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Genetics

The scientific study of heredity

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Gregor Mendel

The father of genetics

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What is the male sex structure on a plant?

The stamen

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What is the female sex structure of a plant?

The pistil

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Where are the plants' sperm cells found?

The pollen

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Fertilization

When the male and female reproductive cells join in sexual reproduction.

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Self pollination

When the sperm cell in the pollen fertilizes the egg cell of the same plant.

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True breeding

Self pollinating that results in the offspring being identical to their parent.

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How is self pollination prevented?

Cutting away the pollen-bearing male parts called the stamen.

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Cross pollinating

Taking pollen grains from one plants and dusting them on another.

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What did Mendel's experiments allow him to do?

Cross breed plants with different characteristics and study the results.

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Trait

A specific characteristic that varies from one individual to another.

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What traits did Mendel study?

Seed shape, seed color, pod shape, pod color, flower position, flower color, and plant height.

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What is significant in how these traits vary with the pea plant species?

They each only had two contrasting characteristics.

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What did Mendel call the original pair of plants' generation?

P (parental)

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True or false: Mendel called the first generation of offspring the F1 generation.

True

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Hybrids

The offspring that result from a cross between parents with different traits.

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Factors (genes)

Determined biological inheritance.

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Alleles

Different forms of genes

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The Principle of Dominance

Some alleles are more dominant while other are recessive. Recessive can only be seen in the absence of dominant alleles.

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How did Mendel get his F2 generation?

By allowing his F1 generation to self pollinate.

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Law of Segregation

The alleles segregated from one another during the formation of gametes.

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Probability

The likelihood that a particular event will occur.

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True of false: past outcomes ALWAYS affect future outcomes.

False

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Punnett Square

A diagram used to predict the possible outcomes of genetic crosses.

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Homozygous

Organisms that have two identical alleles for a particular trait.

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Heterozygous

Organisms that have two different alleles for a particular trait.

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Phenotype

Describes the physical characteristics

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Genotype

Describes the genetic make up.

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What did Mendel get in he F2 generation when he did a two-factor cross?

He found combinations of the two alleles not found in either parent.

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Principle of Independent Assortment

Genes for the different traits can segregate independently during the formation of gametes.

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Incomplete dominance

Neither allele is dominant over the other. (Red+white=pink)

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Codominance

Both alleles contribute to the phenotype. (Black+white=black with white dots)

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Multiple alleles

Genes have more than two alleles (blood type)

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Polygenic traits

Traits controlled by two or more genes (skin color)

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True or false: Mendel's principles can be applied to all organisms.

True

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What else plays a role in determining characteristics?

The environment

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Homologous chromosomes

Chromosomes that have a corresponding chromosome from the opposite-sex parent.

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Diploid

Cell that contains both sets of homologous chromosomes. (2N)

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Haploid

Cell that contains only a single set of chromosomes. (N)

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What cells are haploid?

Gametes

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Meiosis

The process of reduction division in which the number of chromosomes per cell is cut in half by separating homologous chromosomes in a diploid cell.

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What are the 3 main steps in meiosis?

Interphase
Meiosis 1
Meiosis 2

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Interphase 1

DNA gets replicated forming duplicate chromosomes.

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Prophase 1

Each chromosome pairs with its corresponding homologous chromosome to form a tetrad.

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Crossing over

Homologous chromosomes exchange portions of their chromatids, producing new combinations of alleles. (Prophase 1)

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Metaphase 1

Spindle fibers attach to chromosomes.

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Anaphase 1

Chromosomes are pulled toward opposite ends of the cell.

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Telophase 1 and cytokinesis

Nuclear membrane forms and the cell separates into two.

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True or false: interphase 2 does not exist

True

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Prophase 2

Two diploid daughter cells, each with the same number of chromosomes as the original cell. No chromosomes replicated.

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Metaphase 2

Chromosomes align in the center of the cell.

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Anaphase 2

Sister chromatids separate and move toward opposite ends of the cell.

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Telophase 2 and cytokinesis

4 haploid daughter cells.

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Polar bodies

Three gametes produced but not involved in reproduction. (Disintegrate into body)

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Thomas Hunt Morgan

Questioned why many traits were inherited together.

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Gene linkage

Chromosomes assort independently, not individual genes. Each chromosome is actually a group of linked genes.

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Name one reason why a cell divides.

-Information overload; too much DNA.
-Exchange of materials or ratio of surface area: volume gets too small.