Cells 🔬

• Prokaryotic cells lack a nucleus and other membrane-bound organelles.
• Both eukaryotic and prokaryotic cells contain a nucleus, cytoplasm, ribosomes, mitochondria, DNA, and chloroplasts
• The cytoplasm is responsible for the chemical reactions that take place in the cell
• Ribosomes are responsible for protein synthesis in the cell. They are made up of RNA and proteins
• The plasma membrane is made primarily of a bilayer formed from phospholipids as a consequence of their hydrophobic and hydrophilic regions
• Cytosol is the liquid part of the cytoplasm - it is a fluid substance made of water and dissolved solutes
• Dissolved substances in the cytosol are needed to carry out the metabolic processes required to keep the cell alive
• Ribosomes catalyze the synthesis of polypeptides during translation
• Ribosomes are composed of two subunits that come together to from a functioning structure
• The ribosomes are made from dozens of proteins arranged on a scaffold composed or ribosomal RNA that functions as a ribozyme
• Prokaryotes have smaller ribosomes, they are 70S
• Eukaryotes have larger ribosomes, they are 80S
• DNA is not enclosed in a membrane, it is found freely in the cytoplasm in prokaryotic cells
• prokaryotic cells divide by binary fission, while eukaryotic cells divide by mitosis, meiosis and binary fission
• prokaryotic have no membrane bound organelles, while eukaryotic have membrane bound organelles
• prokaryotic cells can have plasmids while eukaryotic cannot
• DNA in prokaryotic cells are not wrapped around proteins
• Prokaryotic cells have flagella that rotate to move, while eukaryotic cells have flagella that whip back and forth to move
• Prokaryotic cell walls contain peptidoglycan, while eukaryotic contain cellulose or chitin
• Pili/pilius enable the cell to attach to surfaces, swap DNA with other cells and harpoon DNA in the environment
• The (slime) capsule helps the cell keep from dehydrating and adhere to surfaces
• Nucleus contains the DNA, which stores information for making proteins via translation and transcription
• The nucleus contains the nucleolus, which is where ribosome subunits are made
• 'Free' ribosomes float in the cytoplasm synthesizing polypeptides used within the cell
• 'Bound' ribosomes are attached to the RER, synthesizing polypeptides that are secreted from the cell or become integral proteins in the cell membrane
• The rough endoplasmic reticulum (RER) is a series of connected flattened membranous sacs that play a central role in the synthesis and transport of polypeptides
• The smooth endoplasmic reticulum (SER) us a series of connected membranous sacs that are continuous with the RER
• The SER's main functions are the synthesis of phospholipids and cholesterol for the formation and repair of membranes
• The golgi apparatus is a series of flattened membrane-bound sacs that are involved in the modification and packaging of proteins into vesicles
• Vesicles are membrane-bound sacs that contain and transport materials within cells
• Transport vesicles move molecules between locations inside the cell by budding off one organelle compartment and fusing it with another
• Secretory vesicles secrete molecules from the cell via exocytosis. They are also how new phospholipids are added to the cell membrane
• Lysosomes are small sacs that contain enzymes that break down waste products
• Mitochondria is surrounded by a double membrane and are adapted for production of ATP (energy) by aerobic cellular respiration
• Chloroplasts are adapted for photosynthesis, which captures light energy and uses it with water and carbon dioxide to produce glucose
• Within chloroplasts are light-absorbing pigments such as chlorophyll
• Mature plant cells have a central vacuole that occupies 30%-90% of the cell volume
• Plant vacuoles also maintain turgor pressure against the cell wall. The turgor pressure is a mechanism for the plants to remain upright
• The cytoskeleton helps the cells maintain their shape, organizes cell parts and enables cells to move and divide.
• The cytoskeleton is made up of microtubules, actin filaments, and intermediate filaments