Welcome to Part 2 of Bio 219
Lecturer – David Ray
Contact info:
Office hours – 1:00-2:00 pm MWTh
Office location – LSB 5102
Office phone – 293-5102 ext 31454
E-mail – david.ray@mail.wvu.edu
Lectures and other resources are available online at
http://www.as.wvu.edu/~dray.
Go to ‘Courses’ link
Chapter 10:
The Nature of the Gene and the
Genome
Inheritance
• It was clear for millennia that offspring
resembled their parents, but how this
came about was unclear.
• Do males and females harbor
homunculi?
• Do the components of sperm and egg
mix like paint?
• What role do gametes and
chromosomes play?
The Gene
• A review of Gregor Mendel’s work
– Goal was to mate or cross pea plants having different inheritable
characteristics & to determine the pattern by which these
characteristics were transmitted to the offspring
– Four major conclusions
–
–
–
–
1. Characteristics were governed by distinct units of inheritance (genes)
• Each organism has 2 copies of gene that controls development for each trait, one from
each parent
• The two genes may be identical to one another or nonidentical (may have alternate
forms or alleles)
• One of the two alleles can be dominant over the other and mask recessive alleles
when they are together in same organism
2. Gametes (reproductive cells) from each plant have only 1 copy of the gene for each trait;
plants arise from union of male & female gametes
3. Law of Segregation - an organism's alleles separate from one another during gamete
formation (into that organism’s gametes , see point 2).
4. Law of Independent Assortment - segregation of allelic pair for one trait has no effect on
segregation of alleles for another trait. (i.e. a particular gamete can get paternal gene for
one trait & maternal gene for another)
Mendelian Inheritance
• Simple Mendelian inheritance
– Attached earlobes
– PTC (phenylthiocarbamide) tasting
– ‘uncombable hair’
• Complex (multigenic) inheritance
– Eye color
– Height
• Studying inheritance in humans is difficult
for ethical reasons but more easily done in
other organisms
Mendelian Inheritance
• Named for Gregor Mendel
– 1822-1884
– Studied discrete (+/-, white/black) traits in pea
plants
Mendelian Inheritance
• A classic experiment
• What did it tell Mendel?
– That pod color was inherited as
a discrete trait, inheritance was
not ‘blended’ for this trait
– That one trait was ‘dominant’
over the other
• yellow + green ≠ yellow-green
• yellow + green = yellow
Mendelian Inheritance
• By continuing the experiment,
more can be learned
– The trait that was ‘lost’ in the first
generation (F1) was regained by the
second (F2)
• yellow + yellow = yellow and green
– The cause of the trait was not
destroyed, but was harbored unseen
in the parent
– There was a definite mathematical
pattern to the occurrence of the traits
(3:1)
Mendelian Inheritance
• Mendel concluded:
– Heredity was caused by discrete
‘factors’ (genes)
– These ‘factors’ remain separate
instead of blending
– The ‘factors’ came in different ‘flavors’
(alleles)
– Each offspring must inherit one gene
from each parent (2 total)
– The phenotype (appearance) of the
plants was determined by the
genotype (actual combination of
alleles)
Mendelian Inheritance
• The true-breeders only had one type of
allele (homozygous)
• Each parent passes on one of the alleles
they have to the offspring
• The first generation will all be heterozygous
(have two different alleles)
• One of the alleles is able to block the other
(is dominant vs. being recessive)
• The F1’s pass on both of their alleles in a
random manner
• Mendel’s Law of Segregation – two alleles
for each trait separate randomly during
gamete formation and reunite at fertilization
Mendelian Inheritance
• Mendel’s results held true
for other plants (corn,
beans)
• They can also be
generalized to any
sexually reproducing
organism including
humans
Mendelian Inheritance
• Humans don’t typically have families large enough to see
mendelian ratios
• Inheritance can be tracked through the use of pedigrees
• Are the traits in white and black dominant or recessive?
Mendelian Inheritance
BB
bb
Bb
Bb
Bb
Bb
Bb
Bb
bb
Bb
bb
bb
bb
Bb
• If the trait indicated in
black is dominant we
would expect the cross
Bb
between 2 and 3 to
produce either ~50%
black trait and ~50%
white trait offspring or
100% black trait
offspring
Bb
• That ain’t the case
Mendelian Inheritance
bb
BB
Bb
Bb
Bb
Bb
Bb
Bb
• If the trait indicated in
black is recessive we
would expect the cross
between 2 and 3 to
produce all white trait
offspring
• Although it is possible
for individual 3 to have
a Bb genotype, it is
unlikely
• What is the genotype of
#2’s sister?
