IV. Cell Biology | 59. Principles of the organization of the eukaryotic cells; compartmentation; main features of subcellular organelles Flashcards
I. Basics
1. What are the features of cells?
- The cell is the smallest unit that can carry out all activities we associate with life.
- Cells are the building blocks of complex multicellular organisms.
- It is composed of many inorganic and organic ions and molecules, including water, salts, carbohydrates, lipids, proteins and nucleic acids. => These molecules are organized to form structures within the cell and its biochemical pathways.
II. Comparison of prokaryotic and eukaryotic cells
1. What is the different between
the definition of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Organisms without a cell nucleus, or any other membrane-bound organelles.
- Most are unicellular, but some prokaryotes are multicellular - Eukaryotes:
- Organisms whose cells are organized into complex structures by internal membranes and cytoskeleton.
- The most characteristic membrane bound structure is the nucleus
II. Comparison of prokaryotic and eukaryotic cells
2. What is the different between
the cell type of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Mostly unicellular, but some are multicellular - Eukaryotes:
- Mostly multicellular
II. Comparison of prokaryotic and eukaryotic cells
3. What is the different between
the cell size of prokaryotes and that of eukaryotes?
- Prokaryotes:
- 0,1 to 5,0 μm in diameter - Eukaryotes:
- 10 to 100 μm in diameter
II. Comparison of prokaryotic and eukaryotic cells
4. What is the different between
the nucleus of prokaryotes and that of eukaryotes?
- Prokaryotes:
- True membrane bound nucleus is absent.
- Nucleus lacks nuclear membrane and nucleolus.
- Such a nucleus is called nucleoid - Eukaryotes:
- Nuclear membrane and nucleolus are present
II. Comparison of prokaryotic and eukaryotic cells
5. What is the different between
the permeability of nuclear membrane of prokaryotes and that of eukaryotes?
- Prokaryotes: Absent
- Eukaryotes: Selective permeability
II. Comparison of prokaryotic and eukaryotic cells
6. What is the different between
the Genome of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Single, closed, circular, double-stranded DNA
- Few million base pairs - Eukaryotes:
- Linear, double-stranded DNA.
- 46 chromosomes, 3.3 billion base pairs
II. Comparison of prokaryotic and eukaryotic cells
7. What is the different between
transcription + translation of prokaryotes and that of eukaryotes?
- Prokaryotes: Occur simultaneously
- Eukaryotes:
- Transcription occurs in nucleus
- Translation occurs in cytoplasm separately
II. Comparison of prokaryotic and eukaryotic cells
8. What is the different between
the sexual reproduction of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Asexual - Eukaryotes:
- Sexual - involves meiosis
II. Comparison of prokaryotic and eukaryotic cells
8. What is the different between
the Cell division of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Binary fission: cell divides, forming two cells.
- Budding: a bud forms and separates from the mother cell.
- Fragmentation: walls form inside the cell, which then separates into several cells. - Eukaryotes:
- mitosis
II. Comparison of prokaryotic and eukaryotic cells
8. What is the different between
the Cell division of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Binary fission: cell divides, forming two cells.
- Budding: a bud forms and separates from the mother cell.
- Fragmentation: walls form inside the cell, which then separates into several cells. - Eukaryotes:
- mitosis
II. Comparison of prokaryotic and eukaryotic cells
9. What is the different between
the plasma membrane of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Lacks sterol and carbohydrate - Eukaryotes:
- Sterol and carbohydrates are present (serve as receptors)
II. Comparison of prokaryotic and eukaryotic cells
10. What is the different between the duration of cell cycle of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Short, takes 20-60 minutes to complete - Eukaryotes:
- Long, takes 12-24 hours to complete
II. Comparison of prokaryotic and eukaryotic cells
11. What is the different between the Cell wall of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Usually present, chemically complex.
- Typical bacterial cell wall is composed of peptidoglycan.
- Some species of bacteria produce a capsule or slime layer that surrounds the cell wall. - Eukaryotes:
- Only in plant cells and fungi (chemically simple)
II. Comparison of prokaryotic and eukaryotic cells
12. What is the different between the Flagella of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Each flagellum consists of a basal body, hook and filament.
- They produce a rotatory motion - Eukaryotes:
- Long projections made of two central and nine pairs of peripheral microtubules (9+2 structure).
- Extends from the cell surface covered by plasma membrane.
II. Comparison of prokaryotic and eukaryotic cells
13. What is the different between the Cytoskeleton of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Absent - Eukaryotes:
- Microtubules: hollow tubes made of subunits of tubulin proteins.
- Microfilaments: solid, rod-like structures consisting of actin protein.
- Intermediate filaments: tough fibers made of protofilaments.
