one specific form of a gene, differeing from other alleles by one or a few bases only and occupying the same locus as other alleles of the gene.
The smallest possible change is when one base in a gene is replaced by another. An example of this type of mutation is sickle cell anemia
chromosomes with the same genes in the same loci but not necessairly the same alleles of those genes.
during prophase I the position of each pair of chromosomes when the spindle attaches is random
sometimes chromosomes that should separate and move to opposite poles during meiosis do not separate and instead they both move to the same pole
chromosomes are arranged in pairs according to their size. Peformed using cells collected by chorionic villus sampling for prenatal diagnosis of chromosome abnormalities.
Chromosome supercoil, homologous chromosomes (bivalents) pair up (synapsis), crossing over occurs resulting in chiasma, centrioles move to opposite poles in animal cells and the nuclear membrane reaks down.
the two chromosomes of each bivalent move to opposite poles, thus halving the chromosome number, each chromosome consists of two identical sister chromatids, if crossing over occured they are not identical.
Chromosome supercoil, homologous chromosomes (bivalents) pair up (synapsis), crossing over occurs resulting in chiasma, centrioles move to opposite poles in animal cells and the nuclear membrane reaks down. [EXCEPT THERE ARE NO HOMOLOGOUS CHROMOSOMES TO PAIR UP, THUS NO CROSSING OVER]
spindle microtubules attach to centromeres, bivalents line up at the equator, at the end of the phase the centromeres divide.
The centromeres spilt, then the two chromatids of each chromosome move to opposite poles
nuclear membrances form, the cel divides to form two haploid cells [EXCEPT TWO CELLS DIVIDE TO FORM FOUR HAPLOID CELLS WHICH WILL DEVELOP INTO GAMETES, THE CHROMATIDS ARE NOW KNOWN AS CHROMOSOMES
during crossing over in prophase I, all the chromatids of two homologous chromosomes become tightly paired.
the reassortment of genes or characters into different combinations from those of the parents
the way one pair of homologous chromosome is segregated (assorted) during formation of gametes (meiosis) is independent of the way any other pair is segregated. (due to random orientation)
an allele that has the same effect on the phenotype whether it is present in the homozygous or heterozygous state
an allele that only has an effect on the phenotype when present in the homozygous state
an individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this allele
the association of a characteristic with gender, because the gene controlling the characteristic is located on a sex chromosome. (usually the X)
are produced by a recessive sex allele on the X chromosome. The allele is X^h and the dominant allele is X^H
are produced by a recessive sex allele on the X chromosome. The allele is X^b and the dominant allele is X^B
fragments of DNA move in an electric field and are separated according to their size.