Cells Flashcards
Who discovered cells?
Robert Hooke
Who observed the first live cells and called them animalcules?
Antonie van Leeuwehoek
Who proposed the idea that all plants are made of cells?
Schleiden
Who proposed the idea that all animals are made of cells?
Schwann
What is cell theory?
all organisms are made of cells
cells are the basic units of life
all cells come from other cells
Resolution
the minimum distance two points can be apart and still be distinguished as separate
transmission electron microscope
electrons are transmitted through object viewed
scanning electron microscope
electrons beamed on surface of object bounce off and are collected to make image
surface area to volume ratio
as a cell’s size increases, its volume increases much more rapidly than its surface area
Bacteria Cell Walls
Composed of Peptidoglycan- carbohydrate mixture cross-linked with proteins
Gram + bacteria-think, single layer cell wall. Stains purple.
Gram - bacteria-multilayered cell wall. Stains red
How well antibiotics work depends on what cell wall is made of
Flagellum
long tail-like structure used for movement
transport proteins
move substances across membrane
receptor proteins
receive signals from the environment and cause changes in cell
marker proteins
identify a cell asa to what type it is
Nuclear Envelope
around nucelus, 2 phospholipid bilayers (selectively permeable)
continuous with endoplasmic reticulum
scattered with nuclear pores- holes that act as channels letting certain substances in and out of the nucleus
actin filaments
long, made of protein called actin. responsible for movement
microtubules
made of protein called tubulin
intermediate filaments
made of protein called vimentin. most sturdy part of cytoskeleton. once formed, they don’t break
endosymbiosis
theory that today’s organelles evolved by a symbiosis where one species of prokaryote was engulfed by another prokaryote and lived inside it. this was the precursor to the first eukaryotic cell
transmembrane proteins
float in or on membrane
support fibers
provide passageway for substances and info cross membrane
exterior protein and glycolipids
selections of membrane get built in ER, are sent to Golgi body which adds chains of sugars to membrane proteins or lipids= “Sugar coating”
transport proteins
allow only certain substances through
enzymes
carry out reactions on the surface of the membrane
cell-surface receptors
detect chemical messages
cell-surface identification markers
identify cells to other cells
cell adhesion proteins
used to glue cells together
attachment proteins
attach proteins which interact with other cells to the cytoskeleton
ion channel
protein channels that span the membrane and allow ions to move across in either direction
carrier
a membrane protein which transports ions, sugars, amino acids, etc.
facilitated diffusion
when carriers help in the transport
What are the three characteristics of facilitated diffusion?
specific, passive, and saturates
specific
can only pick up a certain kind
passive
doesn’t use energy
saturates
if all carrier proteins are in use, even if concentration gradient goes up, transport won’t increase. they won’t go anywhere if the carriers are already saturated.
aqueous solution
mixture of substances in water
solvent
substance which dissolves another
solute
substance being dissolved
osmosis
net movement of water across a membrane by diffusion
aquaporins
water channels in the membrane
osmotic concentration
the concentration of all the solutes in a solution
hyperosmotic
solution has more solutes
hyposmotic
solution has less solutes
isoosmotic
the concentrations of the solutes are the same
hydrostatic pressure
pressure of the cytoplasm against the cell wall
osmotic pressure
pressure that must be applied to cell membrane to get the water to quit moving
extrusion
contracting a vacuole
isosmotic solutions
body circulates an isosmotic solution that bathes the cells and maintains balance
turgor pressure
internal pressure in plant cells pressing on membrane- if it is lost, plant wilts
phagocytosis
moving solids
pinocytosis
moving liquids
receptor-mediated
when certain molecules go into the cell. specific receptor for specific molecules to go into the cell to go where they need to go.
sodium-potassium pump
proteins that move sodium and potassium.
more than 1/3 of all energy spent by an animal cell is used in moving sodium and potassium ions.
Most animal cells have low concentrations of sodium and high concentrations of potassium inside.
the maintain this difference by actively pumping sodium out of the cell and potassium into the cell.
