Cell Theory and Cellular Organelles

A comprehensive set of question-and-answer flashcards covering historical contributors to cell theory, major cell organelles, their structures, and functions.

Who authored “Micrographia” and improved the early compound microscope?

Robert Hooke

Which scientist perfected the simple microscope (200–300×) and first observed living cells called “animalcules”?

Anton van Leeuwenhoek

Who disproved spontaneous generation by showing maggots come from fly eggs, not rotting meat?

Francesco Redi

Which botanist helped develop the first two tenets of cell theory and stated that all plants are made of cells?

Matthias Schleiden

Who worked with Schleiden to formulate the first two cell-theory tenets?

Theodor Schwann

What Latin word is the term “cell” derived from, and what does it mean?

“Cellula,” meaning small room or storeroom

What is the most prominent membrane-bound organelle that houses chromosomes?

The nucleus

Name the five structural parts of the nucleus.

Nuclear envelope, nuclear pores, chromatin, nucleolus, nucleoplasm

During which nuclear process is DNA duplicated before cell division?

DNA replication

Which organelle orchestrates the flow of genetic information known as the Central Dogma (DNA → RNA → Protein)?

The nucleus

What is the basic structural framework of the plasma membrane?

A semipermeable phospholipid bilayer with embedded proteins and cholesterol

List two key functions of the cell (plasma) membrane.

Selective transport of nutrients/wastes and maintenance of cell shape (with cytoskeleton support)

What rigid outer structure is present in plants, fungi, bacteria, and algae but absent in animal cells?

The cell wall

Name the three main layers of a typical plant cell wall.

Primary cell wall, middle lamella, secondary cell wall

Which polysaccharide is the main component of plant cell walls?

Cellulose

What is the cell wall of fungi primarily made of?

Chitin

What is the bacterial cell wall composed of?

Peptidoglycan

Which double-membrane organelle in plants contains chlorophyll for capturing sunlight?

Chloroplast

What are the stacked disc structures inside chloroplasts where light-dependent reactions occur?

Grana (stacks of thylakoids)

Which cycle in the chloroplast stroma fixes carbon dioxide into sugars?

The Calvin cycle

What double-membrane organelle is nicknamed the “powerhouse of the cell”?

Mitochondrion

What are the inner-membrane folds of mitochondria that increase surface area for ATP production?

Cristae

Name two key functions of mitochondria besides ATP production.

Regulating apoptosis/signaling and calcium homeostasis

Which ER type is studded with ribosomes and synthesizes secretory proteins?

Rough endoplasmic reticulum

Which ER type lacks ribosomes and synthesizes lipids and stores Ca²⁺?

Smooth endoplasmic reticulum

What membrane-bound vesicle contains hydrolytic enzymes to digest cellular debris?

Lysosome

What cytoskeletal filaments form hollow 24-nm tubes used in mitotic spindle formation?

Microtubules

What organelle serves as the primary microtubule-organizing center in animal cells?

Centrosome

What cylindrical structure, composed of nine microtubule triplets, helps organize spindles?

Centriole

Which large, membrane-bounded compartment in plant cells stores water, ions, and pigments and provides turgor pressure?

Central vacuole

Which organelle modifies, sorts, and ships proteins from the ER in stacked cisternae?

Golgi apparatus (Golgi bodies)

What organelle breaks down fatty acids and neutralizes hydrogen peroxide using catalase?

Peroxisome

What universal molecular machines translate mRNA into protein?

Ribosomes

What are the sizes of prokaryotic and eukaryotic ribosomes, respectively?

70S (50S + 30S) and 80S (60S + 40S)

Name the three major components of the cytoskeleton.

Microtubules, microfilaments (actin), intermediate filaments

Which motor protein moves cargo toward the plus end of microtubules (cell periphery)?

Kinesin

Which motor protein moves cargo toward the minus end of microtubules (near the nucleus)?

Dynein

Which motor protein interacts with actin filaments for muscle contraction and cytokinesis?

Myosin

What semi-liquid matrix fills the cell between plasma membrane and nucleus, embedding organelles?

Cytoplasm (cytosol + suspended components)

What term describes the total living content of a cell, including cytoplasm and nucleus?

Protoplasm

State the first two classic tenets of cell theory.

1) All living organisms are composed of one or more cells. 2) The cell is the basic unit of structure and function in living things.