what is genetics?
study of molecular variation in organisms and the inheritance of that information
what are characteristics for good model organisms when studying genetics?
GROS
G- generation time is rapid
R - reproduction is quick
O - offspring are plentiful
S - space taken up is small
what is a monohybrid cross?
cross between two individuals that are both heterozygous for the certain phenotype
what is incomplete dominance?
when two alleles interact in a way that both are expressed (wavy hair is caused by Cc genotype)
what are polytene chromosomes?
large chromosomes that can be seen
what is a phenotype?
physical and observed expression of a particular trait/genotype
what is a genotype?
complete genetic set of an organism
what is the Law of Segregation?
homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
How do you determine the number of different gametes?
2^n
n= # of heterozygous genes
what is heterozygosity?
the presence of a heterozygous alle
what is the relationship between the number of gamete allele possibilities and the number of heterozygous alleles present?
the number of gamete possibilities increases as heterozygosity increases
why is human genetics difficult to study?
- long generation time
- small numbers of offspring
- immoral and unacceptable
what are pedigrees?
family trees that track certain traits, frequently those that cause diseases
how do you determine if traits are recessive or dominant?
look for mating where two parents with same phenotype and child with opposite phenotype
- affected parents and unaffected child, dominant trait
- unaffected parents and affected child, recessive trait (only possible if parents are heterozygous and child is homozygous recessive)
why should we approach a pedigree and assume any results of a cross are equally possible?
- although one result may be less likely, the less likely one cannot be excluded as results are random
what are antibodies?
defensive proteins in blood that can recognize and bind to foreign substances
what are antigens?
substances that elicit an antibody response
what does Allele IA produce?
glycoprotein antigen A on RBC surfaces
what does Alelle IB produce?
glycoprotein antigen B on RBC surfaces
what are the characteristics of alleles IA and IB?
- both are dominant - one copy is sufficient to express its phenotypic effect
- both are codominant - both are expressed when both are present
what happens to a person with Type A blood when it comes across Type B blood?
- doesn’t produce Anti-A antibodies
- produces Anti-B antibodies as it recognizes antigen B as foreign
what happens to a person with Type B blood when it comes across Type A blood?
- doesn’t produce Anti-B antibodies
- produces Anti-A antibodies as it recognizes antigen A as foreign
what happens to a person with Type AB blood when it comes across any blood?
- doesn’t produce Anti-A or Anti-B antibodies
what happens to a person with Type O blood when it comes across any blood?
- produces anti-B and anti-A antibodies as it recognizes antigen A and antigen B as foreign
