Download Physical Anthropology

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
Alleles
A
B
O
Genotype
codominant
recessive
AA, AO
BB, BO
OO
AB
Phenotype
A
B
O
AB
ABO Differences
Rh (Rhesus) Blood Group
Alleles
Genotype
Phenotype
D
dominant
DD, Dd
Rh+
d
recessive
dd
Rh-
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:
Codon
GGA CTC CTC TTT
#5
Amino Acid #6
#6
#7
Glutamic Acid
#8
The “Mutated” Situation
(HbS allele)
DNA:
Codon
GGA CAC CTC TTT
#5
Amino Acid #6
#6
Valine
#7
#8
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
Alleles
Genotype
Phenotype
HbA
dominant
HbA HbA
normal
HbS
recessive
HbA HbS
sickle-cell trait
HbS HbS
sickle-cell anemia
Red Blood Cells
‘donut’ shaped
sickle 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
• About 8% of African
Americans are carriers
of sickle cell disease
• More than 70,000 people
have sickle cell disease
• Two million people have
sickle cell trait
• Sickle cell disease occurs
in 1 in every 500 African
Americans
• 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 advantage
could 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/originsof-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 infection
33 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