Cell structure Flashcards
list the structural differences between an animal cell and a plant cell
plant:
-cell wall made of cellulose
-chloroplasts
- large permanent vacuole
list the structural similarities between animal and plant cells (9)
-cell membrane
-nucleus
-mitochondria
-ribosomes
-golgi body
-cytoplasm
-rough endoplasmic reticulum
-smooth endoplasmic reticulum
-lysosome
what is the function of the cell surface membrane
controls the movement of molecules in and out of the cell
(4)
what is the function of the nucleus
directs the synthesis of proteins
contains cell’s DNA
controls all metabolic processes
manufactures ribosomes and RNA
what is the function of mitochondria
site of cellular respiration
produces energy in the form of ATP
what is the function of golgi apparatus
processes and packs proteins and lipids
forms lysosomes
what is the function of ribosomes
site of protein synthesis
what is the function of rough endoplasmic reticulum
packages and modifies proteins
what is the function of smooth endoplasmic reticulum
site of synthesis of lipids
what is the function of lysosomes
break down materials
some cells programmed for apoptosis (cell break down and death)
what are the pros of light microscopes
cheap
portable
can see living material
quick and easy to prepare
what are the cons of light microscope
low magnitude
low resolution
how do scanning electron microscopes (SEM) work
a beam of electrons passes across the surface of the specimen and scatters, building up a 3D image
how do transmission electron microscopes (TEM) work
beam of electrons pass through a thin section of the specimen. areas the absorb more of the electrons appear darker on the image produced
pros of TEM
very high resolution
short wavelength of light
cons of TEM
expensive
needs a vacuum
has a complex staining process
the specimen must be cut very thinly (so is dead)
is 2D not 3D
what are the stages of cell fractionation
Homogenization
Filtration
Ultracentrifugation
describe Homogenization (2 marks)
sample placed in a cold, isotonic, buffer solution.
The tissue containing solution is then homogenized using a homogenizer. This breaks the plasma membrane of the cells and releases the organelles
describe filtration (1 mark)
solution filtered trough gauze to separate large debris that wasn’t broken up, leaving a mixture of organelles
describe centrifugation (2 marks)
placed into a centrifuge
first spun at a low speed,
largest, heaviest organelles (such as the nuclei) to settle at the bottom of the tube.
drained off and placed into another tube,
Spun at a higher speed.
mitochondria to settle at the bottom
repeat at higher speed
ribosomes at the bottom of tube
why kept ice cold
stops enzyme activity, prevents digestion of organelles
why kept buffered
maintains pH, enzymes and proteins won’t denature
why kept isotonic
prevents osmosis so no lysis of organelles
what is the magnification formula
magnification= image size divided by actual size
what is 1 meter in nanometers
1m=1000mm
1mm=1000µm
1µm=1000nm
therefore 1m=1,000,000,000nm