II. Comparison of prokaryotic and eukaryotic cells
13. What is the different between the Ribosomes of prokaryotes and that of eukaryotes?
- Prokaryotes:
- Smaller - Eukaryotes:
- Larger
- Some attached to ER, some free in cytosol
(Granules composed of RNA and protein)
II. Comparison of prokaryotic and eukaryotic cells
14. What is the different between the organelles of prokaryotes and that of eukaryotes?
- Prokaryotes:
- All membrane-enclosed organelles are missing - Eukaryotes:
- ER, Golgi, mitochondria, lysosomes + peroxisomes, (chloroplast) are present
III. Compartmentation
1. What is the definition of Compartmentation?
Compartmentation refers to the way organelles in eukaryotic cells live and work in separate areas within the cell, in order to perform their specific functions more efficiently
III. Compartmentation
2. Compartmentation refers to the way organelles in eukaryotic cells live and work in separate areas within the cell, in order to perform their specific functions more efficiently
=> List these functions
- Metabolic units are separated according to morphology and functionality
- Proteomes and metabolomes are (more or less) specific
- Well-regulated transport processes
- Distribution of tasks (specialization) and mutual cooperation (mitochondria: energy production, ER: protein synthesis and maturation)
- Efficient enzymatic reactions due to high local substrate concentration (serial reactions: e.g. mitochondrial respiratory chain)
- Sequestration/isolation of compounds or reactions of potential toxicity (ER: detoxification, peroxisome: H2O2 production and breakdown)
IV. Subcellular organelles - NUCLEUS
3. What are the features of of nucleus
- The genetic information is stored in and originates from the nucleus, the control center of the eukaryotic cell
- It is bound by a nuclear envelope, consisting of a double membrane perforated with nuclear pores that communicate with the cytoplasm
- DNA in the nucleus associates with histone proteins to form chromatin, which is organized into chromosomes (heterochromatin = inactive, euchromatin = active)
- The outer membrane is continuous with the ER membrane
IV. Subcellular organelles - NUCLEUS
4A. What is Nuclear pore complex?
- Double membrane of the nuclear envelope is penetrated by nuclear pores, through which selected macromolecules and larger complexes enter/exit the nucleus
- Protein fibrils protrude from both sides of the pore complex; on the nuclear side, they converge to form a basketlike structure.
IV. Subcellular organelles - NUCLEUS
4B. What are Components of Nuclear pore complex?
- Cytosolic fibrils
- Membrane ring proteins
- Scaffold nucleoporins
- Channel nucleoporins
- Nuclear basket
IV. Subcellular organelles - NUCLEUS
4C. How does transport work through Nuclear pore complex?
- Nucleus to cytosol:
- mRNA, tRNA, ribosomes - Cytosol to nucleus:
- Enzymes of DNA + RNA synthesis
- DNA-associated proteins (histone)
IV. Subcellular organelles - NUCLEUS - Nucleoskeleton and lamina
5A. What are the features of Nucleoskeleton and lamina?
- Consists of intermediate filaments
- The nuclear lamina is a scaffold-like network of protein filaments, surrounding the nuclear periphery
- Consist mainly of intermediate filament-proteins like lamin A, C and B, which together form a complex meshwork underneath the inner nuclear membrane
IV. Subcellular organelles - NUCLEUS - Nucleoskeleton and lamina
5B. What are the functions of Nucleoskeleton and lamina?
- Maintenance of the nuclear envelope and nuclear shape
- Spatial organization of the nuclear pores within the nuclear membrane
- Regulation of transcription
- Anchoring the interphase heterochromatin
- Role in DNA replication
IV. Subcellular organelles - NUCLEUS - Nucleolus
6A. What is nucleolus?
The most prominent structure in the nucleus of an eukaryotic cell (seen in LM) and not covered by a membrane
- Site of rRNA synthesis and processing, and their assembly with ribosomal proteins
- It is a large aggregation of macromolecules, like rRNA genes, precursor RNAs, rRNA-processing enzymes, ribosomal proteins and partly assembled ribosomal subunits which allows rapid movement
- The size of the nucleolus reflects the number of ribosomes that the cell is producing
IV. Subcellular organelles - NUCLEUS - Nucleolus
6B. What are sub-compartments in the nucleolus?
- Maintenance of the nuclear envelope and nuclear shape
- Spatial organization of the nuclear pores within the nuclear membrane
- Regulation of transcription
- Anchoring the interphase heterochromatin
- Role in DNA replication
IV. Subcellular organelles - NUCLEUS - Nucleolus
6C. What are functions of these sub-compartments in the nucleolus?
IV. Subcellular organelle - PLASMA MEMBRANE
8. What is the role of PLASMA MEMBRANE?
- The plasma membrane separates the interior of a cell from its outside environment.
