Chapter 4: A Tour of the Cell

Three questions about the chapter:
  1. What are the two main types of microscopes?
   The two main types of microscopes are light and electron microscope.
   2. What are the two main types of cells?
   The two main types of cells are prokaryotic and eukaryotic cells.
   3. What is the function of the mitochondria?
   Its function is to produce energy.


Five main facts from the reading:
   
   1. Eukaryotic cells are bigger and more complex than prokaryotic cells.
   2. The nucleus is the cell's genetic control center.
   3. The endoplasmic reticulum is a biosynthetic factory.
   4. Lysosomes are digestive compartments within a cell.
   5. Chloroplasts convert solar energy to chemical energy.


Diagram:

This diagram shows the main differences between the prokaryotic and the eukaryotic cells. We can see that the eukaryotic is bigger, more complex, and has more organelles than the prokaryotic.
























Link: https://www.etap.org/demo/biology1/instruction3tutor.html


Summary:
    The introduction of the chapter talks about the moving of cells.  We can see the little cells and their move through microscopes and micrographs (pictures taken through microscopes). We know that almost all cells move, and some of them move with an incredible speed.
    The next section of the chapter taught us that microscopes reveal the world of the cell. There two main different types of microscopes: light microscope (LM) and electron microscope (EM). There two types of electron microscope: the scanning electron microscope (SEM) and the transmission electron microscope (TEM).  With the microscope we can examine the different types of cells. Most of the cells are microscopic (very small). They are two different types of cells: prokaryotic cells and eukaryotic cells. Prokaryotic cells are smaller and structurally simpler than eukaryotic cells. Both types of cells have plasma membrane, chromosomes, cytoplasm, DNA, and ribosomes. Eukaryotic cells are partitioned into functional compartments. They also have various organelles in the cytoplasm. Many of the chemical activities of cells, activities known collectively as cellular metabolism, occur within organelles. The structure of membranes correlates with their functions. The nucleus is the cell's genetic control center. It contains most of the cell's DNA and controls the cell's activities by directing protein synthesis. Eukaryotic chromosomes are made up of a material called chromatin, which is a complex of proteins and DNA. Ribosomes make proteins for use in the cell and export. Free ribosomes are suspended in the fluid of the cytoplasm, while bound ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope. Many cell organelles are connected through the endomembrane system. An extensive network of flattened sacs and tubules called the endoplasmic reticulum is the prime example of the direct interrelatedness of parts of the endomembrane system. 
   The endoplasmic reticulum is a biosynthetic factory. There are two types of endoplasmic reticulum: smooth, called like this, because it lacks attached ribosomes, and rough, which has ribosomes that stud the outer surface of the membrane. Some of the other organelles and their functions are: the Golgi apparatus, which finishes, sorts, and ships cell products. Lysosomes are digestive compartments within a cell. Vacuoles function in the general maintenance of the cell. Mitochondria harvest chemical energy from food. Chloroplasts convert solar energy to chemical energy. 
   The cell's internal skeleton helps organize its structure and activities. The network of protein fibers is called cytoskeleton. There are three main types of fibers of the cytoskeleton: microfilaments, intermediate filaments, and microtubules. Cilia and flagella move when microtubules bend. Problems with sperm motility may be environmental or genetic.
   There are three types of cell junctions that are found in animal tissues: tight junctions, which prevent leakage of extracellular fluid across a layer of epithelial cells, anchoring junctions, which are fastened cells together into strong sheets, and gap junctions, which are channels that allow small molecules to flow though protein-lined pores between neighboring cells.
Key Terms:
1. Chromosomes - they cary genes made of DNA.
2. Ribosomes - tine structure that make proteins according to instructions from the genes.
3. Cytoplasm - the entire region between the nucleus and the plasma membrane.
4. Nucleoid - the region where the DNA of a prokaryotic cell is coiled into.
5. Organelles - little organs in the cytoplasm in eukaryotic cells.
6. Nucleus - contains most of the cell's DNA and controls the cell's activities by directing protein synthesis.
7. Nuclear envelope - a double membrane perforated with protein-lined pores that control the flow of materials into and out of the nucleus.
8. Lysosomes - the digestive compartments within a cell.
9. Peroxisome - an organelle that is not part of the endomembrane system but is involved in various metabolic functions.
10. Mitochondria - organelles that carry out cellular respiration in nearly all eukaryotic cells, converting the chemical energy of foods such as sugars to the chemical energy of a molecule called ATP.