1.2 transport across cell membranes and 1.6 respiration Flashcards
two main components of a cell membrane
phospholipids
proteins
what is a selectively permeable membrane
describe the membrane that contains channel forming proteins that allow molecules to travel directly across membrane through pores. it is describes as selectively permeable because the size of pores created by channel forming proteins controls the size of the molecules that can travel through eg small molecules eg water can move through but large molecules like starch cannot
function of proteins in membrane
enzymes - speed up chemical reactions inside cells
hormone receptors- to receive and respond to specefic hormone messages
channel forming proteins- structural part of membrane that allows the transport of molecules across membrane
carrier proteins- structural part of membrane that is involved with active transport of molecules across membrane
passive transport
movement of substances down a concentration gradient from earin of high concentration to a area of low concentration THIS DOES NOT REQUIRE ENERGY
define consent ration gradient
the gradient differs to the difference between the two gradients the greater the diff in two concentrations the steeper the gradient is going to be
two examples of passive transport
diffusion
osmosis
diffusion
the movement of molecules from a higher concentration gradient to a lower concentration gradient
examples of substances that can enter and exit cells by diffusion
O2
CO2
glucose
importance of diffusion in organisms
glucose and oxygen will diffuse into cells as these are raw materials needed for aerobic respiration
co2 will diffuse out of cells as this is a waste product for respiration
definition of osmosis
the movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane
effects of osmosis on animal cells in diff solutions
if animal cells are placed on a solution with a higher water concentration than the content of the cells they will gain water by osmosis and eventually burst when the cell membrane is stretched so far that it ruptures
if an animal cell is placed in solution with a lower water concentration than the cells then the water will move out of cells by osmosis and the cells will shrink
effects of osmosis on plant cells in diff solutions
if plant cells are places in solution with a higher water concentration that the context of cells they will gain water by osmosis and the cells will swell and become turgid
if plant cells are places in solution with a lower water concentration than the content of the cells then the water will move out of cells by osmosis and gen cell will become plasmalused
active transport
movement of molecules and ions across the cell membrane against the concentration gradient using membrane proteins and energy
role of membrane proteins in movement of molecules ions by active transport
operate as carriers that pick up and transport molecules ions from one side of membrane where they are in a low concentration and move them to the other side of the membrane where they are released into high concentration
substances that move by active transport
ions such as sodium Na possasum K chloride CI we magnesium Mg move by active transport
compare actuve and passive transport in terms of energy requirements
passive - requires no energy
active transport requires energy
respiration definision
is a series of enzyme controlled chemical reactions that releases the chemical energy stored in glucose
chemicals that control the rate of respiration
the chemical energy released by glucose by respiration is used to generate a chemical calledATP THIS ATP is then used to transfer energy to other chemicals reactions inside the cellsb
examples of cellular activities that require energy transferred by Atp
muscles cell contraction
cell division
protein synthesis
transmission of nerve impulses
respiration pathways
respiration in presence of oxygen- aerobic respiration
respiration in the absense of oxygen- fermintation pathway
chemicals first realeased in first stage of respiration
glucose is broken down to release two molecules of pyrovate and a small quantity of energy in the form of 2 molecules of ATP
summary word equation for aerobic respiration
glucose + oxygen —-> carbon + water + energy
word equation for fermentation in yeast and animal cells
animal- glucose -»» lactate + energy
plants- glucose —-»> carbon dioxide + ethonal + water
compare aerobic and fermentation in terms of breakdown products and energy release
breakdown products
aerobic - carbon water and atp
feemintation in animals- lactase and atp
fermi station in plants- ethanol carbon dioxide and atp
energy released
aerobic- large number of ATP molecules
fermentation in animals- low number of Atp
plants- small number of atp
compare aerobic and fermentation in terms of their locations inside cells
all respiration pathways begin in cell cytoplasm of oxygen is present then aerobic respiration is completed in mitochondria if oxygen is absense then the process of fermentation is completed in cytoplasm
link between energy requirements of cell and the number of mitochondria present in that cell
the hugher the energy requirement for the cell the greater the number of mutochondrai present in cell. This is bc the higher the number of mitochondria means that cell can do more aerobic respiration therefore make more atp to supply greater energy for cell Ecample - sperm, muscle and liver contain high number of mitochondria because they are all very active cells compared to the small number of mitochondria found in relatively inactive skin cells
