The Hierarchy of Life
8. Organ System
Types of Cell
a. Prokaryotic – unicellular organism that lacks membrane-bound organelles, all the intracellular water-soluble components ( proteins, DNA, and metabolites ) are located together in the cytoplasm enclosed by the cell membrane, rather than in separate cellular compartments.
cocci – spherical (eg. Staphylococcus aureus, Diplococcus pneumoniae, Streptococcus pyogenes)
bacilli – rod-shaped (eg. Lactobacillus, Helicobacter pylori, Salmonella typhi, Klebsiella pneumoniae, Bordetella pertussis, Clostridium botulinum)
spirochaete – spiral-shaped ( eg. Treponema pallidum, Leptospirosis )
vibrio – comma-shaped (eg. Clostridium tetani)
b. Eukaryotic – any organism whose cells have a cell nucleus and other organelles enclosed within membranes. Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the golgi apparatus.
Animal and Plant Cell
a. nucleus – directs activities of the cell, contains DNA
b. chromatids – genetic strands that makes up an organism
c. cytoplasm – serves as the muscle of the cell, holds in place the other organelles in the body.
d. mitochondria – powerhouse of the cell
e. lysosome – engulfs foreign substances found in the cell. The lysosomes also act as the waste disposal system of the cell by digesting unwanted materials in the cytoplasm, both from outside the cell and obsolete components inside the cell.
g. golgi bodies – golgi apparatus / golgi complex, a major collection and dispatch station of protein products received from the endoplasmic reticulum (ER). The Golgi can be thought of as similar to a post office: it packages and labels items which it then sends to different parts of the cell or to the extracellular space.
h. ribosomes – protein builders or the protein synthesizers of the cell.
i. cell membrane – selectively permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival.
j. smooth endoplasmic reticulum – Smooth ER (SER) acts as a storage organelle. It is important in the creation and storage of lipids and steroids.
k. rough endoplasmic reticulum – Rough ER (RER) was also mentioned in the section on ribosomes and is very important in the synthesis and packaging of proteins.
l. vacuole – storage bubbles found in cells. Vacuoles also play an important role in plant structure. Those vacuoles gain and lose water depending on how much water is available to the plant.
m. chloroplast (plant cell) – food producers of the cell. Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells. Chlorophyll molecules sit on the surface of each thylakoid and capture light energy from the Sun.
n. cell wall (plant cell) – Cell walls made of cellulose are only found around plant cells and a few other organisms. Cellulose is a specialized sugar that is classified as a structural carbohydrate and not used for energy. Protein covering from plants and fruits is known as pectin. In animals, its known as keratin while in insects it is known as chitin.
Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells.
There are three known accessible sources of autologous adult stem cells in humans:
- Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest).
- Adipose tissue (lipid cells), which requires extraction by liposuction.
- Blood, which requires extraction through apheresis, wherein blood is drawn from the donor (similar to a blood donation), and passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.
- Stem cells can also be taken from umbilical cord blood just after birth.
Meiosis (for reproduction)
Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction. During reproduction, when the sperm and egg unite to form a single cell, the number of chromosomes is restored in the offspring. Meiosis begins with a parent cell that is diploid, meaning it has two copies of each chromosome.
Mitosis (for growth and repair)
Mitosis is the process in which a eukaryotic cell nucleus splits in two, followed by division of the parent cell into two daughter cells. The word “mitosis” means “threads,” and it refers to the threadlike appearance of chromosomes as the cell prepares to divide.
Metabolism – the use of energy of the body.
- Anabolism – uses ATP molecules to build larger molecules from smaller building blocks.
- Catabolism – breaks down large, complex molecules to provide smaller molecules and energy.
a. Glycolysis – synthesis of glucose to 2 ATP, Pyruvate, H2O, NADH.
b. Kreb’s Cycle – synthesis of Pyruvate and Acetyl CoA to NADH, FADH, 2 ATP.
c. Electron Transport Chain – synthesis of NADH, FADH, H2O to 34 ATPs.
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