Biological Anthropology Ways in Which We Differ (and why that can matter)
Biological Anthropology
Ways in Which We Differ(and why that can matter)
Red Blood Cells
App. 30 trillion RBC in the human body
you are both destroying (and making) new red blood cells at a rate of around 2.7 million cells
per second.
Every red blood cell contains about 270 million hemoglobin molecules, each one capable of carrying four oxygen molecules
Let’s Start Outside?
ABO Blood Group
Genotype
AA, AO
BB, BO
OO
AB
Phenotype
A
B
O
AB
Alleles
A
B
O
codominant
recessive
ABO Differences
Rh (Rhesus) Blood Group
Genotype
DD, Dd
dd
Phenotype
Rh+
Rh-
Alleles
D
d
dominant
recessive
Maternal/Infant Rh Incompatibility
Now Let’s Go Inside…
Red Blood Cells
App. 30 trillion RBC in the human body
you are both destroying (and making) new red blood cells at a rate of around 2.7 million cells
per second.
Every red blood cell contains about 270 million hemoglobin molecules, each one capable of carrying four oxygen molecules
Two Forms of Beta Hemoglobin
• Normal Hemoglobin (A)
• Mutated Hemoglobin (S)
Beta Hemoglobin
• Protein consists of 146 amino acids
• Gene consists of 438 bases (146 X 3)
• Protein comes in two forms
The “Normal” Situation(HbA allele)
DNA: GGA CTC CTC TTTCodon #5 #6 #7 #8
Amino Acid #6 Glutamic Acid
The “Mutated” Situation(HbS allele)
DNA: GGA CAC CTC TTTCodon #5 #6 #7 #8
Amino Acid #6 Valine
The Difference is in Codon #6
Normal allele: CTC Normal A.A.: Glutamic Acid
Mutated allele: CAC Substituted A.A.: Valine
Everything else is the same:
145 identical amino acids
437 identical DNA bases
Sickle-Cell
Genotype
HbA HbA
HbA HbS
HbS HbS
Phenotype
Alleles
HbA
HbS
dominant
recessive
normal
sickle-cell trait
sickle-cell anemia
Red Blood Cells
‘donut’ shapedsickle shaped
A simple mutation with multiple effects
Sickle-Cell in the U.S.
• Sickle cell anemia is the most common inherited blood disorder in the US
• More than 70,000 people have sickle cell disease
• Sickle cell disease occurs in 1 in every 500 African Americans
• About 8% of African Americans are carriers of sickle cell disease
• Two million people have sickle cell trait
• Approximately 1 in 12 African Americans has sickle cell trait
Balanced Polymorphism
Situation in which selection maintains
two or more phenotypes
for a specific gene
Heterozygote Advantage
What advantagecould sickle-cell offer?
Malaria
• Infectious disease caused by
• Falciparum plasmodium
• Mosquito is carrier
Malaria
• perhaps the most deadly organism in the world (to humans)
• 300-500 million people in the world
• 1-1.5 million people die each year
Malaria• Parasite infects
blood
• Part of life cycle occurs in red blood cells
• Population continuously infected
Distribution of Malaria
Distribution of the HbS
allele
The Connection
• Heterozygote has greatest fitness in malarial environment
• Both high in frequency
Viruses
• Not alive
• Require host cell to reproduce
• Symptoms and effects relate to which host cells are used
Viruses
• Viruses use the cells genetic machinery to make new copies
Influenza A Virus
•Highly variable surface structures
•Mutates readily
•Avoidance behaviors
frequent handwashing
covering coughs
having ill persons stay home, (except to seek medical care)
minimize contact with others in the household who may be ill with swine-origin influenza virus.
Model of the influenza A virus showing HA and NA receptors projecting from the surface of the virus.Source: http://www.udel.edu/chem/white/C647/FluVirus.GIF; accessed May 5, 2009.
H1N1 Virus
H1N1 Virus
A “triple reassortment” virus consisting of human, avian, and swine influenzas
Virus strains 90% identical to H1N1 have been circulating in swine for approximately 10 years
Combination of viral strains thought to have arisen when live pigs were transported between North America and Eurasia
Source: http://www.gate2biotech.com/origins-of-the-swine-flu-virus/; accessed on 24 Nov. 2009
HIV Virus
• HIV uses T-cells as hosts
• T-cells are part of the body’s immune system
• Infection can lead to AIDS
From HIV to AIDS
• HIV+– exposure to virus and
antibody production
• CD4 (t-cell) count drops after infection, rebounds, then diminishes
• ≤ 200 = “AIDS”– Acquired Immune
Deficiency Syndrome
A global view of HIV infection33 million people [30–36 million] living with HIV, 2007
2.2
Ebola Zaire
Electron micrograph of Zaire Ebola virus. This is the first photo ever taken, on 10/13/1976 by Dr. F.A. Murphy, now at UC Davis, then at CDC. Diagnostic specimen in cell culture at 160,000 x magnification.
Ebola Zaire
Majority of cases are lethal
The virus’ genome consists of 18,959 nucleotide bases
Animal Source?
Cumulative reported cases in Guinea, Liberia, and Sierra Leone
provided in WHO situation reports beginning on March 25, 2014 through the most recent situation report on November 26, 2014.
Source: http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/cumulative-cases-graphs.html; accessed 30/11/2014