Henry Family Blog

Back to the basics.  Hmmm..we are supposed to go over this on our own for my class.  It’s a review of course.  Most people had this in high school.  That was a while ago so I think I need A LOT of review.  Anyone remember this well enough to be tested on it?

Within the cell you have three main parts; the cytoplasm, the nucleus and the cell membrane.

The cytoplasm is a reservoir that contains two components: cytosol and organelles.  The cytosol is mostly water and dissolved particles.  The organelles found in the cell are mitochondria, lysosomes, golgi apparatus, endoplastmic reticulum and ribosomes.  Each organelle is important to the cell’s function.  The mitochondria has a double thick membrane and self replicates.  It’s main role is to produce energy (ATP).  There are different amounts of mitochondria in each cell.

Lysosomes are irregularly shaped and not always present in cells.  They contain enzymes to breakdown proteins and carbohydrates.

The golgi apparatus is a flattened sac that surrounds the nucleus.  They are more abundant in secretory cells.  It contains different enzymes that permit it to modify, sort and package proteins to be transported wherever they are needed.  They also modify proteins made by the endoplasmic reticulum.

The endoplasmic reticulum is a complicated network of tubules and vesicles throughout the cytoplasm.  There are two types: granular(rough) and agranular (smooth).  The granular contains ribosomes and RNA and is involved in protein synthesis.  Agranular; in the liver aids glycogen storage and synthesis; in the testes aids steroid synthesis; in the liver and kidneys aids drug detoxification; in the muscle cells aids Ca2+ storage and release which means there is excitation and coupling.

Ribosomes is where there is protein synthesis which is composed by packages of ribosomal RNA formed within the nucleolus. 

The nucleus is found in most cells except for red blood cells and platelets.  It is surrounded by the nuclear envelope and contains nuclear pores which control the passage of substances throughout the membrane.  E.g. Proteins go in, RNAs go out.  The nucleus also contains chromosomes which contain DNA.  Inside the nucleus is the nucleolus which is a mesh-work of fine threads and granular material.

The cell membrane is a barrier that contains the cytoplasm.   It is an ever-moving sea of lipids that act as a barrier to charged or polar substances while some proteins act as a gatekeeper that regulate the traffic of molecules in and out of the cell.  The cell membrane has a lipid bilayer which is 75% phosphololipids, 20% cholesterol and 5% glycolipids.  The lipids have polar and non-polar parts.   The polar head is hydrophilic (water-loving) vs. non-polar, fatty acid tail which is hydropolic (water-fearing).   The membrane permeability is selective.  Whether substances enter or leave the cell depends on their size and concentration gradients.

Well, there is it.  These are supposed to be easy, gimme points.  What do you think?

Tags: Education //