Mendelian Inheritance
• Using the information from the previous slides we can
deduce most individual’s genotypes
Bb
BB
B?
bb
Bb
B?
B?
Bb
Bb
bb
Bb
Bb
Bb
Bb
Bb
Bb
Bb
bb
Bb
bb
bb
bb
bb
Bb
bb
bb
Mendelian Inheritance
• The examples above are referred to as
monohybrid crosses since they deal with
only one trait at a time
• Mendel also followed dihybrid crosses in
which two traits are followed at once
• Would the traits segregate as a single unit
or independently?
Mendelian Inheritance
• A dihybrid cross
Mendelian Inheritance
• A dihybrid cross produced all
possible phenotypes and
genotypes
• Thus, all of the alleles behaved
independently of one another
• Mendel’s Law of Independent
Assortment – Each pair of alleles
segregates independently during
gamete formation
The Gene
• A review of Gregor Mendel’s work
– Goal was to mate or cross pea plants having different inheritable
characteristics & to determine the pattern by which these
characteristics were transmitted to the offspring
– Four major conclusions
–
–
–
–
1. Characteristics were governed by distinct units of inheritance (genes)
• Each organism has 2 copies of gene that controls development for each trait, one from
each parent
• The two genes may be identical to one another or nonidentical (may have alternate
forms or alleles)
• One of the two alleles can be dominant over the other and mask recessive alleles
when they are together in same organism
2. Gametes (reproductive cells) from each plant have only 1 copy of the gene for each trait;
plants arise from union of male & female gametes
3. Law of Segregation - an organism's alleles separate from one another during gamete
formation (into that organism’s gametes , see point 2).
4. Law of Independent Assortment - segregation of allelic pair for one trait has no effect on
segregation of alleles for another trait. (i.e. a particular gamete can get paternal gene for
one trait & maternal gene for another)
Clicker Question
• Like most elves, everyone in Galadriel’s family has pointed ears (P),
which is the dominant trait for ear shape in Lothlorien. Her family
brags that they are a “purebred” line. She married an elf with round
ears (p), which is a recessive trait. Of their 50 children (elves live a
long time), three have round ears.
• What are the genotypes of Galadriel and her husband?
• ♀ = Galadriel; ♂ = husband
• A. ♀ PP; ♂PP
• B. ♀ pp; ♂ pp
• C. ♀ PP; ♂ Pp
• D. ♀ Pp; ♂ pp
Review from last time
• Office hours are MWTh, not MTW
• Mendel crossed pea plants with easily discernible traits
to develop four ideas
• Genes are the carriers of inheritable traits
• Genes can come in different versions – alleles
• Law of Segregation – the alleles separate when gametes
are formed
• Law of Independent assortment – the alleles of one gene
segregate without regard to the alleles of other genes
• All of these ideas are important to our understanding of
chromosomes and genome structure
Chromosomes
• Mendel made no effort to describe what carried the genes, how
they were transmitted, or where they resided in an organism
•
1880s – Chromosomes are discovered because of:
–
–
–
•
1. Improvements in microscopy led to…
2. observing newly discernible cell structures..
3. and the realization that all the genetic information needed to build & maintain a complex
plant or animal had to fit within the boundaries of a single cell
Walther Flemming observed:
–
–
1. During cell division, nuclear material became organized into visible threads called
chromosomes (colored bodies)
2. Chromosomes appeared as doubled structures, split to single structures & doubled at next
division
– Were chromosomes important for inheritance?
Chromosomes
• Are chromosomes important for inheritance?
– Uhhh, yeah.
– Theodore Boveri (German biologist) - studied sea urchin eggs fertilized
by 2 sperm (polyspermy) instead of the normal one single sperm
• 1. Disruptive cell divisions & early death of embryo
• 2. Second sperm donates extra chromosome set, causing abnormal cell
divisions
• 3. Daughter cells receive variable numbers of chromosomes
• Conclusion - normal development depends upon a particular combination of
chromosomes & that each chromosome possesses different qualities
• There is a qualitative difference among chromosomes
Chromosomes
• Are chromosomes important for inheritance?
