Chapter 3: Cells- The Living Units Flashcards
Cell Theory
cell is the smallest unit of life; all organisms are made of one or more cells; cells only come from other cells via mitosis or meiosis
What are the three main parts of the human cell?
plasma membrane, cytoplasm, and nucleus
What are parts of the extracellular material?
extracellular fluid, cellular excretions, and extracellular matrix
Extracellular Fluid
internal fluid located outside cells; includes interstitial fluid, blood plasma, and cerebrospinal fluid; dissolves and transports substances in the body
Cellular Excretion
include substances that aid in digestion (intestinal and gastric fluids) and some that act as lubricants (saliva, mucus and serous fluids)
Extracellular Matrix
nonliving material in connective tissue consisting of ground substance and fibers; seperates the living cells; most abundant
Plasma Membrane
composed of phospholipids, cholesterol, and proteins, that encloses cell contents; out limiting cell membrane; separates interstitual fluid and extracellular fluid
Phospholipids
polar, hydrophilic head and nonpolar, hydrophobic tail; forms the phospholipid bilayer of the plasma membrane; the hydorphilic heads face out while the hydrophobic tails face in
Cholesterol
20% of plasma membrane is cholesterol; wedges its plate like hydrocarbon rings between the phospholipid tails, which stiffens the membrane
Transport Protein
spans the membrane and may provide a hydrophilic channel across the membrane that is selective for a particular solute OR some hydrolyze ATP as an energy source to actively pump substances across the membrane
Integral Proteins
firmly inserted into the lipid bilayer; most are transmembrane proteins that span the entire membrane and protrude on both sides; all have hydrophobic and hydrophilic regions which allows them to interact with the tails and heads of the membrane
What are some of the functions of cells and examples?
connect body parts, form lining, transport gases, etc; fibroblasts: part of connective tissue; erthrocytes: transport, red blood cells; epithelial: linings; skeletal and smooth muscle cells: move organs or body parts; Fat cells: store nutrients; White blood cells: fight disease
Interstitial Fluid
bathes all cells; contains substances cells need
Blood Plasma
liquid component of blood; not in blood; it is outside of them in the bloodstream
Cerebrospinal Fluid
CSF; found in the brain and spinal cord
Cellular Secretions
saliva, mucus, gastric juices
Extracellular Matrix
nonliving material consisting of proteins, polysaccharides, and fibers
All cells have….
plasma membrane, nucleus, and cytoplasm; except red blood cells- they get rid of their nucleus to make room to transport nutrients throughout the body
Plasma Membrane
selectively permeable outer boundary of cell; separates ICF from ECF
Cytoplasm
intracellular fluid (ICF) that contains organelles
Nucleus
control center of the cell; largest organelle in the human body
Structure of the Plasma Membrane
lipid bilayer embedded with proteins; fluid mosaic
What are the membrane lipids?
phospholipids, cholesterol
Phospholipids
make up 80% of membrane; hydrophilic head and two hydrophobic tails
Cholesterol
lipid (hydrophobic); makes up 20% od membrane; sandwiched between phospholipid tails; allows membrane to be more or less fluid; more cholesterol=less fluid; maintains membrane fluidity
What are the membrane proteins?
integral and peripheral proteins
Integral Proteins
embedded in some way (does not ncessarily have to be through the entire plasma membrane) to the fatty acid tails; if taken out it destroys the membrane
Peripheral Proteins
outside of membrane on the hydrophilic heads; can be removed
What are the functions of the membrane proteins?
transport, receptors, anchor cytoskeleton fibrs, link cells together
Membrane Carbohydrates
short branching monosaccharides are attached to some extracellular surface (not the inside) proteins and phospholipids; they function as “name tags”; announcing to white blood cells who they are (a kidney cell) and who they belong to (you)
Glycoprotein
protein with a carb attached to it
Glycolipid
Carb attached to one of the fatty acid tails
Cell junctions…
link cells together
Tight Junctions
water/materials can not pass between them; impermeable; fuse cells together (a band not the whole cell); prevents materials from passing between cells- it makes the materials go through the cells; found in epithelial of skin and lining of digestive tract
Desmosomes
spot welds; holds cells together in certain spots so its flexible; bind cells together in spots allowing tissue to be flexible; allows materials to pass between cells; found in epithelial of skin and heart muscle cells
Gap Junction
hold cells together but allow rapid communication among cells ; channels that allow ions to pass from cytoplasm of one cell to cytoplasm of an adjacent cell; found in electrically excitable tissues (heart muscle, smooth muscle)
Passive Transport
ATP not required (kinetic energy used not ATP); substances move from high to low concentration; includes simple diffusion, facilitated diffusion, and osmosis
Simple Diffusion
pass through bilayer without help; typically hydrophobic molecules or really small molecules
Facilitated Diffusion
has to pass through a protein (because it may be too big or simply can not go through the membrane alone) but still does not use ATP
Osmosis
water can move through bilayer because it is so small but aquaporins (proteins) are the main way water moves into cells; movement of h2o depends primarily on solute concentration; water always moves passively
Active Transport
requires ATP; substances move from lower to higher concentrations (against the gradient)
Sodium Potassium Pump
example of active transport; they are constantly working to keep sodium and potassium at their respective levels; high na+ and low k+ outside cell and low na+ and high k+ inside ceel
Only muscle and nerve cells can….
