Content Benchmark L.8.A.1
Students know heredity is the passage of genetic instructions from one generation to the next
generation. E/S
Inside almost every cell of every living thing is the blueprint for building that organism. This
blueprint contains information on all of the organism’s inherited characteristics. The blueprint is
deoxyribonucleic acid, or DNA. Much like a blueprint, DNA provides step by step instructions
for building each part of the final product. The final product would be an organism. DNA
accomplishes this by providing the instructions to make all of an organism’s proteins. In humans
for example, this blueprint gives the instructions for making a protein called melanin, which will
determine how dark or light a person’s skin will be. In plants, DNA gives the instructions for
proteins that influence traits like plant height and flower color. Where does the DNA and the
information it holds come from? It is inherited from an organism’s parents through reproduction.
During sexual reproduction, each parent donates half of its genetic material to the offspring. So,
each parent gives half of the blueprint, and when they are put together, they form a complete
blueprint from which the offspring can be made. Heredity is the reason organisms can look
similar to their parents, yet also look unique. A thorough understanding of heredity requires at
least a basic understanding of DNA, RNA, proteins synthesis, cell division, reproduction and
genetics principles.
DNA Structure
Just a little less than a century ago, scientists were still trying to figure out what molecule held
genetic information. In the early 1990s they knew cells were made of nucleic acids, proteins,
lipids, and carbohydrates; but they did not know which of these was passed from parent to
offspring. During this time, people thought DNA was too simple of a molecule to code for the
variety of traits found in most organisms. Scientists believed proteins were more likely the
genetic material because there were a greater variety of proteins known. Many experiments were
done to find out which molecule contained the genetic material, but none definitively showed it
was DNA until the 1950s. Alfred Hershey and Martha Chase proved that DNA, not protein was
the genetic material in viruses. This experiment led most scientists to believe DNA was the
genetic material for all life.
Soon after Hershey and Chase’s discovery, two scientists named James Watson and Francis
Crick proposed the first accurate model of DNA’s structure. They used research done by other
scientists such as Erwin Chargaff, Rosalind Franklin, and Maurice Wilkins to decipher the
molecular structure of DNA. Watson and Crick’s model showed that DNA is a double helix
(shown on the right side of Figure 1) and is composed of nucleotides (shown in the bottom left of
Figure 1). Nucleotides are made of a sugar, phosphate, and a nitrogenous base (these components
are also shown in Figure 1).The nitrogenous bases are adenine (A), thymine (T), cytosine (C),
and guanine (G). Notice that if adenine is on one side, thymine is opposite and if cytosine is on
one side, guanine is opposite. These are considered complimentary base pairs and they always
pair together in DNA.
Figure 1. The Structure of DNA.
(From http://www.accessexcellence.org/RC/VL/GG/dna2.html)
For more information on DNA history, go to
http://nobelprize.org/educational_games/medicine/dna_double_helix/readmore.html
For detailed information and an animation of DNA, go to
http://www.johnkyrk.com/DNAanatomy.html
DNA, RNA, and Protein Synthesis
The nitrogenous bases of DNA – A, T, C, and G provide the basis for DNA to code for genetic
characteristics. There can be hundreds to billions of nucleotides on just one side of the DNA
strand, depending on the organism. The order of the nitrogenous bases on the nucleotides is
called the base sequence. The base sequence is comprised of all the codes for each gene that an
organism has. A gene is a specific nucleotide sequence on the DNA that codes, or contains the
genetic instructions, for one protein. To discover how these genes are turned into proteins, we
must take a closer look at RNA.
While DNA holds the genetic instructions for making proteins, it is ribonucleic acid, or RNA,
that must read and translate them. Protein synthesis involves two parts, transcription and
translation. It also involves 3 kinds of RNA- messenger RNA (mRNA), transfer RNA (tRNA),
and ribosomal RNA (rRNA). A summary of the process is pictured in Figure 2 and explained
below it.
Figure 2. Protein Synthesis
(From http://www.accessexcellence.org/RC/VL/GG/protein_synthesis.html)
In transcription (#1 on Figure 2), mRNA transcribes, or copies down a gene from DNA. An
enzyme called RNA polymerase opens the necessary gene in the DNA and begins adding
complimentary nucleotides to “copy” the gene base sequence. RNA does not contain thymine;
instead, it contains uracil (U). Therefore, as mRNA copies the gene from DNA, it pairs adenine
with uracil, thymine with adenine, guanine with cytosine and cytosine with guanine. Once the
gene base sequence has been copied, the mRNA leaves the nucleus to travel to the ribosome
where the protein will be made.
