Chapter 4: Introduction to Eukaryotic Cells – Guided Study Notes

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Tailored notes based on your materials, expanded with key definitions, examples, and context.

Q1. Besides the presence of 70S ribosomes in chloroplasts and mitochondria, the presence of which organic molecule in eukaryotes is similar in shape to the molecule in bacteria?

Background

Topic: Comparative Cell Biology

This question is testing your understanding of similarities between eukaryotic and prokaryotic cells, specifically regarding certain organic molecules found in both.

Key Terms:

70S ribosomes: Ribosomes found in prokaryotes and in some eukaryotic organelles.
Organic molecule: Refers to molecules containing carbon, such as lipids, proteins, nucleic acids, or carbohydrates.

Step-by-Step Guidance

Recall that mitochondria and chloroplasts in eukaryotes have features similar to bacteria, supporting the endosymbiotic theory.
Think about the main structural molecules in cell membranes of both bacteria and eukaryotes.
Consider which organic molecule forms the bilayer structure in both cell types.
Review the shape and function of this molecule in both eukaryotic and prokaryotic cells.

Try solving on your own before revealing the answer!

Final Answer: Phospholipids

Phospholipids are the organic molecules that are similar in shape in both eukaryotes and bacteria. They form the fundamental structure of the plasma membrane in both cell types.

Q2. Use Table 4.1 Eukaryotic vs Prokaryotic Cells to distinguish the differences between the following eukaryotic and prokaryotic characteristics: organisms (unicellular/multicellular), cell division, nucleus, ribosomes, chromosomes, membrane-bound organelles

Background

Topic: Cell Structure and Function

This question asks you to compare and contrast key features of eukaryotic and prokaryotic cells.

Key Terms:

Unicellular/Multicellular: Refers to whether organisms are made of one or many cells.
Cell division: The process by which cells reproduce (e.g., mitosis, binary fission).
Nucleus: Membrane-bound organelle containing DNA in eukaryotes.
Ribosomes: Structures for protein synthesis (70S in prokaryotes, 80S in eukaryotes).
Chromosomes: DNA structures; linear in eukaryotes, circular in prokaryotes.
Membrane-bound organelles: Organelles surrounded by membranes (e.g., mitochondria, ER).

Step-by-Step Guidance

List each characteristic mentioned in the question.
For each, recall the typical feature in prokaryotes (e.g., bacteria) and in eukaryotes (e.g., animals, plants, fungi, protists).
Use a table or bullet points to organize the differences for each characteristic.
For example, consider whether each cell type is usually unicellular or multicellular, how they divide, and whether they have a nucleus or membrane-bound organelles.

Try solving on your own before revealing the answer!

Final Answer:

Organisms: Prokaryotes are usually unicellular; eukaryotes can be unicellular or multicellular.
Cell division: Prokaryotes use binary fission; eukaryotes use mitosis/meiosis.
Nucleus: Prokaryotes lack a nucleus; eukaryotes have a true nucleus.
Ribosomes: Prokaryotes have 70S ribosomes; eukaryotes have 80S (cytoplasm) and 70S (organelles).
Chromosomes: Prokaryotes have circular chromosomes; eukaryotes have linear chromosomes.
Membrane-bound organelles: Prokaryotes lack them; eukaryotes have them.

Q3. Why doesn’t penicillin kill eukaryotic cells? Hint: what molecule does penicillin target?

Background

Topic: Antibiotics and Cell Wall Structure

This question tests your understanding of how antibiotics like penicillin work and why they are selective for bacteria.

Key Terms:

Penicillin: An antibiotic that targets bacterial cell wall synthesis.
Peptidoglycan: The molecule in bacterial cell walls targeted by penicillin.
Eukaryotic cells: Animal and plant cells, which have different cell wall structures or none at all.

Step-by-Step Guidance

Recall the main structural difference between bacterial and eukaryotic cell walls.
Identify the molecule that penicillin specifically targets in bacteria.
Consider whether this molecule is present in eukaryotic cells.
Think about why the absence or presence of this molecule would affect penicillin’s action.

Try solving on your own before revealing the answer!

Final Answer:

Penicillin targets peptidoglycan, which is found in bacterial cell walls but not in eukaryotic cells. Because eukaryotic cells lack peptidoglycan, penicillin does not harm them.

Q4. What is the difference between mitosis and meiosis?

Background

Topic: Eukaryotic Cell Division

This question is about the two main types of cell division in eukaryotes and their outcomes.

