Cell Structure Flashcards
outline how to prepare a temporary mount for a light microscope
obtain thin section of tissue
place drop of water on tissue
stain tissue to make structures visible
add coverslip with mounted needle at 45 degrees
describe how light microscopes work
lens focus rays of light and magnify specimen
different structures absorb different wavelengths
reflected light transmitted to observer via objective lens and eyepiece
describe how a transmission electron microscope works
pass high energy beams of electrons through thin specimen
more dense structures appear darker as absorbed more electrons
describe how a scanning electron microscope works
focus beam of electrons onto surface using electromagnetic lens
reflected electrons hit collecting device and amplified to produce image
describe how a laser scanning confocal microscope works
focus laser beam using objective lens
fluorophores in the sample emit photons
light focused through a pinhole onto a detector
define magnification
how much bigger image is than specimen
define resolution
how detailed the image is-how well each point is distinguished
why do samples need to be stained
coloured dyes bind to the structures
facilitates absorption of wavelengths of light
describe structure of nucleus
surrounded by nuclear envelope-semi permeable double membrane
nuclear pores allow substances to leave/enter
dense nucleolus made of RNA and proteins
what is the function of the nucleus
contains DNA coiled around chromatin into chromosomes
controls cellular processes
describe structure and function of rough endoplasmic reticulum
system of membranes enclosing fluid filled space
surface covered with ribosomes
folds and processes proteins
what is the function of the smooth endoplasmic reticulum
synthesises and processes lipids
describe structure and function of the golgi apparatus
stack of membrane bound flattened sacs
cis face aligns with rough endoplasmic reticulum
modifies and packages proteins
synthesis of glycoproteins
describe structure of ribosomes
large subunit joins amino acids
small subunit with mRNA binding site
describe the relationship between the organelles involved in production and secretion of proteins
ribosomes that synthesis proteins are attached to the RER
golgi apparatus which modifies proteins for secretion aligns with the RER
describe the structure of a mitochondrion
surrounded by a double membrane
folded inner membrane form cristae
fluid matrix contains respiratory enzymes
describe structure of a chloroplast
double membrane
thylakoids (flattened discs) stack to form grana-contain photosystems
intergranal lamellae-tubes attaching thylakoids
stroma-fluid filled matrix
what is the function of mitochondria
aerobic respiration to produce ATP
what is the function of chloroplasts
photosynthesis to convert light energy into chemical energy
describe the structure and function of lysosomes
sac surrounded by single membrane
embedded H+ pump maintains acidic conditions
contains digestive enzymes
invades cells or breaks down components
describe structure and function of plant cell wall
made of cellulose microfibrils for mechanical support
plasmodesmata form apoplast pathway to allow molecules to pass between cells
what are bacterial and fungal cells made of
bacteria=peptidoglycan
fungi=chitin
Describe the structure and function of centrioles
Spherical group of nine microtubules arranged in triplets
Migrate to opposite poles of cell during prophase
Describe structure and function of plasma membrane
Phospholipid bilayer with intrinsic and extrinsic proteins embedded
Isolates cytoplasm from environment
Selectively permeable to regulate transport of substances
Explain role of cholesterol in cell surface membrane
Connects phospholipids and reduces fluidity
Explain role of glycoproteins in cell surface membrane
Cell signalling, recognition and binding cells together
describe the structure and function of flagella
hollow tube made of protein flagellin
rotates to propel organism
describe the structure and function of cilia
hairlike protrusions
move back and forth to waft foreign substances away
what is the importance of the cytoskeleton
provides mechanical strength
aids transport
enables cell movement
what are the similarities between eukaryotes and prokaryotes
cell membrane
cytoplasm
ribosomes
what are the differences between eukaryotes and prokaryotes
prokaryotes smaller
prokaryotes have smaller ribosomes (70s) and eukaryotes have larger (80s)
prokaryotes have no membrane bound organelles
