Eukaryotes and prokaryotes

What is the structure and function of the nucleus?

The nucleus is a circular structure surrounded by a double nuclear envelope with nuclear pores, filled with nucleoplasm containing chromatin. It encloses DNA, providing instructions for protein synthesis.

What is the role of the nucleolus?

The nucleolus is a darkly staining structure within the nucleus that produces RNA molecules, nucleotides, and co-enzymes needed for protein synthesis.

Describe the structure and function of mitochondria.

Mitochondria have a double membrane with highly folded inner surfaces called cristae. They produce ATP during aerobic respiration and contain DNA and ribosomes for enzyme production.

What is the function of the smooth endoplasmic reticulum?

The smooth endoplasmic reticulum is a system of interconnected tubes and sacs that produces fats, oils, triglycerides, sterols, phospholipids, and modifies steroidal hormones.

What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

Rough endoplasmic reticulum is covered in ribosomes and is involved in the translation of proteins, which are assembled into peptide chains inside its flattened sacs.

What is the function of the Golgi apparatus?

The Golgi apparatus modifies proteins, packages them for release from the cell, and creates lysosomes.

What are lysosomes and their function?

Lysosomes are vesicles formed from the Golgi apparatus that contain hydrolase enzymes, which catalyze hydrolysis reactions to break down substances by adding water.

What are vesicles and their roles in the cell?

Vesicles are temporary structures formed from the endoplasmic reticulum and Golgi apparatus, used to store and transport substances into and out of cells.

What is a permanent vacuole and its function?

Permanent vacuoles are formed when several vesicles fuse together, serving different functions in plants and fungi.

Describe the structure and function of chloroplasts.

Chloroplasts have a double membrane enclosing the stroma and thylakoid membranes arranged in grana, serving as the site of photosynthesis in photoautotrophic organisms.

What is the significance of microfilaments, intermediate filaments, and microtubules in the cytoskeleton?

These components provide structural support, shape, and facilitate movement within the cell, along with the action of motor proteins.

What is the difference between eukaryotic and prokaryotic cells?

Eukaryotic cells have membrane-bound organelles and a defined nucleus, while prokaryotic cells lack these structures.

What is the role of ribosomes in the cell?

Ribosomes are responsible for protein synthesis, translating mRNA into peptide chains.

How do nuclear pores function in the nucleus?

Nuclear pores allow substances needed for protein synthesis and DNA replication to enter and exit the nucleus.

What is the matrix of mitochondria composed of?

The matrix contains DNA, ribosomes, and enzymes necessary for respiration.

What is the function of cristae in mitochondria?

Cristae increase the surface area for reactions involved in ATP production during aerobic respiration.

How do lysosomes contribute to cellular digestion?

Lysosomes use hydrolase enzymes to catalyze hydrolysis reactions, breaking down waste materials and cellular debris.

What is the function of thylakoid membranes in chloroplasts?

Thylakoid membranes are involved in the light-dependent reactions of photosynthesis, capturing light energy.

What is the significance of the stroma in chloroplasts?

The stroma is the fluid-filled space surrounding thylakoids where the Calvin cycle occurs, synthesizing glucose from carbon dioxide.

What are ribosomes made from?

Ribosomes are made from ribosomal RNA (rRNA) and proteins.

What is the function of tRNA in protein synthesis?

tRNA transports amino acids, which are the building blocks of proteins.

How do prokaryotic ribosomes differ from eukaryotic ribosomes?

Prokaryotic ribosomes are different in size and sedimentation rates compared to eukaryotic ribosomes, although both have large and small sub-units made from proteins and rRNA.

What is the role of capsules in bacterial cells?

Capsules absorb water, enable adherence to surfaces, protect against predation, and hinder the action of antibiotics.

What are flagella and their function in bacteria?

Flagella are long projections made from flagellin that propel the cell forward through rotation.

What is the structure of a flagellum?

A flagellum consists of a long cylindrical structure made from flagellin, a hook, and a protein disc that is rotated by motor proteins.

What are pili and their role in bacteria?

Pili are short projections that facilitate horizontal gene transfer and can play a role in bacterial virulence.

What is the cytoskeleton and its main components?

The cytoskeleton is a network of protein threads within the cytoplasm, composed of microfilaments, intermediate filaments, and microtubules.

What are the functions of microfilaments in the cytoskeleton?

Microfilaments, made from actin, are involved in movement within the cell.

What is the function of intermediate filaments?

Intermediate filaments provide structural support and anchor cell organelles in place.

What is the role of microtubules in cells?

Microtubules provide structural functions and facilitate the movement of cilia and flagella.

What are centrioles made of?

Centrioles are small, hollow cylinders made of microtubules.

What is the difference between cilia and flagella?

Cilia are small, hair-like structures that move substances along the cell surface, while flagella are longer and propel the cell forward.

What type of DNA do bacterial cells typically have?

Bacterial DNA is typically a single continuous strand that is often circular.

What are plasmids and their significance in bacteria?

Plasmids are extra-chromosomal DNA molecules that may help bacteria survive adverse conditions.

What is the nucleoid in prokaryotic cells?

The nucleoid is the region where the single chromosome of bacterial DNA is located.

What is the significance of the Svedberg unit (S) in ribosome structure?

The Svedberg unit measures sedimentation speed, which relates to the size, shape, and density of ribosomal particles.

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have membrane-bound organelles and a nucleus, while prokaryotic cells do not.

What are the four common components all cells share?

All cells share a plasma membrane, cytoplasm, ribosomes, and genetic material (DNA).