Organelles Flashcards
Role of nucleus?
o Contains the DNA
how many nucleoli in a cell?
atleast one
are nucleoli membrane bound?
no
describe function of nucleolus
contain active dna (chromatin pulled away); produces rRNA
how many bilayers does the nuclear membrane contain?
2
inner membrane of nuclear envelope is supported by
nuclear lamina (intermediate filaments; they are crosshhatched)
the outer membrane of the nuclear envelope is supported by the
cytoskeleton
what is embedded into nuclear envelope’s bilayers?
nuclear pore complexes
The nuclear membrane is continuous with the
endoplasmic reticulum
describe ribosome structure
made of rRNA and proteins; contain a large and small subunit
role of ribosomes?
translate proteins
where are ribosomes found?
free in cytoplasm, or bound to rough ER
what does and doesnt the endomembrane system have?
Includes plasma membrane; nuclear envelope endoplasmic reticulum vesicles golgi apparatuslysosome/vacuoles
Does NOT contain mitochondria, chlrorplasts, peroxisomes
difference in structure between rough and smooth er?
rough has ribosomes attached. Smooth doesn’t.
describe role of rough ER in protein
proteins passed into lumen of ER
carbs can be added to proteins to form glycoproteins
synthesis role of rough ER?
makes proteins (due to ribosomes) and phospholipids
roles of smooth ER?
Metabolises carbs
Makes lipids, phospholipids, steroid hormones
Detoxifies drugs and poisons
Stores calcium
general role of golgi apparatus?
receives, sorts, ships and manufactures stuff
describe how golgi apparatus enables transport of vesicles
o Transport vesicle containing proteins breaks off of ER
o Vesicle sent to cis golgi (means golgi is on the same side as ER), and fuses with cis-golgi to form cisternae (long vesicles)
o cisternae “mature”
o vesicles bud off the trans-golgi
o transported to places within the cell (or outside); messenger proteins and cytoskeleton ensure the transport is regulated.
lysosomes contain
digestive (hydrolytic) enzymes; v acidic
roles of lysosomes:
phagocytosis and autophagy (of damaged organelles)
role of vacuole in single celled organisms? eg amoeba
expels water or lets it in to maintain osmotic pressure
structure of peroxisomes?
contain lipid bilayer and crystalline core.
role of peroxisomes?
transfer hydrogen from various compounds to oxygen, forming H2O2 (detoxifies alcohol in liver_
glyoxysomes are
specialised peroxisomes in plant tissue
role of glyoxysomes?
Break down fat reserves in seeds to produce sugars for the growing seedling
describe how mitochondria/chloroplasts were formed.
aerobic/photosynthetic prokaryote was engulfed by ancient eukaryote - forming first aerobic/photosynthetic eukaryotes.
Endosymbiosis as engulfed cell gained protection, whereas other cell gained glucose/ATP
evidence for endosymbiotic origin of chloroplast/mitochondria?
similar size to prokaryotes
both have double membrane
divide by binary fission, like bacteria
DNA is circular
structure of mitocondria
o Has an enclosing outer membrane and an internal highly folded membrane (cristae) and inside a matrix (fluid)
structure of chloroplast?
o Double-membrane bound
o Thylakoids: membranous, fluid filled flattened disks.
Grana (sing. granum): stacks of thylakoids (g is for group)
• Stacks of thylakoids ensure that photons are captured by atleast one
Chlorophyll is embedded into thylakoid membranes, as are some enzymes in the first stage.
o Stroma: fluid in chloroplasts, which bathes the grana.
Contains some enzymes involved in the second stage, and ribosomes and DNA