Key Terms:

Mitosis: Cell division resulting in two genetically identical daughter cells.
Meiosis: Cell division resulting in four genetically unique daughter cells with half the chromosome number.

Step-by-Step Guidance

Recall the purpose of mitosis (growth, repair, asexual reproduction) and meiosis (sexual reproduction).
Think about the number of cell divisions and the number of resulting cells in each process.
Consider the genetic similarity of the daughter cells to the parent cell in each process.
Note the chromosome number in the resulting cells compared to the original cell.

Try solving on your own before revealing the answer!

Final Answer:

Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically unique haploid cells. Mitosis is for growth and repair; meiosis is for sexual reproduction.

Q5. What two eukaryotic organelles divide using a process similar to binary fission?

Background

Topic: Organelle Division and Endosymbiotic Theory

This question tests your knowledge of organelles that replicate independently within eukaryotic cells.

Key Terms:

Binary fission: A form of asexual reproduction typical of prokaryotes.
Endosymbiotic theory: The idea that some organelles originated from prokaryotic cells.

Step-by-Step Guidance

Recall which organelles have their own DNA and can replicate independently of the cell cycle.
Think about which organelles are believed to have evolved from prokaryotic ancestors.
Identify the two organelles that divide in a way similar to bacteria.

Try solving on your own before revealing the answer!

Final Answer:

Mitochondria and chloroplasts divide by a process similar to binary fission, supporting the endosymbiotic theory.

Q6. What is the difference between endocytosis and exocytosis?

Background

Topic: Membrane Transport in Eukaryotic Cells

This question is about how cells move substances into and out of the cell using vesicles.

Key Terms:

Endocytosis: Process of taking substances into the cell by engulfing them in a vesicle.
Exocytosis: Process of releasing substances from the cell by fusing a vesicle with the plasma membrane.

Step-by-Step Guidance

Define endocytosis and exocytosis in your own words.
Think about the direction of movement (into or out of the cell) for each process.
Consider the role of vesicles in both processes.

Try solving on your own before revealing the answer!

Final Answer:

Endocytosis brings substances into the cell, while exocytosis releases substances from the cell. Both involve vesicles and the plasma membrane.

Q7. Are endocytosis and exocytosis active or passive processes?

Background

Topic: Cellular Transport Mechanisms

This question tests your understanding of energy requirements for different types of membrane transport.

Key Terms:

Active process: Requires energy (usually ATP).
Passive process: Does not require energy.

Step-by-Step Guidance

Recall the definitions of active and passive transport.
Think about whether moving large molecules or particles across the membrane requires energy.
Consider the involvement of vesicles and cytoskeletal elements in these processes.

Try solving on your own before revealing the answer!

Final Answer:

Both endocytosis and exocytosis are active processes because they require energy to move substances across the membrane using vesicles.

Q8. What is the difference between pinocytosis and phagocytosis?

Background

Topic: Types of Endocytosis

This question is about the two main forms of endocytosis and what types of materials they transport.

Key Terms:

Pinocytosis: "Cell drinking"; uptake of liquids and small molecules.
Phagocytosis: "Cell eating"; uptake of large particles or cells.

Step-by-Step Guidance

Define pinocytosis and phagocytosis.
Compare the size and type of material taken up in each process.
Think about which cells commonly perform phagocytosis (e.g., immune cells).

Try solving on your own before revealing the answer!

Final Answer:

Pinocytosis involves the uptake of liquids and small molecules, while phagocytosis involves engulfing large particles or cells.

Q9. What is a phagocyte and what is its function?

Background

Topic: Immune Cells and Phagocytosis

This question is about specialized cells that perform phagocytosis and their role in the body.

Key Terms:

Phagocyte: A cell that engulfs and digests foreign particles, bacteria, or dying cells.
Immune response: The body's defense against pathogens.

Step-by-Step Guidance

Define what a phagocyte is.
Describe the main function of phagocytes in the immune system.
Think of examples of phagocytic cells (e.g., macrophages, neutrophils).

Try solving on your own before revealing the answer!

Final Answer:

A phagocyte is a cell that engulfs and digests pathogens, debris, or other particles as part of the immune response.

Q10. Name four eukaryotic kingdoms.

Background

Topic: Biological Classification

This question is about the major groupings of eukaryotic organisms.

Key Terms:

Kingdom: A high-level taxonomic category.
Eukaryote: Organisms with cells containing a nucleus.

Step-by-Step Guidance

Recall the main kingdoms in the domain Eukarya.
List the kingdoms that include multicellular and unicellular eukaryotes.
Think about examples of organisms in each kingdom.

Try solving on your own before revealing the answer!

