Anatomy of the Cell Flashcards
What features are common to all eukaryotic cells?
An outer membrane An inner cytosol A cytoskeleton Membrane bound organelles Inclusions
What is the plasmalemma?
a phospholipid bilayer which separates the cytoplasm from the outer environment
What is special about the plasmalemma?
it is amphipathic
it is selectively permeable
What can be found in the plasmalemma?
cholesterol
integral proteins
transmembrane proteins
What organelles can be found in the cytoplasm?
Mitochondria RER SER Golgi apparatus Lysosomes Nucleus Inclusions
What is the function of the mitochondria?
energy production
What is the function of the RER?
protein synthesis
What is the function of the SER?
cholesterol and lipid synthesis
What is the function of the golgi apparatus?
modification and packaging of secretions
What is the function of lysosomes?
hydrolytic enzymes for intracellular digestion
What are the three main classes of filaments in the cytoskeleton?
microfilaments - actin
intermediate filaments - 6 classes of protein
microtubules - a & b tubulin
What are the functions of microtubules?
to move intracellular organelles and vesicles around the cell
What do microtubules associate with to move?
kinesin - towards cell periphery
dynein - towards cell centre
Where is the nucleus found?
in a nuclear envelope with inner and outer membranes and nuclear pores
What is the nuclear envelope continuous with?
the RER and is studded with ribosomes
what is the nucleolus?
a 1-3µm dense area within the nucleus
define euchromatin
DNA that is actively undergoing transcription
define heterochromatin
DNA that is condensed and not undergoing transcription. tightly wound and appears as dark splotches in the nucleolus
where are ribosomes formed?
nucleolus
What are ribosomes made up of?
small and large subunit
What does the small unit of ribosomes do?
binds RNA
What does the large unit of the ribosome do?
catalyses formation of peptide bonds
Where is SER common?
in cells that synthesise cholesterol
Where is RER common?
in active cells that produce lots of proteins i.e. plasma cells –> antibodies
How might the golgi apparatus modify molecules?
add sugars
cleave
glycosylate
move into granules or vacuoles
what is special about mitochondria?
contain their own DNA which is passed on from the mother
Where are the most mitochondria found?
in cells which require lots of protein and lipid synthesis i.e. liver and muscle cells
What are the three types of intercellular junction?
Occluding
Anchoring
Communicating
What is the function of occluding junctions?
formation of a diffusion barrier
Where would you find an occluding junction?
at the apical membrane of the cell
What are occluding junctions also known as?
tight junctions, zona occludens
What is the function of the anchoring junctions?
to provide mechanical strength especially where cells are likely to undergo stretch
What are desmosomes?
anchoring junctions which are common in skin; link via cadherin molecules
What are hemi-desmosomes?
molecules which link submembrane filaments of a cell to the EC matric through transmembrane proteins
What is another name for communicating junctions?
gap junctions
What is the subunit of the gap junction?
connexins
Where are gap junctions found?
in epithelia and smooth and cardiac muscle
In what ways can material move across the cell membrane?
diffusion transport proteins vesicles endocytosis phagocytosis