– Whatever the genetic material is, it must behave in a manner consistent
with Mendelian principles
– Ascaris egg & sperm nuclei had 2 chromosomes each before fusion
– Somatic cells had 4 chromosomes
– Haploid vs. Diploid
• Haploid – having a single complement of chromosomes in a cell
• Diploid – having a double set of chromosomes in a cell
• Humans gametes? Human somatic cells?
– meiotic division must include a reduction division during which
chromosome number was reduced by half before gamete formation
• If no reduction division, union of two gametes would double chromosome
number in cells of progeny
• Double chromosome number with every succeeding generation
Chromosomes
• Are chromosomes the carriers of genetic information
•
•
•
•
– Whatever the genetic material is, it must behave in a manner consistent
with Mendelian principles
Walter Sutton (1903) –pointed directly to chromosomes as the carriers of
genetic factors
Studied grasshopper sperm formation and observed:
23 chromosomes (11 homologous chromosome pairs & extra accessory (sex
chromosome))
2 different kinds of cell division in spermatogonia
–
–
•
mitosis (spermatogonia make more spermatogonia)
meiosis (spermatogonia make cells that differentiate into sperm)
Hypothesized that homologous pairs correlated with Mendel's inheritable
pairs of factors
Chromosomes
• In meiosis, members of each pair
associate with one another then
separate during the first division
• This explained Mendel's proposals
that :
– hereditary factors exist in pairs that
remain together through organism's life
until they separate with the production of
gametes
– gametes only contain 1 allele of each
gene
– the number of gametes containing 1 allele
was equal to the number containing the
other allele
– 2 gametes that united at fertilization
would produce an individual with 2 alleles
for each trait (reconstitution of allelic
pairs)
– Law of segregation
A a
AA aa
AA aa
A A
Aa
a
a
Chromosomes
• What about Mendel’s Law of
Independent Assortment?
– Having traits all lined up on a
chromosome suggests that they
would assort together, not
independently….
– as a linkage group
– Experiments in Drosophila
showed that most genes on a
chromosome did assort
independently… how?
– Crossing over and
Recombination to the rescue!
Human
chromosome 2
Chromosomes
• What about Mendel’s Law of
Independent Assortment?
– 1909 –homologous chromosomes
wrap around each other during
meiosis
– breakage & exchange of pieces of
chromosomes
Chromosomes
Typically, several cross-over events will occur between
well-separated genes on the same chromosome. Therefore,
genes E and F or D and F are no more likely to be co-inherited
than genes on different chromosomes.
Genes that are very close together (A and B), on the other hand,
are less likely to have cross-over events occur between them.
Thus, they will often be co-inherited (linked) and do not
strictly follow the Law of Independent Assortment.
Chromosomes
• Chromosome mapping via
linkage maps
• Since the likelihood of alleles
being inherited together is
influenced by their proximity…
• Genetic maps were possible by
determining the frequency of
recombination between traits
Clicker Question
• Three genes (1, 2, and 3) are present on a chromosome. The
recombination frequencies between them are:
• 1-2 = 11%
• 1-3 = 2%
• 2-3 = 13%
• Which diagram best approximates the relative locations of the genes
on the chromosome?
A.
1
2
3
B.
C.
D. 1 2
2
1
2
3
1 3
3
Review from last time
• Based on Mendel’s work, people now had a conceptual framework
on which to base ideas on the physical nature of inheritance
• One of the potential locations for genes was on chromosomes
• During meiosis, chromosome behave much like the hypothesized
genes appear to behave
• Chromosomal abnormalities have severe effects on organismal
development and survivability
• The law of independent assortment at first appeared to be a problem
for chromosomal inheritance
• Recombination and crossing over allow for independent assortment
to occur in most cases
• Tracking linked genes allowed for the first genome ‘maps’
• Despite the fact that proteins look like better candidates for the
genetic material, DNA actually is
• DNA is a polymer made up of deoxyribose (sugar), phosphate, and
a nitrogenous base
Chemical Nature of the Gene
• Review of nucleic acid
structure:
– Phosphate
– Sugar
• Ribose or deoxyribose
– Nitrogenous base
•
•
•
•
Purines
Adenine and Guanine
Pyrimidines
Cytosine andThymine/Uracil
Chemical Nature of the Gene
• Review of nucleic acid
structure:
– Chargaff’s rules
– [A] = [T], [G] = [C]
– [A] + [T] ≠ [G] + [C]
– Suggested base pairing to
Watson and Crick, who later
went on to describe the overall
structure of DNA in vivo
Chemical Nature of the Gene
• Review of nucleic acid
structure:
– Sugar-phosphate backbone
– Nitrogenous base rungs
– Directional – 5’ to 3’
Chemical Nature of the Gene
• Review of nucleic acid structure:
• Is DNA the genetic material?
