chapter 3 cells Flashcards
cells
are the basic structural and functional unit of living organisms
vary in size, shape and function
what are the 3 main parts of the cells?
plasma (cell) membrane
cytoplasm
nucleus
plasma membrane
forms the boundaries of the cell –> operates the intracellular from extracellular fluid
structure is described by “fluid mosaic model”. it consist of a bilayer of fluid lipids (98%) within which are a verity of protein (2%)
lipid component of membrane is 75% phopholipids, 20% chlosterla and 5% glycolipids
phospholipids molecules are arranged in 2 layer
function as selectively permeable barrier that regulates the flow of materials into and out of the cells
phospholipids
molecules that have polar heads (hydrophilic) and non polar tails (hydrophobic)
phospholipids molecules are organized with their heads facing both sides of the membrane and their tails pointing towards each other
fluid mosaic model
refers to its made up of different things
glycolipids
phospholipid with a sugar group attached to it
selectively permeable
only some things can pass through it
what are the two types of membrane proteins?
intergral transmembrane proteins and peripheral membrane proteins
intergral transmembrane proteins
extend through the phospholipid bilayer. in contact with the outside and the inside of the membrane
peripheral membrane proteins
are associated loosely with only one side of the membrane. don’t go all the way through they are in contact with EITHER the outside OR the inside
what are the membrane protein functions?
transporter = as channels or carriers
receptor for chemical messenger (bind to something and can active or reactive the cell in some way)
enzyme that catalyze recation
marker in cell recognition
anchors to cells cytoskeleton
membrane permeability
a membrane is permeable to substance that can pass through impermeable to substance that can’t
cell membranes are selectively permeable
- allow some things to pass more easily than others
usually permeable to bipolar, uncharged and small molecules
usually impermeable to ions, charged or polar molecules exception: water
membrane transport
getting things across the membrane
they are a variety of mechanics for transport of substance across membranes.
in passive processes, substances move down their concentration gradients (from high to low) with no energy required from the cell
active process
energy is required to move substances against their concentration gradients from low to high or for substances otherwise unable to pass
pass transport- diffusion
net movement of molecules from an area of high to an area of low until equilibrium is reached
how is rate affected?
temperature
particle size- (smaller particles move faster, larger particles move slower)
[] gradient- the bigger the difference between the two areas the faster the reaction
surface area- smaller are going to decrease (more traffic). larger are is going to increase because you go faster.
distance - shorter distance the rate will be faster
what are the two types of diffusion?
simple
faciliated
simple diffusion
non polar and lipid soluble substances diffuse directly through the lipid bilayer eg. CO2, O2, fat soluble vitamins (A D E K)
facilitated diffusion
polar and charged molecules require transmembrane proteins as carriers or use ion channels to move through the lipid bilayer. eg. glucose, amino acids, ions
passive transport
energy is not required
passive transport- OSMOSIS
net movement of water from an area of high [water] to an area of low [water] though a semipermeable membrane, until equilibrium is reached.
similar to diffusion but this is strictly for water. during osmosis water can pass through the membrane, polar molecule bc the electrons are shared unequally. can go through the phospholipid gaps. the other way it can get through is through aquaporins dedicated protein channels to allow only water to pass through
osmotic pressure
the ability of a solution to attract or draw in water
the greater the # of solute particles in a solution, the greater the osmotic pressure.
more dissolved particles (solute) in a solution, the less space for water
the greater the tendency to draw in water
active transport
substances cross the membrane by moving against their concentration gradient and energy is required
primary active transport
energy from ATP hydrolysis (break ATP, breaking off the last phosphate of and release all of the energy to form ADP + a free floating phosphate) changes the shape of a transporter protein and it “pumps” a substance across the membrane
eg. Na+\K+ pumps transport Na+ out of the cell and K+ in.
