Chapter 3 - The Cellular Level of Organization Flashcards
Cell & Three components
living structural and functional units enclosed by a membrane. Membrane, nucleus, cytoplasm
Plasma membrane
flexible outer surface, separating internal from external. Regulates flow of materials and communicate.
Cytoplasm
cellular contents between plasma and nucleus, fluid portion is cytosol, within which are organelles
Nucleus
large organelle with DNA.
Fluid mosaic model
molecular arrangement of the plasma membrane resembles continually moving sea of fluid lipids that contains a mosaic of proteins
lipid bilayer
two back to back layers made up of three types of lipid molecules, phospholipids, cholesterol, and glycolipids.
phospholipid
lipids that contain phosphorous
cholesterol
a steroid with an attached OH group
glycolipid
lipids with attached carbohydrate groups
amphipathic
polar and non polar parts
Polar = phosphate head, water loving.
Not polar = hydrophobic = tails
Integral proteins
extend through lipid bilayer
transmembrane
span entire lipid bilayer, protrude into cytosol and extracellular. Amphipathic.
Glycocalyx
the carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat. Acts like signature so cells recognize each other. Basis of immune response.
Ligand
Receptors for cellular recognition, a specific molecule that binds to a receptor is called a ligand
Factors that influence diffusions rates
Steepness of the concentration gradient. Temperature. Mass of the diffusing substance. Surface area. Diffusion distance.
Aquaporins
transport water across cell membranes in response to osmotic gradients
Hydrostatic pressure
pressure of fluid on the walls. pressure of fluid in confined space
Tonicity
The ability of a solution surrounding a cell to cause that cell to gain or lose water
Isotonic solution
equal concentrations of impermeable solutes on either side of the membrane
Hypotonic solution
a solution that contains fewer dissolved particles (such as salt and electrolytes) than is found in normal cells and blood. Used to give IV
Hemolysis
rupture or destruction of red blood cells
Lysis
disintegration of a cell by rupture of the cell wall or membrane
Symporter/Antiporter
proteins that are used in transport of substances across a cell membrane. Anti=opposite direction
Diffusion
Movement of molecules or ions down a concentration gradient due to their kinetic energy until they reach equilibrium.
Simple diffusion
Passive movement of a substance down its concentration gradient through the lipid bilayer of the plasma membrane without the help of membrane transport proteins.
Nonpolar, hydrophobic solutes: oxygen, carbon dioxide, and nitrogen gases; fatty acids; steroids; and fat-soluble vitamins. Polar molecules such as water, urea, and small alcohols.
Facilllitated diffusion
Passive movement of a substance down its concentration gradient through the lipid bilayer by transmembrane proteins that function as channels or carriers.
Polar or charged solutes: glucose; fructose; galactose; some vitamins; and ions such as K, Cl, Na, and Ca2.
Osmosis
Polar or charged solutes: glucose; fructose; galactose; some vitamins; and ions such as K, Cl, Na, and Ca2.
Solvent: water in living systems
Active Transport
Active process in which a cell expends energy to move a substance across the membrane against its concentration gradient by transmembrane proteins that function as carriers.
Polar or charged solutes
Primary active transport
Active process in which a substance moves across the membrane against its concentration gradient by pumps (carriers) that use energy supplied by hydrolysis of ATP.
Na, K, Ca2, H, I, Cl, and other ions.
Secondary active transport
Coupled active transport of two substances across the membrane using energy supplied by a Na or H concentration gradient maintained by primary active transport pumps. Antiporters move Na (or H) and another substance in opposite directions across the membrane; symporters move Na (or H) and another substance in the same direction across the membrane.
Antiport: Ca2, H out of cells. Symport:
glucose, amino acids into cells.
Transport in vesicles
Active process in which substances move into or out of cells in vesicles that bud from plasma membrane; requires energy supplied by ATP.
Receptor-mediated endocytosis
Ligand–receptor complexes trigger infolding of a clathrin-coated pit that forms a vesicle containing ligands.
Ligands: transferrin, low-density lipoproteins (LDLs), some vitamins, certain hormones, and antibodies.
Phagocytosis
“Cell eating”; movement of a solid particle into a cell after pseudopods engulf it to form a phagosome.
Bacteria, viruses, and aged or dead cells
Bulk-phase endocytosis
“Cell drinking”; movement of extracellular fluid into a cell by infolding of plasma membrane to form a vesicle.
Solutes in extracellular fluid
Exocytosis
Movement of substances out of a cell in secretory vesicles that fuse with the plasma membrane and release their contents into the extracellular fluid.
Neurotransmitters, hormones, and digestive enzymes.
Transocytosis
Movement of a substance through a cell as a result of endocytosis on one side and exocytosis on the opposite side.
