Cell structure 🧬 Flashcards
(17 cards)
What are organelles?
Parts of a cell.
Each contain specific function.
Describe function (sub-structures) of nucleus.
Large organelle surrounded by nuclear envelope—-> double membrane.
Contains nuclear pores.
Contains nucleous (made of RNA and proteins) which assembles ribosomes.
What is the function of nucleus?
Control cell activities (transcription of DNA)
Nuclear pores allow substances (RNA) to move between nucleus and cytoplasm.
Describe vesicles.
Fluid-filled sacs
Transport substances around the cell.
Some formed in Golgi or endoplasmic reticulum.
Describe lysosomes.
Contain digestive enzymes.
No clear internal structure.
Break down cell walls of bacteria/invading cells.
Describe ribosomes.
Site of protein synthesis
Either floats in the cytoplasm or attached to RER.
Made of proteins and RNA.
Not surrounded by membrane.
Describe mitochondria
Site of cellular respiration.
Very active cells = lots of mitochondria.
Double membrane.
Inner membrane highly folded to form cristae —> fluid interior called matrix
Membrane-forming cristae contain enzymes used in aerobic respiration.
Role of cytoskeleton.
Network of fibres necessary for shape/stability of cell.
Makes up centrioles
Allows cell to change shape for endo/exo-cytosis
Facilitates movement of organelles.
What make up the cytoskeleton?
Three components:
Microfilaments—->
~Made from actin.
~Responsible for cell movement/cell contraction during cytokinesis.
Microtubules—->
~Globular tubulin proteins polymerised to form tubes
~Form scaffold-like structure that determines shape of cell.
Intermediate fibres——>
~Give mechanical strength to cells.
Describe centrioles
Composed of microtubules.
Involved in assembly + organisation of spindle fibres during cell division.
Role of flagella.
Whip-like extension
Enable cell mobility
Used as sensory organelle that can detect changes in cell environment.
Role of cilia.
Hair-like extensions.
Can be mobile or stationary
Mobile cilia beat rhythmically, causing objects to move.
Stationary cilia used in sensory organs such as the nose.
9+2 arrangement
2 central microtubules surrounded by 9 pairs of microtubules arranged in a wheel.
Pairs of parallel microtubules slide over each other causing cilia to move in a beating motion.
What are the roles of organelles involved in protein synthesis?
Synthesise proteins for internal use and secretion.
Coordinate production of proteins.
What is the endoplasmic recticulum?
Network of membranes in enclosed flattened sacs called cisternae.
Connected to outer membrane of nucleus.
2 types of Endoplasmic recticulum.
SER —> responsible for lipid and carbohydrate synthesis and storage.
RER—-> ribosomes bound to surface and responsible for synthesis and transport of proteins.
Describe Golgi apparatus
Compact structure formed from cisternae.
No ribosomes
Role of modifying and packaging proteins into vesicles.
Either secretory or stay in cell.
What is the overall process of protein production?
Protein synthesised on ribosomes bound on RER.
Passed into the cisternae and packaged into transport vesicles.
Vesicles with newly synthesised proteins move towards Golgi via cytoskeleton
Vesicles fuse with Golgi and protein is modified
Secretory vesicles carry protein which fuse with cell surface membrane via exocytosis.
