Example OneDiscuss how new discoveries in genetics are contr.docx

Example One
Discuss how new discoveries in genetics are contributing to our
understanding of the HIV virus
and how some folks exposed to HIV have been able to escape
developing AIDS.
The HIV virus daily infects 14,000 people, however some
individuals’ odds of contracting the
virus are very low. Dr. Donald Mosier of the Script Institute
was puzzled by this and launched a
genetic study to determine why certain individuals are resistant
to the HIV virus. What Dr.
Mosier discovered was the resistant people inherited a deletion
mutation that gave them
protection. Within the deletion mutation, the receptor CCR5, is
excluded. This deleted section
of the CCR5 receptor functions as a lock, therefore people born
with the mutation will not get
the HIV virus. Those individuals that are homozygous – have
two copies of the same deletion
gene, are immune to the virus and are protected. Individuals
that are heterozygous – have two
different genes – have some protection from HIV because their
body have half the “locks.” Dr.
Mosier further studied populations and discovered the deleted
mutation was higher in certain
parts of the world and among Caucasians.
Explain the genetic connection between phenotype and genotype
discovered by Mendel in the
19th century.

Genetics helps to understand human diversity, not only in
today’s world but in the past as well.
When studying genetics it is important to understand the
relationship between phenotype and
genotype. A phenotype is defined as an observable physical
characteristic whereas a genotype
is the set of specific genes an organism carries (Allen, Anton,
Stanford 60). In the video lesson,
Anne Stone commented the phenotype can be impacted by the
environment. For example, if
there is not sufficient food or there is disease, this can impact
an individual’s height which is a
phenotype. Anthropologist Geneticist Joanna Mountain
explained a phenotype can be
“measurements and anything we can describe about a person
from appearance to metabolism.”
Utilizing the garden pea plant to conduct his experiment,
Gregor Mendel was able to recognize
traits were passed on from parents to offspring. He knew traits
were inherited but did not know
how this inheritance worked. Mendel’s Principles of
Segregation which states in an organism,
alleles occurs in pairs and when gametes sex cells get produced,
alleles separate so each
gamete contains one member of each pair. Further experiments
by Mendel lead him to
conclude in a unit of inheritance, meaning offspring received
receive genes from each parent.
Theses principles laid the foundation for future scientists to
study inheritance.
Vocabulary
Phenotype – observable characteristics; expression of genetic

instructions; something you can
measure
Genotype – genetic make-up of an individual; every person has
a unique genotype made of
genes inherited from parents
Recessive – a masked trait or covered up
Dominant – mask recessive characteristics
Principles of Segregation – in an organism, alleles occurs in
pairs; when gametes get produced
alleles separate so each gamete contains one member of each
pair
Homozygous – two copies of the dominant alleles are present
Heterozygous – two different alleles at the loci for a gene
Mendelian traits- effected at one gene locus; ex: clef chin
Locus – the location of a gene on a chromosome
Polygenic – a particular trait is influenced by multiple genes;
ex: skin color, height …lots of gene
contribute…”human variation is polygenic.”
Populations – communities of people; can be members of an
ethnic group
Allele Frequency - the allele is the variant and may vary among
populations

Micro evolution – small change in allele frequencies in a
population over generations
Gene flow – the exchange of genes between populations
Gene drift – the genetic make-up of a population is altered by
random factors because the
population is small.
Example Two
a. Explain the genetic connection between phenotype &
genotype discovered by Mendel in the
19th century.
c. Discuss how new discoveries in genetics are contributing to
our understanding of the HIV
virus & how some folks exposed to HIV have been able to
escape developing AIDS.
The genetic connection between genotype and phenotype
discovered by Mendel in the 19th
century explains that Phenotype as explained by Joanna L.
Mountain Phd. an Anthropologist
Geneticist, “Anything that you can measure about a person or
anyway that you can describe a
person for example their appearance is described as the
phenotype”. Genotype is the genetic
makeup of an individual. Every individual has a unique
genotype. The Genotype codes for the
Phenotype. The power lesson explains that you can compare the
genotype to a blue print or a
plan versus the finished product or completed structure.

