The document describes several key organelles found within eukaryotic cells, including their structure and functions. The endoplasmic reticulum is described as a network of sacs and tubules involved in protein transport and synthesis. Ribosomes on the ER synthesize proteins. Mitochondria are described as the powerhouses of the cell that produce ATP through cellular respiration. Lysosomes contain digestive enzymes and break down molecules. Peroxisomes contain enzymes involved in lipid metabolism. Chloroplasts in plant cells perform photosynthesis. Vacuoles in plant cells store waste and substances.

2. 1. In the year 1945- The lace like membranes of the endoplasmic reticulum were
first seen in the cytoplasm of chick embryo cells.
2. ER are considered as one of the components of cytoskeleton along with
microtubules, microfilaments and intermediate filaments.
3. These are first of all observed by Porter, Claude and Full am in (1945) as a
network.
4. The term ”Endoplasmic reticulum” was first used by Porter and Fullman
(1952)
 Location
1. Present in almost all eukaryotic cell.
2. These are found to be absent in mature erythrocytes,ova,embryonic cells and
prokaryotes.
3. The ER often occupies most of the cytoplasm.

3. Amount
•The ER varies in amount from cell to cell. In spermatocytes, it is
represented by a few vacuoles only.
•In the cells of adipose tissue, it is quite simple, having the form of a few
tubules.
•The cells that are actively synthesizing proteins, such as liver and pancreatic
cells and fibroblast, have abundant ER.
•Endoplasmic reticulum forms 30-60 % of the total membrane in a cell.
PHYSICAL STRUCTURE-
The ER is 3-dimensional network of intracellular. It is formed of three types
of element:
1-Cisternae
2-Tubules
3-Vesicles

4. Cisternae-
These are flattened , unbranched, sac-like element.
They lie in stacks parallel to one another.
They bear ribosomes on the surface that, therefore, appears
rough.
It contain glycoproteins named ribophorin-I & ribophorin-II
that bind the ribosomes.

5. Tubules-
These are irregular branching element which form a network
along with other element.
These are often free of ribosomes.
Vesicles-
These are oval and rounded ,vacuole like element.
These are also free of ribosomes.
All the element of ER freely communicates with one another,
and contain a fluid called endoplasmic matrix, in the ER lumen.
These matrix is different from cytoplasmic matrix outside the
ER
The ER may pass from one cell to another through the
plasmodesmata in the form of desmotubules.

6. Ribosome - protein
synthesizer consisting of
two subunits
Larger one, “50S”, is upper
picture. Smaller is “30S”
(They look the same size
here because of space
restrictions.)

7. Ribosome basically a protein factory. Subunits each have
role in making of proteins
To understand exactly what each subunit does, it’s
necessary to walk through protein synthesis step by step

8. Process starts from DNA
through “transcription”
“Translation” is where
ribosome comes in.
Translation occurs when
protein formed from code
on mRNA
Ribosome carries out the
translation of the
nucleotide triplets

9. Chart - visual image of
transcription and
translation in protein
synthesizing
DNA and RNA have
nucleotides that determine
kind of protein
3 nucleotides = 1 amino acid
of a protein

10. Golgi apparatus is named after the scientist
who discovered it.
Camillo Golgi was an Italian biologist who
discovered this organelle with a light
microscope in 1898.
He developed a method that stained it
intensely and made possible the
demonstration of its occurrence in a wide
variety of cell types.
This method is known as Golgi Staining or
Golgi Impregnation.

11. The Golgi is composed of stacks of
membrane-bound structures known
as Cisternae.
A cisterna (plural cisternae)
comprises a flattened membrane
disk that makes up the Golgi
apparatus.
Usually a Golgi has 6-7 cisternae.
Each Golgi stack has a distinct
orientation.
A complex network of tubules and
vesicles is located at the edges of
these cisternae.

12. The side faces the Endoplasmic reticulum is Cis Face and is the entry face that
receives small membrane vesicles from the ER.
Vesicles from the endoplasmic reticulum fuse with the cis-Golgi network and
subsequently progress through the stack to the trans-Golgi network.
The cis is the site at which transport vesicles bringing newly synthesized products
from the endoplasmic reticulum with and add their contents to the Golgi cisternae.
A complex network of anatomizing (connecting) membrane tubules attach to and
cover cisternae on the cis face and serve as a docking site for transport vesicles.
 Each region contains different enzymes which selectively modify the contents
depending on where they are destined to reside.

13. The side faces the cell membrane is Trans Face and is the exit face where vesicles leave
the Golgi and move to their targets, including the exterior of the cell.
 As the last station of the Golgi complex, the trans-Golgi network (TGN) plays a pivotal
role in directing proteins in the secretary pathway to the appropriate cellular destination.
Proteins synthesized on membrane-bound ribosomes are transported through the
Golgi apparatus and, on reaching the trans-Golgi network, are sorted for delivery to
various cellular destinations.
Sorting involves the assembly of cytosol-oriented coat structures which preferentially
package cargo into vesicular transport intermediates.
Protein sorting into different transport vesicles requires specific interactions between
sorting motifs on the cargo molecules and vesicle coat components that recognize these
motifs.

