© Fall 2005, Pflugerville ISD, 7th Grade Homeroom Warm Up 2-28-14 List the 4 major layers of the Earth from the hottest to the coolest. Also list at least

© Fall 2005, Pflugerville ISD, 7th Grade

Homeroom Warm Up2-28-14

List the 4 major layers of the Earth from the hottest to the coolest. Also list at least one fact about each layer.


Science Warm Up 2-28-14

Scientist theorize that the Atlantic Ocean is slowly increasing in width. Which is the best approximation of the rate at which lithospheric plates beneath the Atlantic Ocean are moving?

A. 2 millimeters per yearB. 2 centimeters per yearC. 2 meters per yearD. 2 kilometers per year


Vocabulary WordsYou should be able to define all of the following words

1. Genes2. Genotype3. Phenotype4. Chromosome5. Inherited Trait6. Recessive Trait7. Dominant Trait8. Heredity9. Homozygous10. Heterozygous


What is genetics?

• The scientific study of heredity


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Gregor Gregor MendelMendel

(1822-1884)(1822-1884)The Father The Father of Geneticsof Genetics


Gregor Johann MendelGregor Johann MendelAustrian monkAustrian monkStudied the Studied the inheritanceinheritance of traits in of traits in pea plantspea plantsDeveloped the Developed the laws of laws of inheritanceinheritanceMendel's work was Mendel's work was not recognized until not recognized until the turn of thethe turn of the 20th 20th centurycentury

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Gregor Johann MendelGregor Johann Mendel

Between 1856 and Between 1856 and 1863, Mendel 1863, Mendel cultivated and tested cultivated and tested thousands of pea plantsthousands of pea plants

He found that the He found that the plants' offspring plants' offspring retained traits of the retained traits of the parentsparents

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Mendel stated that Mendel stated that physical traits are physical traits are inherited as inherited as “particles”“particles”Mendel did not know Mendel did not know that the “particles” were that the “particles” were actually actually Chromosomes & Chromosomes & DNADNA

Particulate InheritanceParticulate Inheritance


Why peas?Why peas?

Can be grown in a Can be grown in a small areasmall area Produce Produce lots of lots of offspring offspring Produce Produce purepure plants plants when allowed to when allowed to self-self-pollinatepollinate several several generations generations Can be Can be artificially artificially cross-pollinatedcross-pollinated

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Mendel and His Peas

• Mendel tested 7 traits:1. Flower color2. Flower position3. Seed color4. Seed shape5. Pod shape6. Pod color7. Plant height

http://www.fieldmuseum.org/exhibits/traveling_mendel.htm


Mendel and His Peas

• Mendel crossed flowers that were true-breeding for each characteristic.

• He crossed a purple (PP) flowered plant with a white (pp) flowered plant. (Parent Generation)

http://biology.kenyon.edu/courses/biol114/KH_lecture_images/Mendel/Mendel.html


Mendel and His Peas

• The first generation (F1) of plants all had purple flowers.

• Where did the white color go??

(Pp)

(Pp)

(Pp) (Pp)

Purple Parent (PP)


Mendel and His Peas• Mendel took two of his

first generation (F1 x F1) purple flowered plants and crossed them together.

• In the second generation (F2) he had 3 purple flowered plants, and 1 white flowered plant.

(PP) (Pp)

(Pp) (pp)

Purple Parent (Pp)


Mendel and His Peas

• Mendel noticed in the first generation, all of the white flowers seemed to disappear.

• He called this a recessive trait. • The white color faded into the

background at first. • It showed up in the next generation

when he pollinated the flowers.


Mendel and His Peas

• The color (purple) that seemed to mask over the recessive color was named the dominant trait.


Mendel and His Peas

• Mendel was responsible for figuring out that each plant carried two sets of instructions for each characteristic (one from the “mom” and one from the “dad”).

• Like many scientists, his work was not accepted until after his death.


Let’s Review

1. If you crossed a true-breeding black rabbit with a true-breeding white rabbit, all of the offspring would be black. Which trait is dominant in rabbits: black fur or white fur?

2. Which trait is recessive?


Answer

• The trait for black fur is dominant over the trait for white fur. The white fur trait is recessive.

http://www.buckeyevalleyfarms.freeservers.com/photo.html

(Bb)

(Bb)

(Bb) (Bb)

Black Rabbit (BB)


Mendel and His Peas

Vocabulary1. Heredity- the passing of traits from parent

to offspring.2. Dominant trait- the trait observed when at

least one dominant allele for a characteristic is inherited

3. Recessive trait- a trait that is apparent only when two recessive alleles for the same characteristic are inherited


Mendel and His Peas

4. Genes- a segment of DNA that carries hereditary instructions and is passed from parent to offspring. Genes are located on chromosomes.

5. Alleles- multiple forms of the same gene6. Genotype- an organisms inherited

combination of alleles7. Phenotype- an organisms inherited

appearance


Probability• The likelihood of a

particular event occurring. Chance

• Can be expressed as a fraction or a percent.

• Example: coin flip.


Punnett Square

• Developed by Reginald Punnett.

• A diagram used to show the probability or chances of a certain trait being passed from one generation to another.


Reading Punnett squares

• Gametes are placed above and to the left of the square

• Offspring are placed in the square.• Capital letters (Y) represent dominant alleles.• Lower case letters (y) represent recessive

alleles.


• Homozygous = when an organism possesses two identical alleles. ex.– YY or yy

• Heterozygous = when an organism possesses different alleles. ex.– Yy


Phenotype vs genotype

• Genotype The genetic makeup Symbolized with letters Tt or TT

• Phenotype• Physical appearance of

the organism• Expression of the trait• Short, tall, yellow,

smooth, etc.


Punnett square example


More Practice2-28-14

Unit A : Chapter 1 : Section 1


Punnett square review:


Science Closure2-28-14

In a certain breed of dog, short hair (H) is dominant to long hair (h). A short-haired dog (Hh) is crossed with a long-haired dog (hh). A Punnett square of this cross is shown below. What is the probability that one of the puppies produced by these parents will have short hair?

A. 0%B. 25%C. 50%D.100%

Unit A : Chapter 1 : Section 1


Science Closure2-27-14

The image shows a chromosome. What is located on the chromosome?

• A cells• B genes• C enzymes• D organelles

Documents

© Fall 2005, Pflugerville ISD, 7th Grade Homeroom Warm Up 2-28-14 List the 4 major layers of the Earth from the hottest to the coolest. Also list at least