Translation occurs in the cytoplasm (#2 on Figure 2). In translation, the mRNA first binds to a
ribosome. Ribosomes are made of rRNA and provide the environment for protein synthesis. The
mRNA molecule is read 3 bases at a time. These 3 base sequences are called codons. Each codon
codes for a specific amino acid. Amino acids are the building blocks of proteins. The amino
acids are brought to the ribosome one at a time by tRNA. Once all the codons are read and all the
amino acids have bonded to form a protein, the mRNA and ribosome release the protein. The
protein goes on to perform its function.
Although middle school students are not responsible for protein synthesis, it is necessary
background information for teachers to understand heredity.
For an animated simulation of protein synthesis and further explanation, go to
http://www.lewport.wnyric.org/JWANAMAKER/animations/Protein%20Synthesis%20%20long.html and,
http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302
For information on how mutations affect the expression of DNA, see MS TIPS Benchmark
L.8.A.2
Meiosis and Gamete Formation
In eukaryotic organisms, DNA strands can be incredibly long due to the fact that it takes
hundreds or thousands of nucleotides to code for one protein. For example, the DNA in just one
human cell can be over 2 meters long from end-to-end! How does all of that DNA fit into a cell?
The DNA coils tightly around itself and special proteins to form chromosomes. Human DNA has
46 chromosomes as shown in Figure 3, which is a human karyotype. A karyotype is a picture of
an organisms chromosomes, lined up next to their homologues. Homologous chromosomes, or
homologues, are chromosomes that are the same size, the same shape, and have the same genes.
These homologous chromosomes may not have the same base sequences for the genes. For
example, a gene that codes eye color would be located on the same spot in two homologous
chromosomes; but one of the genes may code for blue eyes on one chromosome while the other
codes for brown eyes on the other chromosome. These different forms of a gene are called
alleles. Each parent donates one chromosome to the homologous pair. In order for this to be
possible, each parent of any organism would need to produce a cell with half the total number of
chromosomes for that organism. Or, in other words, a cell with only one homologue would be
produced. This cell, used for sexual reproduction, would be called a gamete and is produced
through the process of meiosis.
Figure 3. Human Karyotype and Chromosome Structure.
(From http://www.accessexcellence.org/RC/VL/GG/human.html)
Figure 4 depicts a simplified summary of meiosis. The figure shows 4 chromosomes, or 2
homologous pairs. In prophase 1, the chromosomes duplicate themselves, which is what gives
them the X-shape. In metaphase 1, the homologues line up next to each other in the middle of the
cell. Two events happen at this step that creates genetic variation among the gametes produced.
The first is independent assortment. The homologues will line up and be separated randomly. In
the figure, two chromosomes of the original four come from the mother and two come from the
father. When the chromosomes are pulled to each side of the cell to create two new cells, (as
seen in Anaphase 1 and Telophase 1), the daughter cells of the first cell division may end up with
two chromosomes from the same parent or they may end up with one chromosome from each
parent cell. The second event is crossing over. When homologues line up next to each other,
parts of the chromosome may be swapped. This results in the daughter cells of the first division
having different chromosomes than the parent cell. After two daughter cells are produced by the
first division in meiosis, a second division occurs. In this division, each of the chromosomes are
split in half. Notice the four daughter cells that result after Telophase 2 have half the number of
chromosomes as the parent cells. These daughter cells would be considered gametes.
Figure 4. Meiosis Overview.
(From http://www.accessexcellence.org/RC/VL/GG/meiosis.html)
Gamete formation is also where mutations can happen, for more information, see MS TIPS
Benchmark L.8.A.2
For meiosis animated simulations, go to
http://www.lewport.wnyric.org/jwanamaker/animations.htm and,
http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/ and,
http://www.cellsalive.com/meiosis.htm
For a meiosis tutorial, see
http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/main.html
Genetics
Now that we have seen how gametes form, let’s take a look at how hereditary information is
passed through these gametes. First, we will need some background information on genetics.
