The Cell: Structure and Function

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Questions and Answers

What are the two subunits that make up tubulin proteins in microtubules?

Alpha and beta tubulin (correct)

Alpha and lambda tubulin

Beta and theta tubulin

Gamma and delta tubulin

What is the primary role of the centrosome in animal cells?

Microtubule organization (correct)

Energy production

Cell division regulation

Synthesis of proteins

How do plant and fungal cells differ in their arrangement of microtubules compared to animal cells?

They have more complex microtubule structures.

They have centrosomes with centrioles.

They do not have centrosomes with centrioles. (correct)

They lack microtubules entirely.

Which structures extend outward from the plasma membrane to enable cell movement?

Flagella and cilia Signup and view all the answers

What is the functional unit of living organisms?

Cell Signup and view all the answers

What is the role of centrioles during cell division?

Arranging mitotic spindles Signup and view all the answers

Which of the following best describes differentiation?

The process by which cells assume specialized structure and function Signup and view all the answers

What is the primary function of the plasma membrane?

To facilitate communication and nutrient transfer Signup and view all the answers

What is the structure and function of the endoplasmic reticulum (ER)?

An extensive system of flattened membranes for protein modification Signup and view all the answers

Multicellular organisms differ from unicellular organisms in that multicellular organisms have:

More specialized cell functions Signup and view all the answers

What characteristic of phospholipids contributes to the formation of the plasma membrane's bilayer structure?

Amphipathic nature Signup and view all the answers

What structural feature differentiates the two ends of a microtubule?

Different polarity Signup and view all the answers

Which type of fatty acid increases the fluidity and flexibility of the plasma membrane?

Unsaturated fatty acids Signup and view all the answers

What role does cholesterol play in the plasma membrane?

It mediates the flow of materials and information Signup and view all the answers

How are motile cilia different from flagella?

They are shorter and found in larger numbers. Signup and view all the answers

Which statement about cell boundaries is NOT true?

The plasma membrane is impermeable to all substances Signup and view all the answers

What primarily occurs during the G1 phase of the cell cycle?

Protein synthesis and metabolic activity Signup and view all the answers

What is the role of RNA polymerase in the transcription process?

To attach to the promoter region and synthesize mRNA Signup and view all the answers

How long does the S phase of the cell cycle last?

5 hours Signup and view all the answers

What happens during the process of translation?

A chain of amino acids is formed using mRNA as a template Signup and view all the answers

What characterizes the M phase of the cell cycle?

Cell division occurs resulting in genetically identical daughter cells Signup and view all the answers

What is the primary function of ribosomes attached to the rough ER?

Synthesize proteins Signup and view all the answers

What are the two types of cell division?

Mitosis and meiosis Signup and view all the answers

Which of the following is NOT a function of the smooth ER?

Protein synthesis Signup and view all the answers

What is the main function of ribosomes in a cell?

Produce and sequence proteins Signup and view all the answers

What is the role of lysosomes in a cell?

Digest cellular waste Signup and view all the answers

What additional role does the rough ER play besides synthesizing proteins?

Synthesize new phospholipids Signup and view all the answers

What vital function do peroxisomes perform in the cell?

Sequester oxidative reactions Signup and view all the answers

What process occurs in mitochondria to produce ATP?

Cellular respiration Signup and view all the answers

What structural feature of mitochondria increases its surface area?

Cristae Signup and view all the answers

Which organelle is responsible for photosynthesis?

Chloroplasts Signup and view all the answers

Which structure is responsible for transporting and packaging proteins and lipids?

Golgi apparatus Signup and view all the answers

Which type of cells typically lose their ability to undergo mitosis?

Terminally differentiated cells Signup and view all the answers

What balances cell division and differentiation?

Cell death (apoptosis) Signup and view all the answers

What is the role of the liver in terms of regeneration?

It is the only organ capable of natural regeneration of lost tissue. Signup and view all the answers

How long does an average cell cycle last?

17-18 hours Signup and view all the answers

Which statement is true about facultative dividers?

They retain the capacity to divide when needed. Signup and view all the answers

Study Notes

The Cell

Cells are the fundamental units of all living organisms, classified as unicellular or multicellular.
Multicellular organisms, like humans, exhibit diverse cell types, reflecting functional and structural specializations through differentiation.

Parts of the Cell and their Functions

Plasma Membrane
- Composed of a phospholipid bilayer, it regulates nutrient transfer, cell attachment, and communication.
- Amphipathic properties allow spontaneous bilayer formation in aqueous environments.
- The presence of unsaturated fatty acids enhances fluidity and flexibility.
Cytoskeleton
- Microtubules and actin filaments provide structural support and facilitate cellular transport.
- The centrosome organizes microtubules, essential for cell division and cell shape maintenance.
Endoplasmic Reticulum (ER)
- Rough ER contains ribosomes for protein synthesis and lipid production.
- Smooth ER synthesizes lipids, detoxifies drugs, and stores calcium ions for signaling.
Golgi Apparatus
- A series of flattened sacs responsible for modifying, packaging, and delivering proteins and lipids in vesicles.
Mitochondria
- Double-membraned organelles where ATP is produced through cellular respiration, utilizing chemical energy from nutrients.
Lysosomes
- Membrane-bound vesicles containing digestive enzymes for breaking down cellular waste and invasive pathogens.
Peroxisomes
- Organelles involved in oxidative reactions and detoxification of reactive oxygen species.
Ribosomes
- Composed of rRNA and proteins, they synthesize proteins by translating mRNA.
Chloroplasts
- Organelles in plants and algae that perform photosynthesis, converting light energy into chemical energy.

The Cell Cycle

A series of events that leads to cellular division and replication, lasting about 17-18 hours.
Divided into phases:
- G1 (Gap 1): Cell is metabolically active; protein synthesis occurs; cells can enter a non-dividing state (G0).
- S (Synthesis): The DNA is replicated, resulting in chromosomes with identical sister chromatids.
- G2 (Gap 2): Preparation for cell division; completion marks the end of interphase.
- Mitosis (M): Final step where the cell divides into two genetically identical daughter cells, lasting 1-2 hours.

Types of Cell Division

Mitosis: Division of somatic (body) cells, resulting in two identical cells.
Meiosis: Division of gametic (sex) cells, leading to genetically diverse cells.

Apoptosis

A form of programmed cell death that balances cell division and differentiation, critical in development and tissue homeostasis.
The liver is notable for its ability to regenerate, requiring only 20% of its mass to function effectively.

Key Functions of Cell Structures

Plasma membrane maintains homeostasis through selective permeability.
Endoplasmic reticulum synthesizes, modifies, and transports proteins and lipids.
Golgi apparatus packages and directs cellular products.
Mitochondria generate energy necessary for cellular processes.

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Description

Explore the fundamental units of life with this quiz on cell structure and function. Learn about the different parts of the cell, including the plasma membrane, cytoskeleton, and endoplasmic reticulum, and their unique roles. Test your knowledge about unicellular and multicellular organisms.