NOVA: Life Science Workbook

LIFE SCIENCE WORKBOOK

Core camp activity manual

NOVA CAMP Grade Level

6

7

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Copyright Š2020 by NOVA

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ISBN: 978-0-447-49429-5 Printed in the United States of America

First Edition 1 3 5 7 9 10 8 6 4 2

Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . .

4

MOLECULES. . . . . . . . . . . . . . . . . . . . . . . . .

8

. . . .

9 10 11 11

ACTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . .

10 10 12

How to write a chemical formula. .

DNA. . . . . . . . . . . . . . . . . . . . . . . .

Mutations. . . . . . . . . . . . . . . . . . . .

Human Genome. . . . . . . . . . . . . . .

. . . .

. . . .

Extracting DNA from a strawberry . . .

Instructions. . . . . . . . . . . . . . . . . . . . .

Glossary/Index . . . . . . . . . . . . . . . . . . . . . .

16

Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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S LIFE

SCIENCE E Carbon, because of its ability to combine in many ways with itself and o ther elements, has a central role in the chemistry of living organisms.

MOLECULES

Learning the chemistry of living things

This is the carbon molecule. Carbon’s abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth, enables it to serve as a common element for all known life.

C

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Additionally, living organisms are commonly comprised of hydrogen, nitrogen, oxygen and phosphorous.

When combined, they form most organic compounds we see all around us. For example: Water!

Water is made out of two hydrogen molecules and one oxygen molecule.

How to Write a Chemical Formula Every compound contains a specific ratio of elements. A CHEMICAL FORMULA is sort of like the compound’s recipe-it describes the ingredients and their quantities. In a chemical formula, each element is writ ten using its chemical symbol, which is a one or two letter symbol, with a subscript beneath the symbol defining the number of atoms.

EXAMPLE: Sugar contains 12 carbon, 22 hydrogen, and 11 oxygen atoms.

So the chemical formula is C12H22O11.

Life Science

9

DNA

The blueprint of life Living organisms have many different kinds of molecules, including small one, such as water and salt, and very large ones, such as carbohydrates, fat, proteins and DNA. All living organism contain DNA, also known as deoxyribonucleic acid. DNA is a long molecule found in the nucleus of a cell. The DNA contains the genetic blueprint (code) for how an organism looks and functions.

Traits such as hair or eye color get passed down from parent to offspring through DNA (strands of genetic material that store hereditary information).

DNA is tightly coiled around protein molecules to form chromosomes.

Think of DNA as a zipper. During cell replication, the DNA is unzipped.

Each side of the zipper is later paired up with a new complementary zipper half that is identical to the other

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missing side of the zipper. The result is two new identical zippers. Each complete zipper contains half of an old zipper and half of a new zipper.

Complementary nitrogen bases comprise the teeth of the zipper.

The complementary nitrogen bases fit together, so complementary base pairs always go together. There are four types of nitrogen bases: ADENINE, THYMINE, CYTOSINE, and GUANINE, represented by the letters A, T, C, and G. The order of these letters (nitrogen bases) is the “language� that tells a cell how to build an organism: AGGCATCGAATCG... etc., for billions of letters!

The A on one strand always pairs with the T on another, and the C always pairs with the G, which means there are always equal amounts of A and T, and equal amounts of C and G.

A Here’s a mnemonic to easily remember base pairing:

T

Adenine + Thymine

A Trait Could Grow.

C

G

Cytosine + Guanine

Mutations

The Human Genome

Sometimes mistakes are made when DNA is replicated. These mistakes are called MUTATIONS, and they can be caused by UV light, chemicals, and X-rays, among other things. Some mutations can cause an organism to die. Many are too small to make a difference in survival. Every once in a while, mutations can create traits that can help the organism survive. Genetic mutations are one of the ways organisms evolve.

Humans have thousands of genes.

All of these genes are located on our chromosomes, and together all the genes make up what is called the human GENOME. Scientists have been working for a long time to map the location of each gene on our chromosomes. This project is called the HUMAN GENOME PROJECT. Scientists are trying to map the location of genetic diseases in order to help prevent and better understand them.

ROSALIND FRANKLIN was the first person to discover DNA’s double helix shape. However, a pair of two male scientists were attributed with the discovery after using her data without her consent.