Long before scientists knew that DNA was the genetic material, a monk named Gregor Mendel
studied genetics in pea plants. His experiments led to the discovery of several important genetic
principles. Mendel discovered that some alleles for genetic traits are dominant and some traits
are recessive. Alleles are alternate forms of genes. When the dominant allele for a gene is
present, it will mask the appearance of the recessive allele. For example, in his pea plants,
Mendel discovered that green pea pods were dominant over yellow pea pods. The parent pea
plants will each give one allele for pea pod color to their offspring. If one parent gave the allele
for green pea pods and the other parent gave the allele for yellow pea pods, then the offspring
would have green pea pods. This passing down of alleles is related to the previously discussed
concept of meiosis. At the end of meiosis, each gamete contains one homologue of each
chromosome for the given organism. This means the gamete also contains one allele for each
trait on that chromosome. Each parent donates one allele to the offspring for each gene.
For more information on Gregor Mendel, go to
http://www.mendelweb.org/MWtoc.html and,
http://www2.edc.org/weblabs/Mendel/mendel.html
Genetic traits are often symbolized by letters. Dominant alleles are often symbolized by capital
letters, like ‘G’ for green pea pods. Recessive alleles are often symbolized by lower case letters,
like ‘g’ for yellow pea pods. So the offspring from the previous example would have the
genotype Gg and a phenotype of green pea pods. Genotype is the genetic makeup, while
phenotype is the physical appearance of an organism. This genotype is called heterozygous,
because there is one dominant and one recessive allele. Genotypes that have two of the same
allele, such as GG or gg would be considered homozygous dominant and homozygous recessive,
respectively.
When the genotype of parents is known, Punnett Squares can be used to determine the possible
genotypes of the offspring. For example, the allele for being tall (T) in pea plants is dominant
over the allele for being short, so if we breed a heterozygous plant (Tt) with a homozygous
recessive plant (tt). The possible offspring genotypes are shown in Figure 5. Punnett squares can
also help us determine the probability that offspring will turn out a certain way. Figure 5 shows
that there is a 50% chance that an offspring of these parent plants would be tall and a 50%
chance that it would be short. Punnett Squares shows the possible gamete combinations that
would be made by parents during meiosis. So, in this example, for the Tt parent, meiosis would
produce a gamete with the T allele in it 50% of the time and a gamete with t in it 50% of the
time. The tt parent would only produce gametes with t in them. This Punnett square is an
example of a monohybrid cross, which mean it only contains one inherited trait. Punnett squares
can be much larger when they are used for dihybrid or trihybrid crosses.
Figure 5. Punnett Square for Tt and tt Pea Plant Cross
(From http://users.adelphia.net/~lubehawk/BioHELP!/psquare.htm)
For step by step instructions on making Punnett squares, go to
http://users.adelphia.net/~lubehawk/BioHELP!/psquare.htm
For an online animated tutorial of making Punnett square and how they relate to breeding and
probability, go to
http://www.usoe.k12.ut.us/CURR/Science/sciber00/7th/genetics/sciber/intro.htm
For a Punnett square calculator (shows you the Punnett square if you type the genotypes), go to
http://www.changbioscience.com/genetics/punnett.html
For more information on selective breeding, see MS TIPS Benchmark L.8.A.3.
Now let’s take a look at a human trait that is often passed down through generations. The trait is
thumb straightness. In human, as discussed in previous sections, there are 46 chromosomes.
When meiosis occurs and gametes are formed, the resulting cells have 23 chromosomes, which
means one homologue and one allele for each gene. In humans, the allele for hitchhikers thumb
(h) is recessive, while the allele for a straight thumb (H) is dominant. These thumb types are
pictured in Figure 6. Each person has two alleles for this trait. A genotype of HH or Hh would
result in a straight thumb, while hh would result in hitchhikers thumb.
Hitchhiker's Thumb
Regular Thumb
Figure 6. Hitchhiker Thumb Compared to a Straight Thumb
(From http://www.ncrtec.org/tl/camp/gene/thumbs.htm)
Now let’s take two parents, a male with hitchhikers thumb and a female with a homozygous
straight thumb (hh and HH respectively). When their gametes are formed through meiosis, the
male will produce gametes with the h allele. The female will produce gametes with the H allele.
When the gametes fuse together to form a zygote during fertilization, the zygote would receive
the genotype Hh and therefore have a straight thumb. Let’s say the offspring of this child was a
female who has children with a male who has the genotype Hh. Both parents will have straight
thumbs, but it will be possible for them to have a hitchhiker thumbed child. Each parent will
form some gametes with the H allele and some with the h allele. As demonstrated in the Punnett
Square in Figure 7, there is a 25% chance that they will have a child with hitchhiker’s thumb and
a 75% chance they will have a child with straight thumbs. This example illustrates how a
recessive trait can be passed through generations and stay hidden or unseen in some individuals.
