Anatomy of the cell Flashcards
eukaryote
any cell or organism that possesses a clearly defined nucleus
what do Eukaryotic cells have
an outer membrane, and the interior of a eukaryotic cell is composed of organelles, the cytoskeleton, and the cytosol
what does the plasmalemma (outer membrane) do
Separates cytoplasm from outside environment, forming a selectively permeable barrier
what does the phospholipid bilayer contain
- Hydrophilic heads at outer and inner surfaces
- Hydrophobic tails at centre
- integral proteins
what can the phospholipid bilayer do
exocytose and endocytose material
what is the cytosol
solution of proteins, electrolytes and carbohydrates which the cellular components are embedded
what does the nuclear envelope do
enclose the nucleus
what does the nuclear envelope contain
Inner and outer nuclear membrane with the perinuclear cistern in the middl
explain why the outer nuclear membrane is outer
it is studded with ribosomes
what do Nuclear pores do
allow the transport of molecules across the nuclear envelope
what does the nucleus contain
chromosomes
euchromatin
DNA is more dispersed and undergoing transcription
heterochromatin
DNA highly condensed and not undergoing transcription
what is the nucleus the site of
RNA synthesis
where are ribosomes formed
in the nucleolus
how are ribosomes formed
Small subunit binds RNA, large subunit catalyzes peptide bond formation
rer
studded with ribosomes, responsible for protein synthesis and initiation of glycoprotein formation
ser
involved in continuous processing of proteins from RER and lipid synthesis
Golgi apparatus
Composed of a group of flattened, membrane bound cisternae
what happens at the Golgi apparatus
Transport vesicles arrive at Golgi from SER; Golgi modifies and packages them
what does the cytoskeleton consist of
protein filaments which allow movement of organelles and also movement of the cell itself
microfilaments
composed of actin, involved in cellular movement, cytokinesis, endo and exocytosis etc., 7nm
Intermediate filaments
6 proteins that bind intracellular elements together and to the plasmalemma, >10nm
microtubules
composed of alpha and beta tubulin, originate from centrosome, polar, dynein and kinesin attach and move along them, 25nm
endocytosis
membrane invaginates, fuses, newly made endocytic vesicle buds into cell
exocytosis
works in reverse to endocytosis
phagocytosis
bacteria binds to cell surface, cell engulfs it to form phagosome, binds with lysosome containing digestive enzymes
Occluding junctions
link cells to form a diffusion barrier
what are occluding junctions also known as
tight junctions or zonula occludens
Anchoring junctions
provide mechanical strength
Adherent junctions
link submembrane actin bundles of adjacent cells via cadherin molecules
desmosomes
link submembrane intermediate filaments of adjacent cells
hemidesmosomes
link submembrane intermediate filaments of cells to extacellular matrix through transmembrane proteins
what is each junction
Each junction is a circular patch studded with pores
Communicating junctions (gap junctions)
allow movement of molecules between cells
