Holt McDougal Biology Vocab Ch. 6

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Somatic cell
Cell that makes up all of the body tissues and organs except gametes
Gamete
Sex cell(egg or sperm)
Homologous chromosomes
Chromosomes with the same length, appearance, and copies if genes, although the alleles may differ
Autosome
Chromosome that contains genes for characteristics not directly related to the sex of the organism
Sex chromosome
Chromosome that directly controls the development of sexual characteristics
Sexual reproduction
Process by which two gametes fuse and offspring that are a genetic mixture of both parents are produced
Fertilization
Fusion of an egg and sperm cell
Diploid
(46 chromosomes)Cell that has two copies of each chromosome, one from an egg and one from a sperm
Meiosis
Form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction
Gametogenisis
Process by which gametes are produced through the combo of meiosis and other maturational changes
Sperm
Male gamete
Egg
Female gamete
Polar body
Haploid cell produced during meiosis in the female of many species; these cells have little more than DNA and eventually disintegrate
Trait
Characteristic that is inherited
Genetics
Study of heredity patterns and variation of organisms
Haploid
(23 chromosomes)
Cell that has only one copy of each chromosome
Purebred
Organisms whose ancestors are genetically uniform
Cross
Mating of two organisms
Law of segregation
Meldel's first law:
Organisms inherit two copies of genes, one from each parent, and organisms donate only one copy of each gene in their gametes because the genes separate during gamete formation
Gene
Specific region of DNA that codes for a particular protein
Allele
Any of the alternative forms of a gene that occurs at a specific place on a chromosome
Homozygous
Characteristics of having two of the same alleles at the same locus of sister chromatids
Heterozygous
Characteristics of having two different alleles that appear at the same locus of sister chromatids
Genome
All of an organisms genetic material
Genotype
Collection of all of an organisms genetic info that codes for traits
Phenotype
Collection of all organisms physical characteristics
Dominant
Allele that is expressed when two different alleles are present in an organisms genotype
Recessive
Allele that is not expressed unless two copies are present in an organisms genotype
Punnet square
Model for predicting all possible genotypes resulting from a cross or mating
Monohybrid cross
Cross or mating between organisms that involves only one pair of contrasting traits
Test cross
Cross between an organism with an unknown genotype and an organism with a recessive phenotype
Dihybrid cross
Cross/mating between organisms involving two pairs of contrasting traits
Law of independent assortment
Mendel's second law: allele pairs separate from one another during gamete formation
Probability
Likelihood that a particular event will happen
Crossing over
Exchange of chromosome segments between homologous chromosomes during meiosis one
Genetic linkage
Tendency for genes located close together on the same chromosome to be inherited together