• What must the genetic material do?
• Store genetic information
• Be replicable and inheritable
• Be able to express the genetic message
• DNA fits the bill for two of these
Genome Structure
• Genome – the complete genetic
complement of an organism; the unique
content of genetic information;
•
•
•
Early experiments to determine the structure of the
genome took advantage of the ability of DNA to be
denatured
Denaturation – separation of the double helix by the
addition of heat or chemicals
How to monitor this separation?
• DNA absorbs light at ~260nm
• ss DNA absorbs more light, dsDNA less light
Clicker Question
• Which of the following 12 bp double helices will denature most
quickly?
A. 5’-AATCTAGGTAC-3’
3’-TTAGATCCATG-5’
C. 5’-AATTTAGATAT-3’
3’-TTAAATCTATA-5’
B. 5’-GGTCTAGGTAC-3’
3’-CCAGATCCATG-5’
D. They are all DNA, they will all
denature at the same rate.
Genome Structure
• DNA renaturation (reannealing) – the reassociation
of single strands into a stable double helix
• Seems unlikely give the size of some genomes but
it does happen.
• What does renaturation analysis allow?
•
•
•
Investigations into the complexity of the genome
Nucleic acid hybridization – mixing DNA from different
organisms
Most modern biotechnology – PCR, northern blots, southern
blots, DNA sequencing, DNA cloning, mutagenesis, genetic
engineering
Genome Structure
• Genome complexity - the variety & number of DNA
sequence copies in the genome
• Renaturation kinetics – what determines renaturation
rate?
• Ionic strength of the solution
• Temperature
• DNA concentration
• Incubation length
• Size of the molecules
Genome Structure
• Complexity in bacterial and viral genomes
A Cot curve uses the
Concentration and time
necessary for a genome
to renature to characterize
a genome
Simple genomes have
simple Cot curves
• MS-2 virus – 4000 bp genome
• T4 virus – 180,000 bp genome
• E. coli – 4,500,000 bp genome
Why do the smaller genomes
renature more quickly?
Genome Structure
• Complexity in eukaryotic genomes
• Eukaryotic Cot curves are more complex because the
genomes consist of different fractions
Genome Structure
• Complexity in eukaryotic genomes
• Highly repetitive DNA – Satellite DNAs - ~1-10% of
eukaryotic genomes
• Identical or nearly identical, tandemly arrayed
sequences
• Minisatellites – 10 – 100 bp repeats
• 5’- ATCAAATCTGGATCAAATCTGGATCAAATCTGG-3’
• Microsatellites – 1 – 10 bp repeats
• 5’-ATCATCATCATCATCATCATC-3’
Genome Structure
• Complexity in eukaryotic genomes
• Highly repetitive DNA – the
importance of satellite DNA
•
•
Centromeric DNA – the sections of
chromosomes essential for proper cell
division are mostly microsatellite DNA
DNA fingerprinting utilizes polymorphic microand minisatellite DNA – CODIS loci
Genome Structure
• Complexity in eukaryotic genomes
• Repeat expansion and human pathogenicity
•
•
•
•
•
•
A CAG expansion in the huntingtin gene is associated with severity of
Huntington’s disease
CAG expansion produces long runs of glutamates in proteins
Polyglutamate chains tend to aggregate.
Inverse relationship between CAG repeat size and severity of
disease.
