Lec 3 Plant cell

What are the intended learning outcomes for the study of plant cells?

Describe plant cell organelles and their functions; identify various types of plant cells and tissues; understand the life cycle of different plant groups; compare and contrast simple permanent and complex tissues; familiarize with the various structures of each plant organ; explain the different processes of plant reproduction.

How is a cell defined in biological terms?

A cell is the principal structural and functional unit of every organism, where all materials are organized into specific cell structures, becoming living matter.

Who was Robert Hooke and what was his contribution to cell biology?

Robert Hooke was an English scientist who observed tiny, hollow structures in cork through a microscope and called them 'cells' because they resembled the rooms of monks.

What did Anton van Leeuwenhoek discover?

Anton van Leeuwenhoek observed living cells in pond water and other samples through a simple microscope, coining the term 'animalcules' for some of them, which include bacteria and protozoa.

What significant discovery did Robert Brown make in 1833?

Robert Brown discovered the nucleus in plant cells, identifying it as a key component of cells.

What was Matthias Jakob Schleiden's contribution to cell theory?

Matthias Jakob Schleiden declared that all plant tissues are composed of cells and that an embryonic plant arises from a single cell.

What did Theodor Schwann contribute to the understanding of cells?

Theodor Schwann discovered that animal parts are made up of cells and helped formulate the cell theory, stating that the cell is the smallest unit of structure for all organisms.

What are the three main tenets of the cell theory?

1. The cell is the smallest unit of structure for all organisms. 2. All organisms consist of one or more cells. 3. Living cells come only from other living cells.

What did Rudolph Virchow add to the cell theory?

Rudolph Virchow added that all living cells come only from other living cells, encapsulated in the phrase 'Omnis cellula e cellula'.

What is the significance of the term 'cellulae' as used by Robert Hooke?

'Cellulae' refers to the tiny, hollow structures Hooke observed in cork, which he named 'cells' due to their resemblance to monk's rooms.

What types of cells did Anton van Leeuwenhoek observe?

Anton van Leeuwenhoek observed red blood cells, sperm cells, and various microorganisms, contributing to the understanding of living cells.

What was the impact of Matthias Schleiden's observations on plant biology?

Schleiden's observations led to the conclusion that all plants are made of cells, forming a foundational concept in plant biology.

How did Theodor Schwann's work relate to both plants and animals?

Schwann's work established that both plants and animals are composed of cells, thereby unifying the study of biology across different life forms.

What does the phrase 'Omnis cellula e cellula' mean?

It means 'all cells come from cells,' emphasizing that living cells arise only from pre-existing living cells.

Who were the three German scientists instrumental in developing the cell theory?

Matthias Schleiden, Theodor Schwann, and Rudolph Virchow.

What is the significance of the nucleus in plant cells?

The nucleus is a key component of cells, playing a crucial role in cell function and heredity.

What did Robert Brown refer to when he mentioned an 'opaque spot' in cells?

He referred to the nucleus, which he identified as a significant structure within plant cells.

What is the basic unit of life according to cell theory?

The cell is considered the basic unit of life.

What did Robert Hooke use to observe cells?

Robert Hooke used a compound microscope to observe cork.

What is the historical significance of the year 1665 in cell biology?

It marks the year when Robert Hooke first described cells, laying the groundwork for cell theory.

What is the role of microscopes in the study of cells?

Microscopes allow scientists to observe the structure and function of cells, leading to discoveries about their composition and role in living organisms.

What are the main domains of Eukaryotic cells?

Domain Eukarya includes Protists, Fungi, Plants, and Animals.

What are the key features of Eukaryotic cells?

Eukaryotic cells contain a membrane-bound nucleus, specialized organelles, and a plasma membrane.

What distinguishes Prokaryotic cells from Eukaryotic cells?

Prokaryotic cells lack a membrane-bound nucleus and are structurally simpler.

What are the two domains of Prokaryotic cells?

The two domains are Bacteria and Archaea.

What are the three shapes of bacterial cells?

Bacterial cells can be Bacillus (rod), Coccus (spherical), or Spirilla (spiral).

Where do Archaea typically live?

Archaea live in extreme habitats.

What structures are absent in Prokaryotic cells compared to Eukaryotic cells?

Prokaryotic cells lack a nuclear membrane, endoplasmic reticulum, mitochondria, Golgi bodies, and lysosomes.

