Cellular Structures and Functions

1. Log scale. This was mentioned briefly; it allows you to look at the cell size.

2. Given a picture of a cell (somewhat similar to the one below) and had to identify the different parts of the cell. Here is the completed version. Thereafter, we explained the functions of each of the different parts.

Nucleus: Contains the genetic material, also known as DNA. Controls all cellular activities.

Cytoplasm: Consists of cytosol and organelles.

NOTE: Cytosol is an aqueous matrix where organelles are suspended. (Cyto = cells, Sol = Gel-like matrix)

Cell wall: Provides structural support to plant. Provides protection from mechanical damage

Vacuole: Storage of organic compounds (e.g. proteins) and inorganic ions. Disposal site for toxic metabolic by-products. Containment of pigments. Offer plant protection by accumulating toxic compounds. Allow cell growth and elongation as water accumulates in the vacuole

Question: Why do plants need a bigger central vacuole as compared to animal cells?

Answer: Because plants need a place to store toxic waste, whereas animals give out their own toxic waste in the form of feces. HCN (Hydrogen cyanide = Animals' waste)

Lysosome: Digest food taken from food vacuole. (Via phagocytosis) Breaking down damaged organelle (Via autophagy)

Chloroplast: Contains chlorophyll, converts CO2 and H2O in the presence of light into glucose. (Soluble carbohydrates, triose phosphate, 3C Sugars)

NOTE: We were taught that glucose is the word used for stored food. However, we just learnt that the correct term is soluble carbohydrates.

Cell surface membrane: Controls the movement of substances in and out of the cell.

NOTE: It's commonly called Cell membrane, but the more accurate term is Cell surface membrane. 

Mitochondrion (Singular. Plural: Mitochondria) : Powerhouse of the cell. Produces ATP via aerobic respiration

NOTE: ATP - Adenosine Triphosphate. How it looks: Two layers of membrane. With cristage (meaning there are lines inside) 

Golgi Apparatus: Process and packages / Modification (Adding other chemicals to the protein, e.g. sugar, which is also known as glycoprotein) proteins in the form of either a transport vesicle or secretory vesicle, from the Rough ER, for delivery to other organelles in the cell after they have been synthesized.

Smooth Endoplasmic Reticulum (ER): Involved in lipid synthesis/metabolism, detoxification of drugs, and carbohydrate metabolism

NOTE: Metabolism: Catabolism (Breaking down), Anabolism (Building up)

Rough Endoplasmic Reticulum (ER): Modify proteins. These proteins are destined for export/are targeted to other organelles

Ribosomes: Synthesize proteins (just polypeptides (amino acids)) in the cell, for the cell and to be exported from the cell. 

NOTE: Polypeptide = Protein

3. Extra:

Ulcers: Autoimmune disease. They are not caused by bacterial infections, and is by our own body cells treating other body cells as "enemies", and choosing to "fight against" them. Hence, anti-bacterial cream would not be effective. Some effective methods are: Upper-limb exercise and get our digestive system going. (Eat in moderation and healthily) 

Cilium (Singular. Plural: Cilia): Sweeps out mucus and any trapped particles in trachea

Microvilli is usually absent in plant cells, and more present in animal cells.