cell structure

• The nucleus is the largest organelle in eukaryotic cells and contains DNA, which holds genetic information for producing proteins.
• DNA is packed with histone proteins to form chromatin.
• The nucleolus is a dense region inside the nucleus that produces ribosomes.
• The nuclear envelope is a double membrane that separates the nucleus from the rest of the cell.
• Nuclear pores allow mRNA and ribosomes to travel between the nucleus and cytoplasm.
• Ribosomes are organelles involved in protein synthesis and can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum.
• Ribosomes are made in the nucleolus and then sent out to the cytoplasm.
• Eukaryotic cells have various types of membrane-bound organelles that carry out specific functions.
• The nucleus is the largest organelle in eukaryotic cells and contains DNA, the genetic information for producing proteins.
• Light or Optical microscopes have poor resolution due to the wavelength of light.
• Transmission electron microscopes have higher magnification and resolution as electrons pass through specimen.
• Capsule, plasmids, and flagellum may be present in Mycoplasma.
• The cell wall of Mycoplasma is made up of a glycoprotein called murin.
• Scanning electron microscopes create 3D images as electrons bounce off the surface.
• Laser scanning confocal microscopes use laser light to create high-resolution 3D images.
• Resolution is the minimum distance between two objects to view them as separate.
• Light microscopes use wavelength of light, electron microscopes use wavelength of electrons to determine resolution.
• Magnification refers to how much larger the image is compared to the actual object.
• Four types of slide preparation for light microscopes: dry mount, wet mount, squash slide, and smear slide.
• Wet mounts are most common and used for viewing living aquatic organisms.
• Squash slides are used for viewing thin layers of cells.
• Smear slides are used for examining blood cells in a blood sample.
• Eyepiece graticule is a scale inside the eyepiece of a light microscope used to measure the size of an object.
• Different lenses on microscope cause different magnifications, so calibration is necessary.
• Calibration involves using a stage micrometer to align with the eyepiece graticule and counting how many divisions on the graticule fit into one division on the stage micrometer.
• Staining is used to make cell components more visible under the microscope.
• Differential staining involves using different chemical stains to stain different parts of the cell different colors.
• Crystal violet and methylene blue are positively charged stains, and Gram's stain is commonly used to identify bacteria.
• Gram-positive bacteria appear blue or purple due to thick peptidoglycan cell wall.
• Eukaryotes include animals, plants, and fungi.
• Ribosomes are made up of two subunits of protein and RNA and are the site of protein synthesis.
• Mitochondria contain their own ribosomes and loops of DNA.
• 13 organelles in eukaryotic cells: Nucleus, Flagella, Cilia, Centrioles, Cytoskeleton, Endoplasmic reticulum (ER), Rough ER, Smooth ER, Golgi apparatus, Vesicles, Lysosomes, Peroxisomes, Mitochondria, Chloroplasts, Vacuoles.
• 70s ribosomes are found in prokaryotic cells, while circular DNA is not contained within a nucleus.
• The plasma membrane controls what enters and exits the cell.
• Ribosomes are found in the cytoplasm of eukaryotic cells or in mitochondria and chloroplasts for eukaryotes.
• Chloroplasts contain thylakoids and grana and contain enzymes needed for photosynthesis.
• Laser scanning confocal microscopes use fluorescent dyes and high light intensity to create a 2D or 3D image.
• Plants have cellulose in their cell walls, while fungi have chitin.
• Prokaryotic cells are much smaller than eukaryotic cells and have no membrane-bound organelles.