These individuals carry the allele for the recessive trait, but do not express it.
H
H
H
HH
Hh
h
Hh
Hh
Figure 7. Punnett Square of a heterozygous cross for hitchhikers thumb
Heredity is often not as simple as monohybrid crosses. Most human characteristics are
polygenic, which means they are controlled by many genes. Eye color, for example, is controlled
by at least three genes and there may be more. Many human traits are also complex characters,
which means the environment plays a role in the phenotype. Skin color, for example, can be
influenced not only by several genes, but by the amount of sunlight a person’s skin receives.
Some traits are incompletely dominant. This means that in heterozygous individuals, the
phenotype is somewhere in between the phenotypes of the homozygous individuals. For
example, if a curly haired Caucasian and a straight hair Caucasian have children, the child will
have wavy hair. Some traits are controlled by multiple alleles, such as the ABO blood types in
humans. The three alleles for blood typing are A (IA), B (IB), and O (i). The IA and IB alleles are
also codominant, which means that if a person has both alleles, they are both expressed as the
phenotype and that person would have AB blood. The type O (i) allele is recessive to A (IA) and
B (IB) allele. In order to have type O blood, an individual must inherit a recessive allele (i) from
each parent. If an individual inherits an A allele (IA) from one parent and an O allele (i) from
another parent, then the individual will have type A blood (IA i) because the A allele is dominant
to the O allele.
For more information on blood typing and inheritance see
http://www.biology.arizona.edu/Human_bio/problem_sets/blood_types/Intro.html
Some traits are sex-linked, which means they are found on the sex chromosomes. These traits,
such as colorblindness, are usually located on the X chromosome and are more prevalent in men.
For colorblindness, women would only be colorblind if the colorblind allele were on both X
chromosomes; but in men, the allele only needs to be on their one X chromosome. Some traits
are sex-influenced, which means males and females will show different phenotypes when they
have the same genotype. Pattern baldness is an example of a sex-influenced trait, as it is
dominant in males but recessive in females. Many genetic traits found in organisms, especially in
humans, are not controlled by two alleles where one allele is dominant and one is recessive; but
that kind of trait is the simplest way to explain heredity.
For more information on the genetic and environmental influences on organisms see MS TIPS
Benchmark L.8.A.4.
For an animated tutorial on the basics of genetics, go to
http://learn.genetics.utah.edu/units/basics/tour/
For a guide to understanding genetic conditions, go to
http://ghr.nlm.nih.gov/
For an overview of heredity concepts and genetics, see
http://library.thinkquest.org/20465/info.html
For several links to other DNA and genetics websites, go to
http://sciencespot.net/Pages/kdzbiogen.html
Asexual Reproduction
Asexual Reproduction is a process that involves only one organism. This process does not
involve meiosis. Offspring in asexual reproduction are usually exact copies of the parents, unless
mutations occur. Asexual reproduction mainly occurs in single-celled organisms, though it does
also occur in some multicellular organisms.
Many types of bacteria reproduce asexually in a process known as binary fission. This process is
pictured in Figure 7 below.
Figure 7. Binary Fission
(From http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect06.htm )
Some fungi, such as yeast also reproduce asexually. Yeast use a process called budding in which
the offspring “buds” off the parent. Budding of yeast is pictures in Figure 8 below.
Figure 8. Budding of Yeast
(From http://mpf.biol.vt.edu/research/budding_yeast_model/pp/intro.php )
Some species of star fish can also reproduce asexually. The parent star fish body splits in half
and each “daughter” regenerates the other half of its body to form two separate star fish.
For more information and examples on asexual reproduction, visit
http://regentsprep.org/Regents/biology/units/reproduction/asexual.cfm and,
http://www.ucmp.berkeley.edu/glossary/gloss6/asexual.html
For more information on asexual reproduction in plants, visit
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AsexualReproduction.html
For more information on asexual reproduction in animals, visit
http://biology.about.com/library/weekly/aa090700a.htm
Content Benchmark L.8.A.1
Students know heredity is the passage of genetic instructions from one generation to the next
generation. E/S
Common misconceptions associated with this benchmark
1. Students incorrectly believe that if no one else in the family is affected, the condition is
not inherited.
