Cells: Organelles And Compartmentalisation Flashcards
What are organelles?
Subunits of cells that perform specific functions
What is compartmentalisation in cells?
The organisation of different functions and processes within subcellular structures separated by plasma membranes
What is a plasma membrane?
Thin, selectively permeable layer or phospholipid and protein molecular that controls what comes in and out of the cell
What does cell compartmentalisation allow for?
- The development of specialised structures
- The cell can separate chemical reactions and where they occur
- Increase the rate of chemical reactions
What are membrane-bound organelles?
Examples of compartmentalisation, structures that carry out a particular function.
E.g. Lysosomes
What are the structures in cells that are considered not membrane-bound?
- **cytoskeleton*: network of proteins for shape and movement of molecules around cell not enclosed by membrane, no metabolic processes
- cell wall: protects against mechanical stresses +support not enclosed by membrane, no metabolic processes
- cytoplasm: matrix that surrounds organelles, no specific function
What membranes surround the nucleus?
Double membrane:
Inner
Outer membrane: ribosomes attached, continuous, joined to part of the rough endoplasmic reticulum
Where does gene transcription and translation occur in prokaryotes?
In the cytoplasm simultaneously
—> allows for rapid responses to an environmental stimuli
—> means that protein is produced soon after mRNA is finished
Where does gene transcription and translation occur in eukaryotes?
Dues to compartmentalisation of the nucleus it occurs separately:
— after transcription, post- transcriptional modification needs to occur to form mature mRNA in the nucleus before translation in ribosome
—> this reduces change of errors occurring in mRNA code
—> this separation not possible in prokaryotes as no nucleus
What is another advantage of compartmentalisation of the nucleus and cytoplasm?
Allows cytoplasm to send signals to nucleus:
Cytoplasm receives extracellular signal (e.g. hormone or growth gactor
Message passed on to nucleus to change gene expression through increased/decreased transcription
[altering gene expression allows cell to produce different amounts/types on proteins for diff conditions]
What are lysosomes?
Compartmentalised spaces in cells that break down and recycle waste materials in cell
What is an example of lysosomes helping in breaking down materials?
Macrophages use phagocytes vacuoles (which are joined by lysosomes) to break down pathogens into parts
Then can be used to develop immune response
Why is compartmentalisation important for lysosomes and macrophages?
The breakdown of waste materials requires enzymes
Enzymes could be damaging to other parts of cell
Isolating enzymes in phagocytoc vacuoles protects rest of cell && efficient breakdown as confined to small space, efficient reaction, higher conc.