Life Science

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ACTIVITY

Extracting DNA from a strawberry

Materials

□ □ □ □ □ □ □ □ □ □ □ □ □ □

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Rubbing alcohol Measuring cup Measuring spoons Salt Water Dish-washing liquid soap Glass bowl Cheesecloth Funnel Tall drinking glass Two large strawberries Resealable sandwich bag Small glass jar Bamboo skewer

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Take it out of orbit You can try using this DNA extraction activity on lots of other things. Grab some oatmeal or kiwis from the NOVA basket and try it again

Preparation

□ □

□

□

Chill the rubbing alcohol in the freezer.

(You’ll need it later.)

Mix one half teaspoon of salt, one third cup of water and one tablespoon of dish-washing liquid in a glass or small bowl. Set the mixture aside. This is your extraction liquid.

Completely line the funnel with cheesecloth.

Insert the funnel tube into the tall drinking glass (not the glass with the extraction liquid in it).

Discard the green tops from the strawberries.

Life Science

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ACTIVITY

Instructions

1. Put the strawberries into a resealable plastic sandwich bag and push out all of the extra air. Seal the bag tightly.

2. With your fingers, squeeze and smash the strawberries for two minutes.

How do the smashed strawberries look?

3. Add three tablespoons of the extraction liquid you prepared to the strawberries in the bag.

Push out all of the extra air and reseal the bag. How do you think the detergent and salt will affect the strawberry cells?

4. Squeeze the strawberry mixture with your fingers for one minute. How do the smashed strawberries look now?

5. Pour the strawberry mixture from the bag into the funnel. Let it drip through the cheesecloth and into the tall glass until there is very little liquid left in the funnel (only wet pulp remains). How does the filtered strawberry liquid look?

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6. Pour the filtered strawberry liquid from the tall glass into the small glass jar so that the jar is one quarter full.

7. Measure out one half cup of cold rubbing alcohol.

8. Tilt the jar and very slowly pour the alcohol down its side. Pour until the alcohol has formed approximately a one-inch-deep layer on top of the strawberry liquid. You may not need all of the one half cup of alcohol to form the one-inch layer. Do not let the strawberry liquid and alcohol mix.

9. Study the mixture inside of the jar. The strawberry DNA will appear as gooey clear/white stringy stuff. Do you see anything in the jar that might be strawberry DNA? If so, where in the jar is it?

10. Dip the bamboo skewer into the jar where the strawberry liquid and alcohol layers meet and then pull up the skewer. Did you see anything stick to the skewer that might be DNA? Can you spool any DNA onto the skewer?

11. Were you able to see DNA? In which layer was the DNA located?

Life Science

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GLOSSARY

A

C

E

Atom

Cells

Elements

An atom is the smallest constituent unit of ordinary matter that constitutes a chemical element.

Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. They are so small that accurately predicting their behavior using classical physics – as if they were billiard balls, for example – is not possible. This is due to quantum effects. Current atomic models now use quantum principles to better explain and predict this behavior.

The cell (from Latin cella, meaning “small room”) is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. Cells are often called the “building blocks of life”. The study of cells is called cell biology, cellular biology, or cytology. Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Most plant and animal cells are only visible under a microscope, with dimensions between 1 and 100 micrometers.

A chemical element is a species of atom having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z). For example, the atomic number of oxygen is 8, so the element oxygen describes all atoms which have 8 protons.

B Base Bases are substances that, in aqueous solution, release hydroxide (OH−) ions, are slippery to the touch, can taste bitter if an alkali, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor or contain completely or partially displaceable OH− ions. Examples of bases are the hydroxides of the alkali metals and the alkaline earth metals (NaOH, Ca(OH)2, etc.—see alkali hydroxide and alkaline earth hydroxide).

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Compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. Two atoms of the same element bonded in a molecule do not form a chemical compound, since this would require two different elements.

One hundred eighteen elements have been identified: the first 94 occur naturally on Earth, and the remaining 24 are synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant element (by mass) making up Earth, while oxygen is the most common element in the Earth’s crust.

O

P

Organisms

Protein

UV Light

An organism is any individual entity that embodies the properties of life. It is a synonym for “life form�. Organisms are classified into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli.

Humans, squids, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development.

Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells, and organisms, and transporting molecules from one location to another.

Ultraviolet (UV) is electromagnetic radiation with wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation is present in sunlight, and contributes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercuryvapor lamps, tanning lamps, and black lights.

Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific three-dimensional structure that determines its activity.

U

X X-Ray X-rays are types of electromagnetic radiation probably most well-known for their ability to see through a person’s skin and reveal images of the bones beneath it. Advances in technology have led to more powerful and focused X-ray beams as well as ever greater applications of these light waves, from imaging extremely small biological cells and structural components of materials like cement to killing cancer cells.

Glossary

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NOTES

Write notes here

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Notes

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