Eukaryotic Cells: Nucleus and Ribosomes (A-level Biology)

Eukaryotic Cells: Nucleus and Ribosomes

Nucleus

  • All eukaryotic cells have a nucleus.
  • The nucleus houses the genetic information of a cell. DNA is packaged in the form of chromatin which in turn is packed into chromosomes. These chromosomes are stored in the centre of the nucleus.
  • The nucleus has its own membrane. This membrane is a double membrane which is called the nuclear envelope. Like the cell surface membrane, this membrane also regulates what gets into and out of the nucleus.
  • Substances enter and exit the nucleus through nuclear pores. These pores are found throughout the nuclear membrane. They are the highly regulated points of entry and exit for the majority of substances entering and leaving the nucleus.
  • The nucleus has a secondary region inside of it called the nucleolus. The nucleolus is the region of the nucleus where ribosomal RNA (rRNA) is assembled into ribosomes. There may be multiple nucleoli.
  • The nucleus controls all of the activities of a cell. Because the nucleus houses the DNA, the nucleus also regulates all the cellular processes. It does so by not only regulating the replication of DNA, but by also regulating a process known as DNA transcription. This is the process by which the genetic information stored in DNA is turned into RNA, which in turn is made into protein by ribosomes.
A-level Biology - Eukaryotic Cells: Nucleus and Ribosomes
A-level Biology – Eukaryotic Cells: Nucleus and Ribosomes

Ribosomes

  • Ribosomes are small organelles with two subunits. Ribosomes are tiny, often shown as dots in the cytoplasm. A ribosome has a large and small subunit. In eukaryotes, the type of ribosomes present are known as 80S ribosomes.
  • Ribosomes are mostly found floating in the cytoplasm. Ribosomes are not membrane bound organelles. Most ribosomes are free in the cytoplasm, but some are bound to the endoplasmic reticulum.
  • Ribosomes are made up of RNA and protein. They are made up of RNA called ribosomal RNA (rRNA) and proteins. Because of this, ribosomes are type of ribonucleoprotein.
  • Ribosomes make protein. Ribosomes receive genetic information from the DNA in the form of messenger RNA. Ribosomes read the messenger RNA, and use the instructions stored in it to make proteins.
A-level Biology - Eukaryotic Cells: Nucleus and Ribosomes
A-level Biology – Eukaryotic Cells: Nucleus and Ribosomes
→What are eukaryotic cells in biology?

Eukaryotic cells are a type of cell that is characterized by having a nucleus and other membrane-bound organelles. These cells are found in a wide range of organisms, including plants, animals, and fungi, and are typically larger and more complex than prokaryotic cells.

→What is the role of the nucleus in eukaryotic cells?

The nucleus is the central control center of the eukaryotic cell and is responsible for managing the cell’s genetic material. The nucleus contains the cell’s DNA, which is organized into chromosomes, and is responsible for controlling the cell’s growth and division.

→What are ribosomes and what is their role in eukaryotic cells?

Ribosomes are small, spherical structures that are responsible for synthesizing proteins in eukaryotic cells. They are made up of a combination of RNA and protein and are located in the cytoplasm or on the endoplasmic reticulum. Ribosomes translate the genetic code stored in the DNA into functional proteins that perform a wide range of tasks within the cell.

→How do ribosomes and the nucleus work together in eukaryotic cells?

The nucleus and ribosomes work together in eukaryotic cells to produce functional proteins. The DNA in the nucleus provides the genetic code for the synthesis of proteins, while the ribosomes are responsible for synthesizing the proteins based on that code. The proteins produced by the ribosomes are then used to perform a wide range of functions within the cell.

→What are the differences between eukaryotic and prokaryotic cells?

Eukaryotic cells are different from prokaryotic cells in several key ways. Eukaryotic cells are typically larger and more complex than prokaryotic cells and contain a nucleus and other membrane-bound organelles. Prokaryotic cells, on the other hand, lack a nucleus and have a more simple structure. Additionally, eukaryotic cells typically have a more complex system for the synthesis of proteins, while prokaryotic cells rely on a more simple system.

→Why is the study of eukaryotic cells and their components important in biology?

The study of eukaryotic cells and their components is important in biology because it provides a deeper understanding of the complex processes that occur within these cells. This knowledge can be applied to a wide range of fields, including medicine, biotechnology, and agriculture, and can help researchers to develop new treatments, technologies, and crops. By studying eukaryotic cells, we can gain a better understanding of how life functions at the cellular level and how we can influence and control these processes.

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