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