Inside Life SciencePLEASE HELP The Amazing World Inside a Human Cell

By Alisa Machalek and Emily Carlson

Posted June 29, 2011

Let's take a quick trip inside to see how cells carry out their major tasks.

Imagine you've shrunk down to 3 millionths of your normal size and are now about 0.5 micrometers tall—way

smaller than a dust mite or the width of a hair strand. At this scale, a medium-sized human cell looks as big as

a football field.

Nucleus

From your new perspective, the cell's somewhat spherical nucleus catches your

attention. It looks about 50 feet wide. Occupying up to 10 percent of the cell's

interior, the nucleus is the most prominent organelle, or cellular compartment. It

contains the cell's genetic material, DNA, which guides the making of billions of

protein molecules that participate in nearly every cellular process.

Membranes

The double membrane that bounds the nucleus flows into the ribosome-studded rough endoplasmic reticulum

(purple). Proteins are processed and lipids are manufactured in the smooth endoplasmic reticulum (blue) and

Golgi apparatus (green). Credit: Judith Stoffer, jStoffer Medical Illustration.

Encasing the cell is a membrane with special gates, channels and pumps that let in or

force out selected molecules. The membrane protects the cell's internal

environment—a thick brew called the cytosol made of salts, nutrients and proteins

Questions:
Cell Structure and Functions Activity Worksheet

Instructions: Read the article The Amazing World Inside a Human Cell, and then answer the following questions.

Background Information

Read the introductory paragraphs, and answer the following questions in your own words. Use complete sentences, and provide textual evidence to support your answers.

How many cells does the human body have, and how many different types are there?

What does the author want readers to imagine as they begin reading? Why?

Text-dependent Questions

Use quotes from the text or summarize the text in your own words to answer the following questions or prompts. Use complete sentences, and provide textual evidence to support your answers. Note: The first one has been completed for you.

What material does the nucleus contain? What is the purpose of this material?

The nucleus contains "the cell's genetic material, DNA." DNA makes protein molecules to help with almost every cellular process.

Using evidence from the text, describe the purpose of the cell membrane.

How do the two types of endoplasmic reticulum differ?

Using evidence from the text, describe the purpose of the Golgi complex.

Based on this excerpt, summarize the job of mitochondria.

Excerpt: "About the size of pickup trucks from where you're floating, the organelles called mitochondria convert energy from your food into adenosine triphosphate, or ATP, to power biochemical reactions. A typical cell burns through 1 billion molecules of ATP every 1 to 2 minutes."

Fact vs. Opinion

Read each statement and decide if it is a fact (can be proven with evidence) or an opinion (personal belief).

Different cell types also have special duties, like building skin or bone, pumping out hormones, or making antibodies.

Animal cells are more interesting than plant cells.

Proteins are processed and lipids are manufactured in the smooth endoplasmic reticulum and Golgi apparatus.

Structure and Purpose

Use the text and visuals to answer the following questions. Use complete sentences, and provide textual evidence to support your answers.

How do the authors structure (arrange) the article?

What is the purpose of the subheadings?

What is the purpose of the images and captions in the article?

What is the purpose of the article?

How does the final paragraph relate to the main idea of the article?