Chapter 14 Flashcards
Ancient theory: Homunculus
A supposed microscopic but fully formed human being from which a fetus was formerly believed to develop.
Ancient theory: Blending
Colors of the parents mix just like colors. Hypothesis- eventually everyone will be uniform.
Mendel- “particulate inheritance” theory
Hereditary elements are passed on in discrete units rather than “blended” together at each new generation.
Character
A heritable feature that varies among individuals. Color is a character, the specific color is a trait.
Traits
Variants for a character. Color is a character, the specific color is a trait.
“True Breeding”
Always produces identical offspring with regard to character under study.
Example: a plant with purple flowers is true-breeding if the seeds produced by self-pollination in successive generations all give rise to plants that also have purple flowers.
Self-pollinating
Plant which produces pollen to fertilize itself.
Hybridization
Mating or crossing of 2 true/pure-breeding varieties
Law of Independent Assortment
The alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.
Happens in metaphase 1.
Mendel’s second law
Law of Segregation
2 alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes. Depending on tetrad formation, can happen during anaphase I or anaphase II.
One gamete = just G, not Gg or gg or GG.
Codominance
Red flower + White flower = Red/white flower.
A type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual.
Incomplete Dominance
Red flower + White flower = Pink flower
A form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype
Monohybrids
The offspring of two individuals that differ in respect of a single gene. Need to be different at at least one locus.
Dihybrid Cross
A hybrid that is heterozygous for alleles of two different genes. 2 different characters.
Multiple Alleles
Cases where more than two different alleles of the same gene are present in a population, such as blood type.
Pleiotropy
Where a single gene controls/influences multiple phenotypic results. Unrelated results.
Polygenic inheritance
Where a single trait is controlled by more than 2 genes. A bellshape curve distribution of phenotypes. An ABC genotype, vs multiple alleles, which is an I_ai, I_bi, or ii.
Nature vs. Nurture
Environment vs Genetic coding.
I.e. soil ph affecting hydrangea flower colors.
Human Inheritance Patterns
identify genotypes and predict future inheritance patterns of human traits.
Multifactorial
Many factors affect phenotype - genetics and environment.
Dominantly Inherited Disorders
Don’t need to be homozygous to be expressed. Huntington’s disease can be Hh or HH. Achondroplasic dwarfism.
Achondroplasic Dwarfism
Extremely rare. Dominantly inherited disorder.
Fetal Testing.
Also known as prenatal testing. Can identify whether your baby is more or less likely to have certain birth defects
Newborn Screening
A PKU (phenylketonuria) screening test is a blood test given to newborns one to three days after birth. The test measures the amount of phenylalanine (Phe) in the baby’s blood. A normal level is less than 2 milligrams per deciliter (mg/dL)
Epistasis
alleles of 1 gene totally mask allele expression of a totally seperate (another locus) gene.
Amniocentesis
Amniocentesis (also called amnio) is a prenatal test that takes amniotic fluid from around your baby in the uterus (also called womb). The fluid is tested to see if your baby has certain health conditions.
16-20 weeks.
Chorionic Villus Sampling
(CVS) Is a prenatal test that involves taking a sample of tissue from the placenta. The test is used to diagnose certain birth defects and genetic abnormalities in a baby.
Uses ultrasound to make sure they control needle.
Heterozygote superiority
Sickle-cell anemia - ss
Sickle-cell trait - Ss
Normal cell - SS
Ss has ‘heterozygote superiority’, because the deformed cells (due to mal-formed cell) provide some resistance to the malarial protozoan.
Carriers
Phenotype = normal
Genotype = contains recessive disorder allele