Donald Mosier Phd MD Immunologist is studying the types of
genetic variation that makes
people virtually immune to HIV as said in the DVD lesson. He
explains how HIV resistant people
have a deletion mutation gene called CCR5 that deletes the
section in DNA that contains
receptors to enter the cell and become infected with HIV. The
DVD lesson explains how some
certain populations carry the mutation gene and how it is passed
to on. According to the DVD
lesson Microevolution is the change in allele frequencies that
occur over time within a
population. This change is due to 4 different processes,
mutation or changes in DNA sequence
of a cells genome, Selection or the process by which traits that
make it more likely for an
organism to survive and successfully reproduce become more
common in a population, Genetic
drift or the change is the frequency in a allele occurs in
population due to random sampling,
and gene flow or the exchange of genes between population.
Definitions:
Phenotype : the set of observable characteristics of an
individual resulting from the interaction of
its genotype with the environment.
Genotype: the genetic constitution of an individual organism
Recessive: pertaining to a gene whose phenotype is masked by a
dominant gene.

Dominant: An allele or a gene that is expressed in an
organism’s phenotype, masking the effect
of the recessive allele or gene when present
Homozygous Dominant: two copies of dominant alleles are
present.
Melanin: a dark brown to black pigment occurring in the hair,
skin, and iris of the eye in people
and animals.
Populations: all the inhabitants of a particular town, area, or
country
Allele Frequency: Variant in frequency from one population to
another.
Microevolution: is the change in allele frequencies that occur
over time within a population
Gene flow: exchange of genes between population
Genetic Drift: the change is the frequency in a allele occurs in
population due to random
sampling
Copyright © 2013 Pearson Education, Inc. All rights reserved.
Exploring Biological Anthropology:
The Essentials, 3rd Edition

CRAIG STANFORD
JOHN S. ALLEN
SUSAN C. ANTÓN
*
As you work through this set of chapter slides, keep in mind the
notations that are included from your instructor. Open, read
carefully, download if necessary, and use in conjunction with
your reading and video lesson study. All these components
supplement each other. The wise student will keep this in mind.
Chapter 4
Genetics: From Genotype to Phenotype
*
How does an organism end up looking like it does? Read on
and learn.
From Genotype to Phenotype
Structural Genes
Regulatory Genes
*
Structural genes contain the information to make a protein.
Regulatory genes direct the expression of structural genes,

without coding for a protein themselves. Think of the
regulatory gene as the traffic cop.
From Genotype to Phenotype (cont’d)
Genotype
Phenotype
*
Think here of the blue print vs. the finished product.
Architectural plan vs. completed structure.
Phenotype refers to one’s particular traits or characteristics.
This individual has blue eyes, so he inherited a genetic marker
for this trait.
*
From Genotype to Phenotype (cont’d)The ABO Blood Type
SystemRecessive, dominant and co-dominant alleles
Obesity: A Complex InteractionGenes, environment, and
phenotype
*
The first here (ABO) refers to the genetic system for one of the

proteins found on the surface of red blood cells. It consists of
one gene with three alleles..A, B, and O.
The second item here is very well documented in our times. Go
to chapter four and flesh out your understanding of it.
Mendelian GeneticsGregor Mendel (1822-1884)Experiments in
particulate inheritanceDiscovered dichotomous
variationDeveloped a series of postulates about inheritance
*
Simply put, genetics as understood by the pioneering scientist
named Mendel (a priest), even though the term “gene” had not
yet been coined. Figure that one out!
Look him up in the textbook and listen carefully to the video
lesson as to who Mendel was and his amazing work in and
around the time of Darwin, even though they did not even know
each other existed.
*
Mendel’s PostulatesHereditary characteristics are controlled by
particulate unit factors that exist in pairs in individual
organisms

