Meiosis, genetics, heredity Flashcards
Tetrads
2 pairs of homologous chromosomes, four chromatids, joined by one centromere in Prophase I of meiosis I
Crossing over
When individual chromatids of a tetrad exchange genetic information with each other resulting in rearrangement of the genetic info for each developing gamete
Independent assortment
A term referring to the way crossing over rearranges genetic material during prophase I of Meiosis I
Nondisjunction
An error in the formation, replication, or crossing over of chromosomes such that the DNA sequence is not correct. Cause of some diseases and genetic defects.
Haploid chromosome number
Half the diploid chromosome number for a species. Gametes of a species are always haploid.
Diploid chromosome number
Term describing the chromosome number of somatic cells. The diploid chromosome number is unique to a specific species
Twisted double helix
The name for the shape of the DNA molecule
James Watson and Frances Crick
Scientists credited with discovery of the twisted double helix shape for the DNA molecule
Sugar phosphate backbone
The two molecules that comprise the sugar phosphate backbone of the DNA molecule
Nucleotides that comprise DNA
Adenine, thymine, guanine, and cytosine
Nucleotide base-pairing in DNA
Bases always pair as follows: A&T and C&G
Genotype
Letters representing the alleles for a particular genetic trait
Phenotype
The actual appearance represented by a specific genotype
Dominant
An allele represented by a capital letter that indicates a trait that is always expressed if that allele is present
Recessive
An allele represented by a lower case letter that is only expressed if both recessive alleles are present (one from each parent
Allele
A specific location on a chromatid where genetic info for one or more traits resides
Homozygous
Two alleles that are the same, such as AA or aa. These genotypes are referred to as homozygous dominant (AA) or homozygous recessive (aa)
Heterozygous
Two different alleles (Aa)
Punnet square
A genetics tool (multi-pane square) that allows one to perform specific genetic crosses to determine the genotypes and phenotypes of the F1 generation resulting from the cross between two specific parents with known genotypes
Pure-bred
An individual that is homozygous dominant for a specific trait.
Hybrid
An individual that is heterozygous for a specific trait
Heredity
The passing of genetic traits from one generation of a species to another through sexual reproduction and the transfer of DNA to successive generations
Probability
The likelihood that something will occur
Gametes in plants
Ovules (female) and pollen grain (male)
