38 terms

4.5b Non-membrane bound organelles

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Are ribosomes membrane-bound?
No; ribosomes have no membrane.
What two substances to ribosomes contain?
They contain ribonucleic acid (RNA) and proteins.
Name the 3 hollow areas of the ribosome.
E, P, and A sites
Where are ribosomes synthysized? Where do they move to on completion?
Nucleolus; cytosol.
What two states do ribosomes have?
Bound or free states.
Where are bound ribosomes found?
Attached to the external surface of the ER membrane to form rough ER.
What is function of bound ribosomes?
They are synthesize 3 specialized proteins
What 3 functions do bound ribosomal specialized proteins exhibit?
They are exported from the cell, become integral proteins in the plasma membrane, or serve as enzymes within lysosomes.
Where are free ribosomes found?
Suspended within the cytosol.
What is the function of free ribosomes?
They synthesize the majority of proteins within a cell.
What are the 3 main functions of the cytoskeleton?
It provides intracellular structural support and organization of organelles, cell division, movement of materials.
Where are anchor points located for the cytoskeleton to bind to?
Anchor points are located in the plasma membrane.
What are anchor points made of?
Anchor points are proteins.
What 3 separate protein molecules form the cytoskeleton?
Microfilaments, intermediate filaments, and microtubules.
What are the smallest components of the cytoskeleton?
Microfilaments are.
What is the diameter of microfilaments?
7 nm.
What are microfilaments composed of?
Actin protein monomers organized into two thin, intertwined protein filaments.
What analogy is used to describe microfilaments?
Two twisted pearl necklaces.
What structure of the cytoskeleton performs the following functions: maintain cell shape, form internal support of microvilli, separate two cells formed during cytokineses, facilitate cytoplasmic streaming, participate in muscle contraction?
The microfilament does.
What is the size range of intermediate filaments?
Between 8 and 12 nm in diameter.
What are two examples of intermediate filaments?
Keratin, neurofilaments are.
Are intermediate filaments more or less rigid than microfilaments?
They are more rigid.
What are the largest structures of the cytoskeleton?
Microtubules are.
What is the diameter of a microtuble?
Approximately 25 nm in diameter.
What are microtubules composed of?
Tubulin.
What structure of the cytoskeleton performs the following functions: maintain cell shape, form protein components of cilia and flagella, participate in cellular transport of vesicles, and separate chromosomes during cell division.
Microtubules do.
What unique characteristic do microtubules have?
They can be elongated or shortened as needed to complete their function.
To which organelle is the centrosome situated close to?
It is close to the nucleus.
Which function does the centrosome play a role in?
Organizing microtubules within the cytoskeleton; creation of mitotic spindle for cell division.
What pair of structures is located in the centrosome?
The centrioles.
What are the major protein-digesting organelles located within both the cytosol and nucleus of cells?
Proteasomes are
What non-membrane bound organelle degrades cell proteins through an ATP dependent pathway?
Proteasomes do.
What types of proteins do proteasomes digest?
Damaged proteins, incorrectly folded proteins, and normal proteins that are no longer needed by the cell.
What by-function is achieved through proteasomes normal function?
Quality control of exported cell proteins.
In what processes is the quality control of exported cell proteins by proteasomes important?
Regulation of cellular metabolism, cell division, and cell signaling.
What protein-marker tells a proteasome that it is ready for digestion?
Ubiquitin does.
What two different organelles are labeled as "garbage men" and "garbage disposals?" From where does the difference in these two monikers come from?
Lysosomes are called "garbage men" due to their clean up activity, transporting and digesting old cells and unwanted substances that enter through the plasma membranes. Proteasomes are "garbage disposals" because they specifically break down proteins, though they do not transport them anywhere within the cell.
Which non-membrane-bound organelle functions primarily in digestion within the cell?
The proteasome does.
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