Cellular Scale: Appreciating the Vastness of the Small

Biology Grades High School 7:19 Video
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Lesson Description

Explore the relative sizes of biological components, from water molecules to cells, to understand the complexity and organization of living systems.

Video Resource

Scale of cells | Structure of a cell | Biology | Khan Academy

Khan Academy

Duration: 7:19
Watch on YouTube

Key Concepts

  • Relative scale of biological components
  • Nanometers and micrometers as units of measurement
  • Hierarchical organization in biological systems
  • Complexity within cells

Learning Objectives

  • Students will be able to compare and contrast the sizes of water molecules, proteins, viruses, and cells.
  • Students will be able to convert between nanometers and micrometers.
  • Students will be able to explain the importance of scale in understanding cellular complexity.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they think of when they hear the word 'small' in biology. Mention atoms, molecules, and cells and discuss how they tend to be grouped together in thinking, but aren't equal in size. Briefly introduce the video and its purpose: to explore the scale of these components.
  • Video Viewing (10 mins)
    Play the Khan Academy video 'Scale of cells | Structure of a cell | Biology | Khan Academy'. Instruct students to take notes on the sizes of different biological components mentioned in the video.
  • Scale Comparison (15 mins)
    Have students compare sizes in a chart. Column 1: Component. Column 2: Size. Column 3: Size relative to water molecule (e.g. Hemoglobin is ~20x the size of a water molecule.)
  • Discussion and Analysis (10 mins)
    Facilitate a class discussion using the questions below. Encourage students to refer to their notes and the size comparison charts.
  • Wrap-up (5 mins)
    Summarize the key takeaways of the lesson. Emphasize the importance of understanding scale in biology to appreciate the complexity within cells.

Interactive Exercises

  • Scale Model Building
    Have students create a scale model (using different materials like beads, clay, etc.) representing the sizes of water molecules, hemoglobin, HIV virus, and red blood cells. Define a scale (e.g., 1 cm = 1 nanometer) and ask students to calculate the required size for each component in the model. This reinforces the magnitude difference.

Discussion Questions

  • Why is it important to understand the relative sizes of biological components?
  • How does the video help you visualize the size differences between molecules, proteins, viruses, and cells?
  • What are some implications of the relative size differences for the functioning of cells?

Skills Developed

  • Scientific Visualization
  • Data Interpretation
  • Analytical Thinking

Multiple Choice Questions

Question 1:

What unit of measurement is one billionth of a meter?

Correct Answer: Nanometer

Question 2:

Approximately how wide is a water molecule?

Correct Answer: 0.275 nanometers

Question 3:

Which of the following is the largest?

Correct Answer: Red Blood Cell

Question 4:

What is the approximate diameter of the HIV virus?

Correct Answer: 120 nanometers

Question 5:

Which cell is infected by HIV?

Correct Answer: T-cell

Question 6:

Which of the following contains roughly 280 million hemoglobin molecules?

Correct Answer: Red Blood Cell

Question 7:

How many nanometers are in a micrometer?

Correct Answer: 1,000

Question 8:

If you were to compare a red blood cell to a human hair, the width of the human hair would be about:

Correct Answer: The width of the screen

Question 9:

What instrument is used to see red blood cells and T-cells in the video?

Correct Answer: Electron microscope

Question 10:

Proteins are composed of

Correct Answer: amino acids

Fill in the Blank Questions

Question 1:

A __________ is one billionth of a meter.

Correct Answer: nanometer

Question 2:

The diameter of hemoglobin is approximately _____ nanometers.

Correct Answer: 5

Question 3:

The HIV virus infects __________ cells.

Correct Answer: T

Question 4:

Red blood cells are measured in __________ , which are millionths of a meter.

Correct Answer: micrometers

Question 5:

Each red blood cell contains approximately 280 million molecules of __________.

Correct Answer: hemoglobin

Question 6:

A water molecule is comprised of oxygen and _____ molecules.

Correct Answer: hydrogen

Question 7:

The video contrasts molecular, viral, and ________ scale.

Correct Answer: cellular

Question 8:

Hemoglobin's main function is to bind and transport _______.

Correct Answer: oxygen

Question 9:

The structure of DNA determines the structure of __________.

Correct Answer: proteins

Question 10:

A virus uses a cell's __________ to reproduce itself.

Correct Answer: machinery

Educational Standards

B.LS1.1:Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. B.LS1.2:Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

Teaching Materials

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