Substances, such as antibodies, across endothelial cells. This is a common route for substances to pass between blood plasma and interstitial fluid.
Cytosol
Composed of water, solutes, suspended particles, lipid droplets, and glycogen granules.
Fluid in which many of cell’s metabolic reactions occur.
Cytoskeleton
The cytoskeleton is a network in the cytoplasm composed of three protein filaments: microfilaments, intermediate filaments, and microtubules.
The cytoskeleton maintains shape and general organization of cellular contents; responsible for cell movements.
Centrosome
Pair of centrioles plus pericentriolar material.
The pericentriolar material contains tubulins, which are used for growth of the mitotic spindle and microtubule formation.
Cilia and flagella
Motile cell surface projections that contain 20 microtubules and a basal body.
Cilia: move fluids over cell’s surface; flagella: move entire cell.
Ribosome
Composed of two subunits containing ribosomal RNA and proteins; may be free in cytosol or attached to rough ER.
Protein synthesis.
Endoplasmic Reticulum
Membranous network of flattened sacs or tubules. Rough ER is covered by ribosomes and is attached to the nuclear envelope; smooth ER lacks ribosomes.
Rough ER: synthesizes glycoproteins and phospholipids that are transferred to cellular organelles, inserted into plasma membrane, or secreted during exocytosis; smooth ER: synthesizes fatty acids and steroids, inactivates or detoxifies drugs, removes phosphate group from glucose-6-phosphate, and stores and releases calcium ions in muscle cells.
Golgi complex
Consists of 3–20 flattened membranous sacs called cisternae; structurally and functionally divided into entry (cis) face, medial cisternae, and exit (trans) face.
Entry (cis) face accepts proteins from rough ER; medial cisternae form glycoproteins, glycolipids, and lipoproteins; exit (trans) face modifies molecules further, then sorts and packages them for transport to their destinations.
Lysosome
Vesicle formed from Golgi complex; contains digestive enzymes.
Fuses with and digests contents of endosomes, pinocytic vesicles, and phagosomes and transports final products of digestion into cytosol; digests worn-out organelles (autophagy), entire cells (autolysis), and extracellular materials.
Peroxisome
Vesicle containing oxidases (oxidative enzymes) and catalase (decomposes hydrogen peroxide); new peroxisomes bud from preexisting ones.
Oxidizes amino acids and fatty acids; detoxifies harmful substances, such as hydrogen peroxide and associated free radicals.
Proteasome
Tiny barrel-shaped structure that contains proteases (proteolytic enzymes).
Degrades unneeded, damaged, or faulty proteins by cutting them into small peptides.
Mitochondrion
Consists of an outer and an inner mitochondrial membrane, cristae, and matrix; new mitochondria form from preexisting ones.
Site of aerobic cellular respiration reactions that produce most of a cell’s ATP. Plays an important early role in apoptosis.
Nucleus
Consists of a nuclear envelope with pores, nucleoli, and chromosomes, which exist as a tangled mass of chromatin in interphase cells.
Nuclear pores control the movement of substances between the nucleus and cytoplasm, nucleoli produce ribosomes, and chromosomes consist of genes that control cellular structure and direct cellular functions.
Transcription steps
- mRNA directs synthesis of a protein.
- rRNA joins
- tRNA binds
Interphase
Period between cell divisions; chromosomes not visible under light microscope.
G1 phase
Metabolically active cell duplicates most of its organelles and cytosolic components; replication of chromosomes begins. (Cells that remain in the G1 phase for a very long time, and possibly never divide again, are said to be in the G0 phase.)
S phase
Replication of DNA and centrosomes.
G2 Phase
Cell growth, enzyme and protein synthesis continue; replication of centrosomes complete.
Mitotic phase
Parent cell produces identical cells with identical chromosomes; chromosomes visible under light microscope.
Mitosis
Nuclear division; distribution of two sets of chromosomes into separate nuclei.
Prophase
Chromatin fibers condense into paired chromatids; nucleolus and nuclear envelope disappear; each centrosome moves to an opposite pole of the cell.
Metaphase
Centromeres of chromatid pairs line up at metaphase plate.
Anaphase
Centromeres split; identical sets of chromosomes move to opposite poles of cell.
Telophase
Nuclear envelopes and nucleoli reappear; chromosomes resume chromatin form; mitotic spindle disappears.
Cytokinesis
Cytoplasmic division; contractile ring forms cleavage furrow around center of cell, dividing cytoplasm into separate and equal portions.
Nucleus
The nucleus consists of a double nuclear envelope; nuclear pores, which control the movement of sub- stances between the nucleus and cytoplasm; nucleoli, which produce ribosomes; and genes arranged on chromosomes, which control cellular structure and direct cellular activities.
