heredity. heredity benchmarks iii.3.ms.1 - describe how the characteristics of living things are...

HeredityHeredity

Heredity BenchmarksHeredity Benchmarks

III.3.MS.1 - III.3.MS.1 - Describe how the Describe how the characteristics of living things are passed characteristics of living things are passed on from generation to generation.on from generation to generation.

III.3.MS.2 – III.3.MS.2 – Describe how heredity and Describe how heredity and environment may influence/determine environment may influence/determine characteristics of an organism.characteristics of an organism.

Breaking down the BenchmarksBreaking down the Benchmarks

III.3.MS.1 - III.3.MS.1 - Describe how the characteristics of Describe how the characteristics of living things are passed on from generation to living things are passed on from generation to generation.generation. ChromosomeChromosome GeneGene Hereditary informationHereditary information Common traits controlled by a single gene pair. Common traits controlled by a single gene pair.

• Wrinkled or smooth seeds in a pea plantWrinkled or smooth seeds in a pea plant• Color of horse hairColor of horse hair• Human traits such as tongue rollingHuman traits such as tongue rolling

Breaking down the BenchmarksBreaking down the Benchmarks

III.3.MS.2 – III.3.MS.2 – Describe how heredity and Describe how heredity and environment may influence/determine environment may influence/determine characteristics of an organism.characteristics of an organism.

Inherited TraitsInherited Traits Acquired TraitsAcquired Traits

Heredity BasicsHeredity Basics

HeredityHeredity is the passing of traits from is the passing of traits from parent to offspring (children). parent to offspring (children).

The The traitstraits are controlled by are controlled by genesgenes. . The genes are the chemical code found The genes are the chemical code found

in helical (spiral-shaped) molecules of in helical (spiral-shaped) molecules of deoxyribonucleic acid (deoxyribonucleic acid (DNADNA), which are ), which are packed away inside the cells of all packed away inside the cells of all living things.living things.

Inherited TraitsInherited Traits

Inherited traitsInherited traits are those present in the are those present in the genetic makeup of an organism that have genetic makeup of an organism that have been passed on from one generation to the been passed on from one generation to the next. These may include:next. These may include:• Eye color Eye color • Left- or right-handedness Left- or right-handedness • Butterfly wing patterns Butterfly wing patterns • Animal fur colorAnimal fur color

Acquired TraitsAcquired Traits

Acquired traitsAcquired traits develop or occur after an develop or occur after an organism is born. organism is born.

They occur in response to environmental They occur in response to environmental factors such as stress, overall health, factors such as stress, overall health, nutritional choices, chemical exposure, and nutritional choices, chemical exposure, and changes in land use and are not a result of changes in land use and are not a result of the organism’s genetic code. the organism’s genetic code.

These include:These include:• Straightened teeth from wearing braces Straightened teeth from wearing braces • The loss of a limb in an accident The loss of a limb in an accident

ChromosomeChromosome

There are several lengths of DNA in a There are several lengths of DNA in a cell’s nucleus. cell’s nucleus.

Each one is called a Each one is called a chromosomechromosome. .

ChromosomeChromosome

There are two copies of each There are two copies of each chromosome in every cell of an chromosome in every cell of an organism. organism.

One set of chromosomes comes from One set of chromosomes comes from the mother and one comes from the the mother and one comes from the father.father.

GeneGene

A A genegene is one area of a chromosome is one area of a chromosome that has the instructions to make one that has the instructions to make one protein. protein.

DNA works by telling a cell how to DNA works by telling a cell how to make the many different proteins that make the many different proteins that your cells need to work. your cells need to work.

GeneGene

Each DNA molecule forms a threadlike Each DNA molecule forms a threadlike structure, or gene. Genes then in turn structure, or gene. Genes then in turn form chromosomes. form chromosomes.

There are two copies of each There are two copies of each chromosome--one from the father and chromosome--one from the father and one from the mother.one from the mother.

