The organelles outside the endomembrane system: mitochondria, plastids, ribosomes, the cytoskeleton, cilia and flagella, centrosome and centrioles, microbodies, and the nucleus with its chromosomes.
3 lessons, about 1 h 30 min3 simulations10 problems3 practice questionsPython in every lesson
Created by StemPy LabMitochondria and plastids each have two membranes, their own circular DNA and 70S ribosomes. Mitochondria carry out aerobic respiration and make ATP. Plastids are chloroplasts, chromoplasts or leucoplasts. A chloroplast holds stacks of thylakoids, the grana, in a fluid called the stroma.
Ribosomes are made of RNA and protein, with no membrane: 80S in eukaryotes and 70S in prokaryotes. The cytoskeleton of microtubules and filaments gives support, shape and movement. Cilia and flagella have a 9 + 2 axoneme and grow from basal bodies. A centriole is a cartwheel of nine triplets.
Robert Brown described the nucleus in 1831. It has a double nuclear envelope with pores, a nucleoplasm, nucleoli that make ribosomal RNA, and chromatin of DNA and histones. In a dividing cell the chromatin forms chromosomes, named by where the centromere lies. Microbodies are small vesicles of enzymes.
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