood cells are
stained and photographed.
Figure 3. Karyotype of Human Male and Female
You inherit one chromosome of each pair from your mother
and the other from your father. Altogether humans have 23
homologous pairs of chromosomes or a total of 46 chromosomes.
The 23rd pair of chromosomes is called the sex chromosomes while
the first 23 pairs are the body chromosomes.
Genetic Engineering
Figure 4. Diagrammatic Illustration of the Steps in Genetic Engineering
Source: Learner’s Manual
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III. WHAT I HAVE LEARNED
POST TEST
Directions: Read the following questions and choose the letter of the correct
answer. Write the letter of your choice in your notebook.
1. Genetic engineering includes techniques that transfer a specific
genetic information from one organism to another. This is referred to as
_________________________.
a. genetically engineered DNA
b. genetically engineered organism
c. recombinant DNA process
d. recombinant DNA technology
2. What do you call the organism whose genetic information has been
altered using recombinant DNA technology?
a. Genetically engineered organism
b. Genetically classified organism
c. Genetically modified organism
d. Genetically produced organism
3. In humans, what is the total number of chromosomes?
a. 23
b. 46
c. 47
d. 24
4. It is the change in the genetic material of an organism.
a. Mutation
b. Mutagens
c. Mutant
d. Mutate
5. How many chromosomes are involved in translocation?
a. 4
b. 3
c. 2
d.1
6. What type of cell where mutation is not hereditary? It affects the
individual but the defects cannot be passed on to the offsprings.
a. sex cells b. body cells
c. sex organs
d. reproductive
organs
7. It is a trisomy of chromosome 18 which is the second common trisomy
after Down’s syndrome.
a. Klinefelter’s syndrome
c. Cri du chat
b. Turner’s syndrome
d. Edward’s syndrome
8. A kind of chromosomal mutation where there is a loss of a segment of
DNA or chromosome.
a. Deletion b. Inversion
c. Translocation d. Duplication
9. A type of mutation where there is a permanent change in the DNA
sequence that makes up a gene caused by high energy
radiation, the
reaction of chemicals, and high temperature.
a. chromosomal mutation
c. gene mutation
b. deletion
d. inversion
10. Describe what happens if a mutation is present in an organism’s
gametes or sex cells?
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REFERENCES
Acosta, Herma D., et. al (2015). Science 10 Learner’s Material, Unit 3,
Module 2. DepEd
Campbell, N.A., Williamson, B., Heyden, R.J. (2004). BIOLOGY Exploring Life.
Pearson Education Incorporated.
National Institute for Science and Mathematics Education and
Development: Treyes, Rodolfo S., et. al (2006, 2009). BIOLOGY textbook,
Science & Tech. II, DepEd
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DEPARTMENT OF EDUCATION
SCHOOLS DIVISION OF NEGROS ORIENTAL
SENEN PRISCILLO P. PAULIN, CESO V
Schools Division Superintendent
JOELYZA M. ARCILLA EdD
OIC - Assistant Schools Division Superintendent
MARCELO K. PALISPIS EdDJD
OIC - Assistant Schools Division Superintendent
NILITA L. RAGAY EdD
OIC - Assistant Schools Division Superintendent / CID Chief
ROSELA R. ABIERA
Education Program Supervisor – (LRMS)
ARNOLD R. JUNGCO
PSDS - Division Science Coordinator
MARICEL S. RASID
Librarian II (LRMDS)
ELMAR L. CABRERA
PDO II (LRMDS)
MA. ALETTA AARONA REPOLLO GAJELOMO
Writer
__________________________________
ALPHA QA TEAM
LIEZEL A. AGOR
MA. OFELIA I. BUSCATO
ANDRE ARIEL B. CADIVIDA
THOMAS JOGIE U. TOLEDO
BETA QA TEAM
LIEZEL A. BESAS
JOAN B. VALENCIA
LIELIN A. DE LA ZERNA
PETER PAUL A. PATRON
THOMAS JOGIE U. TOLEDO
DISCLAIMER
The information, activities and assessments used in this material are designed to provide accessible
learning modality to the teachers and learners of the Division of Negros Oriental. The contents of this module
are carefully researched, chosen, and evaluated to comply with the set learning competencies. The writers
and evaluator were clearly instructed to give credits to information and illustrations used to substantiate this
material. All content is subject to copyright and may not be reproduced in any form without expressed written
consent from the division.
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SYNOPSIS
ANSWER KEY
This Self Learning Kit is made for
Grade 10 students in the Science 10 topic
on how mutations may cause changes in
the structure and function of a protein.
As you read and learn the content of this
SLK, you shall understand how some
conditions commonly observed among
living organisms are attributed to various
types of mutations and how some these
alteration can be utilized beneficially
through
the
science
of
genetic
engineering.
ABOUT THE AUTHOR
Ma. Aletta Aarona Repollo Gajelomo is a Science
teacher of Siaton National High School, Siaton, Negros
Oriental. She obtained her Bachelor’s degree in
General Science from St. Paul College of Dumaguete
(now St. Paul University of Dumaguete). She earned 36
masteral units (Complete Academic Requirements)
from the University of Southern Philippines in Lahug,
Cebu City. She is currently a Secondary School
Teacher III of Siaton National High School and the
District Science Coordinator (Secondary) of Siaton 2
District.
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