INVESTIGATING INDEPENDENT ASSORTMENT

INVESTIGATING INDEPENDENT ASSORTMENT

Mendel observed the effects of independent assortment when he carried out his dihybrid crosses. When he crossed two plants that bred true for different versions of two traits, the first-generation offspring all displayed the same phenotype (the dominant phenotype for both traits). However, when these plants were crossed, the second-generation offspring included four different phenotypes.

Mendel carefully recorded the numbers of phenotypes among the offspring of many dihybrid crosses. He found that certain combinations of phenotypes among the second-generation offspring occur in a 9:3:3:1 ratio, on the average. We now know that this pattern occurs because genes on pairs of homologous chromosomes are sorted out for distribution into one gamete or another independently of gene pairs of other chromosomes.

Activity

In this activity, you will first access the meiosis tutorial provided by the University of California, Santa Barbara. The tutorial demonstrates the random assortment of chromosomes into gametes. Next you will complete a tutorial quiz about independent assortment. This is part of The Biology Project from the University of Arizona.

Part 1.

Use your browser to go to the meiosis tutorial at

http://www.sumanasinc.com/webcontent/animations/content/independentassortment.html

Use the tutorial to learn how to determine which allele combinations are possible in two or even three trait crosses.

Part 2.

Use your browser to go to the independent assortment tutorial at

http://www.biology.arizona.edu/mendelian_genetics/problem_sets/dihybrid_cross/dihybrid_cross.html

Go through questions 1-9 of the tutorial. If you answer any question incorrectly, review the tutorial material and try again.

When you have completed this much of the tutorial, answer the questions below:

1. What type of gametes will be produced by a plant of genotype AaBb?

            The gametes produced be a plant with genotype AaBb would be AB or Ab or aB or ab

2. What type of gametes will be produced by a plant of genotype aabb?

            The gametes produced be a plant with genotype aabb would be ab

3. List all the genotypes you would find among the offspring of an AaBb x aabb test cross.

            The genotypes would be AaBb, aaBb, Aabb aabb

4. What is the expected phenotypic ratio of the offspring of an AaBb x aabb test cross?

            The expected phenotypic ratio of the offspring of an AaBb x aabb would be 1:1:1:1

5. List all possible gametes from a trihybrid individual whose genotype is RrSsTt.

            The possible gametes for a trihybrid individual with a genotype RrSsTt would be RST or rst or RsT or RSt or rST or rsT or rSt

In sickness and in health

In Sickness and In health

Autosomal dominant disorders cannot skip generations because they are dominant genes so they will show up if the person has it. They can't just be a carrier. So Greg and his mother can't be carriers of myotonic dystrophy. Greg's aunt or uncle can't be homozygous because their mother is the only one with the disorder. Also Greg's mom and one of his uncles doesn't have it. Greg's cousin has a 50% chance of inheriting the gene. Greg and Olga's children have a 0% chance of inheriting the gene because it is a dominant gene and neither Greg nor Olga have the gene.

There are five hallmarks of autosomal recessive inheritance: The first is Males and females are equally likely to be affected. The second is On average, the recurrence risk to the unborn sibling of an affected individual is 1/4. The third hallmark is The trait is characteristically found in siblings, not parents of affected or the offspring of affected. The forth hallmark is Parents of affected children may be related. The rarer the trait in the general population, the more likely a consanguineous mating is involved. The last hallmark is the trait may appear as an isolated (sporadic) event in small sibships. Consanguineous means the amount of shared (identical) DNA or the genetic material. This concept is important when discussing recessive genetic disorders because it means they have some of the same genetic material so they have more of a chance of inheriting the same genes. The factor VIII deficiency is sex linked and not An autosomal recessive trait because it only effects males.

The characteristics of x linked recessive inheritance are the disease is never passed from father to son. Males are much more likely to be affected than females. If affected males cannot reproduce, only males will be affected. All affected males in a family are related through their mothers. Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons. A son never inherits his fathers infected X-Chromosome because A son inherets the fathers Y-Chromosome from his father and one of his mothers X-Chromosomes. For a women to display a sex-linked recessive trait she would need to inherit two infected X-Chromosomes. One from her father and one from her mother. It is 1/2 chance that olga is a carrier of Factor VIII deficency. She has a 1/2 chance of passing it off on to her offspring. Male and female childern will be affected differently because a female child will just be a carrier becasue she will inheret a normal gene from her father where a amle child will show the trait because they don't have a spare X-Chromosome. Their is a 0% chance Greg is a carrier of factor VIII defeicy because he would have to show it not just carrie it because males don't have a spare X-chromosome.

The link to the population genetics wont work so i couldn't find the second equation to help figure out the the rest of the questions. If i get the equation i will update this blog and finish it.

Some of the legal risks and benefits of genetic testing are there is a chance you wouldn't be able to get health insurance because of a preexisting conditions or your insurance will be higher because they know you have a disorder but it hasn't showed yet. The benefits are you Know you have it so you can start doing things to try to prevent it. An unintended consequence of genetic testing could be that people would be less liable to seek medical care out of fear that they could later be denied life or health insurance. Privance laws and laws preventing insurance companys from deneying a person because they have a preexising conditing.

