Introductory Biology

3.3 Cell Organelles

Cells are NEVER static but they are dynamic. Cells contain various organelles inside. The nucleus is like the head quarter of the cells and directs the cell activities. The nuclear envelope  have double membrane of lipid bilayers,  pores for the RNA system, and ribosomal proteins.  Ribosomes are made in the nucleolus. The pores in the nuclear envelope are like security guards and they decide what goes in and what goes out.

An internal membrane system sort out the proteins. Ribosomes make the proteins and are produced out of RNA and protein. The endoplasmic reticulum (ER) have two types; the smooth and rough ER. The smooth ER adds more membranes and also gets rid of toxics. The rough ER are dotted with structure/ ribosomes. The vesicles carry the proteins from the rough ER to the golgi apparatus. Some of the vesicles move to the cell membrane and release their contents outside of the cell. Vesicles like lysosomes, which digests/recycle damaged cellular structures,  stay inside the cell.

Golgi Apparatus -> primary lysosome -> secondary lysosome -> products of digestion -> plasma membrane -> undigested materials

Chromatin are long and thin. They condense into thick molecules like chromosomes. Cell walls help protect/ support the cells. The central vacuole is a large membrane-bound space which stores ions, nutrients, wastes, and water. The central vacuole pushes up against the cell wall so it stays up right.

Cytoskeleton holds the cells together. There are three types of cytoskeletons: microfilaments, microtubule, and intermediate filaments. Microfilaments help move your muscles. Microtubule are hollow tubes made of a bunch of proteins and are the tracks of what the other motor proteins move on. They use the energy of ATP to walk and move. The fibers are hair and really thin. The dynein “walking” moves cilia and flagella by bending back and forth with the little motor proteins of microtubule.

The mitochondria makes the ATP. ATP is almost used in everything a cell performs and is like the” energy currency” of the cells. They are descendants of free-living bacterias because they have their personal DNA and ribosomes. Plants and animals have mitochondria. Mitochondria helps break down glucose molecules and release energy and is stored in the ATP.  Chloroplasts also have their own DNA but they are only in plants.

** Plant cells differ from animal cells because they contain cell walls, chloroplasts, and the central vacuole. Cell walls help support and protect the cell and are produced out of cellulose. Chloroplasts are the ‘site of photosynthesis’ and they use the energy from the sunlight to produce new molecules. They make the plants look green because they contain the pigment chlorophyll. Chloroplasts are descendants of free-living bacteria because have their own DNA. The central vacuole is a space where water, ions, nutrients and wastes are stored. The central vacuole is a large membrane which also keeps the plant upright when it is filled with water, pushing the cell wall into place.


One thought on “3.3 Cell Organelles

  1. Yurika,

    Excellent blog. Your entry is well-organized and thorough. However, you didn’t mention the three aspects of plant cell organization that differ from animal cells.

    Mr. F.

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