Human Genetic's
http://www.ornl.gov/sci/techresources/Human_Genome/publicat/tko/index.html
A worldwide effort is under way to develop and apply the technologies needed to completely map and sequence the human genome.
There are many ethical and moral issues that need to examined as we learn more about this area of study. Be sure to keep these issues in mind.
Vocabulary
- Genetics
- Learning how you are related to or linked to your origin
- Inherited
- Passed down from your parents
- Traits
- Personal Characteristics, things about you—such as eye color, skin color, and blood type—that are specific to you
- Unique
- One of a kind
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- Description: The value of studying genetics is in understanding how we can predict the likelihood of inheriting particular traits. This can help plant and animal breeders in developing varieties that have more desirable qualities. It can also help people explain and predict patterns of inheritance in family lines. (This may explain why you look so much like another relative)
History of Genetics:
A monk named Gregor Mendel discouraged individual traits are determined by discrete factors called genes.Follow the animated lessons below on how Gregor Mendel worked with pea plants to determine "traits.
The page will look like this:
http://www.dnaftb.org/dnaftb/1/concept/
Now play the Interactive and practice crossing the peas.
http://www2.edc.org/weblabs/Mendel/mendel.html
One of the easiest ways to calculate the mathematical probability of inheriting a specific trait was invented by an early 20th century English geneticist named Reginald Punnett . His technique employs what we now call a Punnett square. This is a simple graphical way of discovering all of the potential combinations of genotypes that can occur in children, given the genotypes of their parents. It also shows us the odds of each of the offspring genotypes occurring.
Setting up and using a Punnett square is quite simple once you understand how it works. You begin by drawing a grid of perpendicular lines or using an excel spreadsheet selecting three rows across and three rows down.
Next, you put the genotype of one parent across the top and that of the other parent down the left side. For example, if parent pea plant genotypes were YY and GG respectively, the setup would be:
Note that only one letter goes in each box for the parents. It does not matter which parent is on the side or the top of the Punnett square.
Next, all you have to do is fill in the boxes by copying the row and column-head letters across or down into the empty squares. This gives us the predicted frequency of all of the potential genotypes among the offspring each time reproduction occurs.
In this example, 100% of the offspring will likely be heterozygous (YG). Since the Y (yellow) allele is dominant over the G (green) allele for pea plants, 100% of the YG offspring will have a yellow phenotype, as Mendel observed in his breeding experiments.
In another example (shown below), if the parent plants both have heterozygous (YG) genotypes, there will be 25% YY, 50% YG, and 25% GG offspring on average. These percentages are determined based on the fact that each of the 4 offspring boxes in a Punnett square is 25% (1 out of 4). As to phenotypes, 75% will be Y and only 25% will be G. These will be the odds every time a new offspring is conceived by parents with YG genotypes.
Check out this animation of how it works
http://www.dnaftb.org/dnaftb/5/concept/index.html
An offspring's genotype is the result of the combination of genes in the sex cells or gametes (sperm and ova) that came together in its conception. One sex cell came from each parent. Sex cells normally only have one copy of the gene for each trait (e.g., one copy of the Y or G form of the gene in the example above). Each of the two Punnett square boxes in which the parent genes for a trait are placed (across the top or on the left side) actually represents one of the two possible genotypes for a parent sex cell. Which of the two parental copies of a gene is inherited depends on which sex cell is inherited--it is a matter of chance. By placing each of the two copies in its own box has the effect of giving it a 50% chance of being inherited.
If you are not yet clear about how to make a Punnett Square and interpret its result, take the time to try to figure it out before going on.
Try the simulation below to see how it works with mice
Teaching with Gizmos
Genetics and Mouse Breeding (5:57 minutes)
http://help.explorelearning.com/2005/05/genetics_and_mo.html
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If both parents are carriers of the recessive
allele for a disorder, all of their children will
face the following odds of inheriting it:
25% chance of having the recessive disorder
50% chance of being a healthy carrier
25% chance of being healthy and not have
the recessive allele at all |
Are Punnett Squares Just Academic Games?
If a carrier (Aa) for such a recessive disease mates with someone who has it (aa), the likelihood of their children also inheriting the condition is far greater (as shown below). On average, half of the children will be heterozygous (Aa) and, therefore, carriers. The remaining half will inherit 2 recessive alleles (aa) and develop the disease.
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If one parent is a carrier and the other has a
recessive disorder, their children will have the
following odds of inheriting it:
50% chance of being a healthy carrier
50% chance having the recessive disorder |
After reviewing the information in your text book
Please pick 2-3 of these sites to broaden your understanding of genetics
Understanding genetics-online virtual
http://www.thetech.org/exhibits/online/ugenetics/
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=cooper.section.432
http://www.dnaftb.org/dnaftb/5/concept/index.html
Genetics in Crime Solving
That DNA is unique from person to person but the same from cell to cell in one person can be a handy thing, especially when it comes to DNA fingerprinting. DNA fingerprints can be used for anything from determining a biological mother or father to identifying the suspect of a crime. And, as may someday prove to be the case with Sam Sheppard, it can be used to clear someone's name.
But what exactly is a DNA fingerprint? Well, it certainly isn't an inky impression of a DNA strand. Compared to unimaginably small DNA, a fingerprint is HUGE. So what is it that we're looking at, and how is one of these fingerprints made?
Here's your chance to find out. You'll find out by solving a mystery -- a crime of sorts. Solving the mystery involves creating a DNA fingerprint (we'll supply the lab and all necessary materials) and comparing this fingerprint to those of the suspects.
Are you ready? Then get to work!
Interactive labs
Genetic DNA
Class Project
You will be given two coins. Flipping the coins will determine which disease your offspring will have based on where you placed it on the Chromosome.
Next Research the following diseases
Deaf
National Institutes of Health maintains a user-friendly website giving an
overview of deafness and hereditary hearing loss.
genetic traits worksheet.doc
gen_smilewkst1[1].pdf
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