6) Reproduction, Genetics, and Heredity
pedigree
a chart that tracks which members of a family have a particular trait
binary fission
a form of asexual reproduction, most common in prokaryotes; one cell divides giving rise to a second exact copy
gametes
a reproductive sex cell that has the haploid number of chromosomes; commonly called egg and sperm
Punnett Square
a tool used to predict the probable outcomes of genetic crosses
allele
different forms of a gene (dominant & recessive)
heredity
pass of traits from parent to offspring
mitosis
process of cell division that forms 2 new nuclei, each of which has the same number of chromosomes
meiosis
produces sex cells containing half the genetic material of the parent cells
asexual reproduction
the transfer of genes from one individual to the next generation resulting in an offspring with identical genetic material
chromosomes
thread-like structures located inside the nucleus of animal and plant cells; made from DNA
codominance
two alleles are expressed in heterozygous individuals
haploid
when a cell has half the number of usual chromosomes
Law of Independent Assortment
when two or more characteristics are inherited, individual hereditary factors assorted independently during gamete production, giving different traits an equal opportunity of occurring together.
mutation
A permanent, heritable change in the sequence in a gene or genes on a chromosome
genotype
allele combination for a trait (ex. RR, Rr, rr)
trait
any characteristic that can be passed from parent to offspring
diploid
containing two complete sets of chromosomes, one from each parent
natural selection
driving force for evolution; individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals
Law of Segregation
during the production of gametes, the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent
homozygous genotype
gene combination involving 2 dominant or 2 recessive genes (ex. RR or rr); also called purebred
heterozygous genotype
gene combination of one dominant & one recessive allele (ex. Rr); also called hybrid
recessive allele
gene that show up less often in a cross; represented by a lowercase letter (r)
Law of Dominance
in a cross of parents with pure, contrasting traits, all offspring will be heterozygous and express only the dominant trait
adaptation
inherited characteristics that increase an organism's chance for survival
dominant allele
stronger of two genes expressed in the hybrid; represented by a capital letter (R)
genetics
study of heredity
gene
the basic physical unit of heredity
zygote
the cell produced by the union of two gametes
sexual reproduction
the combining of sex cells, which results in an organism with genetic material from the parent(s)
fertilization
the fusion of a sperm and egg to form a zygote
probability
the likelihood that a particular event will occur
phenotype
the physical feature resulting from a genotype (ex. red, white)
evolution
the slow, gradual change in a population of organisms over time