Plant Structure and Functions - Part 1: Cell History, Structure, and Types

Flashcards covering key historical milestones in cell theory, plant cell organelles and structures, plasma membrane models, plastid types, and comparisons between prokaryotic and eukaryotic cells.

What did Robert Hooke observe when he first identified cells in 1665?

He observed plant cells by examining a section of cork.

What discovery did Anthon Van Leeuwenhoek make in 1674?

He was the first to observe single-celled organisms under the microscope.

What cellular component was first observed by Robert Brown in orchid cells?

The nucleus (observed in hairs and other cells of orchids).

Who discovered the fluid content of the cell in 1835, and who named it 'protoplasm' in 1839?

Felix Dujardin discovered the fluid content of the cell, and Jan Evangelista Purkyně named it protoplasm.

What key principles of cell theory were contributed by Matthias Schleiden and Theodor Schwann?

Matthias Schleiden (1838) stated that plants are composed of cells, and Theodor Schwann (1839) stated that animals are composed of cells.

What concept did Rudolf Virchow contribute to cell theory with the phrase 'Omnis cellula e cellula'?

The generation continuity of cells, meaning that cells arise from pre-existing cells through cell division.

What are the smallest and largest known cells along with their respective dimensions?

The smallest cell is Mycoplasma ($0.1\,\mu m$), and the largest cell is the ostrich egg ($18\,cm$).

How do the shapes of human red blood cells, nerve cells, and human white blood cells relate to their functions?

Human RBCs are circular biconcave for easy passage through capillaries; nerve cells are branched to conduct impulses; human WBCs can change shape to engulf microorganisms.

In this labeled diagram of an animal cell, what organelle corresponds to label #8?

Lysosome

In this labeled diagram of a plant cell, what structure corresponds to label #7?

Chloroplast

In this labeled diagram of a bacterial cell, what structure or region corresponds to label #9?

Nucleoid

What components make up the Fluid Mosaic Model of the plasma membrane?

Phospholipids, cholesterol molecules, proteins, and carbohydrates.

What are the structural features and properties of the two ends of a phospholipid molecule?

The head end contains a phosphate group and is hydrophilic; the tail end is composed of two fatty acid chains (hydrogen and carbon atoms) that are hydrophobic.

What is the function of cholesterol in the lipid bilayer of the plasma membrane?

It maintains membrane consistency, strengthens the membrane by preventing some small molecules from crossing, and ensures it remains fluid and flexible.

What is the glycocalyx and what are its functions?

A layer formed by carbohydrates on the extracellular side of the cell membrane that provides cushioning, protection, cell recognition, and acts as glue to attach cells.

How do exocytosis and endocytosis transport materials across the plasma membrane?

Exocytosis excretes materials (wastes, debris, mucilage, proteins, polysaccharides) via vesicle fusion; endocytosis pinches an outer membrane invagination shut to create a vesicle containing extracellular material.

What structural polysaccharides and polymers make up the plant cell wall?

Polysaccharides cellulose, hemicellulose, and pectin, as well as glycoproteins and polymers like lignin, cutin, or suberin.

What organelle component guides the formation of the cell wall, and what are its three layers?

Cell wall formation is guided by microtubules; its three layers are the primary cell wall, secondary cell wall, and middle lamella.

What are the dimensions of the nucleus diameter and its nuclear membrane pores?

The nucleus diameter ranges from $10\text{--}25\,\mu m$, and nuclear membrane pores have a diameter of about $80\text{--}100\,nm$.

What are the functions of the Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER)?

RER synthesizes secretory proteins and membrane proteins; SER synthesizes lipids, detoxifies drugs and poisons in liver cells, and stores calcium ions in muscle cells.

What are the structural features and two distinct ends of the Golgi body?

It consists of stacks of 5–8 flattened membranous sacs called cisternae, featuring a cis face (near the ER) and a trans face (near the cell membrane).

What enzymes are contained inside lysosomes, and what process do they perform in dead cells?

Lysosomes are filled with hydrolytic enzymes, and in dead cells, they perform autolysis.

What are cristae in mitochondria, and what function do they serve?

Cristae are shelf-like inward projections formed by foldings of the inner mitochondrial membrane that provide surface area for large numbers of enzymes.

What specific pigments give colour to carrots, mangoes, and tomatoes in chromoplasts?

Carrot contains carotene; mango contains xanthophyll; tomato contains lycopene.

What type of food is stored in potato tubers, maize grains, and castor seeds by leucoplasts?

Potato tubers store starch (amyloplasts), maize grains store protein (proteioplasts), and castor seeds store oil (elaioplasts).

According to this classification diagram of plastids, what are the three sub-types of leucoplasts?

Elaioplasts, Amyloplasts, and Proteioplasts.

What structural subunits compose microtubules and microfilaments in the cytoskeleton?

Microtubules are hollow tubules made of alpha-tubulin and beta-tubulin; microfilaments are thin filaments made of actin.

How do prokaryotic cells and eukaryotic cells differ in size, nucleus presence, and mode of reproduction?

Prokaryotes lack a true nucleus, range from $1\text{--}10\,\mu m$, and reproduce asexually; eukaryotes have a true nucleus, range from $10\text{--}100\,\mu m$, and reproduce both sexually and asexually.