Anatomy of the Cell Flashcards
what is a eukaryotic cell?
one with a true nucleus
what is the plasmalemma?
the cell membrane
what is the role of the cell membrane?
separates the cytoplasm from the outside environment
what can move through the cell membrane easily?
water
oxygen
small hydrophobic molecules
what cannot move through the cell membrane?
charged ions
what is an organelle?
a small cellular organ with a specific function that is essential to life
what is the role of the mitochondria?
produces energy (ATP)
what is the role of the rough endoplasmic reticulum?
protein synthesis
what is the role of the smooth endoplasmic reticulum?
cholesterol + lipid synthesis
detoxification
what is the role of the golgi apparatus?
modification and packaging of secretions
what are lysosomes?
hydrolytic enzymes for intracellular digestion
what is an inclusion?
anything else in the cell that isn’t essential to life
what are two ways an inclusion may appear in a cell?
the cell might synthesise it
it could be taken up from the extracellular environment
what are the three main classes of filaments in the cytoskeleton from smallest to largest ?
microfilaments
intermediate filaments
microtubules
what are microfilaments made from and what property does this give them?
actin
this can assemble into filaments and then dissociate, making them very dynamic
what are intermediate filaments made of and what does this lead to?
six main proteins that vary in cell types
cell types can be identified by what makes up their intermediate filaments
what are microtubules composed of?
two tubulin proteins, one alpha and one beta
it is a hollow tubule
where do microtubules originate?
the centrosome
what is included in a microtubule?
stabilising proteins = microtubule associated proteins (MAPS)
what filament allows proteins to move through the cell?
microtubules
what three things are microtubules important in?
cilia
flagella
mitotic spindle
what proteins attach to microtubules and move along them through the cell?
kinesin and dynein
what type of proteins are kinesin and dynein?
ATPase’s
what direction does kinesin move in?
towards the cell periphery
what direction does dynein move in?
towards the cell centre
how do the three filaments form the cytoskeleton?
they attach to each other and the cell membrane, creating a dynamic internal scaffolding in the cell
what organelle is found in a centrosome and what are these made of?
centrioles
made of specialised microtubule segments
what surrounds the nucleus?
a double layered membrane (the nuclear envelope)
this is porous
what is found between the two layers of the nuclear envelope?
the perinuclear cistern
what is found on the surface of the outer nuclear membrane?
ribosomes, continuous with the RER
what RNA molecules are transcribed in the nucleus?
mRNA
tRNA
what RNA molecules are transcribed in the nucleolus?
rRNA
what is the nucleolus?
a dense area in the nucleus
what does the nucleus contain?
euchromatin
heterochromatin
what is euchromatin?
DNA that is more dispersed and actively undergoing transcription
what is heterochromatin?
DNA that is highly condensed and not undergoing transcription
where are ribosomes formed?
the nucleolus
what is each ribosome made of and what does each part do?
large subunit = catalyses peptide bond formation
small subunit = binds RNA
what does the export of ribosomes from the nucleolus depend on?
the nuclear pore complex
what does the endoplasmic reticulum form?
a network of interconnecting membrane bound compartments
what are the two types of endoplasmic reticulum?
rough (RER)
smooth (SER)
what covers the surface of the RER?
ribosomes
what does the amount of RER suggest about a cell?
how active it is
what type of cells have more than a normal amount of SER?
cells that synthesise steroid hormones
which mitochondrial membrane folds and what does this form?
the inner membrane
forms cristae to increase the surface area
which tissue type contains many intercellular junctions?
epithelia
what are the three types of intercellular junctions?
occluding
anchoring
communicating
what does an occluding junction do?
links cells to form a barrier that prevents diffusion
what are other names for occluding junctions?
tight junctions
zonula occludens
what do anchoring junctions do?
link submembrane actin bundles in adjacent cells ti provide mechanical strength
what are other names for anchoring junctions?
adherent junctions
zonula adherens
what is a desmosome?
a type of anchoring junction that links submembrane filaments of adjacent cells
what is another name for desmosomes and where are they common?
macula adherens
common in the skin
what do communicating junctions do?
allow movement of molecules between cells
what are communicating junctions also called?
gap junctions
where are gap junctions commonly found?
epithelial
smooth muscle
cardiac muscle
