Genetics DEFINITIONS

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created 5 years ago by Phyllis_Nwokolo
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1

Trait

The characteristics of an individual

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Gene

A part of DNA that encodes a functional RNA or protein product, and is the molecular unit of heredity.

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Genotype

Genetic constitution of an organism

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Phenotype

Observable and non visible trait or set of traits of an organism produced by the interaction between its genotype and the environment.

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Environmental effects

The extent to which the potential for developing a particular phenotype depends on environmental influences.

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Alleles

Different forms of a gene

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Cross

Mating between two individuals, leading to the fusion of gametes

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Haploid

one set of chromosomes in each cell

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Diploid

two homologous sets of chromosomes.

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True breeding

unchanged trait from parents to offspring for many generations. Usually means that there's homozygosity for the allele for the trait.

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Testcross

It's for confirming the principle of segregation and used to determine the genotype of a mystery individual.

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Dominant and Recessive

If a gene's product is a mutated enzyme then its product is recessive. But, if the gene's product is a mutated structural protein then it will be dominant.

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Single gene traiits

caused by individual mutant genes

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Intermediate Inheritance

Incomplete dominance, sickle cell

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Autosomal Dominant Disorder

Aa * aa

mutant gene is dominant over normal gene

Present in all generations

Affected number equal in men and women

one affected person, have atleast one affected parent

Hereditary breast and ovarian cancer

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Autosomal Dominant

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Autosomal Dominant

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Autosomal Recessive

`Aa * Aa

If more than one person is affected, it's usually the sibling of the affected person

Affected skipping generations

Albinism

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Autosomal recessive

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Quasidominant Inheritance

It's a special case where an affected homozygous marries a carrier. The first part of the pediree shows likea dominant disorger, but the rest of the pedigree shows like recessive mode of inheritance.

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Consanguinity

genetic isolate

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Null hypothesis

states that there is no real difference between the observed data and the predicted data

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statistical analysis

used to determine whether the difference is due to chance.

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chi-square

simple statistical analysis used to test null hypotheses

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EQUATION chi-square

sum of observed minus expected squared over expected

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Metacentric chromosome

centromere in the center, each arms of equal length.

chromosome 1

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submetacentric chromosome

centeromere slightly offset from the center. slight asymmetry in the length of the two arms.

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Acrocentric chromosome

centromere severely offset from the center leading to one very long and one very short arm.

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Telocentric chromosome

centromere at the very end of the chromosome

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Mitosis Interphase

the nucleus and the nuclear envelope are distinct and the chromosomes are in the form of threadlike chromatin

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Mitosis prophase

Chromosomes condense and the nuclear envelope is not apparent

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Mitosis metaphase

chromosomes line up in the center of the cell on the metaphase plate, and spindle fibers are attached to chromosomes.

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Mitosis anaphase

Chromosomes have separated and are moving toward the poles.

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mitosis telophase

chromosomes are at the poles, and the nuclear envelope is re forming and cytoplasm starts dividing.

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Meiosis 1 vs Mitosis

Prophase: In meiosis, crossing over occurs between homologous chromosomes in tethrads' and in mitosis there is no crossing over.

Metaphase: In meiosis, the tetrads align at the metaphase plate while in mitosis, chromosomes align at the metaphase plate.

Anapahse and telophase: In meiosis, homologous chromosomes separate into four daughter haploid cells, whereas in mitosis, the sister chromatids seperate into two haploid cells.