Ch. 4.4- Intracellular Structures Flashcards
What are ribosomes for?
Creating proteins
What are ribosomes made up of?
40S and 60S subunits that make up an 80S ribosome.
Where are ribosomes found?
Free floating in the cytoplasm or attached the rough endoplasmic reticulum
What type of proteins do ribosomes make that are attached to the rough ER?
Makes proteins that are destined for secretion from the cell
What parts of the cell have 70S ribosomes?
Mitocondria and chloroplasts
What are the roles of the cytoskeleton?
Made of protein fibers that maintain shape, help facilitate movement, protect against external forces, and directs transport of vesicles, and other cellular cargo. Helps organize cell division by moving chromosomes and organelles to developing daughter cells.
What are the three main fibers that make up the cytoskeleton?
Microtubules, intermediate filaments, and microfilaments.
What are microtubules made of?
Tubulin. 25 nm in diameter.
Microtubules arise from and are attached to structures called centrosomes.
What do microtubules do during cell division?
They polymerize to make a structure called the spindle.
What does the spindle do?
Helps separate chromosomes and deliver organelles to forming daughter cells.
Describe centrosomes and where they are located.
Located near the nucleus. Made up of two centrioles and surrounding unstructured materials.
Describe centrioles structure
Barrel-shaped structures made of microtubules arranged in a cartwheel structure of nine triplets
Describe intermediate filaments structure and function
Rope-like fibers. 10 nm in diameter.
Contribute tensile strength to oppose external mechanical forces. What they are made of differs from cell type to cell type.
Define microfilaments structure and function.
Fine fibers made up of the protein actin. 3-6 nm. Associated with the protein myosin to facilitate movement. These allows muscles to contract and helps divide cells.
Also act as roadways in cells used by myosin motor proteins.
Also polymerize and depolymerize to facilitate cell movement using pseudopodia. — this is the motility mechanism of amoebae.
Describe nucleus structure and function
Distinct membrane enclosed structure. Houses DNA- orchestrates all cellular activity.
Organized as chromatin (collection of DNA and protein)
Chromatin floats in the liquid nucleoplasm.
Dense part of nucleus (nucleolus) is enriched with RNA.
Has a double membrane structure called the nuclear envelope that controls movement of substances in and out of the nucleus.– this envelope give rise the the ER.
