Study Guide 7! Flashcards
How can we tell the genotype of an individual with the dominant phenotype?
perform a testcross
Testcross
breeding the mysterious individual with a homozygous recessive individual, if any offspring display the recessive phenotype, the mystery parent must be heterozygous
allele
alternative versions of a gene
law of independent assortment
during gamete formation the inheritance of one trait does not influence the inheritance of another trait; all possible combinations of alleles are equally likely to occur
law of segregation
during gamete formation, each parent passes one allele at random to their offspring
complete dominance
phenotype of heterozygote and dominant homozygote are identical
Incomplete Dominance
phenotype of hybrids is somewhere between the phenotypes of the two parents
Codominance
two dominant alleles affect the phenotype in separate, distinguishable ways
multiple alleles
occur when there are more than two versions of a gene, or alleles, for a trait in a population
qualitative traits
characteristics that can be categorized into distinct groups and are often controlled by a small number of genes
quantitative characters
phenotypic traits that can be measured numerically and are genetically more complex than qualitative traits
polygenic inheritance
a pattern of genetic inheritance where multiple genes control a trait or characteristic
Epistasis
gene at one location alters the phenotypic expression of a gene at a second location/locus
Norm of Reaction
the range of phenotypes that a single genotype can produce when exposed to different environmental conditions
multifactorial
conditions or traits caused by a combination of multiple genetic environmental factors
carriers
heterozygous people who carry the recessive allele but are phenotypically normal
________ increases the chance of two carriers mating
incest
cystic fibrosis definition
most common lethal genetic disease in the U.S, most common in European people, results in defective or absent chloride transport channels in plasma membranes
cystic fibrosis symptoms
mucus buildup in internal organs and abnormal absorption of nutrients in the small intestine
Sickle Cell Definition
mostly affects African-Americans, caused by the substitution of a single amino acid in the hemoglobin in red blood cells that causes the cells to look like sickles
sickle cell symptoms
physical weakness, pain, organ damage, paralysis
Huntington’s Disease
degenerative disease of the nervous system with no obvious phenotype effects until the person reaches 35-40
amniocentesis
fetal testing where the liquid in the belly is tested
chronic villus testing (CVS)
fetal testing where the placenta is tested
what two tests allow the baby to be assessed in utero?
ultrasound and fetoscopy
transcription
synthesis of mRNA under the direction of DNA
translation
synthesis of polypeptides under the direction of mRNA, happens in the ribosome
Central Dogma
transcription translation
DNA ————–> RNA —————–> protein
codon
DNA or RNA sequence of three nucleotides (a trinucleotide) that forms a unit of genomic information encoding a particular amino acid or signaling the termination of protein synthesis (stop signals)
how many codons are there and how many do what function?
There are 64 different codons: 61 specify amino acids and 3 are used as stop signals
RNA polymerase
catalyzes RNA synthesis and pries the DNA strands apart and hooks the RNA nucleotides together
A pairs with… (DNA)
T
A pairs with… (RNA)
U
C pairs with…
G