Normal range = (CAG)6 – (CAG)39
Disease range = (CAG)35 – (CAG)121
Genome Structure
• Complexity in eukaryotic genomes
• Moderately repetitive DNA – 10-80% of eukaryotic
genomes
• Coding repeats – Ribosomal RNA genes
• rRNA is necessary in large amounts
• Genes are arrayed tandemly
• Noncoding repeats – Interspersed aka mobile aka
transposable elements
• ~1/2 of your genome
• More on these later
Genome Stability
• Eukaryotic genomes are very dynamic over long
and short periods of time
• Whole genome duplication aka polyploidization
• offspring are produced that have twice the number of
chromosomes in each cell as their diploid parents
• May occur in either of two ways:
•
•
Two related species mate to form a hybrid organism that contains
the combined chromosomes from both parents (occurs most
often in plants)
Single-celled embryo undergoes chromosome duplication but
duplicates are not separated into separate cells, but are retained
in single cell that develops into viable embryo (most often in
animals)
Genome Stability
• Whole genome duplication aka polyploidization
• Polyploidization provides HUGE evolutionary
potential
• "extra" genetic information can:
- be lost by deletion
- be rendered inactive by deleterious mutations
- evolve into new genes that possess new functions
Review from last time
• The structure of DNA was resolved by Watson and Crick and was
aided by the observation of Chargaff’s Rule
• DNA is a directional double helix
• The genome is the complete DNA complement of an organism
• Information on genome content and complexity can be obtained by
DNA denaturation/renaturation experiments
• A Cot curve can provide details about the size and complexity of a
genome
• Eukaryotic genomes typically have three Cot fractions, highly
repetitive, middle repetitive and single copy
• The highly repetitive portions are made up primarily of micro and
minisatellites
• Satellite DNA is important as a functional component and also as a
genetic marker
• The middle repetitive portion can be coding or non-coding
• Genomes are dynamic and can undergo genome duplication
Genome Stability
• Gene duplication - duplication of a small portion of a
single chromosome
• Much more common than whole genome duplication
• Thought to occur most often via unequal crossover
•
•
Misalignment of chromosomes during meiosis
Genetic exchange causes one chromosome to acquire an extra
DNA segment (duplication) & the other to lose a DNA segment
(deletion)
Genome Stability
• Gene duplication – the globin cluster in primates
• Hemoglobin consists of 4 globin polypeptides
• (2 pairs: 1 pair always in ά-family, 1 in β-family)
• combinations differ with developmental stage
(embryonic, fetal, adult)
Genome Stability
• Gene duplication – the
globin cluster in primates
• Each gene is built of 3 exons
(coding sequences) & 2 introns
(noncoding intervening
sequences)
Transposable Elements and the Genome
– Transposable elements are sequences that
are interspersed throughout all eukaryotic
genomes examined.
– They play a role in the structure, function, and
evolution of the genome
Transposable Elements and the Human Genome
– Types of transposable elements
• Class I
– Retrotransposons
– LINEs, SINEs, SVA, LTR, ERV
– Defined as having an RNA intermediate
• Class II
– DNA transposons
– Mariner, hAT, piggyBac
– Defined as having a DNA intermediate
Transposable Elements and the Human Genome
• Class II elements in the human genome
DR ITR
Transposase gene
1 – 3 kb
ITR DR
Autonomous transposon
hAT, mariner, Tc1, piggyBac, etc.
XXX
DR ITR
<1kb
ITR DR
Nonautonomous transposon
MERs (100+ types), Arthur1, FordPrefect
• Class II elements – cut and paste mobilization
• http://www.public.iastate.edu/~jzhang/Transposition.html
Transposable Elements and the Human Genome
• Class I elements in the
human genome
– LTR vs non-LTR
retrotransposons
– LTRs, such as HERVs
are relatively quiet in
the human genome but
do occasionally
retrotranspose
LTR Retrotransposon
TSD LTR
gag
pol
env
1 - 11 kb
LTR TSD
LINE
TSD 5’UTR
ORF1
ORF2
(A)n
6 – 8 kb
SINE
TSD
A B
(A)n
0.1 – 0.5 kb
TSD
3’UTR TSD
Generating Genetic Variation:
Normal SINE mobilization
Reverse transcription
and insertion
Pol III transcription
1. Usually a single ‘master’ copy
2. Pol III transcription to an RNA intermediate
3. Target primed reverse transcription (TPRT) – enzymatic machinery
provided by LINEs
Mobile Element Insertions and Mutation
Promoter
alters gene
expression
disrupts
reading
frame
disrupts
splicing
no disruption
ALU INSERTIONS AND DISEASE
LOCUS
BRCA2
Mlvi-2
DISTRIBUTION
de novo
de novo (somatic?)
SUBFAMILY
Y
Ya5
de novo
Familial
Ya5
Yb8
about 50%
Ya5
Familial
Y
Familial
one Japanese family
Ya5
Yb8
familial
Ya4
C1 inhibitor
ACE
de novo
about 50%
Y
Ya5
Factor IX
2 x FGFR2
GK
a grandparent
De novo
?
