Biology Unit 4 Vocab

genetics

scientific study of heredity

heredity

the passing on of physical or mental characteristics genetically from one generation to another

fertilizaton

process in sexual reproduction in which male and female reproductive cells join to form a new cell

trait

specific characteristics of an individual

hybrid

offspring of crosses between parents with different traits

gene

sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parent to offspring

allele

one of a number of different forms of a gene

principle of dominance

Mendel’s second conclusion which states that some alleles are dominant and others are recessive

segregation

separation of alleles during gamete formation

gamete

sex cell

probability

likelihood that a particular event will occur

homozygous

having two identical alleles for a particular gene

heterozygous

having two different alleles for a particular gene

phenotype

physical characteristics of an organism

genotype

genetic makeup of an organism

punnett square

diagram that can be used to predict the genotype and phenotype combinations of a genetic cross

independent assortment

one of Mendel’s principals that states that genes for different traits can segregate independently during the formation of gametes

incomplete dominacnce

situation in which one allele is not completely dominant over another

codominance

situation in which the phenotype produced by both alleles are completely expressed

multiple alleles

a gene that has more than 2 alleles

polygenic trait

trait controlled by 2 or more genes

homologous

term used to refer to chromosomes in which one set comes from the female parent

diploid

term used to refer to a cell that contains 2 sets of homologous chromosomes

haploid

term used to refer to a cell that contains only a single set of genes

meiosis

a process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

crossing over

process in which homologous chromosomes exchange portions of their chromatids during meiosis

zygote

fertilized egg

nondisjunction

error in meiosis in which the homologous chromosomes fail to separate properly

chromatid

one of 2 identical “sister” parts of a duplicated chromosome

karyotype

micrograph of the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size

monohybrid cross

the hybrid of 2 individuals with homozygous genotypes which result in the opposite phenotype for a certain genetic trait

dihybrid cross

a mating experiment between 2 organisms that are identically hybrid for 2 traits

sperm

the smaller, usually motile male reproductive cell of most organisms that reproduce sexually

ovum

a mature female reproductive cell, especially of a human or other animal which can divide and give rise to an embryo after fertilization by male cell

genome

entire set of genetic information that an organism carries in its DNA

law of segregation

alleles segregated randomly into gametes

mutations

change in the genetic material of a cell

pedigree

chart that shows the presence of absence of a trait according