Eukaryotic Cell Structure and Function of Organelles

In this eukaryotic cell structure and function of organelles post we have briefly explained about characteristics, eukaryotic cell components, and reproduction.

Eukaryotic Cell Structure and Function of Organelles

Animals, plants, and fungi are all eukaryotic Cells, which are large complex organisms. It consists of membrane-bound eukaryotic cell components. Prokaryotic cells lack all of the characteristics of eukaryotic cells.

Thus, they are distinguished by the presence of a clearly organized nucleus with a nuclear membrane and nucleolus, as well as the presence of well-organized cytoplasmic eukaryotic cell components such as mitochondria, plastids, ribosomes, endoplasmic reticulum, lysosomes, Golgi bodies, and so on.

Animal cells, unlike plant and fungi eukaryotic cells, lack a cell wall. Due to the lack of a rigid cell wall, animals were able to develop a wider range of cell types, tissues, and organs. Most animal and plant cells are between 1 and 100 micrometres in size, making them only visible under a microscope.

Eukaryotes account for a small proportion of all living things; microbes outnumber human cells by a factor of ten. Their global biomass, however, is estimated to be roughly equal to that of prokaryotes due to their much larger size.

Classification

Animals, plants, fungi, and protists are the four types of eukaryotes. Protists are eukaryotic organisms that do not include animals, plants, or fungi; this group includes protozoa, slime moulds, and some algae. Animals and plants are multicellular, whereas protists and fungi are usually unicellular.

Kingdom Protista

Kingdom Fungi

Kingdom Plantae

Kingdom Animalia

Eukaryotic Cell Structure and Function of Organelles

Cell Organelles

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer. Eukaryotic cell components are identified by microscopy, and can also be purified by cell fractionation.

Plasma Membrane

A bilipid membranous layer composed of proteins and carbohydrates makes up the structure. It has a fluid nature. Carbohydrates are attached to proteins and lipids on the outer lipid layer, and proteins are embedded within the plasma membrane.

The cell membrane separates the cell from its external environment, and is selectively permeable allowing selective substances to pass into the cell and blocking others. It protects the cell and provides stability.

Eukaryotic Cells

Eukaryotic Cell Components: Plasma Membrane

Cytoplasm

It is a jelly-like substance that is found between the cell membrane and the nucleus. The cytoplasm, which makes up the majority of a cell’s “body,” is constantly streaming. Eukaryotic cell components are found here, and substances such as salts can be dissolved in the cytoplasm.

Nucleus

The cell’s largest organelle. They are spherical bodies that contain numerous eukaryotic cell components, including the nucleolus, and are surrounded by a double membrane known as the nuclear envelope/membrane.

The nucleus contains genetic information (DNA) on chromosomes, which are special strands. The nucleolus is an organelle within the nucleus that produces ribosomal RNA. The nucleus is the “control Centre” of the cell, responsible for cell metabolism and reproduction.

Eukaryotic Cells

Eukaryotic Cell Components: Nucleus

Endoplasmic Reticulum

The Endoplasmic Reticulum is a network of membranous canals filled with fluid. They carry materials throughout the cell. The ER is the “transport system” of the cell. There are two types of ER: rough ER and smooth ER.

Rough Endoplasmic Reticulum is lined with ribosomes and is rough in appearance and smooth endoplasmic reticulum contains no ribosomes and is smooth in appearance.

Rough ER transport materials through the cell and produces proteins. Smooth endoplasmic reticulum contains enzymes that produces and digests lipids (fats).

Ribosomes

Ribosomes are small particles which are found individually in the cytoplasm and also line the membranes of the rough endoplasmic reticulum. Ribosomes produce protein. They could be thought of as “factories of protein synthesis” in the cell.

Golgi Body

Golgi bodies are stacks of flattened, membranous sac-like organelle. It is involved in packaging proteins and carbohydrates into membrane-bound vesicles for export from the cell.

Lysosomes

Lysosomes are small sac-like structures surrounded by a single membrane and containing hydrolase enzymes which breaks down waste materials and cellular debris , when released can break down and worn out eukaryotic cell components so they are also known as a suicide sac.

Mitochondria

These are spherical to rod-shaped eukaryotic cell components with a double membrane. The inner membrane is infolded many times, forming a series of projections called cristae. It releases the energy stored in glucose into ATP (adenosine triphosphate) for the cell. The mitochondria is often referred to as the “powerhouse” of the cell.

Eukaryotic Cells

Eukaryotic Cell Components: Mitochondria 

Vacuoles

Vacuoles are fluid filled eukaryotic cell components enclosed by a membrane. They can store materials such as food, water, sugar, minerals and waste products.

Centrosome

They are small body located near the nucleus and has a dense center and radiating tubules. The centrosomes are the destination where microtubules are made. During mitosis, the centrosome divides and the two parts move to opposite sides of the dividing cell.

Peroxisome

Peroxisomes are eukaryotic cell components that contain oxidative enzymes, such as D-amino acid oxidase, ureate oxidase, and catalase. They are self-replicating, like the mitochondria. Peroxisomes function to rid the body of toxic substances like hydrogen peroxide, or other metabolites. They are a major site of oxygen utilization and are numerous in the liver where toxic by-products accumulate.

Division of Eukaryotic cells

Some eukaryotic cells can divide only by asexual means while other eukaryotic cells divide both sexually as well as asexually.

Asexual reproduction

Asexual reproduction is common in all eukaryotic cells except for reproductive cells that form the male and female gamete. The most common mode of asexual reproduction is mitosis, where the cell grows double its size and then divided to form two identical daughter cells.

Unicellular fungal cells and protists divide by budding where new cells arise on the surface of dividing cells in the form of a chain. Processes like binary fission and multiple fission are also observed in cells of primitive eukaryotes. Some fungi are also known to divide/ reproduce asexually via sporulation.

Sexual reproduction

The cells of the reproductive system in plants and animals are divided by the sexual method. In this method, the cell divided meiotically to form four daughter cells, each with half the number of chromosomes to their parent cell. The sexual reproduction in eukaryotic cells is responsible for the variation in different cells.

Further Readings

Reference

  1. https://byjus.com/biology/eukaryotic cell components/
  2. https://www.toppr.com/guides/biology/cell-the-unit-of-life/eukaryotic-cell/
  3. https://biologydictionary.net/eukaryotic cell components/
  4. https://www.britannica.com/science/eukaryote
  5. https://www.nature.com/scitable/topicpage/eukaryotic cell components/
  6. https://www.springer.com/gp/chemistry/biochemistry