Chromosomal Disorders

Welcome back to blogging! This week we will be focusing on how changes in DNA affect individuals across different populations. To help us complete this complex work, we will be using our blog as a place to answer specific questions about chromosomal mutations. At the end of reading, choose ONE question to write a response on: 

 - HOW IS MEIOSIS AND MITOSIS RELATED TO CHROMOSOME MUTATIONS 
- HOW DO CHANGES IN CHROMOSOMES AFFECT A HUMAN BEING?
- BASED OFF YOUR PREVIOUS RESEARCH, HOW DO THE SYMPTOMS RELATED TO CHROMOSOMAL MUTATIONS AFFECT AN INDIVIDUAL? 

Chromosome Mutation

A chromosome mutation is an unpredictable change that occurs in a chromosome. These changes are most often brought on by problems that occur during meiosis (cell division process of gametes) or by mutagens (chemicals, radiation, etc.). Chromosome mutations can result in changes in the number of chromosomes in a cell or changes in the structure of a chromosome. Unlike a gene mutation which alters a single gene or larger segment of DNA on a chromosome, chromosome mutations change and impact the entire chromosome.


Please note that we are only talking about the chromosome changes. We do not need to worry about point mutations yet.

Chromosome Structure Changes

Duplications and breakages of chromosomes are responsible for a type of chromosome mutation that alters chromosome structure. These changes affect protein production by changing the genes on the chromosome. Chromosome structure changes are often harmful to an individual leading to developmental difficulties and even death. Some changes are not as harmful and may have no significant effect on an individual. There are several types of chromosome structure changes that can occur. Some of them include:

Chromosome Number Changes

A chromosome mutation that causes individuals to have an abnormal number of chromosomes is termedaneuploidyAneuploid cells occur as a result of chromosome breakage or nondisjunction (non-separatin) errors that happen during meiosis or mitosis. Nondisjunction is the failure of homologous chromosomes to separate properly during cell division. It produces individuals with either extra or missing chromosomes. Sex chromosome abnormalities that result from nondisjunction can lead to conditions such as Klinefelter and Turner syndromes. In Klinefelter syndrome, males have one or more extra X sex chromosomes. In Turner syndrome, females have only one X sex chromosome. Down syndrome is an example of a condition that occurs due to nondisjunction in autosomal (non-sex) cells. Individuals with Down syndrome have an extra chromosome on autosomal chromosome 21.

A chromosome mutation that results in individuals with more than one haploid set of chromosomes in a cell is termedpolyploidy. A haploid cell is a cell that contains one complete set of chromosomes. Our sex cells are considered haploid and contain 1 complete set of 23 chromosomes. Our autosomal cells are diploid and contain 2 complete sets of 23 chromosomes. If a mutation causes a cell to have three haploid sets, it is called triploidy. If the cell has four haploid sets, it is called tetraploidy. People who suffer from Down Syndrome can be said to have a triploidy because they have an extra chromosome. 

Now that  you  have read and discussed this post, choose one of the following questions and write a 3-5 sentence response:
 - HOW IS MEIOSIS AND MITOSIS RELATED TO CHROMOSOME MUTATIONS 
- HOW DO CHANGES IN CHROMOSOMES AFFECT A HUMAN BEING?
- BASED OFF YOUR PREVIOUS RESEARCH, HOW DO THE SYMPTOMS RELATED TO CHROMOSOMAL MUTATIONS AFFECT AN INDIVIDUAL? 

Pig Dissections

Hello lovely scholars!

This week we will start our exciting journey into DISSECTIONS! This is truly my favorite time of the year :) Why? Well because so many of you will step into a role that truly demonstrate our school's values, leading your team through difficult procedures and attempting to capture it all. I am going to love it!!!

To prepare yourselves for this long process, please do me a favor and watch some of the clips about pig dissections!

This is extremely important if you think you will be the skilled surgeon who will make the FIRST incision :)

Should we use embryonic stem cells?

Welcome back to another week of Biology!

This week some of you will be completing a Planaria lab while others will be completing some models to talk more about cell differentiation. Last week all of you were exposed to the need of cell division to help grow and heal multicellular organisms. While there are a couple of types of cell division that we have touched upon (asexual vs. sexual), all cells in an organisms composed of many, must know what job or role they will play. For example, our bodies need to have different cells. The cells in our stomach must be specialized enough to withstand the acidic environment of the gastric juices. On the other hand, our eye cells must be specialized enough to capture the different wavelengths of color that radiates from the different objects across the room.

