Lecture 10 - Cells & Organelles Flashcards
what is the primary difference between prokaryotes and eukaryotes?
the presence of a nucleus in eurkaryotes
T or F: prokaryotes transport material into and out of the cell
False
what are the 2 membranes of the nuclear envelope?
- the inner membrane, defines the nucleus
- the outer membrane, contiguous with the ER
_________ _____ fuse the two membranes, which serve as a conduit for transport between the cytoplasm and the __________
nuclear pores, nucleoplasm
what occurs in the nucleus for it to be deemed the information centre of the cell?
DNA replication, transcription, and RNA processing
what is the prominent subdomain of the nucleus and what happens there?
the nucleolus where ribosomal RNA is transcribed and ribosome are assembled
def: consists of tubular membranes and flattened sacs called cistern
endoplasmic reticulum (ER)
what is the internal space of the ER called?
the lumen
the ER is continuous with the _________ _____ _____ ______
outer membrane of the nuclear envelope
def: critical staring point of the protein biosynthetic pathways
rough endoplasmic reticulum
the cytoplasmic side of the RER membrane is covered in what?
studded with robsomes
are free ribosomes associated with the ER?
no
what is the purpose of ribosome on the outside of the RER membrane?
they synthesize polypeptides that accumulate within the membrane or are transported across into the lumen
def: extensively developed in many cells, like skeletal muscle, kidney tubules, steroid producing endocrine cells
smooth endoplasmic reticulum
T or F: the smooth ER has a role in protein synthesis
False, it does not
what does the smooth ER synthesize?
lipids and steroid hormones, prominent in the gonads and adrenal cortex endocrine cells
def: specialized type of smooth ER, critical for the storage and release of calcium ions during muscle contraction
sarcoplasmic reticulum
def: closely related to the ER in proximity and function, consists of a stack of flattened vesicles known as cistern, accepts transition vesicles that bus off the RER and enter the cis side, which faces the RER
golgi apparatus
what does the Golgi apparatus play an important role in?
processing and packaging secretory proteins, and in complex polysaccharide synthesis
def: vesicle sorting station, segregating proteins into vesicles headed to plasma membrane or other intracellular destinations
trans golgi network (TGN)
def: transition vesicle sorting station, sorting of proteins to be sent back to the ER or on to the Golgi
cis golgi network (CGN)
lysosomes are the _________ organelle
digestive
how many membranes do lysosomes have
1
def: pH activated and sequestered enzymes that are synthesized in the ER and transported to the Golgi and packaged into secretory vesicles (lysosomes)
hydrolases
what are hydrolytic enzymes activated by?
proteolytic cleavage in an acidic environment
what maintains the low internal pH of the lysosome?
the ATP-driven H+ pump in the lysosomal membrane
what protects the lysosome membrane from digestion?
a special carbohydrate coating on the inner side of the lysosome membrane
what are 3 degradation pathways utilize the lysosome?
- endocytosis
- phagocytosis
- autophagy (mechanism for degrading intracellular organisms)
once processed by the Golgi complex, materials to be exported from the cell are packaged into __________ __________
secretory vesicles
secretory vesicles fuse with the plasma membrane and release their contents outside the cell by __________
exocytosis
what 4 components make up the endomembrane system?
- ER
- Golgi
- Vesicles
- Lysosomes
what process do these two statements describe:
- proteins leaving the cell
- molecules are added to the plasma membrane
exocytosis of biomolecules
what process do these two statements describe:
- cellular uptake of particles and macromolecules
- nutrients, growth factors, recycling of membrane, membrane repair
endocytosis of biomolecuels
def: cytoplasmic vesicles with a diameter of 0.1-10 mm, surrounded by a single membrane and perform several functions depending on cell type, detoxify harmful compounds, and catabolize unusual substances
peroxisomes
are peroxisomes part of the endomembrane system?
no
what is the vital role of peroxisomes in animal cells?
oxidative breakdown of fatty acids, especially longer chain fatty acids
peroxisomes can both generate and degrade ________ ______
hydrogen peroxide
how do cells protect themselves from hydrogen peroxide?
performing H2O2 generating reactions in the same organelle as catalase which decomposes H2O2 into water and oxygen
what is the organization in mitochondria?
2 membranes, generating 3 regions
def: mitochondria - contains porins, which allow free movement of small molecules and ions across
outer membrane (relativity permeable)
def: mitochondria - acts as a permeability barrier to most solutes
inner membrane (highly impermeable)
the inner membrane is highly folded into _______ that project into the interior of the mitochondria
cristae
the density of crustal is related to the _________ _____ __
respiratory activity of the cell
def: mitochondria - within the inner membrane, contains most of the enzymes associated with mitochondrial function, in addition to DNA and ribosomes
matrix
def: mitochondria - area between the outer and inner membranes
inter membrane space
def: mitochondria - localized regions were protons can accumulate during the electron transport process
intracristal space
what does the mitochondrial matrix contain?
many enzymes involved in mitochondria function as well as DNA molecules and ribosomes
how many rRNA transcripts does a human mitcochondria have?
2
in non-photosynthetic cells, what does the mitochondria serve as?
principle site of ATP production
tissues with high demand for ATP have ______ mitochondria
many
mitochondria are also important in the regulation of ________
apoptosis
def: the site of photosynthesis
chorloplasts
chloroplasts contain a system of flattened membranous sacs called ________ stacked into ________
thylakoids, grana
T or F: photosynthesis is the opposite of mitochondrial reactions
true, its the reverse of the mitochondria reactions that oxidize glucose into CO2
reactions involved in the reduction of CO2 to sugar occur within the ______
stroma
T or F: mitochondria and chloroplasts have their own DNA and ribosomes
true
are both mitochondria and chloroplasts surrounded by double membranes?
yes
about 90% of a plant cell can be occupied by a ________
vacuole
where are toxic compounds stored in plant cells?
vaculous
what is the main function of the central vacuole in a plant cell?
maintain turgor pressure that keeps the plant from wilting
why aren’t ribosomes technically considered organelles?
they are not enclosed by a membrane
each species of ribosomes has a unique type of ________ ___
ribosomal RNA
def: three dimensional array of interconnected microfilaments, microtubules, and intermediate filaments, gives strength and distinctive shape to cells
cytoskeleton
def: comprised primarily of proteins, glycoproteins, and glycosaminoglycans
extracellular matrix (ECM)
what are the functions of the ECM?
- support for cells to form tissues
- substrate for attachment, motility
- growth promoting signals
- rigidity in plants
