MS-LS3-1: Genetic Mutations and Effects

MS-LS3-1
Genetic Mutations and Effects

Middle School

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Learning Objectives

• Define heredity and how genes on chromosomes are passed from parents to offspring.

• Model how genes code for proteins that determine an organism's specific traits.

• Explain how mutations can alter the structure and function of a protein.

• Analyze how altered proteins can have harmful, beneficial, or neutral effects.

Key Vocabulary

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Heredity

Heredity is the process by which physical and mental traits are passed from parents to their children.

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Chromosome

A chromosome is a structure found in the nucleus of a cell, made of tightly coiled DNA.

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Gene

A gene is a specific segment of DNA that provides instructions for building a particular protein.

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Protein Function

The function of a protein, which is its specific job, is determined by its unique shape.

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Gene Variant (Allele)

A gene variant, also known as an allele, is a different version or form of a gene.

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DNA

DNA is the molecule that carries the genetic instructions for the development, functioning, and reproduction of organisms.

Key Vocabulary

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Mutation

A mutation is a permanent alteration in the DNA sequence that makes up a single gene.

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Adaptation

An adaptation is a beneficial trait or characteristic that helps an organism survive in its environment.

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Meiosis

Meiosis is a special type of cell division that results in the creation of sperm and egg cells.

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The Basics of Heredity

• Heredity is the passing of traits from parents to their offspring.

• ​Humans use heredity for selective breeding in plants and animals.

• Gregor Mendel studied pea plants to understand how traits are inherited.

• His work laid the foundation for the modern science of genetics.

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Multiple Choice

What is the definition of heredity?

• The passing of traits from parents to their offspring.

• The study of how plants and animals interact in nature.

• The process of animals learning new behaviors.

• The science of classifying organisms into different groups.

Multiple Choice

What was the primary contribution of Gregor Mendel's work with pea plants?

• It proved that all pea plants are identical.

• It was the first time selective breeding was used.

• It laid the foundation for the modern science of genetics.

• It helped farmers grow different kinds of vegetables.

Multiple Choice

Choose the correct statement with respect to selective breeding.

• Choosing parens with specific traits to develop desired characteristics in the offsprings.

• Creating new traits that did not exist in the parent organisms.

• Preventing any traits from being passed from parents to offspring that are desired.

• All of these are correct.

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Chromosomes and Cell Division

Body Cells

• Scientists discovered structures called chromosomes in the nucleus of every cell.

• Before a typical body cell divides, it first makes a full copy of its chromosomes.

• This process ensures that each new cell gets a complete set of genetic information.

Sex Cells

• Walter S. Sutton observed that sex cells are created through a process called meiosis.

• Unlike body cells, sex cells contain only one set of chromosomes, not two.

• Sutton realized that these chromosomes carried Mendel's 'factors' for inherited traits.

Multiple Choice

What is the main reason a body cell makes a full copy of its chromosomes before it divides?

• To ensure each new cell gets a complete set of genetic information.

• To create sex cells with half the genetic information.

• To make the original cell grow larger.

• To remove the chromosomes from the nucleus.

Multiple Choice

What is the key difference in the genetic makeup between body cells and sex cells?

• Body cells contain two sets of chromosomes, while sex cells contain only one.

• Sex cells are found in the nucleus, while body cells are not.

• Body cells are created by meiosis, while sex cells are not.

• Sex cells have more chromosomes than body cells.

Multiple Choice

Based on Walter S. Sutton's realization, what is the primary role of the single set of chromosomes found in sex cells?

• They carry the inherited traits from parents to their offspring.

• They provide the energy needed for cell division.

• They are responsible for making a cell grow larger.

• They ensure body cells and sex cells have the same traits.

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The Structure of Deoxyribonucleic Acid (DNA)

• DNA, or deoxyribonucleic acid, carries the genetic information found within our chromosomes.

• Scientists Watson and Crick, using data from Rosalind Franklin, discovered its structure.

• The DNA molecule has a double helix shape, similar to a twisted ladder.

• Its rungs have four bases: Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

• The rungs are surrounded by the sugar phosphate molecules.

Multiple Choice

What is the term for the twisted ladder shape of DNA, a structure discovered by Watson and Crick?

• Double helix

• Single strand

• Protein chain

• Cell nucleus

Multiple Choice

How are the different chemical parts of a DNA molecule organized?

• Sugar and phosphate molecules form the sides, and base pairs form the rungs.

• Sugar and base pairs form the sides, and phosphate molecules form the rungs.

• Base pairs form the sides, and sugar and phosphate molecules form the rungs.

• The molecules are arranged in a random, unpatterned structure.

Multiple Choice

If one side of a DNA ladder has the base sequence A-G-T, what must be the sequence of the bases on the other side?

• T-C-A

• A-G-T

• C-T-G

• G-A-C

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From Genes to Traits

• A chromosome is a long, tightly coiled molecule of DNA.

• Specific sections of this DNA molecule are known as genes.

• Each gene provides the instructions for making a specific protein.

• These proteins build structures and determine your physical traits.

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Multiple Choice

What is the primary function of a gene?

• To provide the instructions for making a specific protein.

• To coil together to form a DNA molecule.

• To directly create an organism's physical traits.

• To break down proteins into smaller units.

Multiple Choice

What is the relationship between genes, proteins, and physical traits?

• Genes provide instructions for making proteins, which then determine physical traits.

• Proteins provide the instructions for making genes, which then determine physical traits.

