Sister chromatids
identical copies of the same chromosome (connected at the centromere).
Homologous chromatids
similar but not identical chromosomes; one comes from each parent.
Haploid
a cell with one set of chromosomes (n)
Diploid
a cell with two sets of chromosomes (2n)
Gametes
Sex cells (sperm and egg) produced through meiosis.
Somatic cells
cells that divide through mitosis, not meiosis
Zygote
A fertilized egg (diploid cell formed when gametes fuse)
Alleles
Different versions of a gene
Gene
A section of DNA that codes for a protein or RNA molecule
Genotype
The combination of alleles (e.g., BB, Bb, bb)
Phenotype
Physical expression of the genotype (eg brown eyes)
Dominant
Dominant alleles show up when present (B)
Recessive
Recessive alleles only show up when both alleles are recessive (bb)
Only one recessive is a carrier, typically unaffected (Bb)
Complete dominance