Thursday, March 30, 2006

zygote development

zygote development
Originally uploaded by rfullington.
What does the illustrated process show about the differences in patterns of embryology among kinds of animals?

Hello. Here are your notes from today's lesson.

Today in class we discussed Section 2 of Chapter 25.

  • Symmetry- A balance in proportions of an object or organisms; close agreement in size, shape, and relative position of parts arranged on opposite sides of a dividing line or plane or around a central point.
  • There are three different types of symmetry. Spherical, Radial, and Bilateral symmetry.

  • Spherical symmetry- occurs when any plane divides the body into mirrored halves.
  • Radial symmetry- occurs when any longitudinal plane passes through a central axis divides the body into mirrored halves.
  • Bilateral symmetry- occurs when an organism can be divided down its length(midline) into similar right and left halves.

  • Asymmetry- is an animal that has an irregular shape. (has no symmetry)

  • Body Regions
  • Planes of animal symmetry

  • Body Regions
  1. Anterior indicates the head end; the opposite or tail end is Posterior.
  2. Dorsal is the back side and Ventral is the front or belly side.
  3. Medial is the midline of the body; Lateral is the sides.
  4. A Frontal plane divides the body into Dorsal and Ventral halves.
  5. A Sagittal plane divides the body into right and left halves.
  6. A Transverse plane separates Anterior and Posterior portions.
  7. In vertebrates, Pectoral is the chest region or area supported by forelimbs.
  8. Pelvic refers to the hip region or area supported by hind limbs.

Comparison of body plans.

Coelom- a fluid filled space

3 Types of Body Plans

  1. Acoelomate- no cavity.(flatworm)
  2. Pseudocoelomate- False body cavity, surrounded on one side by mesoderm ( round worm)
  3. Coelomate- true body cavity. surrounded on both sides by mesoderm ( segmented worm)


Exoskeleton- Hard, waxy covering on the outside of the body that provides a framework for support. Exoskeletons are found on animals that are invertebrates. Their exoskeletons Do not grow with the animal, so they have to shed it. Exoskeletons are a good source of protection.

Molting- The process of shedding the exoskeleton.

Endoskeleton- internal skeleton that provides support inside an animals body. Endoskeletons are found within vertebrates, animals with a backbone. and it grows with the animal.

For homework Do the section 2 assessment for chapter 25.

Next person to scribe will be Nicole Norton.. Love you all.... See ya. O, and Nicole have FUN with the next scribe......

Tuesday, March 28, 2006

What is an animal? Ambie is about to tell all.

1. Typical Animal Characteristics

a. Eukaryotic- cells contain membrane bound organelles.
b. Multicellular- cells form tissues and organs.
c. Heterotrophic- depends directly or indirectly as autotrophs.
d. No cell wall (plants do have a cell wall)
e. Animals are motile and sessile (motile means they move, they don't move if their sessile, although most animals that are sessile where motile as larva)

Fertilization- The union of male and female gametes. may occur internally or externally. Most animals produce sexually. One type of animal that dosen't produce sexually is the Hydra.

2. Cell Division
a. Blastulation- Clevage results in a clustor of cells called a blastula or blastocyct. Cells arrange themselves around a fluid filled cavity called a blastocoel.
b. Gastulation- The formation of germ layers. Develope into all the different tissues in your body. The gastrula is a structure made up of two layers of cells with an opening at one end. gastrulation converts the spherical blastula into a more complex configuartion of three germ layers.
c. Endoderm- gives rise to the epithelium of the body and nervous system.
d. Mesoderm- gives rise to the muscular, circulatory, excretory, respratory and reproductive system.
e. Endoderm- gives rise to the lining of the digestive track and organs associated with digestion.

In some animals, the opening in the gastrula becomes the mouth (protostome) in others it becomes the anus (deuterostome) humans form their anus first. Coach says some people stay that way, but I don't see that in the book.

3. Continued Growth and Development

a. Cells in developing embryos continue to change shape and specialize to perform different functions.
b.animals embryos develope into either a Juvenile a smaller version of the adult, or a Larva the intermediate stage of an adult. Larva don't look anything like the parent basically.

For the homework, do the section assessment on page 699, problems 1-6. Do not write the questions.

Hope you enjoyed reading my notes I know I enjoyed writing them, and the new scribe is Rachel!!! Okay luv ya everybody bye!!!

Sunday, March 05, 2006

Whatz Good Class? This is the new scribe by Taylor

Friday in class we made DNA Origami or at least started it. To me it was straight, i didn't finish so i don't really know how its going to look afterwards. But i am excited to see, also after we finish them we're going to hang them up.

Friday, March 03, 2006

Eeny, Meeny, Miny..Domino?

OK, some alleles are dominant and show up...some allelesshow a mixture of the combination. What happened here with this domino chicken? Both alleles are expressed!

Thursday, March 02, 2006

Dihybrid Cross

Give me the phenotypic ratio of the following Dihybrid cross.

Purple Flowers-dominant

Cross a plant that is heterozygous for both traits with a plant that is homozygous tall with white flowers.

Is Dominant Dominant all of the time??

We have been talking about dominant and recessive genes. The dominant allele is expressed (shows) in the presence of a recessive allele. How can a white FOur-o'clock and a violet Four-o'clock produce a purple Four-o'clock when crossed?

Hey! Here's your new scribe.

Mendel's law of independent assortment:

  • Genes for different traits are inherited independently of one another.
  • The alleles can combine in different ways.

Example: TT, Tt, tt

-Mendel crossed pure-bred tall and pure-bred short pea plants.

-The offspring Mendel referred to as a hybrid, often called a "mutt'', it is the offspring of parents with different forms of trait.

-Mendel's F2 Generation led to his discover of a factor being passed through the generation.

-In 1905 Ronald Punnett discovered a way to predict expected gentotypes offspring.

  • Phentotypic ratio- 3 tall: 1 short
  • Genotypic ratio- 1TT: 2Tt: 1tt
  • Homozygous means same such as TT or tt.
  • Heterozygous means different sach as Tt.

-Taylor will be the new scribe!

Wednesday, March 01, 2006

What happened to my hair?

What is the name for pattern baldness? Explain, using genetics, why more men experience male pattern baldness than women.
Can you list any other genetic traits or disorders that work the same way as pattern baldness?