Intro to Cells Unit - Introduction

Q: What did people believe about living things before cells were discovered?

A: People believed in “humours,” the idea that living things were made of elements: phlegm, blood, bile, or black bile. People had no way to see on a cellular level.

Q: Who was Robert Hooke and what did he do in 1665?

A: Robert Hooke was an English scientist who looked at various items of nature through his light microscope on the bark of a cork oak tree. What he saw changed science.

Q: What did Robert Hooke observe in the cork oak tree bark?

A: He saw a grouping of boxes that reminded him of cubical “cells” where monks live. The little boxes were dead plant cells. He then observed other specimens and determined that many things were made of cells.

Q: Who was the first person to observe living cells?

A: A Dutch trader named Anton van Leeuwenhoek.

Q: What did Anton van Leeuwenhoek observe in 1673?

A: He observed protists, which are very small microorganisms. This was the first time living organisms were seen and people realized the world was made up of living organisms.

Q: Why did scientists take so long to develop the cell theory after Hooke and Leeuwenhoek?

A: Even though cells were recorded and observed, scientists did not connect the findings until about 150 years later, when they began to believe all things were made of cells.

Q: Who concluded that all plants are made of cells and when?

A: In 1838, German botanist Matthias Schleiden concluded that all plants were made of cells.

Q: Who concluded that all animals are made of cells and when?

A: In 1839, German zoologist Theodor Schwann concluded that all animals were made of cells.

Q: What did Rudolf Virchow contribute to cell theory?

A: He observed that all cells come from existing cells, helping shape the modern Cell Theory.

Q: What are the three main points of the Cell Theory?

A: 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in an organism. 3. Cells come from existing cells.

Q: How have microscopes advanced since the advent of computers?

A: Scanning electron microscopes (SEMs) produce high-resolution images of cell surfaces, and transmission electron microscopes (TEMs) produce high-resolution images of the insides of cells.

Q: What is a major limitation of SEMs and TEMs?

A: Samples must be prepared in ways that kill the cells being viewed.

Q: What are the different types of cell shapes?

A: Some cells are long and skinny, some are smooth and pliable, and some are rigid and supportive.

Q: How does cell size vary?

A: Cells can be as small as one nanometer or as large as the period on a piece of paper.

Q: Why are all cells small?

A: The size of a cell is limited by its surface area-to-volume ratio.

Q: How is the surface area-to-volume ratio expressed?

A: Surface Area ÷ Volume.

Q: How does the surface area-to-volume ratio affect cell function?

A: As surface area increases, volume also increases, which decreases the surface area-to-volume ratio.

Q: Why are small cells more efficient?

A: Small cells can transport materials faster and be more energy-efficient than large cells.