MT 30 (LEC): Ribosomes

What is the primary function of ribosomes in cells?

Ribosomes are essential for protein synthesis, assembling amino acids into proteins by reading RNA instructions.

Where are membrane-bound ribosomes located?

Membrane-bound ribosomes are found on the rough endoplasmic reticulum (RER).

What type of proteins do membrane-bound ribosomes produce?

They produce enzymes and proteins for cell membranes.

Where can free ribosomes be found in a cell?

Free ribosomes float in the cytosol.

What do free ribosomes produce?

They produce proteins used within the cell’s cytoplasm.

Why are proteins essential for living organisms?

Proteins are essential for growth, metabolism, and biological functions.

What roles do proteins serve in the body?

Proteins include hormones, transport proteins, structural proteins, and immune system components.

How are ribosomes formed in cells?

Ribosomes are formed in the nucleolus using ribosomal RNA (rRNA) and proteins.

What are the two subunits of ribosomes?

Ribosomes consist of a large subunit and a small subunit.

What happens during transcription in protein production?

DNA is copied into messenger RNA (mRNA) in the nucleus.

What is the role of mRNA in protein synthesis?

mRNA carries genetic instructions from the nucleus to the ribosome.

What occurs during translation?

mRNA attaches to the ribosome, and transfer RNA (tRNA) brings the appropriate amino acids to form a protein chain.

What signals the end of translation in protein synthesis?

Translation stops when a stop codon (UAG, UAA, or UGA) is reached.

Do ribosomes synthesize DNA?

No, ribosomes do not make DNA; DNA replication occurs in the nucleus.

What does the smooth endoplasmic reticulum (ER) produce?

The smooth ER produces lipids, including phospholipids and cholesterol.

What size are prokaryotic ribosomes compared to eukaryotic ribosomes?

Prokaryotic ribosomes are smaller (70S), while eukaryotic ribosomes are larger (80S).

Where are eukaryotic ribosomes made?

Eukaryotic ribosomes are made in the nucleolus.

Can viruses produce proteins using their own ribosomes?

No, viruses lack ribosomes and must hijack a host cell’s ribosomes to produce viral proteins.

What do viruses contain that is essential for their function?

Viruses contain genetic material (DNA or RNA) but cannot function independently.

What is the significance of ribosomes in relation to metabolism and growth?

Without ribosomes, metabolism and growth would stop.

What components make up ribosomal proteins?

Ribosomal proteins are composed of proteins combined with ribosomal RNA (rRNA).

What is the role of transfer RNA (tRNA) in protein synthesis?

tRNA brings the appropriate amino acids to the ribosome during translation.

What are some examples of structural proteins mentioned in the notes?

Keratin and collagen are examples of structural proteins.

How are ribosomal proteins transported into the nucleus?

Ribosomal proteins travel from the cytoplasm to the nucleus to combine with rRNA.

What is the function of enzymes produced by membrane-bound ribosomes?

They speed up chemical reactions.

What type of cellular structures do cells with ribosomes form?

Cells with ribosomes form tissues, which then form organs.

What is an energy source and how do proteins help maintain it?

Proteins can act as an energy source and help maintain fluid balance.

What role do ribosomes play in translation specifically?

Ribosomes are where genetic information is converted into proteins during translation.

How do ribosomes contribute to biological functions?

Ribosomes synthesize proteins that are essential for growth, repair, and regulation of cellular processes.

What is the difference in ribosome formation between prokaryotes and eukaryotes?

Prokaryotic ribosomes form in the cytoplasm, while eukaryotic ribosomes are formed in the nucleolus.

What happens when a ribosome reaches a stop codon during translation?

The process of assembling amino acids into a protein chain stops.

What are the components of the genetic code related to ribosomes?

The genetic code consists of instructions for producing proteins, carried by mRNA.

How do ribosomes affect the growth of the cell?

Ribosomes are crucial because they produce proteins that support cellular growth.

What is the general location of ribosomes in prokaryotic cells?

Ribosomes are found freely floating in the cytoplasm of prokaryotic cells.

What is required for ribosome assembly?

Ribosomal RNA (rRNA) and proteins are required for ribosome assembly.

What is the function of structural proteins in organisms?

Structural proteins provide support and shape to cells and tissues.

How are proteins categorized based on their functions?

Proteins can be categorized into hormones, transport proteins, structural proteins, and immune components.

What cellular processes rely on ribosomes?

Processes such as protein synthesis, metabolism, and cellular growth rely on ribosomes.

Can ribosomes function without the presence of RNA?

No, ribosomes require RNA to function properly during protein synthesis.

What is the importance of the rough endoplasmic reticulum (RER) concerning ribosomes?

The rough ER is important because it is where membrane-bound ribosomes are attached for protein synthesis.

How is amino acid assembly achieved in ribosomes?

Amino acid assembly is achieved by ribosomes reading mRNA and facilitating the connection of tRNA molecules.

What type of bonds are formed between amino acids during protein synthesis?

Peptide bonds are formed between amino acids during protein synthesis in ribosomes.

What distinguishes eukaryotic ribosomes from prokaryotic ribosomes?

Eukaryotic ribosomes are larger (80S) and more complex than prokaryotic ribosomes (70S).

What role does the nucleolus play in ribosome production?

The nucleolus is responsible for forming ribosomes using rRNA and proteins.

What happens to proteins synthesized by free ribosomes?

Proteins synthesized by free ribosomes are typically used within the cell’s cytoplasm.

What limitation do viruses have regarding protein synthesis?

Viruses cannot synthesize proteins independently because they lack ribosomes.

What is the outcome of ribosomal malfunction in a cell?

Ribosomal malfunction can lead to halted protein synthesis, affecting cell growth and metabolism.

How do ribosomes interact with mRNA and tRNA in protein synthesis?

Ribosomes read mRNA and facilitate the entry of tRNA to assemble proteins.

What is a significant biochemical consequence of the absence of ribosomes?

The absence of ribosomes would prevent the synthesis of essential proteins, leading to cellular dysfunction.

What signifies the specificity of ribosomes in protein synthesis?

Ribosomes use specific mRNA templates to direct the synthesis of specific proteins.

What characteristic of viral replication relates to ribosomes?

Viruses depend on host cell ribosomes to replicate and produce viral proteins.

Explain the term 'translation' in the context of ribosomes.

Translation is the process by which ribosomes synthesize proteins from mRNA instructions.