Enumerate the functions of all cell organelles
Organelles are the living, highly specialized microscopic structures embedded in the substance of cytoplasm which appears as translucent and homogenous in the living cell. Its structure consists of elements that come into view separately and steady anytime of cellular life, apart from in the reproductive period.
These cells are almost similar in all the organisms ranging from microbes to plants and animals.
Mitochondria: These are sac-like organelles inside the cells. They have their own single-stranded DNA.
- Mitochondria contain enzymes concerned with – Kreb’s cycle, electron transport, and oxidative phosphorylation.
- It is the powerhouse of the cell.
- It is the major site of ATP synthesis. (ATP provides energy for all cellular fractions. It is required for transport of ions across the cell membrane. ATP causes muscle contraction and glandular secretion.)
- Contains DNA, so, it is self-replicable.
Endoplasmic Reticulum: These are also a sac-like structure attached to the nucleus and extend thereof like being suspended in the cytoplasm.
- Smooth endoplasmic reticulum: Synthesis of lipid m the cell, provides enzyme for controlling glycogen breaks down, provides enzymes for detoxification of many substance e.g. drugs.
- Rough (Granular) endoplasmic reticulum: Synthesis of protein in the cell, transmits newly synthesized protein, synthesis of carbohydrate.
Golgi Apparatus (GA): They occupy a considerable amount of cytoplasm. They are formed from the endoplasmic reticulum.
- Capable of CHO synthesis, e.g., hyaluronic acid, chondroitin sulfate
- Substances transported from endoplasmic reticulum to GA are processed to form lysosomes, secretory vesicles e.t.c.
- It packages the secretory products.
- Intracellular vesicles formed by GA replenish the membrane.
Lysosome: This organelle is found in all the cells and contains hydrolytic enzymes.
(a) Provides an intracellular digestive system that allows the cell to digest itself.
- Damaged cellular structures
- Food particles that have been ingested by the cell.
- An unwanted matter such as bacteria.
(b) Regression of tissues e.g. Uterus at pregnancy and mammary glands after lactation.
(c) Contains Bactericidal agents that can kill phagocytized bacteria before they can cause cellular damage.
(d) Removes damaged cells or damaged pacts of cells from tissue.
Peroxisome: These are vesicles which store enzymes of energy metabolism.
It contains oxidase enzymes that are capable of combining oxygen and hydrogen ions from different intracellular chemicals to form H2O2. It performs detoxification activities to the example about half the alcohol a person drinks in detoxifies by the Peroxisomes of the liver cells.
Ribosome: They create proteins.
- Free ribosomes synthesize intracytoplasmic protein e.g. Haemoglobin.
- Ribosomes attached with endoplasmic reticulum synthesize – All transmembrane proteins, most secreted proteins, Proteins stored in Golgi apparatus, lysosomes and endosomes.
Centrosome: These contain centrioles which form spindles and help in separation of genetic material in cell division.
- Helps in mitosis cell division forming a spindle.
- Centrosomes are Microtubule Organizing Centers (MTOC)
- Forms flagella and cilia.
Microtubules: They are hollow and made of protein. They are very important in helping to maintain the cell’s shape.
- Forms mitotic spindle during cell division.
- Serves as dominant structural and functional components of cilia and flagella.
- Maintains asymmetrical cell shape.
- Co-ordinates the complex cell movement.
- Facilitates transport of secretory vesicles within the cell.
Microfilament: They are very thin threads made of protein. Like the microtubules, they help the cell keep its shape.
- Plays a vital role in various cellular contraction
- Plays a dominant role in muscular contraction
- Forms non-muscular contraction