Exam 1 Part two Flashcards
What is meant by passive transport of materials into a cell?
Substances move across a plasma membrane without the expenditure of energy by the cell. Materials move along a concentration gradient (from high to low). No cellular energy (ATP) is needed for it to occur
What are the passive processes
Simple diffusion, osmosis, facilitated diffusion, & bulk filtration
Simple diffusion is
Occurs when substances move across membranes unaided because they are small or non polar. Higher to lower. Continues until evenly distributed
Osmosis is
Water diffuses from one side of the selectively permeable membrane to the other. In the body the movement of water between the blood & the extracellular fluid around cells occurs by osmosis
Facilitated diffusion is
Requires the participation of specific transport proteins that help the specific substances move across the plasma membrane. Glucose & amino acids move across the membrane by this means. Transport is aided by a protein.
Bulk filtration is
Involves the diffusion of solvents & solutes together across the selectively permeable membrane. An example is when fluid & certain solutes are transported from the blood into the extracellular fluid.
Phospholipids are
Make up most of the plasma membrane lipids. They contain both water-soluble & water-insoluble regions. They are called polar meaning they have a charge distributed unevenly through the molecule making one region a positive charge and one region a negative charge. The polar “head” is charged and hydrophilic. The two tails are uncharged and hydrophobic.
What is the fluid mosaic
Proteins and substances such as cholesterol become embedded in the bilayer, giving the membrane the look of a mosaic. Because the plasma membrane has the consistency of vegetable oil at body temperature, the proteins and other substances are able to move across it. That’s why the plasma membrane is described using the fluid-mosaic model.
What is selectively permeable?
The plasma membrane, it regulates the passage of gases, nutrients, & wastes between the internal & external environments. It is essential to a cells existence because it allows the entrance or exit of substances to be regulated or restricted
ATP is
Adenosine triphosphate. It provides the energy for that transport. Releases energy when the bond that attaches its third phosphate to the rest of the molecule is broken
What are the functions of the cell membrane?
Contains receptors for communication; forms intercellular connections; acts as physical barrier to enclose cell contents; regulates material movement into and out of the cell.
What are the various ways that molecules move through the cell membrane?
- Passive transport: Simple diffusion, osmosis, facilitated diffusion, & bulk filtration
- Active transport: Ion pumps & bulk transport
Active transport is
The movement of a substance across a plasma membrane against a concentration gradient. Materials go from low to high. Requires cellular energy (ATP) & sometimes a transport protein
Ion pumps are
Active transport processes that move ions across the membrane are called ion pumps. One type of ion pump is the sodium potassium pump. It moves one ion into the cell while simultaneously removing another type of ion from the cell.
Bulk transportation is
Macromolecules, such as large proteins and polysaccharides, move across the membrane via the active transport processes called exocytosis & endocytosis
Exocytosis is
Large molecules are secreted from the cell & normally packaged within intracellular transport vesicles which move toward the plasma membrane
Endocytosis is
When extracellular macromolecules & large particulate matter are packaged in a vesicle that forms at the cell surface for internalization into the cell.
Organelles are
Complex, organized structures with unique, characteristic shapes. Each type of organelle performs a different function for the cell. They assume specific roles in growth, repair, and cellular maintenance. Two types of organelles are membrane bound organelles and non membrane bound organelles
Membrane bound organelles
1) Endoplasmic reticulum
2) Golgi apparatus
3) Lysosomes
4) Peroxisomes
5) Mitochondria
Non membrane bound organelles
1) Ribosomes
2) Cytoskeleton
3) Microtubules
4) Centrosome & centrioles
5) Cilia & flagella
6) Microvilli
Microvilli is
Thin, microscopic projections extending from the surface of the plasma membrane. Not all cells have microvilli. They normally occur in the small intestine.
Cilia is
Projections extending from the cell. Composed of cytoplasm & supportive microtubules, they are enclosed by the plasma membrane. Usually found in large numbers on the exposed surfaces of certain cells.
Function of cilia
Move fluid, mucus, & materials over the cell surface
Function of microvilli
Increase membrane surface area for increased absorption &/or secretion
Chromatin
When a cell is not dividing, the DNA & it’s associated proteins are in the form of an unwound, finely filamented mass called chromatin. Site of genes in the DNA.
Peroxisomes are
Membrane-enclosed sacs; contain large amounts of enzymes to break down harmful substances. Convert hydrogen peroxide formed during metabolism to water.
Chromatids are
A duplicated chromosome consists of two genetically identical structures called sister chromatids. Each one is composed of an identical DNA double helix and the two sister chromatids are joined together by proteins at a contracted region called the centromere
Centromere is
The region where the two sister chromatids are joined together by proteins
What is interphase? What role does it serve in the cell cycle?
Normal metabolic activities with no change in cytoplasm or nucleus. Cell is NOT dividing and chromosomes are NOT visible. This is the time when DNA is replicated.
Collagen fibers are
Composed of the protein collagen. They are strong, flexible, & resistant to stretching. Most abundant protein in the body.
Elastic fibers are
Contain the protein elastin and are thinner than collagen fibers. They stretch easily, branch, rejoin, and appear wavy.
Reticular fibers are
Thinner than collagen fibers. They contain same protein subunits that collagen has, but are combined in a different way. Tough but flexible. Abundant in the stroma. They support organs & resist external forces.
Neuron v. neuroglia
Neurons: Responsible for control; info processing, storage, & retrieval; internal communication
Neuroglial cells: Support & protect neurons
This type of tissue doesn’t have any striations
Smooth muslce
An example of merocrine secretion
Salivary glands
Ground substance is
Part of extracellular matrix
Goblet cells is
Unicellular exocrine gland
Dense regular connective tissue are
Parallel arrangement of protein fibers
Endothelium lines
Blood vessel lumen
Contains intercalated disces
Cardiac muscle
Scattered arrangement of protein fibers
Dense irregular connective tissue
Avascular is?
A characteristic of all epithelia
Which type of tissue contains a calcified ground substance & is specialized for structural support?
Bone connective tissue