dna, proteins, and ways we are different biological anthropology
TRANSCRIPT
DNA, Proteins, and Ways We Are Different
Biological Anthropology
Remember these guys?
Let’s take a look!
A chromosome contains genes
and genes contain… Deoxyribonucleic Acid
• Present in all living organisms
• Amount varies from organism to organism
• Species can read each others’ DNA
DNA
• Sugar-phosphate backbone”
• Bases are “rungs”adenine = thymine
cytosine = guanine
Genome
the total DNA/genes of a species
• Homo sapiens– app. 3,000,000,000 DNA bases– 35,000 – 40,000 genes
• Honeybee – 300,000,000 DNA bases
• Fruit fly – 13,600 genes
• Bacteria – a few hundred to a few thousand genes
DNA Replication• Produces two identical
strands from one original strand
• Each side of the original is a template for making a new copy of its complement
But what are genes used for?
Protein Synthesis
• A two stage process– Transcription
– Translation
• Our players:– Messenger RNA (mRNA) – the locks
– Transfer RNA (tRNA) – the keys
– Ribosome (“locksmith)
– Amino Acids
Protein Synthesis
1: Transcription• messenger RNA (mRNA) copy of gene is made
• mRNA copy leaves nucleus and goes to cytoplasm
Protein Synthesis
2: Translation
• mRNA copy is “read” by ribosomes
• Ribosomes match tRNA to codons on mRNA
Proteins: the End Result
• One gene codes for one protein
• Differences between individuals due (in part) to differences in their proteins
Protein Synthesis,once again…
• A two stage process1) transcription
2) translation
• The process whereby the DNA message is converted into a protein product
for more information…
Web sites
http://www.dnalc.org/resources/
http://en.wikipedia.org/wiki/
http://www.johnkyrk.com/
http://www.youtube.com/
Key words
• DNA replication
• Protein synthesis
• DNA translation
• Transcription
Evolution defined
A change in allele frequency from one generation to another
drum roll please…
This means that…
the unit of selection is the individual
while
the unit of evolution is the population
Some Examples of Variation in Our Blood Cells
Let’s Start with the 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
Let’s Go Inside…
The Classic Example
Red-Blood Cell Sickling
and Malaria
Red Blood Cells
App. 30 trillion RBC in the human bodyyou 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
Beta Hemoglobin
• Protein consists of 146 amino acids
• Gene consists of 438 bases (146 X 3)
• Protein comes in two forms
Two Forms of Beta Hemoglobin
• Normal Hemoglobin (A)
• Mutated Hemoglobin (S)
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
codominant
codominant
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
Heterozygote Advantage
What possible 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
ABO Differences
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
• The hosts of HIV areCD4 (aka T4 or T-helper) cells
• These 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
Source: US National Institutes of Health - National Institute of Allergy and Infectious Diseases [Public domain],https://commons.wikimedia.org/wiki/File%3AHIV_attachment.gif ; downloaded 24 Nov. 2015
Mechanism by which HIV attaches to and is absorbed into a CD4+ cell