The structural and functional unit or living organisms
What are the three major regions of the cell?
The plasma membrane, cytoplasm, and nucleus.
Describe the nucleus in detail
Round or oval shaped organelle that contains DNA (genetic material of the cell). It is encapsulate by the double layer nuclear envelope and also contains the nucleolus.
What is chromatin?
The DNA in a more loose/thread-like structure within the cell.
What are chromosomes?
Chromatin that has been tightly condensed and replicated that stain dark
What does a dark nucleus indicate?
The cell is dying or undergoing degeneration.
What is the nucleoli?
What occurs there?
Area of the nucleus that contains proteins and RNA. Assembly site for ribosomal particles abundant in the cytoplasm
What are ribosomes?
The site where protein synthesis occurs. The are composed of particles from the nucleoi.
What is the Nuclear envelope?
Double layered, porous membrane that surrounds the nucleus.
What are the nuclear pores?
Protein complexes that regulate the passage of molecules in and out of the nucleus.
What molecules do the nuclear pores permit passage to?
Proteins and RNA.
Define Plasma membrane.
Plasma membrane is composed separates the cell cytoplasm (or contents) from the extracellular fluid.
What are the main structural blocks of the pm?
Phospholipids and Globular proteins. Composed of a polar (hydrophilic) phosphate head group attached to a lipid chain tail that is (hydrophobic).
What does selective permeability refer to? What molecules are able to pass freely through the plasma membrane?
The plasma membrane is able to regulate what enters and exits the cell. Hydrophobic or nonpolar molecules are permitted to pass freely through the membrane because it is mostly composed of a hydrophobic interior.
What are the two basic transport methods?
Passive transport and Active transport.
What is the difference between active and passive transport?
Active transport requires energy to be used to move a molecule across the membrane. Passive transport is the free movement of molecule across the plasma membrane due to concentration gradient and does not require the expenditure of energy.
What are examples of active transport?
Primary active transport is demonstrated by the Na+/K+ pump. that used ATP to pump Na+ into a cell against the concentration gradient. Secondary active transport is the movement of molecules that occurs due to the process of active transport.
Minute fingerlike projections or folds of the plasma membrane.
What is the advantage of microvilli?
It increases the surface area of the cell
What does organelle mean?
Small organ, They are the functional units of cells.
Where are organelles located?
Within the cytoplasm, they are suspended in the cytosol.
What is the endoplasmic reticulum?
A folded system of membranous tubules of cistern (sacs) organelle that is either the site for steroid based hormone synthesis (smooth ER) or post translational modification of proteins, phospholipids, and cholesterol (Rough ER)
What is the defining characteristic between Rough ER and Smooth ER?
Ribosomes are embedded in the membrane of Rough ER.
Does a cell have both?
Depending on the function of the cell. It is not required to have both in every cell.
What else does the Rough ER do?
The external face of the rough ER is involved in phospholipid and cholesterol synthesis.
Describe the Golgi apparatus
A stack of flattened sacs with bulbous ends associated with membranous vesicles generally close to the nucleus. Proteins are delivered by vesicles from teh rough ER where they are modified and segregated then packaged into membranous vesicles.
What are the 3 fates of vesicles produced by the Golgi apparatus?
1. They can become incorporated into the plasma membrane, 2. Become secretory vesicles that release their contents from the cell, or 3. become lysosomes.
Lysosomes are vesicles (membrane bound sacs) that contain an array of digestive enzymes such as acid hydrolases (enzymes capable of digesting worn-out cell structures and foreign substances.
What destination ability do the lysosomes have? what is their nick name due to this property?
They total cell destruction capabilities and have coined the term "suicide sacs"
Enzyme-containing sacs that are important in detoxifying harmful substances, such as free radicals. They are abundant in kidney and liver cells.
They are rod shaped bodies incapsulated in a double-membrane wall with the inner membrane containing folds or cristae. They contain oxidative enzymes that catalyze reactions of the krebs cycle and the electron transport chain that produce high energy containing molecules.
What are the three cytoskeletal elements within the cell?
What is meant by cytoskeleton?
The internal scaffolding of the cell structure.
What is microtubule?
Slender tubules formed of tubulin proteins.
Where are microtubules located?
Radiate from the centrosome (near the nucleus)
What are the functions of the microtubules?
Organize the cytoskeleton and form the spindle during cell division. Also transport substances down the length of elongated cells, suspend organelles, and help maintain cell shape by providing rigidity to the soft cellular substance.
What are the functions of the microfilaments?
Ribbon or cordlike elements that are formed of contractile proteins, primarily actin. They are important in cell motility because they are specialized to contract.
What is the terminal web
Cross linked network of microfilaments that braces and strengthens the internal face of the plasma membrane
What are the functions of the intermediate filaments?
Stable, proteinacious cytoskeletal elements that act as internal guy wires to resist mechanical pulling forces acting on cells.
What is another name for them? What is that role
Paired rod-shaped structures that lie at right angle to each other, close to nucleus, within the centrosome. Composed of 9 triplets of microtubules. Directs the formation of the mitotic spindle, also form the cell projections cilia and flagella (basal bodies).
What are inclusions
Various other substances and structures, including stored foods (glycogen granules and lipid droplet), pigment granules, and crystals of various types, water vacuoles and ingested foreign materials that are not active metabolic machinery of the cell.