When an individual has two different unit factors responsible
for a characteristic, only one is expressed and is said to be
dominant to the other, which is said to be recessive
*
Otherwise put, Mendel’s understanding of the laws of
inheritance, genetically speaking.
Mendel’s Postulates (cont’d)Mendel’s Law of Segregation:
during the formation of gametes, the paired unit factors separate
or segregate randomly so that each sex cell receives one or the
other with equal likelihood
Mendel’s Law of Independent Assortment: during gamete
formation, segregating pairs of unit factors assort independently
of each other
*
You got it. The big boy’s laws continued.
Linkage and AssortmentLinkage: genes found on the same
chromosome are said to be linked. The closer together two
genes are, the greater the linkage
Crossing Over: makes possible the independent assortment of
linked genes
*
Simply put, certain genes are said to be “linked” and are found

very closely together on the chromosome. Crossing over is
what happens when a gene migrates to another “homologous”
chromosome during the first prophase of meiosis. Go for
it…read the relevant page/s on this.
MutationPoint Mutation and Sickle Cell Disease: when a single
base in a gene is changed
Trinucleotide Repeat Disease: involves the insertion mutation
or deletion mutation of several bases in sequence of a
geneHuntington Disease: caused by the repeat of the sequence
CAG (code for glutamine) 40 – 180 times on chromosome 4
*
Any alteration of the DNA that may or may not alter the
function of a cell. Mutations can be good, bad, or even neutral.
Mutation (cont’d)“Bad” MutationsReduction in the protein’s
ability to function, causing mild reduction in fitness with lethal
resultsNeutral Mutations: No change in protein form of
function or slight changes with no effect on reproduction (no
contribution to phenotype)“Good” Mutations:Increases protein’s
ability to function; enhances fitness
*
Yeah, here it is! The good, the bad, and the “innocent” type.

X-Linked Disorders
Genetic conditions that result from mutations to genes
on the X chromosome. They are almost always
expressed in males, who have only one copy
of the X chromosome.
*
Genetic conditions that are entirely x-chromosome based.
Mendelian Genetics in HumansOver the past century, hundreds
of human disorders and diseases have been cataloged, which can
be explained in terms of Mendelian genetic transmissionEarlobe
formPhenylthiocarbamide (PTC) tasting or non-tasting
*
Follow up on this at pp. 62 and following. Very important! On
earlobe form, think “hanging” vs. “attached” earlobe. Check
out your own. What form do you have?
Mendelian Genetics in Humans (cont’d)The Online Mendelian
Inheritance in Man (OMIM) Web site:
(http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=OMIM )
provides an extraordinary database on genetic conditions in
humans, from the most innocuous to the most lethal

*
Go for it! Check out the web site. Live and learn.
Genetics Beyond MendelQualitative variationPhenotypic
variation that can be characterized as belonging to discrete,
observable categoriesQuantitative variationPhenotypic variation
that is characterized by the distribution of continuous variation
within a population
*
Rather self-explanatory. Correct?
Genetics Beyond Mendel (cont’d)Polygenic Traits, the
Phenotype, and the EnvironmentHeritability
The proportion of total phenotypic variability observed for a
given trait that can be ascribed to genetic factors
*
Read up on pp. 72-73.
Genetics Beyond Mendel (cont’d)
Variability caused by genetics
Variability caused by genetics + Variability caused by the

environment
*
Continuation of same reading location.
Genetics Beyond Mendel (cont’d)Heritability and IQ Test Score
PerformanceIQ Test Score Performance
Exhibit continuous variation in human populations, with a
normal distributionGenetics is an important factor in producing
the variation observed within populationsBoth genetics and
environment effect IQ score variation
*
Keep reading. This continues the post Mendelian science of
genetics. By the way, can you spot the misspelling up above
here? Hint…see the final entry in the line up.
Phenylketonuria: Illustrating Mendelian and Post-Mendelian
Concepts
Autosomal recessive condition that leads to the accumulation of
large quantities of the amino acid phenylalanine, which causes
mental retardation and other phenotypic abnormalities
Screening in newbornsNutritional prognosis
*
Very important to know so as to be understanding of

unfortunate folks who, through no fault of their own, are born
with this condition.
Genes and Environments
EnvironmentFrom a gene’s perspective the “environment” is
made up of other genesThe genetic environment is just as
critical to the production of phenotypes as any other kind of
environment
*
Smoke? Binge drink? Do drugs? Pay close attention to this
topic and stay as healthy as possible.

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