Modern Human Variation 1 Flashcards
hardy-wienberg equilibrium equation
p= frequency of the dominant allele in the population
q= frequency of the recessive allele in the population
p^2= percentage of homozygous dominant individuals
q^2= percentage of homozygous recessive individuals
2pq= percentage of heterozygous individuals
what does it mean if traits are seen in the next generation?
the trait is in equilibrium and not evolving
epigenetics
DNA interacts with environment to influence appearance, behaviour, and function
do environmental factors affect genetic expression
- yes, genotype and phenotype interactions
- epigenetics and environmental influences
- changes can be inherited
what is a growing area of research in modern synthesis
- relationship to adult health in humans
- greater understanding of genetic and epigenetic mechanisms
mendelian inheritance
- mendelian traits; discrete traits that work in classic mendelian fashion
- punnet squares; principles of segregation and independant assortment
mendelian traits
- 1:1 genotype-phenotype relationship
- dominant and recessive
- ex. cystic fibrosis, eye colour, ABO blood group, freckles, sickle cell anaemia
- lactase persistence
monogenic
- variations on dominant-recessive pattern
- traits that are controlled by one gene
- codominance
- incomplete dominance
polygenic
Traits that are controlled by multiple genes, has small and similar effect
pleiotropic
producing more than one trait
gene-linked traits
- alleles that are closer together inherited together at a higher frequency
sex-linked traits
ex. colour blindness, hemophilia
hemophilia
- mutation in factor VII (hemophilia A)
- blood clotting tissue
- X-linked trait; mendelian recessive trait, XYX individuals more likely to express, XX individuals carriers
blood components
- red blood cells (erythrocytes); 45%
- white blood cells (leukocytes); <1%
- plasma (albumin, fibrogen, globulin); 55%
- three allele system, 6 possible genotypes
- A and B alleles are codominant
- O alleles is recessive (h antigen)
- AB+ = universal recipient
- OO- = universal donor
functions of blood components
- immune system; antibodies, antigens
- nutrition transport; hemoglobin
- ABO and Rh blood groups; A, B, O types, Rh blood group, Rh D-positive, Rh D-negative
Karl landsteiner
- transfusion
- blood agglutination
- won noble prize
ABO molecular structure
- blood is determined by chromosome 9 (3 alleles)
- A, B, O blood types are phenotypes
antigens
present on cell
antibodies
present in plasma
agglutination (in a type A recipient)
type A blood of donor > anti-B agglutination of type a recipient > no agglutination
agglutination (in a type B recipient)
type B blood of donor > anit-B agglutination of type A recipient > agglutination > hemolysis
Rh blood group
- Rh+ and Rh-
- D antigen
- there are consequences for mixing Rh+ and Rh-
- Rh+ can donate to other + but not -
- Rh- can donate to anyone
haemolytic disease of the newborn
- Incompatibilities between mother and infant blood types
distribution of blood types
- natural selection
- Differential susceptibility to certain diseases and environmental stressors; smallpox and black death, balance between evolutionary forces
clines
- gradual frequency change; suggests gene flow or natural selection
- abrupt changes; genetic drift or founder effect
hemoglobin
- protein structure
- central iron component
- transportation of oxygen and carbon dioxide
- lack of it causes anemia
hemoglobin abnormalities
sickle cell anemia
sickle cell anemia
- linus pauling, harvey itano, SJ singer, and albert wells
- disease due to abnormal protein; sickle shape
- causes clumping and blockages
- 2 allele system; Hb^A (normal), Hb^B (sickle shape)
- codominant
- single amino acid substitution at gene chromosome 11
- Homozygous for Hb^B have a higher proportion of sickle cell anemia (has it)
- heterozygous for Hb^B have some sickle cells but could be asymptomatic (issues arise as oxygen consumption increases
- homozygous Hb^A all normal shape
effects of sickle cell anemia
- decreased life expectancy
- destruction of sickle cells
- clumping and blockages
- accumulation in spleen
where is sickle cell anemia more prominent
- higher proportions in africa and among african americans, arabian peninsula
malaria
- mosquito-borne disease, female anopheles mosquito
- protozoan parasite plasmodium
- distribution is part of mosquito life style; specialized for human interactions
- endemic in tropical regions
- high mortality
- high prevalence in horticulture and agriculture, increased population density, host and vector co-evolution
sickle cell anemia and malaria
- distribution of sickle cell affected by regions with malaria
- where there is a risk of malaria, there is a selection for Hb^A Hb^B genotype
- causes balancing selection
sickle cell anemia frequencies of people that live a normal healthy life
- Hb^A Hb^A = 0.8
- Hb^A Hb^B = 1.00 (advantage)
- Hb^B Hb^B = 0.2
lactase perstistence and lactose intolerance
- lactose; milk sugar
- milk consumption; digestibility due to lactase enzyme
- Maintaining the ability to digest lactose is lactase persistence, regulatory gene
- they have independent origins
- Convergent evolution; independent path/mutation, have a shared phenotype
common feature to all mammals
- mammary glands; modified sweat glands that produce milk
- female nurse live offspring
