biology aos 4

dna

the genetic material of an organism

gene

sequences of bases located on chromosomes that code for specific proteins that control traits

genome

a complete set of genetic instructions for an organism

diploid

having 2 copies of each specific chromosome in each set

haploid

having 1 copies of each specific chromosome in each set

gamete

a sex cell

allele

the different forms of a particular gene

chromosome

a package of dna holding genetic material of an organism

sister chromosome

identical copies of DNA formed by the replication of a chromosome

homologous

matching pairs of chromosomes that have the same genes in the same position

non homologous

non matching chromosomes

karyotype

an individuals complete set of chromosomes shown as an image arranged in size order

meiosis

the process of creating sperm and egg cells

reduction division

production of gametes through cellular division in meiosis 1 that reduces chromosome from diploid to haploid

prophase 1

chromosomes condense, nucleus degrades and crossing over occurs

metaphase 1

homologous chromosomes line up along equator of cell

anaphase 1

spindle fibres pull chromosomes to opposite sides of cell

telophase 1

nucleus forms around chromosomes, cytokinesis occurs

prophase 2

spindle fibres begin to form

metaphase 2

chromosomes line up along equator of cell

anaphase 2

spindle fibres pull sister chromatids to opposite sides of cell

telophase 2

nucleus forms around chromosomes, cytokinesis occurs

cytokinesis

the division of the cytoplasm to create 2 separate daughter cells

crossing over

the corresponding of genes between chromosomes

genotype

the genetic makeup of an organism

phenotype

the observable characteristics of an organism

dominant

a trait that is expressed

recessive

a trait that is present but not expressed

complete dominance

when one allele is fully dominant over another

codominance

when both alleles are expressed in a phenotype

incomplete dominance

when both alleles blend together to create an intermediate phenotype

carrier

when an allele has been inherited but is not expressed

monohybrid cross

a cross in which alleles of only 1 gene is involved

dihybrid cross

a cross in which alleles of only 2 genes are involved

test cross

a cross used to determine an unknown genotype by crossing it with a homozygous recessive genotype

dna replication

when genomes dna is copied in a cell during the s phase of cell division