| How are free living cells and multicellular organisms divided? | Eukaryotes and Prokaryotes. |
| What is the meaning of Eukaryotes? | Eu=true karyon=nucleus |
| What is the meaning of prokaryotes? | pro=before (which means they existed before the formation of nucleus of cells. |
| How are viruses classified? | Neither prokaryotes nor eukaryotes because the are not living things as long as they cannot reproduce autonomously. |
| What is the main difference between Eukaryotes and Prokaryotes? | Presence of membranes between DNA and ribosomes ( eukaryotes have membrane that delimit many compartments (organelles) within the cell including the nucleus. whereas prokaryotes cytoplasm and nucleus are found in the same compartment.)
In addition prokaryotes have no organelles. |
| In general, Give some eukaryotic organisms and prokaryotic organisms | eukaryotic: animal and plant cells, protists fungi protozoa
prokaryotic: eubacteria, archaebacteria PPLO (N.R) |
| Are animal cells all the same? | No, there is no typical cell that can serve as an example since they vary in their sizes, shapes, physiological functions, abundance of organelles and structures. Their range in size is between 10-30 microm while plant cells are usually 100 microm |
| Do all eukaryotes have same organelles? | some organelles are common (mitochondria, golgi body, endoplasmic reticulum), some are specific organelles:( cilia, flagella and microvilli) |
| Give a list of the main structures found in a composite animal cell. | -plasma membrane (plasmalemma) intracting with extramolecular matrix and neighboring cells.
-nucleus
-cytoskeleton (set of filaments and microtubules shape-adhesion -movement)
-endoplasmic reticulum (synthesis and maturation of diverse cell organelles)
-cytosol (aqueous solution filling space between plasmalemma and nuclear envelope)
-ribosomes
-mitochondria (oxidation and cell respiration)
-Golgi body (dictyosomes for maturation and sorting organelles)
-lysosomes (intracellular digestion)
-peroxisomes (oxidation)
-centrosomes (movement)
-cilia and flagella (locomotion) |
| What are the common organelles between animal and plant cells? | All organelles except centrosomes and lysosomes |
| What are the exclusive organelles for a plant cell? | Carbohydrate-rich cell wall, plasmodesmata and plastids such as chloroplast. |
| What is the plant cell wall? | thick structure, located outside of the plasma membrane made of three classes of polysaccharides (cellulose, hemicellulose (glucose+pentoses) ,pectin (uronic acid rich polysaccharides) as well as small amounts of glycoproteins. )
Its matrix is hemicellulose proteins and pectin |
| What is the role of the plant cell wall? | supportive and protective role (against fluctuation of osmotic pressure and intruders)
determines cell shape, growth direction as well as cell-cell adhesion mediation through middle lamella (pectin rich) |
| Talk about plasmodesmata. | interruptions of the cell wall by cytoplasmic bridges between two cells serving for intermolecular exchange of nutrients and material. |
| What are plastids? | Family of organelles involved in many functions such as storing organic compounds and photosynthesis, chloroplast is an example found in green plant cells specialized in using sun light to reduce CO2 and H2O into glucose. |
| Where are vacuoles found? | Only in plants (although it is another term for vesicles) |
| What are vacuoles? | Large compartments, its the result of fusion of smaller vacuoles, bounded by membrane called tonoplast, serve to expand cells volume and water storing or other products for metabolic processes. |
| How are prokaryotes present? | Freely or as colonies/ clusters in semi-solid medium. (colonies are not multicellular organisms all cells remain functionally and structurally as if free) |
| How do prokaryotes grow? and When? | fissiparity (rapid division/ binary fission) / whenever nutrients are available, however some parasitic bacteria proliferate inside a eukaryotic cell. |
| How are prokaryotes classified? | Eubacteria and Archaebacteria |
| What is the mane difference between classes of prokaryotes? | Eubacteria (live in mild conditions)
Archaebacteria live in extreme conditions (thermophile and halophile (high salt like red sea) |
| How do we classify prokaryotes structurally? | coccus (spherical- 1 microm diameter) bacillus (rod) spiral (spirochetes 5-10 microm) average size is 1-2 microm |
| How are prokaryotes simpler than eukaryotes? | cytoplasm is not compatmentalized, however the cell wall is more complex than eukaryotic envelope. |
| What is the nucleiod? | dense region in cytoplasm, contains genetic material not separated by a membrane. |
| How is the bacterial genetic material? | single circular chromosome carrying all information necessary for bacterial life, condensed in nucleiod. |
| What are plasmids? | extrachromosomal DNA circular less than 1000 size of chromosomal, genes that confer resistance against antibiotics, transferred between cells through conjugation , used as vectors for molecular biology. |
| Can a prokaryote function without organelles? | Yes (oxidation from enzymes in membrane or cytoplasm. |
| What occurs when infolding of membrane happens in photosynthetic bacteria? | formation of lamellae separating membrane and form independent structures called chromatophores.. |
| Talk about bacterial ribosomes? | not same in size as eukaryotes, may be on membrane or cytoplasm, cannot be on lamellae . |
| What are bacterial granules? | inclusions stored organic and inorganic compounds sulfur phosphorus.. |
| What constitutes the bacterial envelope? | membrane(lipid bilayer/ without steroids- proteins- selective permeable) + cell wall (peptidoglycans-(glucose and acetylglucosamine) joined by peptide bridges determines shape, protection) |
| What is the septum? | inward growth of cell envelope between two daughter cells during fissiparity . |
| How does cell wall differ among bacterial species? | gram + (thick and enveloped by capsule (peptidoglycan and teichoic acid eg bacillus subtillis)
gram - (thin peptidoglycan without reichoic acid enveloped by lipid bilayer named "outer membrane" - eg escherichia coli) |
| Talk about capsules. | sometimes called glycocalyx, polymers of polysaccharides, cell-cell and cell-support adhesion, invasiveness pathogenic bacteria preventing phagocytosis. |
| Talk about flagella. | serve for locomotion, thread like appaendage having three parts, filament (tail made up of flagellin protein) hook (connection) and basal body ( ankored through the bacterial envelope and provokes motion inside cytoplasm) |
| Talk about pilli. | made of shorter proteins than flagella, serve in adhesion and conjugation, may serve as receptors of viruses at infection stage. |
| Talk about the outer layer of gram - bacterium. | having at the end lipopolysaccharides and at the beginning lipoproteins, outer membrane presenting porins (transporters) may be surrounded by capsule |
