VCU Exam 1 Flashcards
plasma membrane
the outermost membrane of the cell, mostly made up of phospholipids, proteins, and carbohydrates (glycolipids & glycoproteins)
phospholipids
polar hydrophillic head and non-polar hydrophobic tail
phospholipid tail
made out of 2 fatty acid chains.
Kinked chain- unsaturated (in hydrogen), more fluidity
Straight chain- saturated fatty acid, less fluidity
phospholipid bilayer
self-organizing and repairing, form a liposome (sphere) with heads pointing outward
amphipathic
molecules with both hydrophillic and hydrophobic regions
Van der Waals interactions/forces
very weak bonds between phospholipid tails that can easily form or break allowing the tails to be fluid
fluid mosaic model
a longer chain of fatty acid tails has more Van der Waals interactions= stronger bond, less fluidity
the lipid bilayer is a fluid structure that allows molecules to move laterally within the membrane, and is a mosaic (a mixture) of two types of molecules, lipids and proteins.
cholesterol
30% of animal (only) cell membranes, in between the spaces of the tails, less fluidity under normal cell temp, in cold temp it helps retain some fluidity because it won’t let the tails get rigid
peripheral membrane proteins
proteins temporarily attached to the surface of the membrane through weak non-covalent interactions
integral membrane proteins
proteins extend part way into the hydrophobic (tails) region of the membrane, permanently associated with the cell membrane and cannot be separated
transmembrane proteins
extend all the way across the lipid bilayer, also technically considered integral proteins
transporter proteins
have to be transmembrane, transport molecules through a channel going in either directions, can be gated
carrier protein
changes shapes, specific as to what can pass through, can transport more than 1 molecule
receptor proteins
have to be transmembrane, relay a message from one side of the membrane to the other, protein changes shape when a molecule binds to it creating a signal
enzymes
can be integral, peripheral, or transmembrane, speeds up a reaction
ATP synthase
synthesizes ATP = ADP + inorganic phosphate. H+ ions will attach and spin causing ATP synthase to rotate, acting as a transporter
anchors
can be integral or transmembrane, hold another protein in place, hold onto the cytoskeleton fibers, holding onto another protein helping it stay in place
selective barrier
the plasma membrane regulate what molecules can pass through in and out of the cell to maintain homeostasis
diffusion
passive transport (require no energy) molecules move down a conc. gradient (from high to low) through the bilayer
facilitated diffusion
passive transport. large or hydrophillic molecules pass through protein channels or carriers in the plasma membrane
aquaporins
specific protein channel, allow water to flow through the plasma membrane more readily by facilitated diffusion.
osmosis
diffusion of water, water moves from regions of high water conc. to low water conc.
primary active transport
NaK pump moves 3 Na ions out and 2 K+ ions in by using ATP. Na conc. is high on the outside of the cell and K+ conc. is high on the inside of the cell
secondary active transport
transmembrane pump uses ATP to move protons from the inside to the outside creating an electrochemical gradient.
electrochemical gradient
concentration and charge difference between the inside and outside of the cell (outside= positive)
hypotonic
low solute, water moves from the outside in, cell swells or burst. plants prefer to be hypotonic to retain more water (cell wall prevents bursting)
hypertonic
high solute, water moves from the inside out, cell shrinks
isotonic
solute and water concentrations are equal, water will move in both directions but no net movement. animals prefer to be isotonic
contractile vacuoles
present in some single celled organisms to prevent bursting. compartments that take excess water from inside the cell and release it into the outside environment by contraction
antiporter
transport more than one molecule in opposite directions
symporter
transport more than one molecule in the same direction
prokaryotes
bacteria and archaea. single celled, no nucleus or membrane bound organelles, store DNA in nucleoid
eukaryotes
eukarya: plants, animals, fungi, protists. multicellular, has a nucleus that store DNA, enzymes, nucleolus, and membrane bound organelles
endoplasmic reticulum
smooth ER- lipid production, calcium storage, detoxification
rough ER- contain ribosomes (protein production)
transitional ER- products from smooth and rough ER can be stored or transported other places in the cell by budding vesicle
Golgi apparatus
sorts proteins and lipids to other organelles, the plasma membrane, or the cell exterior, produce macromolecules, forming protein complexes, transport protein complexes by vesicles, modify molecules
mitochondria
ATP production by cellular respiration, has its own DNA , ribosomes, enzymes, and a double membrane (squiggly inner membrane for more surface area to fit more electron transport chains)
