Cell structure and function Flashcards
What is a prokaryotic cell?
Simple cells composed of DNA and cytoplasm. for example, bacteria
What is eukaryotic cell?
more complex cells, with a nucleus and membrane bound organelles for example animal cells and plant cells.
What is the structure and function of the nucleus?
Most prominent organelle “Cell Brain”.
▪ Storage and utilisation of DNA.
▪ Surrounded by double membrane (Nuclear envelope).
▪ Contains DNA packaged into chromosomes (visible during division).
▪ The outer nuclear membrane is connected with endoplasmic reticulum.
▪ The inner nuclear membrane encloses the nucleoplasm.
▪ The Nucleolus is the largest structure in the nucleus of eukaryotic cells,
where it primarily serves as the site of ribosome synthesis and assembly.
what is the function of nuclear pores?
to allow the transport of molecules across the nuclear envelope.
This transport includes RNA and ribosomal proteins moving from nucleus
to the cytoplasm and proteins, carbohydrates, signaling
molecules and lipids moving into the nucleus.
what is the structure and function of ribosomes?
Site of mRNA translation and protein synthesis.
▪ Made from complexes of RNAs and proteins
▪ Are not surrounded by a membrane.
▪ Could be freely floating in cytoplasm or attached to Rough ER.
▪ Each ribosome is divided into two subunits
▪ A smaller subunit which binds to a larger subunit and the mRNA
transcript
▪ A larger subunit which binds to the tRNA, the amino acids, and the
smaller subunit
what is the structure and function of the endoplasmic reticulum?
Synthesis of new membrane and protein
▪ An interconnected network of flattened, membrane-enclosed sacs or
tube-like structures known as Cisternae
* Linked to nuclear membrane
* 2 types – smooth & rough
* Rough studded with ribosomes and mainly involved in protein
synthesis.
* While Smooth ER is involved in lipid synthesis.
What is the structure and function of the golgi body?
Sorting, modifying and packaging proteins and lipids.
▪ Forms a dynamic system of membrane stacks.
▪ Proteins synthesised in the ER are packaged into vesicles.
▪ Fuse with the Golgi at the cis face.
▪ These cargo proteins are modified as they progress towards the trans
face.
▪ Bud off as vesicles destined for secretion via exocytosis or for use in
the cell.
▪ Protein folding into functional 3D configurations.
▪ Post-translational modifications of proteins include the addition of
glycosylation and phosphorylation.
What is the structure and function of lysosomes?
Degradation of unwanted material.
▪ Small and irregularly shaped.
▪ Low internal pH (~4.5).
▪ Full of enzymes which degrade unwanted molecules (Proteases,
glycosidases, and sulfatases).
▪ Fuse with endosomes/phagosomes and dispense their enzymes into
it, digesting their contents.
What is the structure and function of mitochondrion?
Site of cellular respiration – Kreb’s cycle & ETC to Generate ATPs.
▪ Surrounded by double membrane with a highly-folded inner membrane
(Cristae).
▪ Contains its own DNA (Circular, covalently closed, double-stranded DNA).
▪ Reproduces by splitting in two.
▪ Number of mitochondria varies with cell type.
what are the porins in the mitcochondria?
The outer membrane contains Porins which form channels that allow molecules of 5000 Da or less to freely diffuse from one side of the membrane to the other.
what is the structure and function of the cytosol?
The liquid matrix around the organelles.
▪ That part of the cell which is not contained in any membrane-bounded compartment.
▪ Cytoplasm = Cytosol + Organelles + various dissolved substances
▪ Cytoplasm does not include nucleus.
▪ Site of glycolysis.
▪ Cell = Cellular membrane + Cytoplasm (Cytosol and organelle)+ Nucleus.
what is the structure and function of the cytoskeleton?
A complex network of interlinking filaments and tubules that
extend throughout the cytoplasm, from the nucleus to the
plasma membrane
▪ Provides a framework for support giving the cell shape and
mechanical resistance to deformation
▪ It can also actively contract, thereby deforming the cell and the
cell’s environment and allowing cells to migrate
▪ It segregates chromosomes during cellular division
▪ Involved in cytokinesis (cell division)
