Cell Structure and Function in Prokaryotic and Eukaryotic Cells

What is the smallest basic unit that has all properties of life?

A cell

What are the two main types of cells?

Prokaryotic cells and Eukaryotic cells

What is a defining feature of prokaryotic cells?

They do not have a nucleus.

What is a defining feature of eukaryotic cells?

They have a nucleus.

What structures are found in all cells?

Cell membrane, cytoplasm, DNA, and ribosomes.

What is the function of the cell membrane?

It defines the boundary of a cell.

What is cytoplasm?

The internal water-based cellular environment where many reactions occur.

What is the role of ribosomes?

They are structures on which proteins are made.

What domains do prokaryotic cells belong to?

Bacteria and Archaea.

What was the early environment on Earth like for prokaryotic cells?

Less oxygen, higher temperature, and more exposure to radiation.

What are the kingdoms included in the Eukarya domain?

Plants, animals, fungi, and protozoans (protists).

What is the endomembrane system?

A system in all eukaryotic cells that includes internal membranes with distinct functions.

What is the function of the rough endoplasmic reticulum (RER)?

It has ribosomes on its surface and makes membrane and secreted proteins.

What does the smooth endoplasmic reticulum (SER) do?

It makes lipids and does not have ribosomes on its surface.

What is the function of the Golgi apparatus?

To modify, package, and ship proteins and lipids made in the RER and SER.

What is the role of lysosomes?

To eliminate waste products and misfolded proteins in animal cells.

What are peroxisomes responsible for?

Helping to rid the cells of free radicals.

What are common symptoms of lysosomal storage disease?

Failure to thrive, abnormal limb and face development, neurological symptoms, and difficulties forming cartilage.

What causes symptoms in lysosomal storage disease?

A defect that reduces enzymes within the lysosome, preventing waste removal.

What is the nuclear envelope?

A double membrane that surrounds the nucleus.

What is the nucleolus?

A dense region within the nucleus where ribosomal subunits are made.

What is chromatin?

The packaging of DNA within the nucleus.

What is nucleoplasm?

The aqueous matrix inside the nucleus.

What is the primary function of the rough endoplasmic reticulum?

Making secreted proteins.

What is the role of mitochondria in cells?

They are ATP-producing organelles that carry out energy-releasing reactions requiring oxygen.

What type of DNA is found in mitochondria?

Circular DNA (mtDNA) inherited from the maternal line only.

What are the two types of mitochondria-related diseases in humans?

Type 1 is caused by mutations in mitochondrial DNA (e.g., MERRF, LHON); Type 2 is caused by mutations in nuclear DNA (e.g., Leigh syndrome).

What is the primary function of the cytoskeleton?

It provides the basis for cell shape, internal organization, intracellular movement, cell communication, and cell movement.

What are the three major components of the cytoskeleton?

Microtubules, actin microfilaments, and intermediate filaments.

What are microtubules composed of?

Hollow cylinders made of tubulin subunits.

What is dynamic instability in microtubules?

It refers to the simultaneous growth at the plus end and shrinking at the minus end, requiring energy.

What are the roles of kinesin and dynein?

Kinesin moves material to the plus end of microtubules, while dynein moves material to the minus end.

What are actin microfilaments made of?

They are composed of actin subunits, specifically G actin (subunits) and F actin (filaments).

What is the role of myosin in relation to actin microfilaments?

Myosin is the motor protein that binds and moves actin filaments, requiring energy from ATP.

What happens to skeletal muscles without ATP?

Actin cannot move, leading to rigor mortis.

What are intermediate filaments and where are they found?

They are the most stable cytoskeletal elements, providing structure and strength, and are present only in animal cells of certain tissues.

What is an example of an intermediate filament protein?

Keratin, found in skin, nails, and hair.

What is the significance of the cytoskeleton in cell movement?

It facilitates intracellular movement of organelles or proteins and overall cell movement.

What is the energy requirement for the growth and shrinking of microtubules and actin filaments?

Both processes require energy.

What is the function of the cytoskeleton in cell communication?

It plays a role in transmitting signals and facilitating interactions between cells.

What are the characteristics of microtubules?

They are polar, dynamic, and involved in cell shape, movement, and division.

What distinguishes intermediate filaments from microtubules and actin filaments?

Intermediate filaments are the most stable and provide structural support, while microtubules and actin filaments are more dynamic.

What role do microtubules play in cancer?

Microtubules in the mitotic spindle allow cancer cells to grow and divide.

What is the function of cancer drugs like taxol?

They target the assembly of microtubules.

Which neurological disorders are associated with aggregates of intermediate filaments?

ALS (Amyotrophic Lateral Sclerosis) and Charcot-Marie-Tooth (CMT).

What type of mutations are linked to a type of dementia associated with Parkinson's disease?

Mutations in microtubule associated proteins.

What common structures do all eukaryotic cells share?

Cell membrane, cytoplasm, DNA, ribosomes, nucleus, endomembrane system, mitochondria, and cytoskeleton.

How do eukaryotic cells specialize based on function?

They develop additional structures unique to specific groups or types of cells.

What are examples of single-celled eukaryotes?

Protozoans and yeast (fungi).

What are examples of multicellular eukaryotes?

Plants, animals, and some fungi.

What extra structures are specific to plant cells?

Central vacuole, chloroplasts, and cell wall.

What is the function of the central vacuole in plant cells?

Stores amino acids, sugars, and wastes, taking up 50-90% of the cell interior in mature cells.

What is the role of chloroplasts in plant cells?

Convert sunlight energy to ATP through photosynthesis and contain their own circular DNA inherited maternally.

What is the endosymbiosis theory?

It suggests that mitochondria and chloroplasts originated from free-living prokaryotes that lost the ability to live independently.

What evidence supports the endosymbiosis theory?

Mitochondria and chloroplasts have a double membrane, their own DNA resembling prokaryotic DNA, and ribosomes.

What is the composition of the plant cell wall?

Made of cellulose and found around the plasma membrane.

What structures are seen in multicellular eukaryotic organisms?

Cell junctions, extracellular matrix, cilia, and flagella.

What are plasmodesmata?

Gap-type junctions in plant cells that allow material to pass between neighboring cells.

What types of cell junctions are found in animal cells?

Tight junctions (seal), adhering junctions (seal), and gap junctions (allow material to pass).

What is the extracellular matrix (ECM)?

A protein matrix that surrounds cells, such as collagen.

What are the functions of the extracellular matrix?

Anchors cells, provides information for cell identity and maturation, guides cell movement during development, and transmits signaling information.

What is the internal structure of cilia and flagella?

Both have a '9 + 2' arrangement of microtubules.

What is ciliary dynein?

A special microtubule motor protein found only in cilia and flagella.

What is the primary function of flagella?

To allow for movement.