Students often believe that if they do not see a characteristic such as in their family, then it
must not be inherited. For example, if a student had a hitchhikers thumb, but their parents
and possibly grandparents did not, then the student may believe something happened to their
thumb to make it bend back. This is especially common with genetic disorders, like
colorblindness, which often skip generations. Drawing Punnett Squares and pedigrees can
help students visualize that some traits or genetic disorders tend to skip generations. The first
resource below explains how to create pedigrees, or family trees.
For information on this and other misconceptions as well as information about why this
misconception is not true, go to
http://genetics.kaiser.org/home/genetics101highlights.htm
For more information on the inheritance of genetic disorders, go to
http://www.mdausa.org/publications/gen_inhr.html
2. Students inaccurately believe that traits are inherited from only one of their parents.
Some students believe girls inherit most of their characteristics from their mothers and boys
inherit most of their characteristics from their fathers. Some students may also believe their
mothers give them more genetic material because they were carried in their mothers as
fetuses. Students may tend to believe they look more like one parent and therefore they
received most of their genetic material from that parent. In reality, each parent contributes
half of their genetic material to their offspring. One parent may pass more dominant traits to
their offspring, which would result in that offspring looking more like that parent. These
misconceptions can be overcome by discussing the processes of meiosis and fertilization.
For information on this and other misconceptions, go to
http://www.project2061.org/publications/bsl/online/ch15/findings.htm
For information on meiosis and fertilization, see
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=cooper.section.2484
3. Students have difficulty with the relationship between genetics, DNA, genes, and
chromosomes.
Students may realize that physical appearances are inherited, but they may not make the
connection that these characteristics have underlying biochemical processes, such as the
production of proteins. As a result they may also not realize genes on DNA are responsible
for these biochemical processes. Chromosomes are passed from parent to offspring. They are
made of DNA, which has genes on it that code for proteins. These proteins cause our
characteristics.
For information on this and other misconceptions, go to
http://www.project2061.org/publications/bsl/online/ch15/findings.htm, and
http://www.genetics.org/cgi/rapidpdf/genetics.107.084194v1 (page 15), and
http://homepage.mac.com/vtalsma/syllabi/2943/handouts/misconcept.html#top
For more information on the link between genetics, DNA, genes, and chromosomes, go to
http://learn.genetics.utah.edu/units/basics/tour/
4. Students have difficulty distinguishing the difference between acquired and inherited
characteristics.
While many of our characteristics come directly from out genetics, that is not the case for all
of our characteristics. Genetics plays a role in some behaviors and diseases, but the majority
of these are the result of one’s environment. Talent is something that can be inherited, but
skills must be practiced in order for talent to develop. This misconception can be overcome
by looking at several examples of inherited characteristics and several examples of acquired
characteristics.
For information and research about this misconception, go to
http://www.msu.edu/~ostrow22/sciencelessonplan.htm
For information on this and other misconceptions as well as lesson plans to overcome it, visit
http://public.doe.k12.ga.us/DMGetDocument.aspx/Fifth%20Grade%20Frameworks%20%20Genetics.pdf?p=6CC6799F8C1371F61DE930EBA3265FC8133CC6DC95D97C40022D
61E56BBE1C86&Type=D, and
http://www.uen.org/Lessonplan/preview.cgi?LPid=69
For activities and information on learned versus inherited behavior, go to
http://utahscience.oremjr.alpine.k12.ut.us/Sciber01/7th/cells/html/inhvsacq.htm, and
http://www.sciencenetlinks.com/lessons.cfm?BenchmarkID=6&DocID=461, and
http://www.computerladyonline.com/PDF%20Instructions%20for%20Activities/Session%20
6/635--6029en--Inherited%20Versus%20Learned.pdf
5. Students inaccurately believe that one gene controls one trait and all genetics show
Mendelian patterns of inheritance
When teaching genetics, it is important to emphasize that there are non-Mendelian patterns of
inheritance. Most traits in humans are not monogenic (controlled by one gene). Monogenic
traits are the first examples that we teach, so students assume that all traits are governed by
one gene. Examples should be given for other patterns of inheritance, such as polygenic
inheritance or linked genes, which will not show Mendelian patterns.
