Download Notes on Prokaryotic and Eukaryotic cells

Notes on Prokaryotic and Eukaryotic cells
Prokaryotic = “before the nucleus” cells lacking a nucleus (bacteria)
Eukaryotic = “after the nucleus” cells that have a nucleus (Plant cells, Animal cells)
*Prokaryotic cells are very small, about the size and shape of mitochondria. They are the
simplest and oldest of cells. They reproduce by Binary fission (the cell copies its DNA
and the cell divides in two, splitting up the cytoplasm, the ribosomes and the cell
membrane
*Eukaryotic cells are large and more complex (contain a variety of membrane bound
organelles…the membranes of organelles are made of the same substances as the outer
cell membrane = phospholipids, proteins and the steroid cholesterol)
*Plant cells are box-like in shape due to the rigid cell wall made of cellulose
*Animal cells are blob-like or round because the cell membrane is fluid and not
contained in a cell wall
*Structures common to both Prokaryotic cells (bacteria) and Eukaryotic cells (Plant
cells, Animal cells)
-cell membrane ( made of phospholipids, proteins and the steroid cholesterol, main job
is to control what substances and molecules enter and leave the cell)
-DNA (deoxyribonucleic acid: stores all of the necessary cell information for maintaining
homeostasis and complete directions for a new identical cell)
-ribosomes: (no membrane, these structures serve as the site where amino acids are
hooked together into proteins. Ribosomes, with the help of RNA create the cells proteins)
(RNA decodes the instructions of DNA and finds a ribosome to help it start making
proteins)
-cytoplasm, the half jelly, half liquid part of the inside of the cell that contains all of the
dissolved salts, sugars, amino acids and other molecules that the cell needs to
function…it also provides support to the structures found inside the cell
_____________________________________________________________________
Eukaryotic cells
Organelles are membrane covered structures that each perform a special job for the
cell
(compare organelles inside a cell to the organs found inside you body)
Organelles are found only in Eukaryotic cells (Plant and Animal cells)
*A List of Organelles that are Common to Both Animal and Plant cells
-Cell membrane: made of phospholipids, proteins and the steroid cholesterol, main job is
to control what substances and molecules enter and leave the cell, also known as the
phospholipid bi-layer. It acts as a gate keeper.
-Nucleus: contains all of the cells information in the form of DNA code, wrapped in a
membrane called the nuclear envelope, the control center of the cell.
-Endoplasmic reticulum part of the inner membrane system (the endomembrane
system) it is a series of folds that is in direct contact with the nucleus. Its main job is the
manufacture of substances for the cell.
The endoplasmic reticulum is divided into two parts:
Rough endoplasmic reticulum: is studded with ribosomes giving it a bumpy or rough
appearance, it is the site of protein production for the cell
Smooth endoplasmic reticulum: has a smooth appearance because it has no ribosomes.
Its job is to manufacture special lipids (steroids like cholesterol, fats, oils and waxes). It
also helps to detoxify drugs and other compounds harmful to the cell
Both of the endoplasmic reticulum (rough and smooth) then send the products they make
directly to the…
Golgi complex: The Gogi complex is a series of membranes that look like a stack of
flattened pancakes. It is not in direct contact with the nucleus and can be found some
distance away from it. Its job is to package the products of the endoplasmic reticulum in
vesicles (little membrane sacks) and distribute them to the areas of the cell that need
them.
Vacuoles: small membrane sacks that can store food, waste and other cell products. Very
similar to vesicles but a little bigger.
Lysosomes: Small membrane sacks filled with digestive enzymes. The lysosome comes
in contact with cell garbage, surrounds it in the membrane and dissolves it. The garbage
is broken down into simple molecules that the cell can reuse or just get rid of.
Ribosomes: The smallest organelle, it is the only one not covered in a membrane. It is
responsible for synthesizing proteins with the help of RNA. RNA decodes the
information found in DNA. RNA then finds a ribosome and the two work with each other
to make a protein by putting together amino acids in a long chain.
Mitochondria (singular: mitochondrion): a small bean shaped organelle that is
responsible for converting the energy found in the bonds of carbohydrates and lipids into
ATP (adenosine triphosphate, a form of energy that the cell can use to perform all of its
life functions) known as the power house of the cell.
*A List of Organelles that are found only in Plant cells
Chloroplast: Small green organelle that is about the size of a mitochondrion. It contains
chlorophyll, a green pigment that harvests energy from the sun. A plant uses carbon
dioxide, water and sunlight and the energy captured by chlorophyll to photosynthesize.
Photosynthesis is the making of sugar (glucose) from simple compounds and sunlight
energy.
Cell wall: a rigid structure made of cellulose that gives a plant cell strength. Remember
cellulose is one of the two polysaccharides that plants make out of excess sugars. Starch
is the other.
Large Central Vacuole: A large vacuole that takes up a large part of the inside of a
plant cell. Its job is to store water and other substances such as sugars and pigments. A
plant that is wilted needs to be watered because the central vacuoles have lost too much
water and the plant becomes limp. Once the plant is watered the central vacuoles fill back
up with water and give the cell the pressure it needs to make the plant stand up straight
again.
An Organelle that is found only in Animal cells:
Centrioles: two barrel shaped organelles that aid the cell in mitosis (cell division). When
the animal cell divides, all of the DNA is condensed into chromosomes and then
duplicated. The Centrioles build the scaffold that will help the chromosomes separate
from each other during cell division (mitosis)