14.  The Golgi apparatus is integral in modifying, sorting, and packaging
macromolecules for cell secretion (exocytosis) or use within the cell.
 It primarily modifies proteins delivered from the rough endoplasmic
reticulum, then sends the modified macro-molecules to different parts of
the cell or outside of the cell.
 It is also involved in the transport of lipids around the cell, and the
creation of lysosomes.
 In this respect it can be thought of as similar
to a post office; it packages and labels items
which it then sends to different parts of the cell.

15.  The Golgi plays an important role in the synthesis of proteoglycans, which are
molecules present in the extracellular matrix of animals.
 It is also a major site of carbohydrate synthesis.
 A newly characterized protein, GAAP (Golgi anti-apoptotic protein), almost
exclusively resides in the Golgi and protects against cell destruction known as
apoptosis by an as-yet undefined mechanism.
 Sometimes vital proteins needed in the rough endoplasmic reticulum are
transported along with the other proteins in the Golgi complex. The Golgi
complex has a mechanism for trapping them and sending them back to the
rough endoplasmic reticulum.

16. Mitochondria (singular, mitochondrion) – are typically tubular
or rod-shaped organelles found in the cytoplasm of most cells
and produces enzymes for the metabolic conversion of food to
energy.
Mitochondria are responsible for converting nutrients into the
energy-yielding molecule adenosine triphosphate (ATP) to fuel
the cell's activities. This function, known as aerobic respiration,
is the reason mitochondria are frequently referred to as the
powerhouse of the cell.

17. FUNCTION

18. Energy conversion
1. The most prominent roles of mitochondria are
to produce the energy currency of the cell, ATP,
through respiration, and to regulate cellular
metabolism.
2. A dominant role for the mitochondria is the
production of ATP, as reflected by the large number
of proteins in the inner membrane for this task.

19. A mitochondrion contains outer and inner membranes
composed of phospholipid bilayers and proteins. The two
membranes have different properties. Because of this
double-membrane organization, there are five distinct
parts to a mitochondrion. They are:

20. Created in the ER, or Endoplasmic Reticulum and sent to
the Golgi Apparatus.
Lysosomes are small organelles filled with digestive
enzymes.
Located in the cytoplasm (portion of cell outside of the
nucleus) of animal eukaryotic cells
The “janitors of the cell”

21. Responsible for the break down of lipids, carbohydrates,
and proteins to be used by the cell
Attach and release their enzymes, which break down the
complex sugars and proteins
Break down organelles that are no longer useful
Remove “junk” that may accumulate in the cell (this
prevents diseases)

23. There are over 50 classified diseases due to Lysosomes not
functioning properly. To name a few..
-Lipidoses
-Lysosomal Transport Disease
-Glycogen Storage Disease type II
The word Lysosome comes from two Greek words- Lysis
meaning destruction, and Soma meaning body.
- Lysosomes contain over 3 dozen different types of
enzymes

24. Small organelles found in both animal and plant cells
Found in free floating cytoplasm
Contain at least 50 enzymes
Produce hydrogen peroxide

25. Breaking down
Enzymes in peroxisomes break down long chain fatty
acids through oxidation
Produce a great deal of metabolic energy supplements
Abundant in organs such as the liver, where lipids are
stored, broken down, and synthesized.

26. Building up
Produce chemicals as well as breaking them down
Make cholesterol in animal cells and produce bile in liver
cells
Contain enzymes for making phospholipids

28. Major organelle of plant and algal cells
Site of manufacture and storage of important
chemical compounds
Has circular, dsDNA copies
Replicates autonomously of the cell
Thought to have been originated from endosymbiotic
bacteria
Plastid genes show maternal inheritance

30. Chloroplasts – green plastids – for photosynthesis
Chromoplasts – coloured plastids – for pigment
synthesis and storage
Gerontoplasts – control dismantling of photosynthetic
apparatus during senescence
Leucoplasts – colourless plastids – monoterpene
synthesis
Leucoplasts include amyloplasts (starch), elaioplasts
(fats), proteinoplasts (proteins) and tannosomes
(tannins)

31. Are densely packed and fall into 2 categories:
Photosynthesis-related genes
Genetic system genes - genes for rRNAs, tRNAs,
ribosomal proteins and RNA polymerase subunits

32. 1. Vacuoles are most important in plant cells
2. Vacuoles have a similar function in fungal cells as
plant cells
3. Contractile vacuoles are found in protists and are
most important in fresh water organisms
4. Vacuoles are important for storage in cells
5. Vacuoles collect harmful waste and dispose of it
6. Animal cells have vesicles, not vacuoles

33. Vacuoles are organelles found in cells. They
store various substances essential to the life of
the cell. They also store waste to later remove
from the cell.

34. Vacuoles, like vacuums, remove waste
products harmful to the cell. In addition,
they store water and essential nutrients for
later use. For this reason, they are called
“storage bubbles”(source 5) or “storage
bins”(source 4).

35. The centrosome, also called the "microtubule organizing center", is an
area in the cell where microtubles are produced.
Within an animal cell centrosome there is a pair of small organelles, the
centrioles, each made up of a ring of nine groups of microtubules. There
are three fused microtubules in each group.
The two centrioles are arranged such that one is perpendicular to the
other.
During animal cell division, the centrosome divides and the centrioles
replicate (make new copies). The result is two centrosomes, each with its
own pair of centrioles. The two centrosomes move to opposite ends of
the nucleus, and from each centrosome, microtubules grow into a
"spindle" which is responsible for separating replicated chromosomes
into the two daughter cells.