lysosomes
break down and digest molecules, damaged organelles to be recycled. acidic pH (4.1) where digestive enzymes function best
peroxisomes
can aid in cellular respiration, detoxification of damaging molecules (free radicals), make hydrogen peroxide (H2O2) in the process of detoxing, which can be damaging, so it is converted to H2O
chloroplasts
only in plant cells, photosynthesis occurs here, contain 3 membranes: outer-> inner-> thylakoid (very important in photosynthesis, contain chlorophyll). Has own DNA, ribosomes, and enzymes
vacuole
takes up most of the volume of a plant cell, mostly involved in storage: store pigment molecules to attract pollination, various ions until needed, and toxins as a defense
toxins
not toxic when stored in vacuoles but can become toxic if ruptured and mixed with the cytoplasm
cytoskeleton
structural protein networks in the cytoplasm
microtubules
hollow tube formed from tubulin dimers (alpha and beta), create cilia and flagella and spindle apparatus used in cell division. largest in diameter
centrosome
only in animals. microtubules push outward to the cell periphery from a microtubule organizing center
intermediate filaments
only in animal cells, medium sized, strong fiber composed of intermediate filament proteins, provides structural support
microfilaments
double helix of actin monomers, smallest in diameter, line the inside of the cell helping with structure and integrity of plasma membrane, forms microvilli and contractile ring (pinches off) in cell division
nuclear lamina (intermediate filaments)
lines the nuclear envelope like the microfilaments line the plasma membrane (protecting the nucleus)
dynamic instability in microtubules and microfilaments
has a plus (+) end and a minus (-) end, the plus end grows faster. dynamic instability is alternating periods of grow rates (in order to find chromosomes in cell division)
motor proteins
aid with cellular movements
microfilaments- myosin
microtubules- kinesin or dynein
myosin in microfilaments
walk along actin using ATP. can attach to 2 microfilaments at once pulling it forward as actin pulls back (muscle contraction). will undergo a conformational (structural) change in order to pull or walk.
kinesin and dynein in microtubules
walk along microtubules, kinesin will walk towards the plus end and dynein will walk towards the minus end (towards the plasma membrane)
cilia (9+2 arrangement)
created by microtubules, nine pairs of microtubules are located around the periphery of these organelles and two microtubules are at the center
cell migration
Cells move by extending a lamellipodium at the leading edge and contracting microfilaments at the trailing edge.
cellular junctions
areas that allows cells to join to other cells or to the extracellular matrix by cell adhesion molecules
adherens juntions
joins 2 different cells together by 1 cadherin from each cell (2 total) form a belt around cells
desmosomes
joins 2 cells together by a cluster of cadherins (like buttons on clothes) linked to intermediate filaments inside the cell- making it stronger, more stable and permanent
hemidesmosomes
hold cells to the extracellular matrix by integrins linked to intermediate filaments
tight junctions
ex: digestive cells, make a seal between cells using various tight junction proteins so molecules have to go through the plasma membrane using a transport mechanism
gap junctions
specifically in animals, form a channel using gap junction proteins allowing molecules to move from one cell to the other in either directions
plasmodesmata
specifically in plants, passages through the cell wall of adjacent plant cells, continuous plasma membranes
extracellular matrix
area to the outside of the cell, mostly composed of a carbohydrate with various polysaccharides and proteins (not as much)
extracellular matrix of plants
is the cell wall: 3 parts- middle lamella, primary cell wall and secondary cell wall, provides structural support
middle lamella
gel like substance, composed of pectin (polysaccharide) , hold cell together and retain high water content
primary cell wall
formed first, composed almost entirely of cellulose and some proteins and pectin, provides some support and structure
secondary cell wall
not present in all plant cells, much thicker and stronger (in wood), composed of cellulose and lignin- provides strength and waterproofing, formed in between the primary cell wall and the plasma membrane
extracellular matrix of animals
produced by fibroblasts made out of collagen (triple helix) and elastin (elasticity and mobility).
fibroblast
mostly extracellular matrix, important for connective tissue: dermis layer of skin, bone, and cartilage
epithelial tissues
a lot of the extracellular matrix, epidermis, lining of blood vessels and intestinal tracts
basal lamina
specialized extracellular matrix, found in epithelial tissue or connective tissue, provides strength (what hemidesmosomes attach to).
