Download 39 Karyotyping and Chromosomes Discovering

33 Karyotyping and Chromosomes Discovering Genetics Pages 229-231
Name: ___________________ Date: _________ Period: _____________
If we look at the nucleus during cell division under the microscopewe could see something like this:
This is the view of Metaphase…
If we look at the DNA strands more closely by
“smearing” (karyotyping), we might identify some
abnormalities in cells.
What is karyotyping used for?
Karyotyping can be used to determine
if a developing embryo has too many or
too few chromosomes AND to determine if a
child is male or female. If there is an abnormal
number of chromosomes, then it is likely that the
embryo will have some development problems that
Down's Syndrome
may cause severe
disfigurement or even
cause death is some
cases. An example might be Trisomy 21. Picture
of a newborn with this syndrome (exhibits
roundish "moon" face). This is the result of too
many chromosomes in
a child.
The “banding” you see
is a result of a special stain (Geimsa) and though
the banding patterns are unique to each
chromosome, they DO NOT show
where specific genes are located.
Scientists can locate the specific genes on a chromosome by using
special techniques that can
isolate a specific gene. Some genes have been
localized on human chromosomes (an
example would be chromosome 7). What
chromosome 7 looks like on karyotyping:
The problem is, we cannot “see” or locate a specific gene with even the
best microscopes. However, scientists have located different genes on
the chromosome (see picture to the right).
Page 2 (Cont. #33 Bio. B)
Each of the numbered portions is the approximate location of a specific gene
that controls some part of the cell or body function. Most scientists estimate
there are between 30,000 to 50,000 genes on all 23 pairs of chromosomes in
the human cell.
Well, what is a gene? A gene is defined “as the basic unit of
inheritance”. A gene is some part of the chromosome that can be passed
from one generation to the next. We associate genes with inheritanceinheritance of traits. We look at a new-born and say, “Oh, he’s got his
father’s eyes and his mother’s hair.” You are really talking about inherited
traits.
Some traits
are more desirable
than others. If we
look at the cell:
we know that the
nucleus contains
the DNA and the
DNA is really
what controls the
cell. The DNA
can be reduced to
hundreds of
thousands of
nucleotides in a
specific sequence
that “tells” the cell
what to do.
Farmers,
scientists, priests,
abbots, doctors and naturalists have all observed plants and animals and
have tried to figure out ways to make plants yield more food and be resistant
to pests and bugs that eat plants. We have tried to give dogs better looks,
give rice more vitamins, and create bacteria that can produce important drug
Page 3 (Cont. #33 Bio. B)
treatments for humans (most human insulin is made by bacteria today). In
the past, we succeeded in breeding certain traits into animals (larger cattle,
cows that give more milk) by selective breeding. Selective breeding can be
when you specifically mate a particular animal that has certain desirable
traits with other animals that have different desirable traits. For the most
part, we have been able to create certain animals and plants that meet our
needs. The problem with selective breeding, it is a “hit or miss” type of
strategy and can take years to get the desired traits.
To accomplish these goals, we had to figure out the patterns of
inheritance. That is how traits are passed from one generation to the next.
Long before humans understood that DNA was the true genetic material,
there have been people who have tried to manipulate traits that would make
a horse faster or stronger. BUT, understanding the Laws governing
inheritance has allowed scientists to make giant advances in gene
manipulation. Unfortunately, there are scientists that believe that we
understand DNA enough to clone plants, animals, and even humans!
Though we have some understanding of how DNA works, we are far from
understanding everything about DNA.
For us to determine if there should be research in human cloning, we
should have some basic understanding of how much we understand (and
don’t understand) about genes and inheritance. This will require researchers
who will identify how genes are controlled.
We learned that during Mitosis during Interphase, the chromosomes
replicated themselves. (We will learn later on just how complex that process
is.) Knowing the random distribution of DNA (genes) to the “daughter” sex
cells (sperm and eggs) through meiosis begins to explain why certain traits
show up more frequently than others and some traits skip generations. If we
only had some basic rules to follow - we might understand why certain traits
showed up in us and predict which traits will show up in our children!
These “rules” and predictions will be addressed in our study of “Genetics”.
Genetics is: “The study of biological inheritance” from organism to
organism.
Answer the following questions here and on your scan-tron.
_____ 1.) What does Karyotyping allow scientists to do?
a.) identify specific locations of genes
b.) create clones of any DNA
c.) allow chromosomes to double easily
d.) identify if there are too many or too few chromosomes and if male or
female
Page 4 (Cont. #33 Bio. B)
_____ 2.) Patterns of inheritance:
a.) are the ways we learn how to make our own traits during our lifetime
b.) determine the rules that govern how traits are passed from generation
to generation
c.) can be seen in a typical karyotyping smear
d.) all of the above are correct
_____ 3.) The banding that you see in Karyotyping:
a.) is the result of a special stain b.)can determine the location of any gene
c.) makes the chromosome larger d.) all of the above are true
_____ 4.) What is a gene?
a.) the amount of DNA that a cell can produce
b.) a basic unit of inheritance (a small portion of DNA)
c.) the area where the DNA is stained
d.) the collection of the entire chromosome
_____ 5.) Inherited traits can be:
a.) magically created by a father or mother
b.) passed on from generation to generation with proteins
c.) the movement of DNA from parents to offspring
d.) developed during your life-time
_____ 6.) DNA:
a.) controls the cell
b.) is a series of nucleotide sequences
c.) controls trait development and passed down from generation to
generation
d.) all of the above are correct
_____ 7.) Before scientists knew about DNA being the source of inheritance
a.) people created organisms with desirable traits through selective
breeding
b.) people had to settle for chance mating to get the desired offspring
c.) people had to live with the organisms they had and hoped for
evolution to take place
d.) none of the above are correct
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_____ 8.) The DNA is made up of hundreds of thousands of nucleotides in a
specific sequence that...
a.) tells the cell what to do
b.) is what makes up the cell membrane
c.) gets expelled as waste
d.) is made up of amino acids
_____ 9.) Genetics is:
a.) the study of the structure of DNA
b.) the study of how cells replicate
c.) the study of biological inheritance
_____ 10.) Down's Syndrome is the result of...
a.) too few chromosomes
b.) too many chromosomes
c.) smoking during pregnancy d.) drinking alcohol during pregnancy
Date: ______________________
Lesson Plan for Handout #33
Biology B
Objective: TLWD ability to explain how karyotyping and Genetics are
related, explaining specifically how we obtain ½ our chromosomes from one
parent and ½ our chromosomes from the other parent. Moreover, students
will be able to define “patterns of inheritance” and “Genetics” and how man
has selectively bred plants and animals to yield the most desirable traits for
feeding large populations of people after being given handout #33.
Content: Patterns of inheritance and Genetics
NJCCCS: 5.3.12.D.1, 5.3.12.D.3
Method: Power point, white board, discussion
Homework: Complete #33
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