bio exam Flashcards
define eukaryote
a eukaryote is a cell or organism with membrane bound organells eg. plant or animal cells
define prokaryote and examples
a prokaryotic cell is a cell or organism without any membrane bound organelles (no nucleus)
mitochondria
the mitochondria are the energy suppliers of a cell, they produce energy in the form of atp by a process of cellular respiration. the mitochondria is not present in prokaryotic cells. lots in cells
nucleus and nucleolus
the nucleus controls all functions of a cell. it controls dn replication during cell division and repair of genetic material. inside the nucleus are many chromatin and the nucleolus, the nucleolus has no outer membrane and is responsible for producing rna that forms part of the ribosomes
what is atp
atp is the usable energy produced by the mitochondria in the process of cellular respiration
what is the difference between plant and animal cell
plant cells have a cell wall whereas animal cells do not
most plants have chloroplasts whereas animal cells do not
plant cells have large vacuoles and animal cels do not
smooth er
the smooth er is involved in the manufacture of substances, detoxifying harmful products, and the storage and release of substances.
rough er
the rough er is involved in transporting some of the proteins to various sites within a cell and also the processing of proteins
unicelular
a single cell
multicelular
orgaism containing multiple cells
SA:V ratio
cella are smaller because they have a bigger sa:v ratio for faster exchange of materials.
the volume of a shape increases faster than the surface area expands therefore as a cube fore example grows bugger the sa:v ratio decreases
the smaller the sa:v ratio (bigger the animal) the less heat is lost eg animals licit in cold environments are generally larger to have a smaller sa:v ratio
flats shapes have larger sa:v ratio eg. giraffe is not round it has long skinny legs and neck which increases sa:v ratio
cell membrane structure
the cell membrane is a fluid (it moves) and is mosaic patterned (because of the proteins embedded in the phospholipids its creates a mosaic pattern). it has a double layer, the upper layer can slide over the lower layer and the whole membrane can break and rejoin. it is made up of phospholipids containing a hydrophilic phosphate head (polar) and a hydrophobic fatty acid lipid tail (non polar).
hydrophilic
attracted to water (head of a phospholipid)
hydrophobic
retracts from water, hates water (fatty acid tail of a phospholipid)
function of the plasma membrane
the function of the plasma membrane is to seperate the internal environment from the external environment of their surroundings, to from a boundary. it controls the exit and entry of materials from the cell and is semi-permeable.
glycoproteins act as like the name tag go a cell, they come to the end of the phospholipids and show the cells identity
the receptors of trans-membrane proteins receive external signals
transporters are embedded in the membrane for materials unable to cross by simple diffusion
crossing the plasma membrane (factors affecting)
molecular size- smaller molecules cross easier, bigger molecules such as proteins and nucleic acids cannot cross by diffusion
presence of a net charge (+ or -)- eg k+ or cl- cannot cross because they are repelled by hydrophobic lipid component
hydrophilic moeclules such as glucose cannot cross because they are replied by hydrophobic lipid component
movement up a concentration gradient cannot occur by diffusion
simple diffusion
simple diffusion is net the movement of substances (small and lipophilic) across the phospholipid bilayer from a region of high concentration to a low concentration. (down the concentration gradient). does not require any input of energy. The end point is when a equilibrium is reached on both sides
osmosis
osmosis is a special case of diffusion where the solvent of movement is water. it is the net movement of water across a semipermeable membrane from a solution of lesser sole concentration to on elf greater solute concentration.
hypotonic
having a lower solute concentration than the cell contents
(large amounts of water coming into the cell). in a red blood cell or in animal cells the uptake of water will cause the ell to swell and eventually cause the membrane to burst dispersing the cell contents.
in plants the cell will swell and become rigid but not burst because of the thick cell wall
hypertonic
having a higher solute concentration than the cell contents
(larger amounts of water coming outside the cell)
the net loss of water from cells causes the cell to shrink, in last cells the cell within its plasma membrane shrinks away form the cell wall.
isotonic
having an equal solute concentration than the cell contents
equal amounts of water coming in and out if the cell
facilitated diffusion
facilitated diffusion enables molecules that cannot diffuse across the phospholipid bilayer to move across the plasma membrane through the agency of transporter proteins such as channel and carrier proteins.
channel proteins
a group of proteins embedded in the phospholipid bilayer and involved in facilitated diffusion. it has a water filled pore through the middle and allows hydrophilic molecules to pass through down the concentration gradient
carrier proteins
carrier proteins are a group of proteins embedded into the phospholipid bilayer and involved in facilitated diffusion. .
it allows hydrophilic molecules to cross the plasma membrane, down their concentration gradient in the absence of a channel protein. it changes its shaper to allow molecules through.
