Cells, Cells, And More Cells!

These past couple weeks have been focused on the basic structure of the cell. Let’s set down the requirements for the cell.

  • All cells have a plasma membrane and a cytosol (the watery part in a cell)
    • The all also have phospholipids, chromosomes in form of DNA, and ribosomes
  • There are two main types of cells:
    • Prokaryotes, which have no membrane and no organelles
    • Eukaryotes, which contain plants, animals, and all have organelles

Here is a website that I found very helpful, it goes in detail about the difference between the two types of cells: http://www.diffen.com/difference/Eukaryotic_Cell_vs_Prokaryotic_Cell

One of the main questions we addressed in class is; why have organelles? At first, this sounds lame but, I didn’t even know what an organelle was. An organelle is part of a eukaryotic cell. While a cell is typically considered to be the smallest self-contained part or independently functioning unit of an organism, organelles are smaller structures within eukaryotic cells that carry out various functions. (2.B.3!) So why are they so important?

  • They are specialized structures which have specialized functions
  • Some of their functions are:
    • partition cells into compartments
    • create different local environments
  • their membranes are sites for chemical reactions

Basically, the organelles are what make up the cell; they keep everything functioning and help carry out all reactions needed for the cell to survive. When I got a basic understanding of what organelles were, I needed to understand what the cell was and how it interacts with other cells. I had no idea how important and detailed cells are! Wowza.

  • What is the job of the cell?
    • to make proteins: So important!! proteins control every cell function.
    • make energy for daily life and for growth (!)
    • make more cells to grow, repair and renew.
  • How does the cell build proteins?
    • all the organelles involved: nucleus, ribosomes, endoplasmic reticulum (ER), golgi apparatus and vesicles.
    • So here is the protein assembly line:

nucleus –> ribosome –> ER –> golgi apparatus –> vesicles (which technically it takes place in the vesicles the whole time)

And then came the looooong lecture on all the organelles, which honestly I am still really confused about. I’m hoping we’ll be able to go over that Organelles packet together in class, really briefly. I filled in some of the information during the lecture, but feel that I didn’t get near enough to understanding all the organelles.

After doing a little research online, I came across the Khan Academy segment on the cell and organelles (When does Khan Academy ever fail?). I found that these basic summaries of each organelle was really helpful, just for a ground understanding of each. And here is the link for a more in-depth explanation.

https://www.khanacademy.org/test-prep/mcat/cells/eukaryotic-cells/a/organelles-article

Screen Shot 2016-12-10 at 12.16.06 AM.png

Also, here is a simple picture of what a cell looks like:

organelles-of-the-cell

I have also had a reoccurring question throughout the week: how did scientists even figure out what a cell looks like? And how do they know all of these organelles exist/how each functions? It seems impossible to know about such tiny cells.

Anyway, at the end of this week we worked on some packets mainly focusing on permeability of cells (2.B.1 and 2.B.2). Basically, cell membranes are selectively permeable towards ions and small molecules. Below is what the cell membrane looks like; it consists of a phospholipid bilayer, and those weird green things are proteins that facilitates what comes in and out of the cell.

cell-membrane

The carbon “heads” of the phospholipids are hydrophilic, while the phosphate “tails” are hydrophobic. This aspect of the phospholipids definitely effects what comes in and out of the cell; fat soluble substances are more easily dissolved through the hydrophobic parts of the membrane, while polar substances/charged molecules are hydrophilic and have to be transported across the membrane through protein carriers.

A few questions that still remained by the end of the week:

When the phospholipids have double bonds, creating more disorganization, how does this affect the permeability of the membrane?

Can hydrophilic molecules pass through the cell membrane in some other way than the protein carriers?

Is there an organelle that is less important than the others/ if one got eliminated, would the cell still run?

 

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