1. Eukaryotic
= are usually found in multicellular organisms
= having cells with "good" or membrane-bound nuclei
= are about 10 times the size of a typical prokaryote and can be as much as
1000 times greater in volume.
= contain membrane-bound compartments in which specific metabolic
activities take place. Most important among these is the presence of a cell
nucleus, a membrane-delineated compartment that houses the cell's DNA.
It is this nucleus that gives it its name, which means "true nucleus".
2. Prokaryotic
= are usually independent
= having cells that lack membrane-bound nuclei
= are distinguished from eukaryotes on the basis of nuclear organization,
specifically their lack of a nuclear membrane.
= also lack most of the intracellular organelles and structures that are
characteristic of eukaryotic cells (an important exception is the ribosome,
which are present in both types of cells).
3. Cell
membrane
= is surrounded by a plasma membrane, which serves to separate and
protect a cell from its surrounding environment and is made mostly from a
double layer of lipids (hydrophobic fat-like molecules) and hydrophilic
phosphorus molecules - phospholipid bilayer
= is said to be 'semi-permeable', in that it can either let a substance
(molecule or ion) pass through freely, pass through to a limited extent or
not pass through at all. Cell surface membranes also contain receptor
proteins that allow cells to detect external signalling molecules such as
hormones.
4. Cytoskeleton
= acts to organize and maintain the cell's shape; anchors organelles in
place; helps during endocytosis, the uptake of external materials by a cell,
and cytokinesis, the separation of daughter cells after cell division; and
moves parts of the cell in processes of growth and mobility
= is composed of microfilaments, intermediate filaments and microtubules
5. Cell nucleus
= is the most conspicuous organelle found in a eukaryotic cell. It houses
the cell's chromosomes, and is the place where almost all DNA replication
and RNA synthesis occur, is spherical in shape and separated from the
cytoplasm by a double membrane called the nuclear envelope which
isolates and protects a cell's DNA from various molecules that could
accidentally damage its structure or interfere with its processing. During
processing, DNA is transcribed, or copied into a special RNA, called
mRNA. This mRNA is then transported out of the nucleus, where it is
translated into a specific protein molecule.
6. Mitochondria = are self-replicating organelles that occur in various numbers, shapes, and
sizes in the cytoplasm of all eukaryotic cells.
= they contain their own genome that is separate and distinct from the
nuclear genome of a cell, they play a critical role in generating energy in
the eukaryotic cell, they give the cell energy by the process of respiration,
adding oxygen to food (typically pertaining to glucose and ATP =
adenosine triphosphate) to release energy
© Veronika Srchová, Jozef Gémeš
7. Endoplasmic
reticulum
= network of vessels forming a membrane in a cytoplasm
= is the transport network for molecules targeted for certain modifications
and specific destinations, as compared to molecules that will float freely in
the cytoplasm
= it has two forms: rough, which has ribosomes on its surface, and
smooth, which lacks them.
8. Golgi
apparatus
= folded membranous structure inside the cell cytoplasm which stores and
transports enzymes and hormones
= a net-like structure in the cytoplasm of animal cells
9. Ribosomes
= is a large complex, composed of many molecules, in prokaryotes only
exist floating freely in the cytosol, whereas in eukaryotes they can be
found either free or bound to membranes
= are the protein production centres
10. Lysosomes
and
Peroxisomes
= The cell could not house such destructive enzymes if they were not
contained in a membrane-bound system.
= are often called a "suicide bag" because of their ability to detonate and
destroy the cell.
11. Vacuoles
= store food and waste, some store extra water
= are often described as liquid filled space and are surrounded by a
membrane
12. Catabolism
= process in which the cell breaks down complex molecules to produce
energy and reducing power
= is the set of metabolic pathways that break down molecules into smaller
units and release energy.
= large molecules such as polysaccharides, fatty acids, nucleic acids and
proteins are broken down into smaller units such as monosaccharides,
fatty acids, nucleotides and amino acids, respectively.
13. Anabolism
= is the set of metabolic pathways that construct molecules from smaller
units. = these reactions require energy
= tend toward "building up" organs and tissues. These processes produce
growth and differentiation of cells and increase in body size, a process that
involves synthesis of complex molecules.
14. Nucleolus
= is a sub-organelle of the cell nucleus
= main function is the production and assembly of ribosome components
= roughly spherical, and is surrounded by a layer of condensed chromatin.
No membrane separates it from the nucleoplasm.
© Veronika Srchová, Jozef Gémeš