Ya5
Ya5
NF1
APC
PROGINS
Btk
IL2RG
Cholinesterase
CaR
Sx
DISEASE
Breast cancer
Associated with
leukemia
Neurofibromatosis
Hereditary desmoid
disease
Linked with ovarian
carcinoma
X-linked
agammaglobulinaemia
XSCID
Cholinesterase
deficiency
Hypocalciuric
hypercalcemia and
neonatal severe
hyperparathyroidism
Complement deficiency
Linked with protection
from heart disease
Hemophilia
Apert’s Syndrome
Glycerol kinase
deficiency
REFERENCE
Miki et al, 1996
Economou-Pachnis and
Tsichlis, 1985
Wallace et al, 1991
Halling et al, 1997
Rowe et al, 1995
Lester et al, 1997
Lester et al, 1997
Muratani et al, 1991
Janicic et al, 1995
Stoppa Lyonnet et al, 1990
Cambien et al, 1992
Vidaud et al, 1993
Oldridge et al, 1997
McCabe et al, (personal
comm.)
Generating Genetic Variation:
Exon shuffling via
SINE mobilization
exon 1
SINE
exon 2
intron
DNA copy of transcript
SINE
exon 2
SINE transcription can extend past the normal stop signal
Reverse transcription creates DNA copies of both the SINE and exon 2
Reinsertion occurs elsewhere in the genome
Genome Analysis
How many human genes?
80,000 Antequera F & Bird A, “Number of CpG islands and genes in
human and mouse”, PNAS 90, 11995-11999 (1993).
120,000 Liang F et al., “Gene Index analysis of the human genome
estimates approximately 120,000 genes”, Nat. Gen., 25, 239-240 (2000)
35,000 Ewing B & Green P, “Analysis of expressed sequence tags
indicates 35,000 human genes”, Nat. Gen. 25, 232-234 (2000)
28,000-34,000 Roest Crollius, H. et al., “Estimate of human gene number
Provided by genome-wide analysis using Tetraodon nigroviridis DNA
Sequence”, Nat. Gen. 25, 235-238 (2000).
41,000-45,000 Das M et al., “Assessment of the Total Number of Human
Transcription Units”, Genomics 77, 71-78 (2001)
Genome Analysis
• Sequencing a eukaryotic genome has become relatively
easy
• Figuring out what it all means is the hard part
• Human genome - ~25-30,000 genes (latest estimate)
• Nematode worm - ~25,000 genes
• Mustard plant - ~25,000 genes
• Puffer fish - ~25,000 genes
• What explains the differences in complexity and function
among different genomes?
• Comparative genomics suggests:
• Alternative splicing (more later)
• Differential regulation (more later)
Genome Analysis
• What explains the differences in
complexity and function among different
genomes?
• The protein-coding portion of the human
genome represents a remarkably small
percentage of total DNA (~1.1-1.6%)
•
•
The great majority of the genome consists
of DNA that resides between the genes &
thus represents intergenic DNA
Each of the 25-30,000 or more proteincoding genes consists largely of
noncoding portions (intronic DNA)
• How do we figure out what is a gene and
what isn’t?
Genome Analysis
• How do we determine what is important in a genome?
• Comparative genomics
• Most of the intergenic & intronic DNA of genome does not
contribute to the reproductive fitness of an individual
• Not subject to any significant degree of natural selection
• Thus, intergenic & intronic sequences tend to change rapidly as
organisms evolve; are not conserved
• Portions of the genome that code for protein sequences &
regulatory sequences that control gene expression are subject
to natural selection; tend to be conserved among related
species.
…
…
Genome Analysis
• Comparative genomics
• Finding the conserved regions tells us much about what makes
organisms similar
• What tells us what makes us (or other organisms) different from one
another?
Genome Analysis
• Comparative genomics
• The chimpanzee genome sequence was completed in 2005
• Much of what makes us human is likely to be determined through
finding differences between our genome and that of the chimp
Genome Analysis
• Comparative genomics
• FOXP2 a regulatory gene common to many vertebrates
• 2 amino acid differences are human specific (found only in
humans, not chimps or any other studied organism)
Genome Analysis
• Comparative genomics
• FOXP2 a regulatory gene common to many vertebrates
• Persons with mutations in FOXP2 gene suffer from a severe
speech & language disorder
• They are unable to perform the fine muscular movements of lips
& tongue that are required to engage in vocal communication
• Changes in FOXP2 that distinguish it from the chimp version
were fixed in human genome in the past 120,000 - 200,000
years; around the time modern humans may have emerged