3 sodium leave and 2 potassium enter in every cycle
each pump can move 300 sodium per second
Coupled transport/ cotransport
many molecules are transported in the cell against the concentration gradient using ATP indirectly. the molecules move with sodium ions or protons
countertransport
when a molecule moves into or out off the cell when another molecule is going in the opposite direction
chemiosmosis
a typer of counertransport where ATP is produced when proton pumps (proteins) move H+ across the membrane by moving H+’s
reception
target cell detects signal molecule
transduction
when signal binds to receptor protein, receptor changes shape. This converts the signal to a form that can bring about a specific cell response. This can be single step or mullti-stepped.
response
signal triggers response from cell
receptor proteins
what cells use in order to select what signals to respond to
direct contact
when cells are close to each other, some of the molecules on the membranes bind together
important in early development
paracrine signaling
they aren’t touching each other but they are close
occurs when signal molecules are taken up by nearby cells
plays role in developmet, coordinating activities with neighboring cells
endocrine signaling
occurs when signal enters an organisms bloodstream and travels some distance
HORMONES- signal molecules that affect cells some distance away from signaling cell
hormones are made by glands and leave a place to get a response to get them where they need to go (target cell)
synaptic signaling
they have to cross the synapse
occurs when the cells of the nervous system provide fast communication with far away cells
neurotransmitters- signal molecules of the nervous system
neurotransmitters don’t travel the bloodstream; the long, fiber-like extensions of nerve cells release them.
synapse- the narrow gap between a nerve cell and its target cell
autocrine signaling
some cells even talk to themsellves
cell surface receptors
proteins which change extracellular signals into intracellular ones causing a change within the cytoplasm
chemically gated ion channes
receptor proteins that let ions through
enzyme receptors
catalyze reaction- goes quicker
G-protein linked receptors
helpers receptor can’t entirely do the job so it has a helper protein
G Protein
a helper protein- used to help get the signal from the membrane’s surface to inside thecell
Signal Binds to receptor protein which is linked to a G protein inside the cell
receptor protein changes shape and twists the G protein
G protein binds to GTP (guanosine triphosphate)
This activated complex of G protein- GTP is free to do a number of things such as activate an ion channel or activate an enzyme
GTP has a short lifespan so for the pathway of transmission to stay on, there must be a continuous supply of incoming signals
second messengers
some enzyme receptors and G linked protein receptors carry the signal’s message by using other substances to do the relaying in the cytoplasm
cAMP
the signal binds to the receptor protein and with the help of a G protein, activates and enzyme in the membrane, adenyl cyclase
this enzyme catalyzes the production of cAMP
cAMP binds to the target protein and starts the response in the cell
Calcuim
the signal binds to the receptor protein and with the help of a G protein activates an enzyme called phospholipase C
Phospholipase C starts the production of inositol triphosphate which binds to and opens calcium channels in the membrane of the ER
This causes release of Calcium into the cytoplasm which causes a change in the cell
Amplifying the Signal
both enzyme-linked and G protein receptor proteins receive signals at the surface of the cell. The target cell’s response rarely takes place there though.
Most of the time, signals go into the cytoplasm by second messengers
This influences enzymes and genes which alters the behavior of the cell
Most signal molecules are found in low concentration so it would take forever to get a response unless the signal is amplified or “turned up”
rapid production of high levels of the final product as opposed to a little bit
the receptor protein receives the signal which activates a stage one protein
these stage one protein activate a large number of stage two proteins
each stage two protein activates a large number of stage three proteins
therefore a single cell surface receptor protein can stimulate a cascade of protein kinases to amplify the signal
most enzymes are regulated by the attachment of the end phosphate on ATP
Glycolipids
most surface markers are this type. responsible for A, B, O blood groups
MHC Proteins
used by the immune system to distinguish “self” from “nonself”cells
Major Histocompatibility Complex Proteins- serve as Id Markers to for each individual
cells of the immune system constantly inspect other cells triggering the destruction of cells that display nonself markers
proteins that indicate tissues can get along with eachother
cell junctions
long-lasting or permanent connections between cells
the type of connection determines what the tissue is like
tight junctions
prevent small molecules from leaking between cells
allows sheets of cells to act like a wall in an organ keeping molecules on one side or the other
anchoring junctions
mechanically anchor cytoskeleton of one cell to the cytoskeleton of another
most common in tissues which experience physical stress like muscles and skin
Desmsomes- anchoring junctions that connect cytoskeletons
communication junctions
allow communication between adjacent cells by linking cytoplasms so molecules can pass through
GAP junctions
in animals; made of connexons
GAPs that molecules can go through
PLASMODESMATA
in plants; occur in gaps in cell wall
spaces in cell wall that molecules go through
What are the three things that cells have in common?
plasma membrane
nucleus or nucleoid
cytoplasm