Hereditary InformationHereditary Information

We are all familiar with the idea that We are all familiar with the idea that traits can be inherited from parent to traits can be inherited from parent to child. child. For example, think of dogs: a purebred For example, think of dogs: a purebred

pair of Great Danes would never produce pair of Great Danes would never produce puppies with the tiny, short-legged puppies with the tiny, short-legged characteristics of a dachshund -- but what characteristics of a dachshund -- but what does that really mean?does that really mean?


Traits are inherited because discrete units Traits are inherited because discrete units called genes are passed from parent to child called genes are passed from parent to child when the child is conceived. when the child is conceived.

These genes are a unique blueprint for an These genes are a unique blueprint for an individual organism, providing all the individual organism, providing all the biological information needed for its pre-birth biological information needed for its pre-birth development and life, as well as for the development and life, as well as for the characteristics that make that individual characteristics that make that individual unique.unique.


Just as in an engine, Just as in an engine, where the removal of where the removal of one part can disrupt one part can disrupt the entire engine's the entire engine's ability to run, so the ability to run, so the removal of the removal of the influence of one gene influence of one gene can have a severe can have a severe effect on the life of an effect on the life of an organism.organism.

Gregor MendelGregor Mendel

In the 1800s In the 1800s Gregor Gregor MendelMendel an Austrian an Austrian monk studied how monk studied how traits were passed traits were passed from one generation from one generation to the next. to the next.

He experimented He experimented with plants (green with plants (green peas). peas).

How do we know genes exist?How do we know genes exist?

He kept careful track of the traits displayed by He kept careful track of the traits displayed by the pea plants produced by cross-fertilization, the pea plants produced by cross-fertilization, discovering that traits of the parent plants were discovering that traits of the parent plants were inherited by the progeny plants in specific inherited by the progeny plants in specific patterns. patterns.

Gregor MendelGregor Mendel Examination of the trait Examination of the trait

inheritance patterns of inheritance patterns of the pea plants the pea plants suggested to Mendel suggested to Mendel that each trait resulted that each trait resulted from two units of from two units of inheritance. inheritance.

Mendel proposed that Mendel proposed that one unit came from one unit came from each parent plant. each parent plant.

We now call these units We now call these units genesgenes..


The study of how The study of how different forms of a different forms of a gene affect gene affect generations of generations of offspring is offspring is geneticsgenetics. .

That is why Mendel That is why Mendel is called the is called the father father of geneticsof genetics..


Mendel also learned that a particular trait Mendel also learned that a particular trait could have several varieties that were could have several varieties that were produced by different versions of the "units produced by different versions of the "units of inheritance" or genes.of inheritance" or genes.

For example, the pea plant flower color could be For example, the pea plant flower color could be pink or white. pink or white.

We use the term We use the term alleleallele to designate a version to designate a version of a gene.of a gene.


Mendel's experiments showed that Mendel's experiments showed that some alleles appeared to be some alleles appeared to be dominantdominant over others. over others. For example, if a pea plant inherits one For example, if a pea plant inherits one

pink flower color gene and one white pink flower color gene and one white flower color gene, the resulting flowers will flower color gene, the resulting flowers will all be pink -- just as if the plant had two all be pink -- just as if the plant had two pink flower color genes. (Pink is the pink flower color genes. (Pink is the dominant flower color in peas; white is the dominant flower color in peas; white is the recessive flower color.)recessive flower color.)


If a gene was not dominant then it If a gene was not dominant then it could be could be recessiverecessive or even a blend. or even a blend.

Genotype/PhenotypeGenotype/Phenotype

Two other concepts that are useful in Two other concepts that are useful in understanding genetics are…understanding genetics are…

phenotype phenotype

andand genotype.genotype.


The The phenotypephenotype of an organism is its of an organism is its observable traits, and these traits are observable traits, and these traits are produced by the organism's produced by the organism's genotypegenotype -- or genes -- for that trait. -- or genes -- for that trait. For example, the pea plant with one pink For example, the pea plant with one pink

and one white flower gene has the and one white flower gene has the genotype pink/white (one pink gene and genotype pink/white (one pink gene and one white gene) while its phenotype is one white gene) while its phenotype is pink (only pink flowers are observed).pink (only pink flowers are observed).


