Monday, September 5, 2011

Signing off

Well, biology student, hopefully this helped you out. If you want more information on the cell organelle, then click 'Here's where I got this info...', and it will bring you to the site where I got my information.
Good luck!
-R

Cilia and Flagella

I always think these two things should be in a pair...
Where it is found:

  • Cilia: attached to the membrane of the cell
  • Flagella: attatched to the membrane of the cell
What it looks like:

Cilia
Flagella

  • Cilia: whip-like projections
  • Flagella: just one whip-like projection (usually longer)





What it does:
  • Cilia: moves liquid past the cell to allow the cell to move
  • Flagella: moves liquid past the cell to allow the cell to move
    • for single cells, like sperm, this allows them to swim, but for cells in an anchored tissue, like cells in our throat, it moves liquid over the cell itself

Cell wall

This is found ONLY in plant cells!
Where it's found: outside of the cell membrane

What it looks like: a thicker and stiffer cell membrane

What it does: strength of the plant, maintain turgor pressure (how rigid it is), passing of substances, protection, and is a reserve for carbohydrates

The Cell Membrane

The cell membrane is essential to cell survival.
Where it is: this surrounds the cell

What it looks like: double layer of phospholipds, protiens, carbohydrates, and cholesterol that encases the cytoplasm and organelles like saran wrap

What it does: anchors the cytoskeleton, attatches cell to extracellular matrix, transport of materials in and out of the cell, recieves and converts signals from other cells, keeps the cell and all of its contents together

Here's where I got this info...

Junctions between cells

There are three junction types I will discuss here:

  1. Tight junction (aka: zonula occludens): this is a site where two cell membranes come very close together and almost seem to be fused; they, in fact, prohibit materials from going between the two cells

2. Desmosomes (aka: macula adherens): interactions of calcium ions and adhesion between cell membranes

3. Gap junction: this is when the cytoplasm of two cells are connected by a channel









Plasmodesmata

These structures are found only in plant cells!
Where they are: between plant cells
What they look like: bridges between cells

What they do: these "cytoplasmic bridges" that extend through the cell wall and connect the cytoplasm of adjacent cells

Cytoskeleton

There are three different types of filaments in the cytoskeleton.
1. Microfilaments: this is a system of filaments that are responsible for anchoring plasma membrane proteins, cell movement, and cell division.

  • usually found in the periphery of the cell, where they assist in anchoring plasma membrane proteins
  • also can be found in bundles where they also act somewhat like muscles

2. Microtubules: positioned near the nucleus, they serve as 'tracks' for organelles such as mitochondria and vesicles ready for excretion

  • very dynamic and important for mitosis where they segregate the choromosomes

3. Intermediate filaments: link the cell surface and the nucleus, and stabilize structural integrity

Chloroplast

The chloroplast is where photosynthesis takes place in plant cells
Where it is: in the cytoplasm

What it looks like: a rod shaped membrane with inner structures, flat disc structures called thylakoids that are arranged into columns called grana

What it does: this organelle, which is found only in plant cells, contains chlorophyll, with which it preforms photosynthesis, giving the plant energy

Here's where I got this info...

Mitochondria- the power house of the cell

This is were most of the energy for the cell is made...
Where it is: in the cytoplasm

What it looks like: a rod shaped organelle with folds of membranes

What it does: PRODUCE ENERGY using the process of oxidative phosphorylation, also storage for calcium ions

Vacuole

Where is it: in the cytoplasm

What it looks like: a bag or a sac inside of a cell

What it does: holds waste products, maintains pH, turgor pressure is maintained by vacuoles in plant cells, unwanted materials are held here, and destroy invading bacteria

Here's where I got the info...

Lysosomes- om nom nom

Lysosomes are the digestive tract of the cell...
Where it is found: in the cytoplasm of the cell

What it looks like: a membrane enclosed bubble of proteins and enzymes, almost like a mini-cell


What it does: degrades material taken in from outside the cell and digest parts of the cell itself, basically the garbage disposal

Where I got this info...

Golgi Apparatus

Where it's found: close to the cell nucleus
What it looks like: a stack of deflated balloons, made of stacks of membrane-covered stacks called cisternae 
What it does: processes proteins from the endoplasmic reticulum, form carbohydrates, sulfate groups are added to proteins, nucleotide sugars are imported in from the cytoplasm to carry out thglycosylation and phosphorylation processes 


Rough Endoplasmic Reticulum

The rough endoplasmic reticulum is involved in synthesizing proteins from the ribosomes attached to its surface.
Where is it: attached to the nuclear envelope, next to the smooth endoplasmic reticulum
What it looks like: once again, is a conglomerate of membrane, tubules, and sacs, and, most importantly, is studded with ribosomes


What it does: assembles proteins from the cytoplasm, folding of proteins, quality control of folded proteins, transfers proteins to the Golgi Apparatus

Smooth Endoplasmic Reticulum

The smooth endoplasmic reticulum is important in many functions in the cell.
Where it is: connected to the nuclear envelope in plant and animal cells

What it looks like: a network of membranes, tubules, and sacs













What it does: carbohydrate metabolism, regulation of calcium ions (used in muscle contraction), synthesizing steroids and lipids, and drug detoxification; transportation of synthesized proteins

Here's where I got this info...

Ribosomes

Ribosomes are essential in cells. They are in charge of protein assembly.
Where it's found: suspended in the cytoplasm or attached to the endoplasmic reticulum

What it looks like: made of two sub units, making it look like a bumpy sphere

What it does: Ribosomes make proteins out of RNA either in the cytoplasm or attached to the endoplasmic reticulum

The Manufacturer- the Nucleolus

The Nucleolus makes some pretty important proteins called ribosomes. Here's some more on the manufacturer:
Where it's found: in the nucleus, but it is not bound by a membrane
                              What it looks like:
What it does: assembles ribosomal units and ships them out of the nucleus, so it is indirectly involved in protein synthesis

Here's where I got this info

The Center of Command- The Nucleus

The nucleus is the head honcho of the cell, and probably one of the best known organelles. Let's take a closer look at the CEO of the cell...
Where it's found: enclosed by a membrane in the cytoplasm of a cell [eukaryotic cells ONLY]

What it looks like: a nucleus doesn't have a defined shape, but it is usually spherical in shape; it has a double layered membrane called the nuclear membrane 


What it does: the nucleus is in charge of the cell. It contains the DNA of the organism, is where DNA transcription (when mRNA is produced) takes place, makes sure that the daughter cells have the correct amount of DNA and are replicated correctly. The nucleus is considered the 'control center' of a cell for this reason.


Here's where I got this info