Organelles Flashcards
Name 3 components of the cytoplasm :
- Organelles
- Cytosol
- Inclusions
Name 3 nonmembrane bound organelles
- Centrioles
- Microtubules
- Nucleoli
What are inclusions bodies ?
Something that the cell could not digest..
Insuluble substances such as glycogen, lipid droplets
even ribosomes can be considered inclusion bodies..?
Mitochondria are _____ membrane bound organelles. They provide energy to the cell and are most abundant in cells that generate and expand energy such as _____.
double membrane
heart muscle, liver cell, some cells of the kidney.
Mitochondria is absent in what kind of cells ?
Erythrocytes
Terminal keratinocytes/corneocytes
What is the role of the cytoskeleton?
Organize the organelles and provide structure to the cell
Mitochondrial are _____ structures that would stain as the colour ____ on LM
Pink
The mitochondrial’s ____ membrane contains large _____ which permit ions and small molecules to enter the intermembrane space.
Outer
Channels
In which part of the mitochondria can you find cytochrome C and what is his role?
The intermembrane contains specific enzymes like cytochrome C.
When cytochrome C is discharged into the cell cytoplasm it initiates apoptosis.
Regarding the mitochondria : The matrix surrounded by the _____ membrane contains :
The matrix is surrounded by the inner mitochondrial membrane
Contains : Soluble enzymes of the kreb’s cycle Electron dense matrix granules (store Ca) Mitochondrial DNA, ribosomes, rRNA.
The mitochondrial innermembrane folds into structures called _____ which can be tubularvesicular or ______.
Cristae
Plate-like
The mitochondrial enzymes system is responsible for generation of ____ in a variety of metabolic pathways (oxidative phosphorylation, citric acid cycle, glycolysis, beta oxidation of fatty acids)
ATP
The ER is organized into a mesh like interconnected maze of branching tubes and flattened lamellae. What are the two types and their difference:
Rough ER : ribosomes attached to their outer surface
Smooth ER : ribosomes-free outer surface
The ER has how many membrane (s) ?
1
What is the main role of the rER
Protein synthesis & post translational modifcations of newly synthesized proteins (proper folding, initial glycolysation)
With TEM ; rER appears as series of membrane limited flattened sacs called ____.
Cisternae
What is the role of ribosomes ?
Syntesis of different classes of proteins.
Note that in the cytosol, many ribosomes are connected by one strand of mRNA which are referred to as polysomes. Polysomes can be found in 2 forms : free polysomes and bound polysomes.
Free polysomes are free in the cytosol
Bound polysomes are attached to the outer surface of the rER cisternae
Ribosomes stain ___ in LM. Why ?
Purple
Basophilic - because they contain a lot of RNA which is acidic
Describe the Golgi apparatus and its role.
Group of flattened sacs with vesicles around the margins.
We can find from 1-100 golgi in every cell.
The role : factory in which protein from the ER are further processed and matured and then put into vesicles so they can be carried to their target destination.
They are prominent in protein-secreting cells.
At the TEM level, they appear to consist of 3 different regions.
What are the 3 defined regions of the golgi apparatus on TEM ?
Cis (Vesicles loaded with proteins leave the rER and fuse with the cis region)
Medial (the process of concentration and maturation involves mvmt of the proteins from the cis to the medial to the trans regions)
Trans (Where mature proteins exit in the form of smaller detached vesicles)
Each region contains different enzymes involved in protein maturation.,
Is it possible to visualize the Golgi with LM ?
Yes.
It appears as a lightly stained area in the cytoplasm of protein-producing cells (e.g. plasma cells).
What is the role of sER and it what kind of cells is it well developed?
Participates in biosynthesis of steroid hormones and membrane lipids
Breakdown of toxins and drugs
Synthesis of TG in the intestinal epithelium
Sequestering of calcium in striated muscle
Smoot ER in striated muscle fibers is called ______.
Sarcoplasmic reticulum.
Responsible for storage of Ca ions / trigger contraction of myofibrils
What are lysosomes ?
Membrane bound cell organelle that contain a large variety of acid hydrolases.
Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself. They may be used to destroy invading viruses and bacteria.
They are found in all cell types.
Profound in neutrophils and macrophages.
Here is what a phagosome looks like in TEM
Digested materials inside the lysosomes are recycled or released to the outside. Indigestible compounds stored in the lysosomes are called _____. In LM, they appear as yellowish, brownish pigments around the nucleus (Lipofuscins). The unreleased indigestible compounds in long-living cells are called _____ (found in neurons and cardiac muscle cells).
Residual bodies
Aging pigments
Lysosomal storage diseases results in accumulation of undigested products. What is an example of disease that results from accumulation of these undigested products :
Tay Sachs disease
(Absence of lysosomal galactoside in neurons which produces concentric lamellar structures in the lysosomes and interfere with normal neuronal function.
Gaucher , Pompe’s, Niemann-Pick disease are other examples.
Peroxisomes look like lysosomes, but have a dark spot in the middle which represents _____.
Catalase
Compare the different organelles visualized by TEM and LM
Distinguish Euchromatin from Heterochromatin
Heterochromatin is the part of the chromosome in which the DNA does not have coding genes. These regions appear dark on microscopy due to compact arrangement of chromatin. These parts are inactive, as they are not involved in transcription, and thus coding for proteins.
Euchromatin is the part of the chromosome in which the coding DNA sequences are present. These parts appear lighter on microscopy, as the chromatin is loosly packed. It is streched out so that transcription can take place. It is prominent in active cells, like liver cells.
What is a barr body ?
A barr body represents the inactive X chromosome in a cell with more than one X chromosome.
Females have only one of there chromosomes that is expressed, so the other one is maintained as facultative heterochromatine.
Barr bodies thus can be used to identify the sex of a fetus.
What is the role of the nucleolus ?
Surrounds transcriptionally active rRNA genes.
It is the primary site of ribosomal production and assembly.
It can vary in size and number across different cell types, but it is usually very visible in cells that are active in protein synthesis.
What is the space between the inner and outer membrane called ?
Perinuclear space
The NPC acts as a close-fitting diaphragm or gated channel and allows for transport of small molecules. A central framework, surrounding the central pore is inserted between the ____ ring and the _____ ring. This last complex anchors a ‘’nuclear basket’’. This complex acts as a gated channel and allows for transport of small molecules.
cytoplasmic
nuclear