What is the Endosymbiotic Theory?

The Endosymbiotic Theory explains the evolution of Eukaryotic cells from Prokaryotic ancestors.

What are the main parts of a plant cell?

Plant cells have a cell wall, cell membrane, organelles (membranous and non-membranous), and inclusions.

What is protoplasm?

Protoplasm is all substances found in a cell, including the nucleus and cytoplasm, surrounded by the cell membrane.

What is the composition of the cell wall in plant cells?

The cell wall consists of cellulose embedded in a matrix of hemicellulose and pectin.

What are the layers of the cell wall?

The cell wall has a primary cell wall and a secondary cell wall with three layers.

What is the function of the plasma membrane?

The plasma membrane acts as a selective barrier to the passage of materials into and out of the cell.

What is the structure of the plasma membrane?

The plasma membrane is a fluid mosaic of two layers of phospholipids with embedded globular proteins and sterols.

What does selectively permeable mean?

Selectively permeable means that the membrane allows certain substances to pass while blocking others.

What is cytoplasm?

Cytoplasm is the fluid material of a cell, excluding the nucleus and vacuole, consisting of cytosol and organelles.

What are inclusions in a cell?

Inclusions are various substances stored in the cytoplasm that are not part of the organelles.

What is cytosol?

Cytosol is the fluid component of the cytoplasm.

What are membranous organelles in a plant cell?

Membranous organelles include the nucleus, endoplasmic reticulum, Golgi bodies, plastids, mitochondria, and vacuoles.

What are non-membranous organelles in a plant cell?

Non-membranous organelles include ribosomes and cytoskeletons.

What is the role of ribosomes in a cell?

Ribosomes are responsible for protein synthesis.

What is the function of the cell membrane?

The membrane allows some substances in while keeping others out.

What are aquaporins?

Aquaporins are proteins that facilitate the transport of water (H2O) across the cell membrane.

What is the composition of cytoplasm?

Cytoplasm is composed of cytosol and organelles, excluding the nucleus and vacuole.

What is the cytosol?

Cytosol is the clear thick liquid that serves as the matrix where all organelles are embedded.

What is the role of the nucleus in a cell?

The nucleus acts as the command center of the cell and contains chromatin and a nucleolus.

What is chromatin?

Chromatin is a substance within the nucleus that contains DNA and histones.

What is the function of the nucleolus?

The nucleolus produces subunits of ribosomes.

What distinguishes rough endoplasmic reticulum (Rough ER) from smooth endoplasmic reticulum (Smooth ER)?

Rough ER is studded with ribosomes and is involved in protein synthesis, while Smooth ER lacks ribosomes and synthesizes lipids.

What is the Golgi apparatus?

The Golgi apparatus is a series of flattened, curved saccules that modify, package, and distribute proteins and lipids.

How does the Golgi apparatus interact with the endoplasmic reticulum?

The Golgi apparatus receives vesicles from the ER on its cis face and prepares them for export from its trans face.

What is the endomembrane system?

The endomembrane system is a series of membranes that transport molecules within the cell, including the nuclear envelope, ER, Golgi apparatus, lysosomes, and vesicles.

What are plastids?

Plastids are round or oval bodies that contain pigments and are absent in animal cells.

What types of pigments do chromoplasts contain?

Chromoplasts contain yellow, orange, red, and purple pigments.

What is the function of leucoplasts?

Leucoplasts are colorless plastids that store starch and other substances.

What is an etioplast?

An etioplast is an intermediate type of plastid that has not been exposed to light and can convert into chloroplasts upon exposure.

What is the role of chloroplasts?

Chloroplasts contain chlorophyll, which traps light for photosynthesis.

What is a gerontoplast?

A gerontoplast develops from a chloroplast that undergoes senescence.

What is etiolation?

Etiolation is a response to inadequate light conditions, resulting in elongated, weak, and pale growth.

What is the function of lysosomes?

Lysosomes contain digestive enzymes that break down cell parts or substances entering by vesicles.

What is the role of ribosomes in the rough endoplasmic reticulum?

Ribosomes synthesize proteins and package them in vesicles.

What is the significance of nuclear pores?

Nuclear pores permit exchange between nucleoplasm and cytoplasm.

What is the structure of the nuclear envelope?

