Biology… in the FUTURE-URe-Ure-ure

Though I haven’t been able to successfully find a clip of the episode, I watched Futurama a few nights ago and laughed out loud! The episode is called “Parasites Lost.”

In it, Fry eats a contaminated sandwich and is subsequently infected with a race of worms that does wonders for his body. To investigate the situation, the doctor and most of the rest of the crew create miniture robotic versions of themselves and explore inside Fry’s body. If anyone has the episode, please let me know. I’d love to show it to the class! I’ll bring the popcorn! =P

My Opinion on Punnett Squares

 Punnett Squares CAN be fun, actually. We’ll just all need to get used to them.

  We can make sure they don’t get quite as confusing as this one, and in a few weeks we’ll take a look at squares with more than two alleles! Exciting?! Of course it is!!! =D

Homework for 4 – 12 – 07

HW2

April 10th – Mendelian Genetics

The Punnett Squares and the different crosses seemed to be a point of difficulty in class today, so here is a recap and some more tips regarding the process of it all!

    Brief History of Mendel: Mendel was a monk who discovered the idea of traits and genes and the mechanism by which they are transferred through the generations. Using pea plants (lots and lots… and LOTS of pea plants), and hand-counting all of his results, he studied the theories of dominance, as well as establishing the laws of segregation and independent assortment. Several factors about Mendel’s experiment made his evidence and conclusions convincing:

First, he was using Visible Phenotypic Traits, and fortunately for Mendel, the seven traits he picked to study behaved according to his theories of dominance.

Second, he was using a species of plants that Provided Plenty of Viable Offspring Each Generation, so his data wasn’t based on several small numbers and possible fluke cases.

And Thirdly, he was sure to isolate male plants from female plants and Controlled Plant Crosses so the data he received was under his control and accidental self-fertilizations could be avoided.

Though he experimented with all seven traits, we focused on his experiments dealing with wrinkled and smooth pea coats. Mendel began his experiment with a cross of a true-breeding smooth parent and a true-breeding wrinkled parent. The progeny, or F1 Generation, yielded only smooth plants. Thus, Mendel could deny the idea of blending (at this moment in the history of genetics at least). And, when he self-crossed the F1 generation, he saw a phenotypic ratio of 3/4 smooth peas to 1/4 wrinkled peas. Genotypically, this generation consisted of  1/4 Homozygous Dominant, 1/2 Heterozygous, and 1/4 Homozygous Recessive progeny.

Mendel concluded that the information for the texture of the pea coat was present in two forms, or what we now call Alleles. These alleles behaved according to the laws of segregation and independent assortment, which was supported by the F2 generation, and abided by the theory of dominance.

Some tips for your homework!

   If you’re having trouble identifying the genotypes of the parents, look for answers in the progeny. Try to identify what phenotype is recessive and which is dominant, and perform your own hypothetical test crosses. Compare your results with what might be the parents’ genotypes, and try to find a logical match!

   Remember that each pair of alleles separates at gametogenesis. Therefore, when you are doing a cross, remember to separate the alleles for both parents!

   Also be sure to look at the fractions of genotype or phenotype ratios in your progeny! If they are not divided into fourths… perhaps there is more than one trait you’re dealing with!

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.

Homework For 4 – 4 – 07

HW 1 

-  This homework is very introductory. As it is the first assignment of the chapter, we’ll try to ease into the material gently. This is due in class on Wednesday!!

Beauty in Biology

 There really is an aesthetic quality to nature. I try to make it a point and present you with colorful but equally insightful imagery as I take you through the world of Biology. Notice in this picture the base pair stacking and the differentiation between the nitrogenous bases? Can you identify which ones are which?

 

And in this picture, even though simplified, there is reference to the organization of nature. You’ll recall that the dimensions of DNA are uniform throughout, and that there are approximately 10 base pairs within every one rotation of the double helix. Note how this doesn’t take into account the random assortment of the base pairs or even that the bases themselves are differently shaped! Extraordinary, isn’t it?!