- Composed of a phospholipid bilayer with embedded proteins
IV. Subcellular organelle - PLASMA MEMBRANE
9. What are the functions of PLASMA MEMBRANE?
- Protect cell from its surroundings
- Cellular transport
- Cellular signaling
- Anchoring of cytoskeleton to provide shape to cell
IV. Subcellular organelle - PLASMA MEMBRANE
10A. What are the 5 components of plasma membrane?
- Phospholipid
- Cholesterol
- Integral proteins (for e.g, integrins)
- Peripheral proteins
- Carbohydrates
IV. Subcellular organelle - PLASMA MEMBRANE
10B. What is the location of phospholipid?
Main fabric of the membrane
IV. Subcellular organelle - PLASMA MEMBRANE
10C. What is the location of Cholesterol?
Attached between phospholipids and between the 2 phospholipids layers
IV. Subcellular organelle - PLASMA MEMBRANE
10D. What is the location of integral proteins of plasma membrane?
- E.g, integrins
- Embedded within the phospholipid layer(s)
- May or may not penetrate through both layers
IV. Subcellular organelle - PLASMA MEMBRANE
10E. What is the location of peripheral proteins of plasma membrane?
- On the inner or outer surface of the phospholipid bilayer
- Not embedded within the phospholipids
IV. Subcellular organelle - PLASMA MEMBRANE
10F. What is the structure and location of carbohydrates of plasma membrane?
- Structure: components of glycoproteins and glycolipids
- Location: generally attached to proteins on the outside membrane layer.
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
11. What are the components of ENDOPLASMIC RETICULUM?
- Rough endoplasmic reticulum (rER)
- Smooth endoplasmic reticulum (sER)
- Golgi apparatus
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
12A. What is Rough endoplasmic reticulum (rER)?
Flattened, parallel, well organized membrane system
with ribosomes bound to its cytoplasmic surface
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
12B. What are the functions of Rough endoplasmic reticulum (rER)?
- Co-translational transmembrane transport of proteins being synthesized in membrane-bound ribosomes
- Orientation of transmembrane proteins. TM proteins have to reach their proper orientation in the ER, since it cannot be changed later in other organelles
- N-glycosylation and the modification of oligosaccharide chains: important in folding, sorting, stability and making proteins hydrophilic
- Folding of proteins (by the help of chaperons)
- Transport of unfolded or misfolded proteins into the cytosol (for protein degradation)
- Retaining ER proteins
- Transport of all other proteins to the Golgi (by the help of vesicles)
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
12C. Why is N-glycosylation and the modification of oligosaccharide chains endoplasmic reticulum (rER)?
Important in folding, sorting, stability and making proteins hydrophilic
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
13A. What is Smooth endoplasmic reticulum (sER) composed of?
Composed of unorganized tubules and partly flattened sacs, lacks bounded ribosomes
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
13B. What are the functions of Smooth endoplasmic reticulum?
- Synthesis of membrane lipids (phospholipids, cholesterol)
- Storage of Ca2+-ions
- Synthesis of steroids
- Detoxification (in the liver)
- Glucose metabolism
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
14A. What does Golgi apparatus consist of?
Consists of flattened membranous sacs (cisternae) that process, sort and modify proteins synthesized on the ER
- Cis-face: located nearest nucleus and receives materials from the ER via transport vesicles
- Trans-face: located nearest the plasma membrane; packages molecules, transporting them out of the Golgi
IV. Subcellular organelle - ENDOPLASMIC RETICULUM
14B. What are the functions of Golgi apparatus?
- Modification of N-oligosaccharide chains of proteins
- O-glycosylation: addition of oligosaccharide chains to proteins
- Proteoglycan synthesis (found in ECM)
- Modification of lipids (glycolipids and sphingomyelin)
- Proteolysis (breakdown of proteins into smaller polypeptides/amino acids)
- Sorting:
Back to ER
Retaining of Golgi proteins Lysosome
Plasma membrane (secretion)
IV. Subcellular organelle - MITOCHONDRIA
15A. What are mitochondria?
- Mitochondria are membrane-bound cell organelles that generate most of the chemical energy needed to power the reactions in the cell = powerhouse of the cell.
- Chemical energy produced is stored in a small molecule, ATP.
IV. Subcellular organelle - MITOCHONDRIA
15B. What is the structure of mitochondria?
- Made of two membranes.
- Outer membrane covers the organelle, while the inner membrane folds over many times and creates structures called cristae.
- The fluid contained in the mitochondria is the matrix.
- In the matrix, we can find the mitochondria’s own ribosomes and DNA floating.
IV. Subcellular organelle - MITOCHONDRIA
15C. What are the functions of mitochondria?
- ATP synthesis (citric acid cycle, beta-oxidation, ETC)
- Storage of caspase (responsible for triggering apoptosis)
- Storage of calcium
- In brown adipose tissue: heat production using the electron transport chain
