EQ: Where does an organism gets its unique characteristics?

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Fri. 3/1/19 NB PG. 2

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1. Turn to page 2 in your

notebook

2. Make a quick list of

the characteristics you

have of the choices on

the left.

TREE

OBJECTIVE:

Find the most and least common combination of three traits in our class!

PTC paper: In 1931, a chemist named Arthur Fox was pouring some powdered PTC into a bottle. When some of the powder accidentally blew into the air, a colleague standing nearby complained that the dust tasted bitter. Fox tasted nothing at all.

▪ Although PTC is not found in nature, the ability to taste it correlates strongly with the ability to taste other bitter substances that do occur naturally, many of which are toxins.

▪ Plants produce a variety of toxic compounds in order to protect themselves from being eaten. The ability to discern bitter tastes evolved as a mechanism to prevent early humans from eating poisonous plants. Humans have about 30 genes that code for bitter taste receptors. Each receptor can interact with several compounds, allowing people to taste a wide variety of bitter substances.

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1. In your notebook:

2. Ask your partner to identify what characteristic they observe on you.

3. PTC paper will be given to you when you are done with the table and it is written in your notebook.

4. CUT OUT your leaf and write down your initials.

BOYS use dark green leaves and GIRLS use light green leaves.

5. Walk over to the tree and follow the branches. SEE INSTRUCTOR.

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Trait YES NO

PTC PAPER

Attached earlobes

Tongue roller

Textbook page 263-266:

▪ Genetics

▪ Fertilization

▪ True-breeding

▪ Trait

▪ Hybrid

▪ Gene

▪ Allele

▪ Segregation

▪ Gamete

DUE BY Tomorow

Textbook page 267-269

•Probability

•Punnett square

•Homozygous

•Heterozygous

•Phenotype

•Genotype

For the following terms:- write & underline the term-define it-draw and color a picture that represents the term and definition, combined

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EQ: How are different

forms of a gene

distributed to

offspring?

NB pg. 5

Title: "Mendel"

1. What did Gregor

Mendel discover in

the results of his first

experiment?

2. What did Mendel

discover in his

second experiment?

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GREGOR MENDEL

Gregor Mendel as a Austrian monk who was born in 1822. He spent a great deal of time in the monastery garden where he was able to carry out experiments into inheritance. He chose to work with peas, which are small and easy to grow, and produce large number of offspring.

▪ Peas are a “model system.”

▪ •Started with “true breeding” plants

▪ •Trait: specific characteristic (e.g., seed color, plant height) of an individual

▪ •Hybrid: created from cross of true-breeding individuals

Mendel’s different groups of true-breeding plants would produce the same set of traits in each generation.

To figure out how traits were inherited from one generation to the next, Mendel crossed individuals from his true-breeding strains to produce hybrids.

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▪ Mendel did not have our modern understanding of genes and alleles, he did understand that male parts of a flower produce male sex cells (sperm) and that female parts of a flower produce female sex cells (eggs), and that these cells join in the process fertilization.

▪ While offspring are produced from only one parent, each offspring forms from the fusion of male and female cells.

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3 of 9 READ

▪ Mendel removed reproductive structuresfrom pea flowers so that only one set remained.

▪ Mendel was looking at seven characteristics in pea plants. His goal was to look for patterns in the traits across generations.

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▪ Genes: passed from one generation to the next; determine an individual’s characteristics

▪ Alleles: the different forms of a gene

With your partner, complete the following sentences:

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Characteristics such as seed color

are determined by ___________ .

Yellow and green seed colors are

determined by _______ .

The allele for yellow seeds is _______

to the allele for green.

WORD BANK:

Alleles

Dominant

Genes

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PRINCIPLE OF DOMINANCE

▪ Some alleles are dominant, some recessive.

▪ An organism with at least one dominant allele will exhibit that trait.

▪ An organism with a recessive allele will exhibit the trait only in the absence of a dominant allele.

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MENDEL’S F1 CROSSES

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When Mendel

crossed plants with

contrasting traits, the

hybrid offspring

showed traits of

only one parent.

7 of 9 READ

▪ Segregation: separation of alleles during gamete formation

Why didn’t the allele for yellow color show in the F1 generation?

Was the recessive allele for yellow color lost in the F1 generation? How do you know?

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THE FORMATION OF GAMETES

▪ during formation of gametes, or sex cells, alleles segregate from each other so that each gamete carries only a single copy of (one allele for) each gene.

Where are the eggs and sperm?

Where does fertilization occur?

SUMMARY: 15

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NB Pg. 7

EQ: How can we use

probability to predict

traits?

Video Questions:

1. How many chromosomes

do we receive from EACH

parent?

2. What are Punnett squares

used for?

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▪ In your notebook write the table below:

1. You and your partner will take turns flipping a coin. 10 times each.

2. Tally mark (/) the number of times out of ten, that the coin lands on either heads up or tails up on your table/ counter.

Heads Tails

Me

Partner

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PROBABILITY AND HEREDITY▪Probability: the likelihood an event will

occur. If you flip a coin, what is the

▪ probability of either outcome: ________

▪ Three coin tosses? _____________

▪ Each flip is an independent event.

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GENOTYPE AND PHENOTYPE-DRAW A T-CHART

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Two organisms may share the same __________

but have different ______________

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HETEROZYGOUS AND HOMOZYGOUS

▪ Homozygous: has two identical alleles for a gene

▪ Heterozygous: has two different alleles for a gene

▪ Which are:

Homozygous? _______ heterozygous? ______

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1 2 3 4

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6 of 8 READ

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The Two-

Factor Cross

7 of 8 READ

SUMMARY OF MENDEL’S PRINCIPLES▪ Inheritance is determined by units called __________ ,

which are passed from parents to offspring.

▪Where more than one form of a gene for a single trait exists, some alleles may be ______________ and others ______________ .

▪Each adult has two copies of each gene—one from each parent. These genes ____________ from each other when gametes are formed.

▪Alleles for different genes usually segregate ____________ of each other.

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WORD BANK:

Dominant

Genes

Recessive

Independently

segregate

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1. You will work with your

partner next to you.

2. Partner 1 will do 1 and

Partner 2 will do 2 and 4

3. CHECK each others

answers.

4. Be prepared to share

out.

If you do not finish

Spongebob WS, it will be

HW

EQ: How does the environment play a role in how genes determine traits?

Feather color in parakeets is controlled by multiple genes

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▪Describe some of the exceptions to Mendel’s principles.

▪Explain the environment’s role in the way genes determine traits.

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INCOMPLETE DOMINANCE

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▪ Some alleles are neither dominant nor recessive.

▪ Incomplete dominance: One allele is not completely dominant over another.

▪ The phenotypes for both alleles are clearly expressed.

▪ Examples: chicken feather color, human protein controlling blood cholesterol levels

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MULTIPLE ALLELES

▪ Many genes exist in more than two forms.

▪ Examples: human blood types, fur color in rabbits

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POLYGENIC TRAITS

▪ •Many traits are produced by the interaction of several genes.

▪ • Examples: eye color in fruit flies, coat color in dogs

▪ • Traits typically show a wide variety of phenotypes.

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▪ Environmental conditions can affect gene expression and influence genetically determined traits.

▪ The __________ of an organism is only partly

determined by its ___________________

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