Cells, Microscopes, and Foundations of Life

These flashcards review key concepts from the lecture notes, including the history of microscopy, the development of cell theory, experiments challenging spontaneous generation, and the structure and function of major cell components.

What is the basic unit of life?

The cell.

What are organisms composed of a single cell called, and give two examples.

Unicellular organisms; examples include bacteria and protozoa.

What term describes organisms made of many cells and visible to the naked eye?

Multicellular (eukaryotic) organisms; they are macroscopic.

What instrument allows us to view objects too small for the unaided eye?

The microscope.

From which Latin word is the term “lens” derived, and why?

From the Latin word "lentil" because early lenses resembled lentil beans.

To roughly what magnification could 13th-century eyeglass lenses enlarge objects?

About 6× to 10× magnification.

Who built the first compound microscope in the late 16th century?

Zacharias Janssen (with the help of his father).

Which scientist first used the term “cells” after viewing cork under a microscope?

Robert Hooke in 1665.

Who constructed microscopes that magnified 70×–275× and discovered “animalcules”?

Antonie van Leeuwenhoek.

Name two kinds of cells Leeuwenhoek was first to observe in both animals and humans.

Sperm cells and egg cells.

Which botanist published 1838 work on plant cells that helped form cell theory?

Matthias Jakob Schleiden.

Which physiologist studied animal cells and co-founded cell theory?

Theodor Schwann.

State the first postulate of cell theory.

All organisms are made up of cells.

State the second postulate of cell theory.

The cell is the basic unit of life.

Who added the idea that all cells arise from pre-existing cells, and in what year?

Rudolf Virchow in 1858 (Omnis cellula e cellula).

Which scientist likely observed cell division earlier, in 1855?

Robert Remak.

What did the theory of spontaneous generation claim?

That living organisms could arise from nonliving matter.

Which Italian scientist’s meat-in-jars experiment refuted spontaneous generation of maggots?

Francesco Redi.

Which 1745 experimenter boiled chicken broth, sealed it, yet still saw microbial growth, supporting spontaneous generation?

John Needham.

Who repeated Needham’s broth experiment but showed no growth when the flask was sealed before boiling?

Lazzaro Spallanzani.

How did Louis Pasteur’s swan-neck flask experiment finally disprove spontaneous generation?

It showed microbes entered broth only when dust could reach it; broth in intact S-neck flasks remained sterile.

Describe the permeability of the cell membrane.

It is semipermeable, allowing selective passage of substances.

What role do membrane proteins play in the cell membrane?

They transport molecules across the membrane.

Why is cholesterol important in the phospholipid bilayer?

It prevents the bilayer from becoming too rigid or too fluid.

What are microvilli and give one function.

Finger-like membrane folds that increase surface area; e.g., they enhance nutrient absorption in intestinal epithelial cells.

What fluid matrix inside the cell suspends organelles?

Cytosol, the liquid component of the cytoplasm.

List three substances found within cytosol.

Electrolytes, metabolites, and ribonucleic acid (RNA).

Name the three major filaments of the cytoskeleton in order from thinnest to thickest.

Microfilaments (7 nm), intermediate filaments (≈10 nm), microtubules (25 nm).

Which protein primarily composes microfilaments?

Actin.

Which protein builds microtubules, and where are microtubules commonly organized?

Tubulin; they are organized at centrosomes.

What is the main function of centrioles during cell division?

They aid in separating and moving replicated chromosomes.

Together with pericentriolar material (PCM), centrioles form what cellular structure?

The centrosome.