The temperature at which a membrane solidifies depends on its fatty acid composition. A membrane rich in unsaturated tails will remain fluid to a lower temperature. How are the proteins attached to cell membrane via lipids? They are attached through lipid-anchored cell membrane proteins. They are attached through myristoylation, palmitoylation, or isoprenylation.
| | | A) | endoplastic reticulum | | | B) | microtubules | | | C) | cytoplasm | | | D) | mitochondria | | | | | | Feedback: The cell's chemical processes take place in a semifluid material called the cytoplasm. This material provides an ideal environment for organelles because of its fluidity. | | 7 CORRECT | | This shows an example of endoplasmic reticulum. What is the significance of its structure? | | | A) | provides a location for DNA production | | | B) | helps decrease surface area | | | C) | allows selective permeability of cell membrane | | | D) | facilitates breakdown of chemical bonds | | | | | | Feedback: The pleats and folds of the endoplasmic reticulum provides a large surface area where cellular functions, such as breaking chemical bonds, can take place.
It is also known as the powerhouse. | | Cell Walls | Cell Walls are a outer protective layer for cells. | | Lipid Bi-layer | The Lipid Bi-layer is apart of the cell membrane that acts as a barrier. And only let certain molecules and and others out. |
P1- Describe the microstructure of a typical animal cell and the functions of the main cell components. The microstructure of a typical animal cell consists of a plasma membrane which is made up of two phospholid molecules, proteins and cholesterol. They form a lipid bilayer which is semi-permeable allowing only certain molecules to diffuse across the membrance. Cholesterol helps ‘to stiffen plasma membranes and is not found in the membranes of plant cells.’ Bailey, About.com. The nucleus regulates all cell activity and is bounded by a double membrane called the nuclear envelope, this membrane separates the contents of the nucleus from the cytoplasm.
The cytoplasm is also where nutrients are absorbed and processed and is where many chemical reactions take place. Cytoplasm This is a semi-fluid material likened to a gel. It holds together the organelles, apart from the nucleus of the cell and supports the cells structure to make it possible for molecules to be transported. The cytoplasm is also where nutrients are absorbed and processed and is where many chemical reactions take place. Mitochondrion Mitochondria are concerned with energy release.
The protein molecule is able to float in the membrane – part of it is embedded in the membrane, part of it sticks into the cytoplasm, and part of it sticks out into the aqueous environment of the cell. What do you suspect about its structure, including its amino acid sequence, to make it behave as it does? * Examine the diagram of the cell membrane below. Is the diagram a “good” illustration of the fluid mosaic model of the cell membrane? What aspects of cell membrane structure are accurately illustrated by it?
This is made by a phospholipid bi-layer containing hydrophilic heads made from a phosphate group and hydrophobic tails which are made from 3 fatty acids which is similar to a triglyceride. The head is facing outwards due to them being polar and so are water soluble & attracted to water, which leads to the hydrophilic tail being the membrane itself and facing away from the water. This makes the membrane partially permeable to lipid soluble molecules which can diffuse in, however water soluble molecules can’t unless their small in size. The bi-layer also contains extrinsic and intrinsic protein carriers (carrier proteins and protein channels), each having their own functions. Protein channels allow molecules that are too big to pass through the carrier proteins to enter in and out the cell via a tube shaped molecule via diffusion which requires a concentration gradient but then sometimes the molecules are too big to go through and therefore undergo facilitated diffusion, however carrier proteins only allow certain molecules with a complementary shape to the binding site of the carrier protein to enter using ATP as the main sources of energy.
The polar heads will interact with water as they are hydrophilic, though the tails/fatty acids are never exposed to water therefore they are hydrophobic (Wisegeek.com/bilayer. 2011). Water itself is polar, and the dual nature of the phospholipid bilayer causes it to arrange itself in such a way that the polar head interacts with water and the non-polar tails to avoid water (Wisegeek.com/bilayer. 2011). The bilayer is selectively permeable which enables it to act as a barrier that keeps proteins, ions and other molecules where they are needed and prevents them from diffusing into areas where they are not (Wisegeek.com/bilayer.
| Nucleolus | The nucleolus is responsible for the cell organelles (e.g. lysosomes, ribosomes, etc.). | Cell membrane | The cell membrane keeps the cell together by containing the organelles within it. Cell membranes are selectively-permeable, allowing materials to move both into and outside of the cell. | Vesicle | Storage in and out of the cell.
Provide physical protection Control permeability Provide sensation Produce specialized secretions There are various specialized types of epithelia. They can be sorted by cell shape and the number of cells between the basement membrane and the exposed surface of the epithelium. The three basic shapes of epithelial are squamous, cuboidal, and columnar. If the basement membrane is only covered by one layer of cells it is called a simple epithelium. If the basement membrane is cover by several layers of cells it is called stratified epithelium.