Final Answer:

The four eukaryotic kingdoms are Animalia, Plantae, Fungi, and Protista.

Q11. Name two phyla of parasitic helminths.

Background

Topic: Parasitology

This question is about the classification of parasitic worms that infect humans and animals.

Key Terms:

Helminths: Parasitic worms.
Phylum: A major taxonomic group below kingdom.

Step-by-Step Guidance

Recall the two main groups of parasitic helminths studied in microbiology.
Think about the common names for these groups (e.g., roundworms, flatworms).
Identify the scientific phylum names for each group.

Try solving on your own before revealing the answer!

Final Answer:

The two phyla are Nematoda (roundworms) and Platyhelminthes (flatworms).

Q12. What are unicellular fungi called?

Background

Topic: Fungal Biology

This question is about the classification of fungi based on their cellular organization.

Key Terms:

Unicellular: Made of a single cell.
Fungi: Eukaryotic organisms including yeasts, molds, and mushrooms.

Step-by-Step Guidance

Recall the two main forms of fungi: unicellular and multicellular.
Think about the common name for unicellular fungi used in baking and brewing.
Identify the scientific term for these organisms.

Try solving on your own before revealing the answer!

Final Answer:

Unicellular fungi are called yeasts.

Q13. Fungi are saprobes. What does this mean?

Background

Topic: Fungal Nutrition

This question is about how fungi obtain their nutrients.

Key Terms:

Saprobe (saprotroph): An organism that feeds on dead or decaying organic matter.

Step-by-Step Guidance

Define the term saprobe or saprotroph.
Think about the ecological role of fungi in decomposing organic material.
Consider how this mode of nutrition differs from that of plants or animals.

Try solving on your own before revealing the answer!

Final Answer:

Saprobes are organisms that obtain nutrients by decomposing dead or decaying organic matter. Fungi are saprobes because they feed on such material.

Q14. What are dimorphic fungi?

Background

Topic: Fungal Morphology

This question is about fungi that can exist in two different forms depending on environmental conditions.

Key Terms:

Dimorphic: Having two forms.
Fungi: Eukaryotic organisms that can be unicellular or multicellular.

Step-by-Step Guidance

Define the term dimorphic in the context of fungi.
Recall the two forms that dimorphic fungi can take (yeast and mold).
Think about what environmental factors might trigger the switch between forms.

Try solving on your own before revealing the answer!

Final Answer:

Dimorphic fungi can exist as either yeast or mold, depending on environmental conditions such as temperature.

Q15. Define mycoses.

Background

Topic: Fungal Diseases

This question is about the terminology used for fungal infections.

Key Terms:

Mycoses: Diseases caused by fungi.

Step-by-Step Guidance

Recall the medical term for infections caused by fungi.
Think about examples of mycoses (e.g., athlete's foot, ringworm).

Try solving on your own before revealing the answer!

Final Answer:

Mycoses are diseases or infections caused by fungi.

Q16. Vaginal yeast infections are mainly caused by which genus of yeast?

Background

Topic: Fungal Pathogens

This question is about the most common fungal genus responsible for vaginal yeast infections.

Key Terms:

Genus: A taxonomic category above species.
Yeast: Unicellular fungi.

Step-by-Step Guidance

Recall the most common yeast genus associated with human infections.
Think about the species name often linked to vaginal yeast infections.

Try solving on your own before revealing the answer!

Final Answer:

The genus is Candida, most commonly Candida albicans.

Q17. What is a dermatophyte? One common dermatophytic infection is called tinea. What are two common names for tinea infections?

Background

Topic: Fungal Skin Infections

This question is about fungi that infect skin, hair, and nails, and the common names for these infections.

Key Terms:

Dermatophyte: A fungus that infects keratinized tissues.
Tinea: A general term for dermatophyte infections.

Step-by-Step Guidance

Define what a dermatophyte is and what tissues it infects.
Recall the common names for tinea infections (e.g., athlete's foot, ringworm).
Think about the genus most often responsible for these infections.

Try solving on your own before revealing the answer!

Final Answer:

Dermatophytes are fungi that infect skin, hair, and nails. Two common names for tinea infections are athlete's foot (tinea pedis) and ringworm (tinea corporis).

Q18. Some eukaryotes have cell walls. Where is it located compared to the organism’s plasma membrane? Do animal cells have cell walls?

Background

Topic: Cell Structure

This question is about the location and presence of cell walls in different eukaryotic cells.

Key Terms:

Cell wall: A rigid structure outside the plasma membrane.
Plasma membrane: The cell's outer membrane.

