April 2nd – An Introduction to Genetics

Remember!! These note break-downs are summaries of the day’s lesson, NOT replacements. Look over these for a quick refresher and to note any topics you may not understand from the lesson so you can come to class with questions! We learn best when we’re the ones asking the questions!! 

There is a lot about genetics that you may already know! Before we look deeper into the topic, you can probably already answer some of these questions:

 Are you aware of any diseases or ailments that “run in your family?”

Why is your hair the color that it is?

   Both of these are simple day-to-day questions that reference the idea of genetics. But, to start, let’s look at what we already know regarding cells and DNA replication:

 Cells can reproduce in different ways:

   Binary Fission: Exact replicates of cells. No DNA transfer. No recombination. “What you see is what you get.”

   Meiosis: Used in sexual reproduction. Recombination can occur. Two parents needed. Diploidy to Haploidy.

DNA is the material that directs the expression of certain traits. It can be thought of as the body’s “blueprint” and in simple organisms like bacteria and unicellular organisms, there is no need for sexual reporduction. Thus, further generations are produced through mitosis or binary fission.

Humans reproduce sexually, or they need two parents in order to produce viable offspring. Sexual Reproduction allows for variation within a species. Variation is the difference in the genes expressed within an individual.

A Gene is a coded region in our DNA that expresses a specific trait. Variations of this trait are called Alleles. In humans, we have 24 chromosomes, each having a homologous chromosome, that brings the number up to 48 in somatic cells. When the gametes of two individuals fuse together, in a process called fertilization, each parent donates one set of chromosomes, and ultimately, alleles, that may or may not be expressed.

~ by dlp2 on April 2, 2007.