Chapter 4 Flashcards
Polygenic traits
Traits that are influenced/ affected by two or more genes
Mainly influenced by environmental factors such as nutrition and exposure to sunlight
Ex: skin, eye, hair color
Mendelian traits
Characteristics that are influenced by ONLY ONE allele/gene
Ex: bloody type, sickle-cell anemia
Mendelian vs. polygenic traits
Mendelian influenced by ONE gene
Polygenic influenced by 2 or more genes
Principle of Segregation
For any particular trait, the pair
of alleles of each parent
separate and only one allele
passes from each parent on to
an offspring
Independent assortment
Genes are passed to offspring independently of each other
The inheritance of one trait does not affect the inheritance of another
Phenotype
The observable, physical expression of genotypes
Genotype
The genetic makeup of an individual
Refers to an organism’s entire genetic makeup or to the alleles at a particular locus
A, AB , O
Gene pool
All the genes shared within a population
Antigens
Molecules structures on the surface of red blood cells
• Any molecule that could become a target of the immune system response…
• Substances, such as bacteria, viruses, foreign blood cells, etc. that stimulate the immune
system’s antibody production
Allele frequency
In a population, the percentage of all the alleles at a locus accounted for by one specific allele
ABO blood group
Consists of 3 alleles
A,B,O
Homo: AA, BB, OO
Hetero: AO, BO
Codominance: AB
Macro evolution
Changes produced only after many generations, such as the appearance of new species
Micro evolution
Small changes occurring within species, such as changes in allele frequencies
Ex: skin pigment
Natural selection
when some individuals of a population are better able
to adapt to their environment and, subsequently, produce more offspring.
• Selective agent: The environment
• Differential productive success between
individuals is the key.
produce more offspring means
greater influence on the gene frequencies of the next generation and are therefore “more fit”
Genetic drift
The change in allele frequencies produced by random factors
Occurs more rapidly in small population size
Founder effect
A type of genetic drift in which allele frequencies are altered by reproductively isolating a small segment of a population from a
larger population.
Causes the smaller population to
diverge genetically from the parent population
Gene flow
Exchange of genes between populations
Sickle cell trait
Heterozygous condition in which a person has one Hb^A allele and one Hb^s allele
They have some normal hemoglobin
Sickle cell anemia
A severe inherited hemoglobin disorder in which red blood cells collapse when deprived of oxygen
Results from inheriting two copies of a mutant allele
Mendel is known for?
He discovered the fundamental principles of how traits are inherited
Did not know about chromosomes
