Plant Cells Unit 02

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Questions and Answers

What is a key characteristic distinguishing prokaryotic cells from eukaryotic cells?

Ability to perform photosynthesis

Existence of membrane-bound organelles (correct)

Size and complexity

Presence of a nucleus (correct)

Which scientist is known for co-founding the cell theory related to plant cells?

Robert Brown

Matthias Schleiden (correct)

Theodor Schwann

Robert Hooke

What model represents the dynamic nature of cell membranes?

Static Layer Model

Rigidity Model

Cell Theory Model

Fluid Mosaic Model (correct)

Which component makes up approximately 40% of the cell membrane composition?

Phospholipid bilayer Signup and view all the answers

What is the primary function of cellular membranes?

Regulate the passage of molecules Signup and view all the answers

What is the primary function of the rough endoplasmic reticulum (ER)?

Protein storage and secretion Signup and view all the answers

Which component is responsible for synthesizing RNA within the nucleus?

Nucleolus Signup and view all the answers

What is the distinguishing feature of smooth endoplasmic reticulum (ER)?

Lipid synthesis and membrane assembly Signup and view all the answers

What is the role of dictyosomes (Golgi bodies) in plant cells?

Modification and processing of proteins Signup and view all the answers

Which part of the plant cell is described as the interconnected mass consisting of protoplasm?

Symplast Signup and view all the answers

How does the structure of the nuclear envelope contribute to its function?

It contains pores for transport of substances Signup and view all the answers

In which scenario is the nucleus of a cell expected to be larger?

In rapidly dividing cells Signup and view all the answers

What is the composition of nucleoplasm?

DNA, enzymes, histones, and water Signup and view all the answers

Which type of molecules can freely pass through a phospholipid bilayer?

Small nonpolar molecules Signup and view all the answers

What type of transport requires ATP expenditure?

Active transport Signup and view all the answers

What role do intrinsic proteins play in transmembrane movement?

Facilitate movement of ions and charged molecules Signup and view all the answers

Which characteristic best describes a selectively permeable membrane?

Permits some substances while restricting others Signup and view all the answers

What component is NOT generally part of a plant cell's cell wall?

Chlorophyll Signup and view all the answers

What is the primary function of plasmodesmata in plant cells?

Increase transport of materials between cells Signup and view all the answers

What is a primary function of the cristae in mitochondria?

To increase surface area for enzyme activity Signup and view all the answers

Which statement about the secondary cell wall is true?

It is located between the primary cell wall and the plasma membrane. Signup and view all the answers

Which of the following correctly describes the stroma in chloroplasts?

The liquid where CO2 is converted into carbohydrates Signup and view all the answers

Which of the following describes the primary cell wall in plant cells?

It is typically thin and composed of cellulose. Signup and view all the answers

What is true about leucoplastids?

They are colorless plastids used for storage. Signup and view all the answers

How does the structure of chloroplasts differ from that of mitochondria?

Chloroplasts contain grana for light reactions. Signup and view all the answers

What role do glyoxysomes play in plant cells?

They convert fats into carbohydrates. Signup and view all the answers

What is the primary product stored in amyloplasts?

Starch Signup and view all the answers

What type of RNA is responsible for coding and decoding genetic information?

mRNA Signup and view all the answers

Which of the following statements about the cytosol is accurate?

It contains various organelles suspended in a viscous fluid. Signup and view all the answers

What is the primary function of the cytoskeleton in a cell?

To aid in cellular support and movement Signup and view all the answers

Which component of the cytoskeleton is responsible for the formation of spindle fibers during cell division?

Microtubules Signup and view all the answers

What characteristic structure do flagella and cilia share?

9+2 microtubule arrangement Signup and view all the answers

What is the main role of vacuoles in animal cells?

Storage of nutrients and waste accumulation Signup and view all the answers

In which type of cells are centrioles most commonly found?

Animal cells and some fungal cells Signup and view all the answers

Study Notes

Overview of Cells

Cells serve as the basic structural and functional units of all living organisms.
All cells arise from preexisting cells; physiological processes like respiration and growth occur at the cellular level.
Significant contributors to cell theory:
- Robert Hooke discovered cells in cork (1665).
- R.J.H. Dutrochet explored osmosis and light effects on plants (1824).
- Robert Brown identified the nucleus and cytoplasmic streaming (1833).
- Matthias Schleiden recognized that all plant parts consist of cells (1838).
- Theodor Schwann expanded the cell theory to all living entities (1839).

Basic Cell Types

Prokaryotic Cells: Lack a nucleus and membrane-bound organelles; examples include eubacteria and archaebacteria.
Eukaryotic Cells: Contain a nucleus and membrane-bound organelles; examples include protists, fungi, plants, and animals.
Key differences in animal cells: lack cell walls, plastids, vacuoles, and glyoxysomes.

Cell Membranes

Cell membranes regulate molecular passage, compartmentalize the cell, and host enzymatic reactions.
Dynamics of membranes are modeled by the Fluid Mosaic Model, allowing for protein diffusion.
Biological membranes are selectively permeable, controlling the movement of substances (e.g., gas diffusion and ionic transport).

Plant Cell Structure

Plant cells generally comprise:
- Cell Wall: Composed primarily of cellulose, providing structure and protection.
- Protoplast: Contains cytoplasm, nucleus, and organelles.
- Cell Inclusions: Storage components within the cell.

Cell Wall

Protects cellular content and regulates size; composed mainly of cellulose and hemicellulose.
Secondary cell walls add rigidity and are impregnated with lignin.
Plasmodesmata allow communication between adjacent plant cells, facilitating material transport.

Cytoplasm and Organelles

Cytoplasm: Fluid part of the cell containing organelles and the nucleus's contents upon removal.
Nucleus: Houses genetic material and includes a double membrane and nucleoplasm. Ribosomes and polysomes are linked to protein synthesis.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes for protein synthesis and storage.
- Smooth ER: Synthesizes lipids and assembles membranes.

Dictyosomes and Golgi Apparatus

Dictyosomes: Modify and package proteins (e.g., glycoproteins) for secretion.
Golgi Apparatus: Composed of multiple dictyosomes, vital for secretion and processing materials.

Mitochondria and Chloroplasts

Mitochondria: Main site for cellular respiration featuring circular DNA and folded membranes for enzyme activity; matrix is where metabolic reactions occur.
Chloroplasts: Convert CO2 into carbohydrates; contain thylakoids for light reactions and stroma for subsequent reactions.

Microbodies and Cytoskeleton

Microbodies: Include peroxisomes and glyoxysomes, involved in specific metabolic tasks.
Cytoskeleton: Network of fibers aiding in support and movement; composed of microtubules, intermediate filaments, and microfilaments.

Motility Structures

Flagella and Cilia: Contain microtubules in a “9+2” arrangement, facilitating movement through sliding doublets activated by dynein proteins.

Vacuoles

Comprised of cell sap, tonoplast encloses vacuoles preventing waste leakage. Functions include maintaining turgor pressure, nutrient storage, and waste accumulation.
Ergastic Substances: Includes crystals, starch, and nitrogenous inclusions, addressing various storage and protective roles.

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Description

Explore the fundamental aspects of plant cells in this quiz unit. Delve into the basic structural and functional units of life, focusing on the unique features of plant cells and their physiological processes. Understand how plant cells compare to other cell types.