Reflective Response Week 8

This week in AP Biology we focused on the structure and support mechanisms of the cell.  The organized structures within the cell are called organelles – each one is specific in helping the cell to function as a working group.

The first organelle we looked into was the cytoskeleton. The cytoskeleton is a network of structural proteins that are connected in the cytoplasm. Microtubules are found in the cytoskeleton and are made up of tubulin monomers which are used as the transportation system for vesicles. Microfilaments and intermediate filaments are also found in the cytoskeleton, which are both made up of actin monomers and help with cell division and protection of the nucleus. The cytoskeletons function is to help with the movement, protection, and structure of a the cell.

The cell membrane is made up of a phospholipid bilayer with proteins, otherwise known as the “Fluid mosaic model”. This is like the security gate into the cell, helping with boundary, transportation, and communication. The phospholipid found in the membrane is amphipathic, meaning it is both polar and non polar, and create a semi-permeable membrane. The membrane proteins include both integral and peripheral proteins. Integral penetrate both bilayers, while peripheral proteins don’t penetrate but are hovering on top. These assist in creating polarity. The Cilia and Flagella are motility related extensions of cytoskeletal proteins. The centrosome is the microtubule and is only found in animal cells.

Cholesterol is a steroid lipid that act as a “temperature buffer” to help with membrane fluidity. Integral proteins span the bi-layer with domains and function with signal translation. Glycoproteins also span the bi-layer but they have short polysaccarides vesicles projecting which serve as identifying maker in cellular populations. Cell walls, on the other hand, are only contained within plant cells. These are too rigid to withstand the turgid pressure for animal cells, so in place we use an extracellular matrix. The “ECM” is a network of connective proteins and protoglycen molecules outside of the cell membrane. This assists in the cell anchorage and communication.

This week we learned much more about the specific functions of organelles, which was useful in figuring out more of the cellular purpose. I’m excited to learn about more organelles such as the mitochondria and Golgi apparatus!

Websites:

Learn About Organelles – ThoughtCo

Cell Membranes | Learn Science at Scitable – Nature

 

Reflection Week 7

This week in AP Biology we started to talk about cell signaling and membrane transport, which ties in with big question #2. First, we talked about diffusion. Diffusion is the spreading of something from a higher concentration to a lower concentration. On Tuesday, we did a lab that had visual examples of the ways cells spread. The main goal of molecules in diffusion is to take up the space given in an equal distribution.

Next, we talked about the main two types of transport which are:

Active: Active transport does require energy. It uses protein and enzymes to control what is coming in and out of the cell. If there were to be a specific protein for a molecule that would make it change to facilitated diffusion.

Passive: Passive transport doesn’t require energy because it follows the natural process of molecule movement from a high concentration to a low one. It is based of the random movement of molecules. Channels are carrier proteins control the diffusion of charged or polar molecules.

Tonicity is the measurement of relative measure of a solution concentration. We learned about three different types of cell solutions.

Hypotonic solution: Where there is less solution in cell than out, so solution wants to diffuse till at equilibrium. These cells can pop.

Hypertonic solution: Basically the opposite of a hypotonic solution, more solution inside the cell than outside, so wants to diffuse till equal. These cells can shrivel up.

Isotonic solutions- equal amounts of solution inside and outside cell. Ideal situation.

Below is a visual representation of hypertonic, hypotonic and isotonic solutions.

There are two types of bulk transport that help bring out or kick out large amounts of molecules.

Endocytosis: the taking in of matter by a living cell by invagination of its membrane to form a vacuole. Phagocytosis: “cell eating”, Pinocytosis: ” cell drinking”, Receptor- mediated endocytosis: “cell being picky” are all subtypes of endocytosis.

Exocytosis: the release of cellular products into outflow

As far as labs go, we did an electronic one on Tuesday that helped us understand the basic mechanisms of cell transport and one on diffusion and osmosis on Thursday. These both extended my knowledge of biochemistry and solidified many of the basics for me.

Next week I would like to learn more about the purpose of different types of molecules going in and out of the body and why they do what they do.

Websites:

https://www.khanacademy.org/test-prep/mcat/cells/transport-across-a-cell-membrane/a/passive-transport-and-active-transport-across-a-cell-membrane-article

https://www.diffen.com/difference/Diffusion_vs_Osmosis