Step-by-Step Guidance

Recall which eukaryotic groups have cell walls (e.g., plants, fungi).
Think about the relative position of the cell wall and plasma membrane.
Consider whether animal cells have cell walls.

Try solving on your own before revealing the answer!

Final Answer:

The cell wall is located outside the plasma membrane. Animal cells do not have cell walls.

Q19. How does the motion produced by eukaryotic flagella differ from prokaryotic flagella?

Background

Topic: Cell Motility

This question is about the structural and functional differences in flagella between eukaryotes and prokaryotes.

Key Terms:

Flagella: Whip-like structures for movement.
Eukaryotic flagella: Composed of microtubules in a 9+2 arrangement.
Prokaryotic flagella: Composed of flagellin protein.

Step-by-Step Guidance

Recall the structural differences between eukaryotic and prokaryotic flagella.
Think about the type of movement each flagellum produces (e.g., whip-like vs. rotary).
Consider the energy source for movement in each case.

Try solving on your own before revealing the answer!

Final Answer:

Eukaryotic flagella move in a whip-like (undulating) motion, while prokaryotic flagella rotate like a propeller.

Q20. Do prokaryotes possess cilia?

Background

Topic: Cell Surface Structures

This question is about the presence or absence of cilia in prokaryotic cells.

Key Terms:

Cilia: Short, hair-like structures for movement or moving substances along the cell surface.
Prokaryotes: Bacteria and archaea.

Step-by-Step Guidance

Recall the structures present on prokaryotic cells (e.g., flagella, pili).
Think about whether cilia are found in prokaryotes or only in eukaryotes.

Try solving on your own before revealing the answer!

Final Answer:

Prokaryotes do not possess cilia; cilia are found only in eukaryotic cells.

Q21. What two areas within a cell are eukaryotic ribosomes located?

Background

Topic: Protein Synthesis

This question is about the locations of ribosomes in eukaryotic cells.

Key Terms:

Ribosome: Organelle for protein synthesis.
Free ribosomes: Float in the cytoplasm.
Bound ribosomes: Attached to the rough endoplasmic reticulum (RER).

Step-by-Step Guidance

Recall the two main locations where ribosomes are found in eukaryotic cells.
Think about the difference between free and membrane-bound ribosomes.
Consider the function of ribosomes in each location.

Try solving on your own before revealing the answer!

Final Answer:

Eukaryotic ribosomes are located free in the cytoplasm and bound to the rough endoplasmic reticulum.

Q22. Do eukaryotic cells possess 70S ribosomes as well as 80S ribosomes? (Hint: mitochondria)

Background

Topic: Ribosome Types in Eukaryotes

This question is about the presence of different types of ribosomes in eukaryotic cells and their locations.

Key Terms:

70S ribosomes: Found in prokaryotes and in mitochondria/chloroplasts of eukaryotes.
80S ribosomes: Found in the cytoplasm of eukaryotes.

Step-by-Step Guidance

Recall the types of ribosomes found in eukaryotic cells and their locations.
Think about the endosymbiotic theory and its implications for organelle ribosomes.
Identify which organelles contain 70S ribosomes.

Try solving on your own before revealing the answer!

Final Answer:

Yes, eukaryotic cells have both 80S ribosomes (in the cytoplasm) and 70S ribosomes (in mitochondria and chloroplasts).

Q23. What are the two main functions of the cytoskeleton?

Background

Topic: Cell Structure and Function

This question is about the roles of the cytoskeleton in eukaryotic cells.

Key Terms:

Cytoskeleton: Network of protein filaments in the cytoplasm.

Step-by-Step Guidance

Recall the two main functions of the cytoskeleton as described in your textbook.
Think about how the cytoskeleton contributes to cell shape and movement.
Consider its role in intracellular transport.

Try solving on your own before revealing the answer!

Final Answer:

The cytoskeleton provides structural support and enables movement (both of the cell and of materials within the cell).

Q24. What is the main macromolecule housed in the nucleus?

Background

Topic: Nucleus Function

This question is about the primary type of molecule stored in the nucleus of eukaryotic cells.

Key Terms:

Macromolecule: Large biological molecule (e.g., DNA, RNA, protein).
Nucleus: Organelle containing genetic material.

Step-by-Step Guidance

Recall the main function of the nucleus.
Think about which macromolecule carries genetic information.
Identify the specific type of nucleic acid found in the nucleus.

Try solving on your own before revealing the answer!

Final Answer:

The main macromolecule housed in the nucleus is DNA (deoxyribonucleic acid).

