introduction to genetics unit 3

7/31/2019 Introduction to Genetics Unit 3

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GeneticsIntroduction to Genetics


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Gregor Mendel

Genetics: the scientific study ofheredity

Gregor Mendel showed that theinheritance of these traits followed

particular laws, which were named

after him.

Gregor Mendels experiments with

peas laid the foundations of the

science of genetics.


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Fertilization: process in sexual reproduction in which

male and female reproductive cells join to form a newcell.

Trait: a specific characteristic of an individual.

Hybrids: offspring of crosses between parents with

different traits.


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An individuals characteristics are

determined by factors that are passed from

generation to the next.


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Genes: sequence of DNA that codes for a protein

and determines a trait; factor passed from parent

to offspring.

Chemical factors that determine traits.

Alleles: different forms of a gene.


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#1 Principle of dominance

States that some alleles are dominant

and others are recessive


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Segregation: Separation of the alleles during gameteformation.

#2 Principle of Segregation - The two factors for acharacteristic separate during the formation of eggs and

sperm.


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#3 The Principle of independent assortment states

that genes from different traits can segregate

independently during the formation of gametes.


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Probability: likehood that a particular event

will occur The principle of probability: can be used to

predict the outcomes of genetic crosses.


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Punnett Square The gene combinations that might result from a genetic

cross can be determined by drawing a diagram known asPunnett Square.

Punnett Square can be used to predict and compare the

genetic variations that will result from a cross.


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Homozygous: organism that have two

identical alleles for a particular trait.

Heterozygous: organism that have

two different alleles for the same

trait.

Phenotype: physical characteristics.

Genotype: genetic make up of an

organism.


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Incomplete dominance: cases in

which on allele is not completely

dominant over another.

Co dominance: refers to arelationship between two alleles

of a gene. It occurs when the

contributions of both alleles are

visible in the phenotype.


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Multiple alleles: manygenes have more than

two alleles such as the

ABO blood groups in

humans. (Even thoughAny diploid individual

can only have at most

two alleles for any

gene)


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Polygenic traits: controlled by two or more

than genes at different loci or chromosomes


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The environmental conditions can affect gene

expression an influence genetically determine

traits.


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Homologous: it means thateach of the 4 chromosomes

that come from the male

parent has a corresponding

chromosome from the femaleparent.


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Diploid: cell that contains both setof homologous chromosomes.

Haploid: set that contain only a

single set of chromosomes.


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Meiosis: produce sex cells by reducing their

chromosomes number by half.

Meiosis is important because it creates genetic variability

in the gametes.

Meiosis ll results in four haploid daughter cells.


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=Comparing Mitosis and Meiosis=

Mitosis results in the production of two geneticallyidentical diploid cells, whereas meiosis produces

four genetically different haploid cells.

introduction to genetics unit 3

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