Again…in simpler terms…Again…in simpler terms…

GenotypeGenotype-What the gene says-What the gene says

PhenotypePhenotype-What you see-What you see

Homozygous/HeterozygousHomozygous/Heterozygous

Homozygous pairs of chromosomes have the Homozygous pairs of chromosomes have the same gene for a given trait. same gene for a given trait. For example, if the gene for brown eyes is B, then the For example, if the gene for brown eyes is B, then the

homozygous pair would be (BB).homozygous pair would be (BB).

Heterozygous pairs of chromosomes have Heterozygous pairs of chromosomes have different versions of a gene for a given trait. different versions of a gene for a given trait. For example, if the gene for brown eyes is B, and the For example, if the gene for brown eyes is B, and the

gene for blue eyes is b, then the heterozygous pair gene for blue eyes is b, then the heterozygous pair would be (Bb). would be (Bb).

Homozygous/HeterozygousHomozygous/Heterozygous

Homozygous gene pair-Homozygous gene pair- SameSame (BB) (bb)(BB) (bb)

Heterozygous gene pair-Heterozygous gene pair- DifferentDifferent (Bb)(Bb)

Punnet SquarePunnet Square

Inference and AnalysisInference and Analysis

Genetics is an elegant and indirect science, Genetics is an elegant and indirect science, but it is very powerful. In genetics, but it is very powerful. In genetics, inferenceinference plays a critical role. plays a critical role. Mendel's experiments led him to infer the Mendel's experiments led him to infer the

existence of genes, but he never actually saw existence of genes, but he never actually saw them. them.

Similarly, Similarly, analysisanalysis of mutations, or defects, of mutations, or defects, in genes help scientists infer normal gene in genes help scientists infer normal gene function.function.

Inference and AnalysisInference and Analysis

By seeing what happens to organisms By seeing what happens to organisms when the function of a gene is when the function of a gene is changed, scientists can make educated changed, scientists can make educated guesses regarding what the normal job guesses regarding what the normal job of the gene is in the cell. of the gene is in the cell.

What kinds of jobs do genes do?What kinds of jobs do genes do?

Genes are responsible for all the Genes are responsible for all the functions of the cell and are used functions of the cell and are used throughout the life of an organism.throughout the life of an organism.

How does Heredity affect You?How does Heredity affect You?

Imagine the phone ringing. Pick it up. Put it to Imagine the phone ringing. Pick it up. Put it to your ear. Notice which ear you are using. your ear. Notice which ear you are using.

Interlock your fingers. Notice which thumb is Interlock your fingers. Notice which thumb is placed on top. Pull your hands apart and repeat placed on top. Pull your hands apart and repeat the process in reverse order. Notice how the process in reverse order. Notice how difficult/awkward it is to have the opposite thumb difficult/awkward it is to have the opposite thumb on top. on top.

Cross and re-cross your arms. Notice which is Cross and re-cross your arms. Notice which is the dominant way you cross your arms. the dominant way you cross your arms.

What other traits have been passed What other traits have been passed on to you? on to you?

Handedness (right vs. left) Handedness (right vs. left) Eye color Eye color Rolling your tongue in a "U" shape Rolling your tongue in a "U" shape Free or attached ear lobes Free or attached ear lobes Widow’s peak ("V" hairline on forehead) Widow’s peak ("V" hairline on forehead) Hair on fingers between first and second Hair on fingers between first and second

knuckle knuckle Cleft chin Cleft chin

Let’s Chart It!Let’s Chart It!

Wow!! We have inherited a lot of different Wow!! We have inherited a lot of different traits. traits.

Let’s collect the data and record it in a Let’s collect the data and record it in a chart, so that we can better understand chart, so that we can better understand that our individual traits are a blend of our that our individual traits are a blend of our parents genetic information. parents genetic information.

heredity. heredity benchmarks iii.3.ms.1 - describe how the characteristics of living things are...

Documents