• Physical traits create proteins, which then provide instructions for making genes.

• Genes are made of proteins, which are found on the chromosome.

Multiple Choice

If the section of a DNA molecule that makes up a specific gene were changed, what would be the most likely consequence?

• The protein associated with that gene may be formed incorrectly, affecting a physical trait.

• The entire chromosome will be deleted from the organism's DNA.

• The organism will immediately develop an entirely new, unrelated trait.

• There will be no effect on the organism because proteins can fix any errors.

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How a Protein's Shape Determines Its Job

Transporting Oxygen

• Hemoglobin proteins in red blood cells have a specific, folded three-dimensional shape that allows them to function correctly.

• This unique shape allows them to effectively bind with and transport oxygen from the lungs to your tissues.

• If the hemoglobin's shape alters, its ability to carry the right amount of oxygen is greatly reduced.

Digesting Food

• Digestive enzymes are proteins that work to break down large food molecules into much smaller pieces.

• Their shape works like a lock that will only fit a specific food molecule, which acts as the key.

• A change in the enzyme’s shape means it can no longer connect with and digest its target molecule.

Multiple Choice

What is the most important factor that determines a protein's specific job or function?

• Its three-dimensional shape

• The cell it is located in

• The amount of energy it contains

• The temperature of the body

Multiple Choice

What do hemoglobin and digestive enzymes have in common regarding how they function?

• They both transport oxygen from the lungs to tissues.

• They both break down large food molecules into smaller pieces.

• They both bind to specific molecules to perform their tasks.

• They are both located inside of red blood cells.

Multiple Choice

Based on the information about hemoglobin and enzymes, what is the most likely consequence if any protein's specific three-dimensional shape is altered?

• The protein's function would be greatly reduced or completely lost.

• The protein would start performing a different function.

• The protein would become more efficient at its original job.

• The protein would be unaffected and continue to work normally.

Mutations and Their Effects

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Beneficial Mutations

• ​These mutations can create new traits that help an organism survive.

• ​A new adaptation can give the organism a significant survival advantage.

• ​A penguin's wings adapted for swimming is a well-known example.

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Harmful Mutations

• ​These mutations can cause diseases and reduce an organism's fitness level.

• ​They may change a protein’s structure, leading to serious health problems.

• ​Sickle cell anemia is caused by a mutation in a gene.

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Neutral Mutations

• ​These DNA changes have no observable effect on the organism's traits, e.g., Heterochromia.

• ​They do not provide any advantage or disadvantage to the organism.

• ​The protein’s function remains the same despite the DNA sequence change.

Multiple Choice

Which statement best describes the effects of mutations?

• They can be beneficial, harmful, or have no effect on an organism.

• They always provide a survival advantage to an organism.

• They always cause diseases or reduce an organism's fitness.

• They only change DNA and never affect an organism's traits.

Multiple Choice

How can a mutation in a gene lead to a harmful condition like sickle cell anemia?

• It can alter the structure of a protein, leading to health problems.

• It creates a new trait that helps an organism swim better.

• It has no observable effect on the organism's traits or survival.

• It gives the organism a significant advantage in its environment.

Multiple Choice

If a mutation changes a DNA sequence but the protein it codes for continues to function normally, how would this mutation be classified and why?

• Neutral, because it does not impact the organism's ability to survive.

• Beneficial, because it provides a new adaptation for survival.

• Harmful, because it reduces the organism's fitness level.

• Harmful, because any change in a protein's structure is a disease.

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Adaptations and Changing Environments

• Adaptations develop slowly over many generations, taking a very long time.

• They cannot keep pace with rapid or sudden changes in the environment.

• Adélie penguins are adapted to sea ice, where their main food, krill, lives.

• As warming melts the ice, krill decline, causing the penguin population to shrink.

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Multiple Choice

Which statement best describes the process of adaptation?

• Adaptations develop slowly over many generations.

• Adaptations occur quickly within an animal's lifetime.

• Adaptations are rapid responses to sudden environmental changes.

• Adaptations only affect an animal's behavior, not its body.

Multiple Choice

What is the relationship between the speed of adaptation and a rapidly changing environment?

• Slowly developing adaptations may not be able to keep up with rapid changes.

• Rapid environmental changes cause adaptations to develop more quickly.

• Adaptations are not affected by the speed of environmental changes.

• Only animals with rapid adaptations can cause environmental changes.

Multiple Choice

Based on the relationship between Adélie penguins and their environment, what is the most likely reason their population is shrinking?

• The penguins' main food source is declining as its sea ice habitat melts.

• The penguins are unable to adapt to the colder water temperatures.

• The penguins are evolving too quickly for the environment to support them.

• The penguins have adapted to eat krill, which are becoming too numerous.

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Common Misconceptions

Misconception	Correction
Traits are inherited only from one parent.	An organism inherits a set of genes and chromosomes from each parent.
All mutations are harmful.	Mutations can be harmful, neutral, or beneficial.
Individual organisms can adapt during their lifetime.	Populations adapt over many generations, not individual organisms.

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Summary

• Genes on chromosomes code for proteins that determine an organism's traits.

• A protein's function depends on its specific 3D structure, determined by the gene.

• Mutations are changes to genes that can alter a protein’s structure and function.

• The effects of a mutation can be beneficial, harmful, or neutral.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1 (Not confident)

• 2 (A little confident)

• 3 (Mostly confident)

• 4 (Very confident)