Q25. What occurs in the nucleolus of a eukaryotic cell?

Background

Topic: Nucleolus Function

This question is about the specific function of the nucleolus within the nucleus.

Key Terms:

Nucleolus: Dense region within the nucleus.
Ribosome synthesis: Production of ribosomal RNA and assembly of ribosome subunits.

Step-by-Step Guidance

Recall the main function of the nucleolus.
Think about the components of ribosomes and where they are made.
Consider the process of ribosomal RNA (rRNA) synthesis.

Try solving on your own before revealing the answer!

Final Answer:

The nucleolus is where ribosomal RNA is synthesized and ribosome subunits are assembled.

Q26. What is the function of rough endoplasmic reticulum (RER)? What structures make RER rough?

Background

Topic: Endomembrane System

This question is about the role of the RER in the cell and its structural features.

Key Terms:

Rough endoplasmic reticulum (RER): Organelle involved in protein synthesis and processing.
Ribosomes: Structures attached to the RER, giving it a rough appearance.

Step-by-Step Guidance

Recall the main function of the RER in protein synthesis.
Think about what gives the RER its "rough" appearance under a microscope.
Consider the fate of proteins synthesized on the RER.

Try solving on your own before revealing the answer!

Final Answer:

The RER synthesizes and processes proteins; it appears rough due to ribosomes attached to its surface.

Q27. What is the main function of smooth endoplasmic reticulum?

Background

Topic: Endomembrane System

This question is about the role of the smooth ER in the cell.

Key Terms:

Smooth endoplasmic reticulum (SER): Organelle involved in lipid synthesis and detoxification.

Step-by-Step Guidance

Recall the main functions of the SER as described in your textbook.
Think about the types of molecules synthesized by the SER.
Consider the role of the SER in detoxifying harmful substances.

Try solving on your own before revealing the answer!

Final Answer:

The main function of the smooth ER is lipid synthesis and detoxification of harmful substances.

Q28. What is the function of the Golgi apparatus?

Background

Topic: Endomembrane System

This question is about the role of the Golgi apparatus in processing and shipping cellular products.

Key Terms:

Golgi apparatus: Organelle involved in modifying, sorting, and packaging proteins and lipids.

Step-by-Step Guidance

Recall the main function of the Golgi apparatus in the cell.
Think about how proteins and lipids are processed and shipped to their destinations.
Consider the role of vesicles in this process.

Try solving on your own before revealing the answer!

Final Answer:

The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport within or outside the cell.

Q29. What is the function of lysosomes and peroxisomes?

Background

Topic: Cellular Organelles

This question is about the roles of two types of vesicles in eukaryotic cells.

Key Terms:

Lysosome: Organelle containing digestive enzymes.
Peroxisome: Organelle involved in breaking down fatty acids and detoxifying harmful substances.

Step-by-Step Guidance

Recall the main function of lysosomes in digestion and recycling of cellular material.
Think about the role of peroxisomes in breaking down toxic substances.
Consider the types of enzymes found in each organelle.

Try solving on your own before revealing the answer!

Final Answer:

Lysosomes digest and recycle cellular waste; peroxisomes break down fatty acids and detoxify harmful substances.

Q30. What is the main function of mitochondria? What is the relationship between the number of mitochondria per cell and the activity level of the cell?

Background

Topic: Cellular Respiration

This question is about the role of mitochondria in energy production and how their abundance relates to cell activity.

Key Terms:

Mitochondria: Organelles known as the "powerhouses" of the cell.
ATP: The main energy currency of the cell.

Step-by-Step Guidance

Recall the main function of mitochondria in producing ATP through cellular respiration.
Think about why some cells have more mitochondria than others.
Consider examples of highly active cells (e.g., muscle cells) and their mitochondrial content.

Try solving on your own before revealing the answer!

Final Answer:

Mitochondria produce ATP for cellular energy. Cells with higher activity levels have more mitochondria to meet their energy demands.

Q31. What is the function of chloroplasts?

Background

Topic: Photosynthesis

This question is about the role of chloroplasts in plant and algal cells.

Key Terms:

Chloroplast: Organelle where photosynthesis occurs.
Photosynthesis: Process of converting light energy into chemical energy.

Step-by-Step Guidance

Recall the main function of chloroplasts in plant and algal cells.
Think about the process of photosynthesis and its importance for energy production.
Consider the types of organisms that contain chloroplasts.

Try solving on your own before revealing the answer!

Final Answer:

Chloroplasts carry out photosynthesis, converting light energy into chemical energy stored in glucose.