40% of the ATP the cell uses is for primary active transport
secondary active transport
coupled transport pf 2 molecules using energy supplied by an ion gradient, rmaintained by a primary active transport pump
eg. Na+ is co-transported with glucose
its indirectly using energy from ATP. Na ions that were being pumped out by the sodium potassium pump creates a build up of sodium on the outside which then wants to float back in. the secondary active transporter goes “oh there is already a build up of sodium that is naturally gonna flow down its concentration gradient ill just piggy back something along with the sodium and bring it into the cell at the same time”. it is capitilizing on the result of the primary active transporter.
energy stored in a Na+ or H+ concentration gradient is used to drive other substances into the cell
antiporter
opposite directions
symporter
same direction
vesicle transport
used for large particles, macromolecules and fluids.
vesicle is a bubble of membrane within that bubble is something like hormones, neurotransmitters or waste, etc
exocytosis
endocytosis
exocytosis
moves a packed vesicle out of the cell by fusing with the cell membrane and releasing its contents.
endocytosis
moves materials into the cell by forming a vesicle
an example of this is phagocytosis (cell eating)
cytoplasm
cellular material between the palms membrane and the nuclear
what are the two major elements of cytoplasm?
-cytosol
-organelles
cytosol
fluid surround the organelles
is 75-90% water with dissolved and suspended components
is the site of many chemical reactions required for a cells existence
organelles
specialized strictures that have specific functions necessary for the life of the cell (“organ of the cell”)
most organelles are membrane-bound
what’s the point of having membrane bound organelles?
used to keep them separate so they can perform their functions without being affected in the cytoplasm.
cytoskeleton, ribosomes are organelles with membranes
name 6 organelles
mitochondria
ribosomes
endoplasmic reticulum (ER)
Golgi complex
lysosomes
cytoskeleton
mitochondria
3/4 of cellular respiration takes place here
oval, elongated organelle
has an outer membrane and an inner folded membrane (cristae- electron transport chain takes place here)
inner fluid is called the matrix
function- produces most of the cells ATP
mitochondria has its own DNA called mitochrian DNA, taken from your mother.
ribosomes
tiny organelles composed of rRNA and protein (not membrane bound)
consists of 2 subunits (created in the nucleolus)
can be “free” ribosomes in cytoplasm or can be attached to the (rough) ER
function: involved in protein synthesis, its the main machinery that helps to build proteins
endoplasmic reticulum
network of membrane-enclosed channels (cisternae) continuous with the nuclear membrane
two types;
rough ER
smooth ER
Rough ER
has ribosomes attached to the external surface
function: protein synthesis and transport of proteins for export
smooth ER
continuation of RER but lack ribosomes
function: site of lipid and steroid synthesis and detoxifies drugs
Golgi complex
series of flattened sacs with bulging ends
function; to modify, sort and package proteins for various destination in cells
One side (cis or entry face) receives transport vesicles from the ER
Contents are modified as they travel from cis face to trans face (exit side) of Golgi.
Contents are packaged into vesicles at trans Golgi
There are 3 zones, flattened membrane disks, one side is cis face it bring proteins and are packaged in vesicles and are absorbed from the cis face as they move through they are being modified at the other side of “pancakes” they are let go.
Secretary vesicle, release things outside the cell.
Transport vesicle bring digestive enzymes to lysosomes.
lysosomes
membrane-bound sacs formed by golgi
contain powerful acid hydrolyses (digestive enzymes)
function; digests substances transported into the cell or digests cellular debris
cytoskeleton
a network of protein filaments that extend throughout the cytosol
function: provides structure and support and also aids in the movement of structure within the cell
nucleus
usually round and found towards the centre of the cell
most cells have a single nucleus
contains jelly-like nucleoplasm
bounded by a double membrane
anucleate
no nucleus (red blood cells)
multicleate
more than one nucleus per cell (eg. skeletal muscle cells)
nuclear structures
the nucleus has three structures:
nuclear envelope
nucleoli
chromatin
nuclear envelope
is a double membrane that controls the movement of substance between the cytoplasm and nucleus (eg. messenger RNA during DNA replication)
lipid bilayer similar to plans membrane
outer membrane is continuous with RER
nuclear pore
nuclear pore
a circular ring of protein extending through the nuclear envelope. it allows for movement between cytoplasm and nucleus
nucleoli
nucleolus (singular), nucleoli (plural)
dark stains round structure(s) found in the nucleus
not enclosed by a membrane
function: produce ribosomes
chromatin
granular, thread-like material composed of DNA and protein of a non-diving cell
threads will become chromosomes when the cell is diving
function; consist of genes which control cellular structure and direct cellular functions by providing instructions for protein synthesis
cell division
process by which cells reproduce themselves
types types of cell division occur;
somatic cell division
reproductive cell division
somatic cell division
a body cell undergoes nuclear division to produce a new body –> MITOSIS
reproductive cell division
a germ cell undergoes nuclear division to produce a gamete
–> MEIOSIS