So what is cell differentiation? It is simply when cells decide to become a specific type and they develop characteristics special to their job. For example, a neuron needs to be long and thin, with many dendrites (arm-like extensions) to quickly pass the information from neuron to neuron. After all, your brain needs to work quickly!! As defined by Kumar, in “Textbook of Human Embryology”, cell differentiation “is the process of a cell changing from one cell type to another. Most commonly this is a less specialized type becoming a more specialized type, such as during cell growth.”

(Figure 1: Stem cell can develop into any of the types of cells shown)

These cells that can turn into any of kind of cell, are called stem cells. Stem cells are commonly found in developing embryos. As humans develop during the nine months of gestation, these stem cells differentiate into the many different types of cells that will make your legs, your lungs, your brain and many more.

Stem cells differ from other cells in the body in several ways

1. Stem cells are unspecialised. They have not developed into cells that perform a specific  

   function.

2. Stem cells can specialise. They can divide and produce cells that have the potential to become other more specialised cell types or tissues. These new cells and tissues are used to repair or replace damaged or diseased cells in the body.

3. Unspecialised stem cells are capable of self renewal. Stem cells are able to divide and produce many copies of themselves. Many cell types once they have become completely specialised (terminally differentiated) have a limited capacity to produce new cells of the same type. If a mature nerve or blood cell is damaged it cannot replace itself.

4. When stem cells divide, each daughter cell can either: a. stay as a stem cell, or b. the daughter cell can undergo many more cell divisions. With each division the cell becomes more specialised until it finally becomes a terminally specialised cell type. There are many intermediate cell types between the pluripotent stem cell and the final specialised cell type. Stem cells play a critical role in normal growth and development by providing new cells for growth and for replacing and repairing used and damaged tissues. Once stem cells have been obtained from the body they can, in the right conditions, be grown in a laboratory. Scientists can then influence what type of cell a stem cell grows into by adding chemicals to the cell culture or changing how the cells are grown.

Where are we most likely to find these cells? A developing embryo!! Yet the use of embryonic stem cells is rather controversial because this would require the destruction of an embryo.

So let’s take a look at these questions to help you write your post:

• Does life begin at fertilization, in the womb, or at birth?
• Is a human embryo equivalent to a human child?
• Does a human embryo have any rights?
• Might the destruction of a single embryo be justified if it provides a cure for a countless number of patients?
• Since ES cells can grow indefinitely in a dish and can, in theory, still grow into a human being, is the embryo really destroyed?

Cancer Among Hispanic populations

Welcome to Blogging :)

Because seeing your lovely faces two hours a week, every other day isn't enough, I have decided that we will learn how to interact with one another through blogging. This is a place, specific to the people in our 2B class, where we will discuss the important and big picture issues found in the field of Biology. Please make sure to reference your scientific interactive notebook to figure out how to post to your class blog.

For our first blog, in alignment with the topic of the week, we will be discussing cancer in Hispanic populations. And while you might be like "Wait Ms. Perez, according to our weekly calendar we will be talking about cellular division called mitosis!" Let me tell you how such an important topic can be related to cellular division.

All of our cells complete a specific type of cellular division called MITOSIS. Your cells complete this complicated process to make more IDENTICAL cells. This process allows our bodies to heal and grow. This process is specifically important when you cut yourself and you need new cells to replace the damaged ones.







As you can see from the model it looks like a very organized process, but this does not happen all at once in every cell. While the process itself never changes, the rate at which each cell completes it really depends on their environment.

According to statistics
"Hispanics are the fastest growing demographic group in the United States. Approximately 16.3% of America's population (50.5 million out of 310 million people) is Hispanic. It is estimated that 112,800 people of Hispanic ethnicity will be diagnosed with cancer and 33,200 will die of the disease in 2012." 

So how do cancer and mitosis relate to one another? 

Well cancer takes place when cells continue to carry out this processes without any kind of control. That's right something as simple as not knowing when or how many times to carry out mitosis is what can result in cancer in our bodies. So how does this happen? And why is this relevant in our communities? 

Well there is very little information about cancer in our communities. And in order for us to understand how cancer works, we really need to understand how mitosis is relevant to our everyday lives.