Anatomy of a Cell Flashcards
What is an eukaryotic cells
outer membrane
inner cystol - solution of proteins electrolytes & carbohydrates
membrane bound organelles
inclusions - other structures in cytoplasm
cytoskeleton - shape/fluidity
What is the cytoskeleton made of
microtubules (25nm) - composed of tubulin
Intermediate filaments (>10nm) - 6 main proteins
Microfillaments (7nm) - composed of actin
What is the plasmalemma
separates cytoplasm from outer environment amphipathic phospholipid bilayer intergral proteins Can exocytose and endocytose material fluid mosaic selectively permeable embedded cholesterol can change shape some membrane proteins diffuse bilaterally, some anchored
function of Golgi apparatus
modification and packaging of macromolecules/secretions from SER eg adds sugars/cleaves proteins
composed of flattened membrane bound cisternae
Transport vesicles arrive at Golgi from SER
function of lysosomes
hydrolytic enzymes for intracellular digestion
function of mitochondria
energy production generate ATP
inner & outer membrane
inner folded to form cristae
synthesis of certain lipids and proteins
function of rough ER
protein synthesis
studded with ribosomes
initiation of glycoprotein
lots in high metabolically active cells
function of smooth ER
cholesterol and lipid synthesis
detoxification
Continues processing of protein from RER
extensive in leydig cell - steroid hormone producing
what are inclusions
dispensable
can be transients
components synthesised by the cell OR
Taken up from extracellular environment
function of cytoskeleton
attach to cell membrane and each other by anchoring and join proteins to form dynamic 3D scaffolding
Describe microtubules
originate from centrosome - organising centre
Polar, radiate outwards
assemble and dissemble
motorway network of cell
What proteins help to move microtubules along
Kinesin - ATPase moves towards cell periphery
Dynein - ATPase moves towards cell centre
attach to microtubules move along them associate with membrane of organelles
Why are microtubules important
important in movement of long processes eg. axonal process of neurons
What are centrioles
composed of specialised microtubule segments
Describe the nucleus
enclosed by nuclear envelope - inner & outer membrane with nuclear pores
continuity with cytoplasmic RER
outer nuclear membrane studded with ribosomes
What is the function of the nucleus
site of RNA synthesis - mRNA, tRNA in nucleus, rRNA in nucleolus
contains chromosomes
What does the nucleus contain
Euchromatin DNA actively undergoing transcription
Heterochromatic DNA highly condensed, not undergoing transcription
describe the endoplasmic reticulum
net-like
forms network of interconnecting membrane bound cell compartments
Function of ribosome
protein synthesis
synthesised in nucelolus
small subunit bind RNA
large subunit catalyses peptide bond formation
what does export of ribosomes depend on
nuclear pore complex
What is synthesised on polysomes floating free in cystol
proteins that are to remain unpacked in cystol
describe the roles of mitochondria
generates ATP via oxidative phosphorylation
synthesis of lipids/proteins
contain own DNA
why do mitochondria have an inner membrane that is highly folded forming cristae
to increase surface area
What are occluding junctions
tight junction
prevent diffusion
link cells to form occlusion barrier
zonula occludens
what are anchoring junctions
provide mechanical strength
adherent junctions
link submembrane actin bundles of adjacent cells
transmembrane cadherin bind together in extracellular space and bind to actin of cytoskeleton
zonula adherens
What are desmosomes
link submembrane intermediate filaments of adjacent cells
what are hemidesmosomes
link submembrane intermediate filaments of cells to extracellular matrix through transmembrane proteins
what are communicating junctions
allow movement of molecules between cells
gap junctions
each junction is a circular patch studded with pores - produced by connexion proteins
found in epithelium, smooth and cardiac muscle
What is endocytosis
membrane invaginate, fuses and newly made endocytotic vesicle buds into cell
receptor mediated
What is exocytosis
opposite of endocytosis, vesicle fuses with membrane releasing contents into extracellular environment
what is the process of phagocytosis
bacteria binds to cell surface, cell engulfs it to form phagosome binds with lysosome containing digestive enzymes producing of phagolysosome
