Organelles of a Cell

Within each cell is an organelle, they carry out certain functions in order to keep the cell alive.

Cell Membrane

Cell Membrane
Both the animal and plant cells have a cell membrane. The cell membrane is very important because it holds all of the cytoplasm and the organelles of that cell. It also determines what may enter and what may leave the cell. The cell membrane consists of a phosphilipid bilayer (which is a phosphate head with two fatty acid tails) with the phosphate heads out and the tails in due to the tails being hydrophobic and heads being hydrophilic. Some certain molecules may not be able to pass by the cell membrane on its own, that is what the carrier proteins are for. The carrier proteins act like a shield from the fatty acid tails and surround the molecule to transport it to the inner of the cell.


Plant's Vacuole, an animal's would be much smaller.
The vacuole is in both the animal and the plant cell but in plant's vacuole is much larger than the animal's. There is a single unit of membrane enclosing the liquid. It also stores more than H2O, it can store, along with H2O, insoluable waste and chemicals. It creates support for the cell by filling up and pushing out the other organelles and cytoplasm of the cell, this is called turgor pressure. Turgor pressure is also linked to osmosis and diffusion (we will cover that in our fifth section).

The Nucleus

The nucleus and all its parts.
The nucleus consists of 4 parts, nuclear envelope, nucleolus, chromatin, nucleoplasm. 
- The nuclear envelope is basically a membrane especially made for the nucleus. It has pores to allow movement in and out of the cell. The outer part of the membrane maybe a continuation of the endoplasmic reticulum.
- The chromatin are long thin strands of DNA. This is very important in cell reproduction. It is basically instructions that control cell heredity and metabolism.
- The nucleolus is a non-membraneous matrix of RNA and protein. The instructions in DNA are copied here. It also does work with ribosomes in the synthesis of protein.
- Nucleoplasm is the liquid that the chromatin and nucleolus are in. Think of it as cytoplasm for the nucleus itself.

Cell Wall (plant only)

Cell Wall, 'Alternating layers of cellulose fibers.'
The cell wall is only a part of the plant cell the animal cell doesn't contain a cell wall. It is made up of alternating layers of cellulose fibers. The cell wall is nonliving and is created from a secretion of the cell membrane. This provides structure and stability to the plant cell and will most importantly protect it from any injuries it may receive. It has "pits" making it totally permeable meaning it doesn't at all decide what may pass or may not. Together with the vacuole it provides skeletal support.

Chloroplasts (plant only)

A chloroplasts and the Granum inside.
The chloroplasts are composed of a double layer of modified membrane (protein, chlorophyll, lipid). the inner membrane invaginates to form layers called "grana" where chlorophyll is concentrated. This is the organelle that does photosynthesis for a plant cell. Without it the plant cell would die.


The centrioles and how they help cell division.
The centriole is what helps the cell divide into two cells. A centriole is nine triplets of microtubules and two centrioles form a centrosome. These centrosome form spindle fibers that grab the chromosomes and pull them apart. 

Endoplasmic Reticulum

Smooth ER and Rough ER.
The ER is sheets of unit membrane with ribosomes on the outside, thus making it rough. It forms a tubular network throughout the cell. The purpose of this is to transport chemicals between cells and within cells. It also provides a large surface area for the organization of chemicals reactions and synthesis. The ribosomes are non-membraneous spherical bodies composed of RNA and protein enzymes. The ribosomes are the site at which protein is synthesized. This also the reason why the ER is the area to do chemical reactions.

The Golgi Apparatus

The Golgi Apparatus.
The golgi apparatus is flattened sacs of membrane. The vesicles pinch off at the edges of the apparatus. This organelle contains chemicals and secrets chemicals in vesicles. It also modifies chemicals to make them functional. A newly synthesized protein is modified and then is transported in a vesicle to do its job.


A mitochondrion.
The mitochondrion is also an organelle that is a modified double unit membrane. Its purpose in the cell is very important, this organelle turns food into energy. Like turning glucose and oxygen into ATP, water, and carbon dioxide.


A lysosome is a membrane bound bag containing hydrolytic enzymes, in other words enzymes that use water to split chemical bonds. This is because that is what  lysosomes are for. Lysosomes are used to break larger molecules into smaller molecules by inserting water into the chemical bond of that larger molecule.

All photos and info were taken from this site: