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Anatomy Chapter 3
Cellular Level of Organization
69
Anatomy
Undergraduate 1
09/22/2006

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Term
general parts of the cell (3)
Definition
Plasma membrane, cytoplasm, nucleus.
Term
plasma membrane
Definition
The cell's outer surface, providing a sturdy barrier. It consists of 2 back-to-back phospholipid layers (with cholesterol, glycolipids) and integral and peripheral proteins.
Term
lipid bilayer
Definition
The basic framework of the plasma membrane, consisting of 2 back-to-back phospholipid layers, cholesterol, and glycolipids.
Term
cytoplasm
Definition
All the cellular contents between the plasma membrane and the nucleus. Contains cytoplasm and organelles.
Term
cytosol
Definition
Fluid protein inside the cell (intracellular) inside the cytoplasm.
Term
organelles
Definition
Permanent structures within a cell that are specialized to serve a specific fundtion in cellular activities.
Term
nucleus of the cell
Definition
Site which contains the genes which control cellular structure and most cellular activities.
Term
integral proteins
Definition
"Transmembrane" proteins that can extend into or across the entire lipid bilayer due to the fact that they are amphipathic.
Term
peripheral proteins
Definition
Proteins found at the inner or outer surface of the plasma membrane and can be stripped away without disturbing membrane integrity.
Term
membrane proteins (6)
Definition
Channel, transporter, receptor, enzyme, cell identity marker, linker.
Term
channel
Definition
Membrane protein that acts as a gate, allowing specific substances in or out of the cell through a pore. Some change shape to open or close for a certain ion.
Term
transporter
Definition
Membrane protein that binds a polar substance at one end, then changes shape to move it through to the other side of the membrane and releases. Allows bigger substances to pass through.
Term
receptor
Definition
Membrane protein that serves as a cellular recognition site to bind a specific molecule.
Term
enzyme
Definition
Membrane protein that catalyzes reactions inside or outside the cell.
Term
cell identity marker
Definition
Membrane protein that acts as a "nametag" for the cell. ex: helps the body know which cells are foreign invaders
Term
linker
Definition
Membrane protein that anchors proteins in plasma membranes of neighboring cells to one another. It provides shape and structural ability for the cell.
Term
fluidity
Definition
Property of the plasma membrane which allows membrane proteins to move, membrane punctures to self-seal. Cholesterol stabilizes this property by making sure the cell doesn't get too floppy.
Term
permeability
Definition
Property of the plasma membrane that selectively allows substances to pass through easily, like water and small, nonpolar, uncharged particles. However, ions and charged or polar molecules are not allowed.
Term
concentration gradient
Definition
The difference in concentration of a chemical between one side of the plasma membrane and another. A substance will move across the plasma membrane down this from where it's more concentrated to where it's less concentrated.
Term
oxygen and sodium ions
Definition
More concentrated outside the cell. They will move down the concentration gradient to the inside of the cell.
Term
carbon dioxide and potassium ions
Definition
More concentrated inside the cell. They will move down the concentration gradient to the outside of the cell.
Term
electrical gradient
Definition
Difference in the distribution of + and - charged ions between one side of the plasma membrane and the other.
Term
electrical charges of the surfaces of the plasma membrane
Definition
Inner is - and outer is +.
Term
what is essential to the life of the cell
Definition
The ability to move substances across the membrane.
Term
passive transport diffusion
Definition
Movement of solutes and solvent (solids and liquids) from an area of high concentration to an area of low concentration until equilibrium is reached. Uses no energy. This is for small, hydrophylic, inorganic ions.
Term
facilitated diffusion
Definition
Passive transport diffusion where a solute binds to a specific transporter on one side of the membrane and is released on the other side. This is for polar and large solutes (i.e. glucose, urea, fructose, galactose, and some vitamins).
Term
influences on rate of passive transport diffusion (4)
Definition
Steepness of gradient, temperature, size or mass of substance, diffusion difference.
Term
active transport diffusion
Definition
Moves solutes (solids) only against their concentration gradient. Requires energy (ATP).
Term
primary active transport diffusion
Definition
Cell directly uses ATP (about 40%). Transponder pumps a substance across the membrane against its concentration gradient.
Term
secondary active transport diffusion
Definition
Cell indirectly uses energy obtained from ATP where energy stored in the form of a sodium or hydrogen ion concentration gradient is used to drive other substances against their own concentration gradient.
Term
symporter
Definition
A couple transporter which moves 2 substances in the same direction.
Term
antiporter
Definition
A coupled transporter which moves 2 substances in the opposite direction.
Term
osmosis
Definition
Net movement of a solvent (liquid) from an area of high concentration of solvent to an area of low concentration of solvent.
Term
tonicity
Definition
How the solution influences the shape of body cells.
Term
isotonic
Definition
No net water movement.
Term
hypotonic
Definition
Cells undergo hemolysis (rupture).
Term
hypertonic
Definition
Cells undergo crenation (shrinkage).
Term
vesicle
Definition
A small membranous sac formed by budding off from an existing membrane.
Term
endocytosis
Definition
When materials are brought "into" the cell and are surrounded by an area of the plasma membrane. This buds off inside the cell. Requires ATP.
Term
types of endocytosis
Definition
Receptor-mediated, phagocytosis, pinocytosis.
Term
exocytosis
Definition
Materials move out of all cells in vesicles that fuse with the plasma membrane. Requires ATP.
Term
cytosol
Definition
Fluid inside the cytoplasm which is 90% water and where many chemical reactions occur.
Term
cytoskeleton
Definition
The structural framework of the cell containing microfilaments, intermediate filaments, and microtubles. Aids in movement of organelles, chromosomes, and whole cells.
Term
centrosomes
Definition
Serve as centers for organizing microtubles in interphase cells and the mitotic spindle during cell division.
Term
cilia/flagella
Definition
Hairlike projections extending from the cell's surface allowing the cell to move.
Term
ribosomes
Definition
Tiny spheres consisting of ribosomal RNA where protein is synthesized. May be associated with rough ER or free.
Term
endoplasmic reticulum
Definition
Network of flattened sac membranes. Can be rough (ribosomes on surface) or smooth (which extends from the rough). Transports substances, synthesizes and packages molecules and stores them, detoxifies chemicals, and releases calcium ions.
Term
golgi complex
Definition
It processes, sorts, and delivers proteins and lipids to the plasma membrane from the rough ER. Contains cisterns. There's usually only one of these per cell.
Term
lysosomes
Definition
Membrane-enclosed vesicles which contain digestive enzymes that digest worn-out organelles and entire cells. Formed by golgi complex.
Term
peroxisomes
Definition
Similar to lysosomes but smaller. Contain enzymes that oxidize substances like alcohol.
Term
mitochondira
Definition
"Powerhouses" of the cell where ATP is produced through aerobic cellular respiration. Have a double membrane and an inner layer containing cristae. They are able to self-replicate using their own DNA. There are 100s to 1,000s of these per cell.
Term
nucleus
Definition
Most prominent feature of a cell. Usually only one of these per cell (but red blood cells have none and skeletal muscles can have several). Controls cellular structure and directs activities. Contains nuclear envelope and nucleoli.
Term
nuclear envelope
Definition
Double membrane which separates the nucleus from the cytoplasm. Contains huge channels called nuclear pores.
Term
nucleoli
Definition
Clusters of protein, DNA, and RNA. Produces ribosomes.
Term
transcription
Definition
When encoded genetic information in DNA is copied onto a strand of messenger RNA, which then leaves the nucleus and enters the cytoplasm.
Term
translation
Definition
When the mRNA is read to determine the amino acid sequence of the protein. This is done by ribosomes in the cytoplasm.
Term
cell division
Definition
An orderly sequence of events by which cells reproduce themselves. Consists of a nuclear division (mitosis and meiosis) and a cytoplasmic division (cytokinesis).
Term
G1 phase
Definition
The part of interphase when organelles and cytosolic componants are duplicated.
Term
S phase
Definition
The part of interphase when DNA is replicated.
Term
interphase
Definition
The phase when the cell carries on every life process except division. It is "at rest".
Term
G2 phase
Definition
The part of interphase when enzymes and other proteins are synthesized.
Term
cell cycle in somatic (body) cells
Definition
Interphase (G1, S, G2), Mitotic (Mitosis [Prophase, Metaphase, Anaphase, Telophase], Cytokinesis)
Term
mitotic phase
Definition
Phase following interphase consisting of mitosis and cytokinesis.
Term
mitosis
Definition
Consists in the distribution of 2 sets of chromosomes into 2 separate nuclei.
Term
prophase
Definition
First stage of mitosis. Chromatin condenses into chromosomes and the nucleolus and nuclear envelope disappear.
Term
metaphase
Definition
Second stage of mitosis. Centromeres of chromatid pairs line up at the exact center of the mitotic spindle.
Term
anaphase
Definition
Third stage of mitosis. Centromers split and the 2 sister chromatids of each pair move toward opposite poles of the cell.
Term
telophase
Definition
Fourth (and final) stage of mitosis. Begins as soon as chromatid movement stops. New nucleoli appear.
Term
cytokinesis
Definition
Second part of mitotic phase and last step before completion of cell division. Begins in late anaphase or early telophase with the formation of a cleavage furrow. Division of cytoplasm and organelles.
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