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These cells contain discrete membrane-bound organelles e.g. nuclei, they are larger than Prokaryotic cells, but unlike prokaryotes, not all eukaryotic cells
have a cell wall.
NUCLEUS: Enclosed by an envelope composed of two membranes perforated by pores. Contains chromosomes and a nucleolus. The DNA in
chromosomes contain genes which code for protein synthesis.
NUCLOLUS: a dense body within the nucleus where ribosomes are made.
RIBOSOMES: made of RNA and protein, found free in the cytoplasm or attached to endoplasmic reticulum. They are the site of protein synthesis.
CELL SURFACE MEMBRANE: Phospholipid bilayer containing proteins forming a partially permeable membrane.
ROUGH ENDOPLASMIC RETICULUM: A system of interconnected membrane-bound, flattened sacs. Ribosomes attached. Proteins made by
these ribosomes are transported through the rER to other parts of the cell.
SMOOTH ENDOPLASMIC RETICULUM: Does not have attached ribosomes, makes lipids and steroids (e.g. reproductive hormones)
GOLGI APPARATUS: Stacks of membrane-bound sacs formed by fusion of vesicles from the ER. Modifies proteins and packages them into vesicles
LYSOSOME: Spherical sacs containing digestive enzymes and bound by a single membrane. Involve in the breakdown of unwanted structures within the
cell, and in destruction of old cells that need to be replace.
CENTRIOLES: one pair in every cell. They are hollow cylinders made up of a ring of nine globular protein microtubules. Involved in the formation of the
spindle during nuclear division and in transport within the cell cytoplasm.
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MITOCHONDRIA: The inner of its two membranes is folded to form finger-like projections called cristae. They are the site of the later stages of
The production of proteins and their route through the cell:
1. Transcription of DNA to mRNA, which leaves nucleus.
2. Proteins made on ribosomes enter rough ER.
3. Protein moves through the ER assuming its 3D shape.
4. Vesicles pinched off the rough ER contain the protein.