osmosis = diffusion of water from an area of high water concentration to low water concentration across a partiallypermeable membrane
net movement of water = overall movement either in or out of the cell membrane
water potential is the chance of water molecules to diffuse out or into a solution (liquid)
water potential = water concentration
turgid plant cell= vacuole increases in size
flaccid plant cell= vacuole decreases in size
active transport is the movement of molecules from a low concentration to a high concentration across a cell membrane against a concentration gradient using ATP
opposite of diffusion
as rate of respirationincreases rate of activetransportincreases because more ATP is produced during respiration
more ATP from respiration used for active transport
ATP is an energy source that your body need/uses for active transport and for your muscles to contract (movement)
simple/small molecules can diffuse through the cell memebrane
for example- aminoacid,glucose,water and oxygen
large and complex molecules such as proteins starch are transported from outside the cell to inside
carrier protein are on the cell membrane and they transport large complex molecules in and out of cell.
image shows carrier protein transporting large complex molecule into cell
mitosis
process where cell divide into two identical cell
mitosis stages
gap phase 1 = cell grow and new cell structure are made
synthesis= cell replicates its DNA
gap phase 2= cell keeps growing and proteins needed from mitosis are made
mitosis
Synthesis Part 1. DNA doublehelixunwinds and splits
free floating nucleotides pair up with exposed bases
complementary based pairs = a binds with t , c binds with g
synthesis part 2:
cross links formed (g/c or a/t binding) = two DNA double helixes
mitosis
stages of mitosis below
cell differentiation
process where cells becomes specialised for their own job.
sperm cells has a tail to move to egg , has lots of mitochondria as it needs lots of energy
Acrosome enzyme used to break down egg membrane
red blood cells
Bin-concave shape (dipped down) to increase SA:V ratio so that morediffusion of oxygen and carbondioxide are inandout of cell
lots of haemoglobin allow moreoxygen to bind to it to form oxyhemoglobin.
RBC has no nucleus = store more haemoglobin.
palisade leaf cell
more chloroplast compared to other parts of plant cells - leaf where photosynthesis occurs so more chloroplasts means more photosynthesis occurs
ciliated and goblet cells - both found in throat and intestine
ciliated cells have cilliar to blow dirt and bacteria away.
goblet cells produce mucus to trap bacteria
stem cells= undifferentiated cells that can differentiate to become specialised cells
two types of stem cells= embryonic and adult stem cells.
embryonic stem cells= differentiate into any type of cell in the body, found in the embryo
adult stem cells = differentiate into some type of cell, found in brain and bone marrow
embryonic stem cells is good because they can be used to treat diseases like diabetes or alzheimer's but unethical - they come from human embryos which is killing them. Adult stem cells is good because they don't kill anyone but bad because they cannot differentiate into all types of cells
main factors affecting movement of substances- diffusion and active transport
SA:V ratio higher = higher diffusion and active transport
temp higher = more diffusion and active transport
concentration gradient higher= more diffusion
transpiration is the loss of water from the leaf by DIFFUSION and EVAPORATION the water loss must be replaced - leads to water flowingup the plant through the xylem
water being lost at leaf reduces water pressure creating a pressuregradient-pressure gradient increases- water pulled up from leaf to root by xylem= the transpiration stream
stomata opens and closes to allow co2 in and water out. when stomata opens water is lost in form of water vapour/steamEVAPORATION
Concentration gradient created where there is high water conc in the leaf and low conc in the air
water is lost by DIFFUSION
image showing change in stomata shape
factors affecting transpiration
light intensity increases= ROT increases until it reaches optimum and plateau (evens out)
temperature increases = ROT increases
wind speed increases - ROT increases until it reaches optimum and plateau (evens out)
humidity increases ROT decreases
osmosis in animal cells
lots of water taken up untill it swells and burst= lysis
water lost by osmosis until cell =crenated
osmosis goes from dilute to concentrated
light intensity means morestomataopen so more water is lost - increase ROT
temperature- higher temperature = more energy in particles- increase ROT and rate of diffusion and evaporation.
wind speed-strongerwinds=faster water molecules are moved so fewer water molecules in air compared to in plant - conc gradient increases diffusion increases
humidity- higher humidity=higher water conc in the air- conc gradient decreases - diffusion decreases
xylem= transport water and minerals from roots to leaves - oneway system
phloem=transport sugars (glucose) from leaf to allother areas of plant (translocation)-twoway system
xylem vessels are made from deadxylem cells
no cell walls so tubes form that water can pass up through
phloem vessels are made from living cells called sieve tube elements
end of each element have sieve plates with tiny holes- allow dissolved sugars to pass through (translocation)
high SA:V ratio= higher diffusion
high conc gradient= higher ROD
capillary walls verythink so short distance for diffusion = higher ROD
artery = thick walls and muscles-can expand and carry blood at high pressure. small lumen
vein= thin walls and muscles as it is under lower pressure. larger lumen have valves-prevent backflow blood.
capillary-one cell thick thin membrane, small lumen & single layer of wall diameter= 7 micrometer