Designer Genes C 2026

trait

any physical characteristic

the genetic makeup of an organism

genotype

a type of cell division that produces reproductive cells in sexually reproducing organisms

meiosis

a probability diagram illustrating the possible offspring between two organisms where male genes are on top of the columns and female traits are on the sides of the rows

punnett square

a situation in which one allele is not completely dominant over another

incomplete dominance

a sex cell possessing a haploid chromosome set

gamete

if an individual is missing a chromosome

monosomy

a cross between two different genes that differ in two observed traits

dihybrid

one of two or more alternate forms of a gene

allele

a cross between two organisms with variations at one genetic chromosome of interest

monohybrid

a diagram depicting the biological relationships between an organism and its ancestors, as well as the inheritance of a disease or trait over several generations

pedigree

refers to one gene affecting many traits

pleiotropy

refers to 2 or more genes affecting one trait

polygenic inheritance

what an organism looks like as a consequence of its genotype

phenotype

a print of the full set of chromosomes of an organism

karyotype

a fertilized egg cell

zygote

a unit of hereditary information

gene

a type of cell division which produces two daughter cells that are genetically identical to the parent cell

mitosis

a chromosomal abnormality characterized by an additional chromosome

trisomy

a failure of homologous chromosomes or sister chromatids to separate properly during cell division

nondisjunction

a change in the nucleotide sequence of an organism’s genome

mutation

both alleles of a gene contribute to an organism’s phenotype

codominance

term used to refer to an organism that has two different alleles for the same trait

heterozygous

when the two alleles are the same

homozygous

an interaction between the products of two genes in which one of the genes modify the phenotypic expression produced by the other

epistasis

dominant allele of the first gene overrides the effects of the second gene (dihybrid cross ratio 12:3:1)

dominant epistasis

recessive alleles of one gene mask the expression of alleles of another gene (dihybrid cross ratio 9:3:4)

recessive epistasis

two dominant alleles from two different gametes are both required to produce a single phenotype (dihybrid ratio 9:7)

complementary epistasis

use genetic engineering to disable or remove a specific gene from an organism to study its function

knockout experiments

Nondisjunction during Meiosis I

Homologous chromosomes fail to separate because tetrads fail to separate during anaphase I, → one gamete with n+1 and one gamete with n-1

Nondisjunction during Meiosis II

Sister chromatids fail to separate during Anaphase II → two normal gametes and two gametes with either extra or missing chromosome

initiation of prokaryotic transcription

RNAP binds to promoter, separates DNA strands, forms transcription bubble

elongation of prokaryotic transcription

RNAP synthesizes new RNA by adding 40 complementary nucleotides/second in the 5’ to 3’ direction, sigma factor releases

rho-independent (intrinsic) termination of prokaryotic transcription

RNAP transcribes inverted repeat and RNA folds back on itself to form a hairpin → RNAP pauses, A-rich region in the DNA creates a weak A-U pairing → hairpin and weak A-U bonds detach RNA from DNA template

rho-dependent termination

rho protein binds to rut site on mRNA, rho climbs up RNA towards RNAP (ATP); when RNAP pauses at G-rich region, rho catches up and uses helicase activity to unwind RNA-DNA hybrid