Stem Cells Webquest

Stem Cells

Research using stem cells is a controversial and often misunderstood area of modern scientific research. In this exercise you will visit the official National Institutes of Health (NIH) website on stem cell information to gain a greater understanding of the fundamentals of this topic.

Activity:

Go to the NIH site on stem cells: http://stemcells.nih.gov/index.asp and click on the Info Center link “Stem Cell Basics.”  Starting with the “Introduction” section, read the information presented.

Use the site’s glossary to find definitions for these important terms:

Cell-based therapies-Treatment in which stem cells are induced to differentiate into the specific cell type required to repair damaged or destroyed cells or tissues.

Differentiation-The process whereby an unspecialized embryonic cell acquires the features of a specialized cell such as a heart, liver, or muscle cell. Differentiation is controlled by the interaction of a cell's genes with the physical and chemical conditions outside the cell, usually through signaling pathways involving proteins embedded in the cell surface.

Embryonic stem cell line-Embryonic stem cells, which have been cultured under in vitro conditions that allow proliferation without differentiation for months to years.

Proliferation-Expansion of the number of cells by the continuous division of single cells into two identical daughter cells.

Plasticity- The ability to change and adapt, especially the ability of the central nervous system to acquire alternative pathways for sensory perception or motor skills.

Pluripotent- Having the ability to give rise to all of the various cell types of the body. Pluripotent cells cannot make extra-embryonic tissues such as the amnion, chorion, and other components of the placenta. Scientists demonstrate pluripotency by providing evidence of stable developmental potential, even after prolonged culture, to form derivatives of all three embryonic germ layers from the progeny of a single cell and to generate a teratoma after injection into an immunosuppressed mouse.

Answer the following questions:

1. What are the unique properties of all stem cells?  Explain in your own words what each property means.

Stem cells are capable of dividing and renewing themselves for long periods; they are unspecialized; and they can give rise to specialized cell types.

2. What are the two main kinds of stem cells used by researchers?  What are the major differences between the two types in terms of their sources and usefulness to researchers?  Give examples for each type of stem cell.

Researchers used embrotic stem cells and adult stem cells. Embryonic stem cells come from embryos. They are useful to the researchers because they can become all cell types of the body. Adult stem cell is a body cell other than gametes. Adult stem cells are limited to differentiating into different cell types of there tissue or origin.

3. List some of the diseases that scientists think may be treated using stem cell research and suggest how stem cells might be used to treat each disease.

Scientists believe they may be able to treat diseases including Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis.

4. What are the necessary characteristics that laboratory-manipulated stem cells will need to have in order to be successfully used in cell-based therapies?

Before being used as theropy stem cells will need to Proliferate extensively and generate sufficient quantities of tissue, Differentiate into the desired cell type(s), Survive in the recipient after transplant, Integrate into the surrounding tissue after transplant, Function appropriately for the duration of the recipient's life, and Avoid harming the recipient in any way.

Stem cell research

South Park
The south park episode Kenny Dies has a lot of true information about stem cells. Trey Parker and Matt Stone did their research for this episode. In this episode they talked about most of the stem cells we get is from aborted fetus or unwanted children as they say. Also they talked about medical researchers anticipate being able to use technologies derived from stem cell research to treat a wider variety of diseases including cancer, Parkinson's disease, spinal cord injuries, Amyotrophic lateral sclerosis, multiple sclerosis, and muscle damage. they Said if you put stem cells next to the cells you need they will clone. There is one thing that is extremely false if you put your stem cells next to a shakey's pizza place they will not form another shakey's pizza place. It was a fun way to learn about stem cells but I would still like to learn more about stem cell research so I will read some articles on stem cells.

Onion Root tip lab

Here is our graph from the Onion root tip lab. It shows what percent of the time the cell is in each phase of mitosis. We found the cell spends most of the time in interphase. 47.24% of the cells we found were in interphase. Interphase is when the cell prepares for cell division. The next longest phase is Prophase. We found 46.85% of the cells in prophase. Prophase is when the chromatin condenses into a highly ordered structure called a chromosome in which the chromatin becomes visible. Telophase is the next longest. 2.4% of the cells we found were in telophase. Telophase is when two daughter nuclei form. Metaphase is the next longest. 1.94% of the cells we found were in metaphase. Metaphase is when condensed & highly coiled chromosomes, carrying genetic information, align in the middle of the cell before being separated into each of the two daughter cells. the shortest phase is anaphase. 1.57% of the cells we found were in anaphase. Anaphase is when when chromosomes separate in an eukaryotic cell.

Onion Root tip webquest

1. What percent of cells were in interphase?

There were 22 out of 38 cells in interphase so 57% of the cells were in interphase.

2. What percent were in mitosis?

 43% of the cells shown were in mitosis.

3. Which phase of mitosis takes the longest?

 Prophase takes the longest

4. During which stage is the nucleolus visible as a dark spot?

 The nucleolus is visable as a dark spot in interphase.

5. How can you recognize a cell in metaphase?

the chromosomes, attached to the kinetochore microtubules, begin to align in one plan

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Cell structure