change their polarity
Vesicular Transport
substances moved across membrane via vesicles; requires ATP; not moving directly through the phospholipid bilayer
Endocytosis
form of vesicular transport; substances imported or brought in to the cell
What are the three forms of endocytosis?
phagocytosis, pinocytosis, receptor mediated endocytosis
Phagocytosis
large external particle surrounded by a pseudopod and becomes inclosed in the vesicle; non-selective
Pinocytosis
fluid-phase endocytosis; brings fluid into the cell (and picks up whatever is in the fluid outside of the cell aka interstitial fluid); non-selective
Receptor Mediated Endocytosis
selective; external substances binds to membrane proteins; only select for one thing
Where is insulin created?
in the beta cells of the pancreas
Exocytosis
substances exported out of the cell; secretion of neurotransmitters, hormones, mucus, etc
Cytoplasm
portion of cell between plasma membrane and nucleus; includes structures and stuff; mostly water; site of most cellular activity
Cytosol
fluid portion containing dissolved solutes
Inclusions
chemical compound and by products of cellular metabolism; ex) glycogen granules, lipid droplets, melanin granules
What is glycogen?
stored energy but can be used immediately unlike fats; liver and muscle cells have glycogen (used in a situation such as fight or flight when you need immediate energy)
What is found in the cytoplasm?
cytosol, inclusions, non-membranous structures, and organelles
Organelle
any membrane bound structure found in cells
What are the non-membranous structures?
ribosomes, centrioles, cytoskeleton
Ribosomes
dark staining granules composed of rRNA and protein; function- produce proteins
Centrioles
paired barrel shaped structures made up of 9 triplets of microtubules; function- during cell division form spindle apparatus
Cytoskeleton
network of three types of rods running through cytosol
What are the three types of rods found in the cytoskeleton?
microfilaments, intermediate filaments, microtubules
Microfilaments
strands of actin; very thin and looks like pearls twisted together; involved in muscle contraction;
Intermediate Filaments
size is between microfilament and microtubule; attach to desmosomes; provide resistance to mechanical strength
Microtubules
think, fat, hollow; form centrioles, spindle apparatus, cilia and flagella
Nucleus
largest organelle; control center of cell; houses DNA (genes); 23 pairs of chromosomes (46 total)
Mitochondria
produces ATP (site of ATP synthesis); double membrane- smooth outer membrane and folded inner membrane (studded with ribosomes)
Rough Endoplasmic Reticulum
studded with ribosomes that produces proteins that are going to be excreted from the cells such as insulin
Smooth Endoplasmic Reticulum
lacks ribosomes; site of lipid metabolism and synthesis; drug detoxification (primarily in liver cells); Ca+2 storage in neurons and muscle cells- muscle cells and neurons can not contract/work without a storage of Ca+2
Golgi Apparatus
modifies proteins made by the rough ER; tags proteins with a “destination tag”; packages proteins for secretion from cell
Lysosomes
suicide sacs; if cell needs to die all lysosomes bursts in the cell; membranous sacs containing digestive enzymes; site of intracellular digestion; such as pulling bacteria in through endocytosis and the lysosomes breaking it down
What are the cellular extensions?tanc
cilia and flagellum and microvilli
Cilia and Flagellum
hairlike extensions containing a central core of microtubules in a 9 + 2 arrangement (9 pairs in sets of two and a pair in the middle); cilia are short and propel substances across cell surface; flagellum are long and propels the cell itself
Microvilli
extensions of the plasma membrane; cytoplasm extends up and forms microvilli; finger like projects (fatter than cilia and flagellum); increases surface area for absorption; intestinal and kidney cells for example