For information on this and other misconceptions as well ideas on how to overcome it, go to
http://www.genetics.org/cgi/rapidpdf/genetics.107.084194v1
For information on non-Mendelian inheritance, go to
http://geneticsmodules.duhs.duke.edu/Design/MainMenu.asp?CourseNum=2, and
http://en.wikipedia.org/wiki/Non-Mendelian_inheritance
For information on polygenic inheritance, go to
http://staff.jccc.net/pdecell/evolution/polygen.html, and
http://waynesword.palomar.edu/lmexer5.htm
For information on linked genes, go to
http://biology.clc.uc.edu/Courses/bio105/sex-link.htm
Content Benchmark L.8.A.1
Students know heredity is the passage of genetic instructions from one generation to the next
generation. E/S
Sample Test Questions
Questions and Answers to follow on a separate document
Content Benchmark L.8.A.1
Students know heredity is the passage of genetic instructions from one generation to the next
generation. E/S
Answers to Sample Test Questions
Questions and Answers to follow on a separate document
Content Benchmark L.8.A.1
Students know heredity is the passage of genetic instructions from one generation to the next
generation. E/S
Intervention Strategies and Resources
The following is a list of intervention strategies and resources that will facilitate student
understanding of this benchmark.
1. Reproduction and Heredity
This website was created by the Utah State Office of Education. It contains worksheets,
quizzes, animations, and descriptions related to the basics of genetics. It also provides ideas
for labs and projects. This website was created for a seventh grade class and has many fun
activities.
To access this information, go to
http://www.usoe.k12.ut.us/CURR/Science/sciber00/7th/genetics/sciber/intro.htm
2. Mendelian Genetics Problems
This website was created through “The Biology Project” at the University of Arizona. There
are several links on the page that allow students to view genetics problems. There are
individual problem sets for monohybrid, dihybrid, and sex-linked crosses. The greatest part
about the web site is that incorrect answers are linked with tutorial to help the students find
the correct answers.
To access these problem sets, go to
http://www.biology.arizona.edu/mendelian_genetics/mendelian_genetics.html
3. Genetics Tutorial
This tutorial was created by GlaxoSmithKline. It is a tutorial designed especially for kids on
DNA, genes, and heredity. It also has education games for kids to play, such as “Build
DNA”, “Build a Protein”, or “Punnetts and Pedigree.” The website also has great animated
explanations for the adults.
To access the general public tutorial, go to
http://www.genetics.gsk.com/generalpublic_flash.htm
To access the student tutorial, go to
http://www.genetics.gsk.com/kids/index_kids.htm
4. From Jeans to Genes
This website gives a fun lesson plan for introducing students to genes and chromosomes. In
this activity, students use pieces of clothing to simulate chromosomes. It also teaches
students to demonstrate genotypes, phenotypes, and use Punnett Squares. The website where
this lesson comes from is by Joell Marchese at Pine Valley Middle School. There are also
other great lesson plans available on this site.
To access this activity, go to
http://www.cccoe.net/tdf/Marchese/jtg/index.html
To access the general website for other lesson plans and information, go to
http://www.cccoe.net/genetics/student.html
5. Crack the Code
This website is the official site of the Nobel Foundation. It gives a brief tutorial on how DNA
is changed into proteins. The tutorial provides excellent pictures and a couple animations. At
the end of the brief tutorial, students can learn more about protein synthesis and DNA. There
is also a game called “Crack the Code,” in which the students must quickly decipher codons
into amino acids.
To access this tutorial and game, go to
http://nobelprize.org/educational_games/medicine/gene-code/index.html
6. The Basics and Beyond
This web site is by The University of Utah, Genetic Science Learning Center. This web site
provides great tutorials on the basics of DNA. Students can build a DNA model, transcribe
and translate a gene, and discover how proteins function. There is also an excellent tutorial
which takes students through protein synthesis to determine how fireflies glow.
For the Basics and Beyond website, go to
http://learn.genetics.utah.edu/units/basics/
For the direct link to “What makes a Firefly glow?” go to
http://learn.genetics.utah.edu/units/basics/firefly/
7. Mitosis, Meiosis, and Fertilization
Models of chromosomes made from pairs of socks are used to illustrate the principles of
mitosis, meiosis, and fertilization in this activity. Students will see how chromosomes divide
in meiosis and mitosis, as well as how they come back together during fertilization. The
activity is by Dr. R. Scott Poethig, Dr. Ingrid Waldron, and Jennifer Doherty of the
Department of Biology, University of Pennsylvania. The site gives both the student
worksheets and a teacher preparation guide.
For information on meiosis and fertilization and student activities, go to
http://serendip.brynmawr.edu/sci_edu/waldron/#mitosis