1.2 Ultrastructure Of Cells Flashcards
What is a eukaryotic cell?
Complicated internal structure. Membranes compartmentalize cell. Compartments called organelles. Have nucleus and true DNA. Larger ribosomes (80S).
What are some advantages of compartmentalization?
Enzymes and substrates can be concentrated where used. Damaging substances can be contained. Conditions (pH) can be maintained. Organelles with contents can be moved around cell.
What is the difference between exocrine and endocrine?
Exocrine cells secrete enzymes through a duct. These cells have lots of rER, Golgi apparatus and vesicles (cause enzymes are proteins).
Endocrine cells secrete hormones by exocytosis straight into bloodstream.
How are plant and animal cells different?
Plant cell: cell wall, chloroplasts, vacuole larger than nucleus, no centrioles.
Animal cell: no cell wall, chloroplasts, or large vacuoles. Has centrioles.
What is a prokaryotic cell?
Simplest cell structure. No membrane-bound organelles. Uncompartmentalized. Has 70S ribosomes. DNA not associated with proteins. Divide by binary fission. Smaller in size.
What is the nucleus?
Double membrane. Contains chromosomes (DNA + protein). Nucleus is where DNA is replicated.
What is the endoplasmic reticulum?
Flattened membrane sacs (cisternae). Rough ER has ribosomes attached. Synthesizes protein which is passed into cisternae and carried by vesicles to Golgi apparatus.
What is the Golgi apparatus?
Flattened membrane sacs shorter than ER. Often curved. No ribosomes. Many vesicles. Processes proteins from rER, carried by vesicles to plasma membrane.
What are lysosomes?
Spherical with single membrane. Formed from Golgi vesicles. Contain high concentrations of protein and digestive enzymes to break down food, organelles, or entire cell.
What is the mitochondria?
Double membrane with invaginated internal membrane to form cristae. Fluid inside called matrix. Usually spherical or ovoid. Produces ATP required for cell respiration. Fat digested here if being used as energy source.
What are free ribosomes?
Not surrounded by membrane. 80S, same as ribosomes attached to rER. Synthesize protein to work in cytoplasm or as enzymes. Constructed in nucleolus.
What is a chloroplast?
Double membrane. Spherical or ovoid. Produce glucose and other organic compounds through photosynthesis. Starch grains present if photosynthesizing rapidly.
What are vacuoles and vesicles?
Single membrane with fluid inside. Vesicles are smaller vacuoles. Plant cells have large vacuoles. Animal cells digest food in vacuoles. Unicellular organisms use vacuoles to expel excess water.
What are microtubules and centrioles?
Small cylindrical fibres that move chromosomes during cell division. Animal cells have centrioles (made of microtubules).
What are cilia and flagella?
Whip-like structures protruding from cell surface. Flagella are larger and usually only one present (sperm). Cilia are small and many. Used for locomotion