The nuclear envelope consists of a double layer of membrane.

What is photo-oxidation?

Oxidative damage to plant tissues caused by excessive exposure to light, particularly high-intensity or prolonged exposure to sunlight.

What is photoinhibition?

Reduction in the efficiency of photosynthesis due to excessive light exposure, which can lead to plant death.

What are the key structural features of chloroplasts?

Chloroplasts are bounded by a double membrane, have an inner membrane that is infolded to form disc-like thylakoids stacked into grana, and are suspended in a semi-fluid stroma.

What pigment is responsible for the green color of chloroplasts?

Chlorophyll, which is found only in the inner membranes of chloroplasts and captures light energy for photosynthesis.

What is the primary function of mitochondria?

Mitochondria are involved in cellular respiration and produce most of the ATP utilized by the cell.

What are the main components of mitochondria?

Mitochondria are bounded by a double membrane, have infoldings called cristae that enclose the matrix, which contains respiratory enzymes.

What are redox reactions?

Redox reactions involve the transfer of electrons from one atom or molecule to another, driving chemical changes and energy transformations.

What is the central vacuole and its primary functions?

The central vacuole is a large membranous sac in plant cells that stores excess materials, contains cell sap, and helps develop turgor pressure.

What is the tonoplast?

The tonoplast is the unit membrane that encloses the central vacuole.

What is the typical volume percentage of the central vacuole in some plant cells?

The central vacuole can occupy up to 90% of the volume of some plant cells.

What are microbodies?

Microbodies are spherical, membrane-bound organelles involved in specific chemical activities, including photorespiration and fat conversion.

What are the two major types of microbodies?

Peroxisomes and glyoxysomes.

What is the function of peroxisomes?

Peroxisomes contain oxidative enzymes involved in the breakdown of hydrogen peroxide (H2O2) and participate in photorespiration.

What occurs during photorespiration?

Photorespiration occurs when carbon dioxide levels drop and oxygen levels increase in leaves, typically on hot, sunny days with water stress.

What is the role of glyoxysomes?

Glyoxysomes are found in fat-rich seeds and are responsible for converting fats and fatty acids into sucrose.

What is the diameter range of microbodies?

Microbodies typically range from 0.3 to 1.5 micrometers in diameter.

What is the significance of turgor pressure in plant cells?

Turgor pressure helps maintain cell structure and rigidity, allowing plants to stand upright.

What is the role of chlorophyll in photosynthesis?

Chlorophyll captures light energy to drive the process of photosynthesis.

How do chloroplasts contribute to plant survival?

Chloroplasts enable plants to perform photosynthesis, converting light energy into chemical energy.

What is the matrix in mitochondria?

The matrix is the inner semifluid space within mitochondria that contains respiratory enzymes.

What surrounds a plant cell instead of a lipid bilayer?

A single layer of lipids.

What energy source is required for early seedling development before photosynthesis begins?

Sucrose.

What are ribosomes composed of?

Ribosomal RNA (rRNA).

What are the two types of ribosomal subunits in eukaryotic cells?

Large subunit and small subunit, specifically 80 S.

What type of ribosomal subunit is found in prokaryotic cells?

70 S.

Where are ribosomal subunits made?

In the nucleolus.

Where can ribosomes be located within a cell?

On the endoplasmic reticulum (making it 'rough') or free in the cytoplasm.

What is the primary function of the cytoskeleton?

To maintain cell shape and assist in the movement of the cell and organelles.

What are the three types of macromolecular fibers in the cytoskeleton?

Microfilaments, microtubules, and myosin filaments.

What are microfilaments responsible for?

Resisting tension, maintaining cellular shape, forming cytoplasmic protuberances, and participating in cytokinesis.

What is the function of microtubules?

Intracellular transport of organelles, component of cilia and flagella, and synthesis of the cell wall in plants.

What are three features unique to plant cells?

Cell wall, central vacuole, and chloroplasts.

What additional organelle is found in animal cells that is not in plant cells?

Lysosomes.

What are the three types of plant cells?

Parenchyma, collenchyma, and sclerenchyma.

What are the characteristics of parenchyma cells?

Typical plant cells with thin, flexible primary walls, large central vacuoles, and alive at maturity.

What distinguishes collenchyma cells?

Unevenly thick primary cell walls, flexibility, and they are alive at maturity.