ORGANELLES AND COMPARTMENTALISATION (B2.2)

What are organelles?

Subunits of cells that perform specific functions

What is compartmentalisation?

The organisation of different functions and processes within specific areas or structures within the cell that are separated by the plasma membrane

What does compartmentalisation allow for?

The development of specialised cell structures

What are examples of specialised cell structures?

• Chloroplasts

• Mitochondria

Where can membrane- bound organelles be found?

Only in eukaryotic cells

What is an advantage of compartmentalisation?

The cell can separate chemical reactions and other cellular processes, which allows for the ability to increase the rate of chemical reactions in a cell.

What are the examples of compartmentalisation?

• Lysomes are compartments that break down and recycle waste materials within the cell.

  • Microphages use phagocytic vacuoltes which are joined by lysomes, to break down pathogens into parts which can then be used to develop an immune response.

  • Breakdown of waste in cells requires use of enzymes, and by isolating the enzymes in the phagocytic vacuoles, it protects the rest of the cell and allows the waste to be broken down safely.

  • Smaller space in the phagocytic vacuoles also allow for faster and more efficient reaction as the enzymes are in higher concentration.

What parts fo a cell are not considered organelles?

• Cytoskeleton: These proteins are not enclosed by a membranes and are not involved in metabolic process like other organelles

• Cell wall:Not surrounded by a membrane and not involved in metabolic processes

• Cytoplasm: Does not have a discrete structure with a specific function but is needed for cell survival

What is an organelles that is not membrane bound, but still considered an organelle?

Ribosomes are structures that make proteins but are not membrane bound, but are organelles because they have a specific function

What is a nucleas?

A double- membrane surround nucleus in eukaryotic cell, with outer membrane part of the rough endoplasmic reticulum

What are the advantages of the compartmentalisation of the nucleus form the cytoplasm?

• Nucleus contains the cell’s DNA and it regulates genes through the transcription of DNA into mnRNA. Cytoplasm is where translation of mRNA into protein happens in prokaryotes

• Eukaryotes have post-transcriptional modification

  • mRNA changed by removing pieces .Working protein can only be made after it has been done. Separation cannot happen in prokaryote as there is no nucleus