-
Lecture 1 - Evolution and Genes (Ch2)
Can you inherit depression?
- Gene → does not cause depression
- Certain combinations of genes can predispose to a particular illness, diathesis stress
model
Taxonomic categorization of evolution
Homo sapiens - current human species
- Y-chromosomal adam = most recent common ancestor from whom all currently living
people are descended patrilineally
- Mitochondrial eve = the most recent woman from whom all living humans are descended
matrilineally through transmission of mitochondrial DNA
Out of Africa Theory - homo sapiens migration 200 000 years ago
Human genetic variation
- People are 99.9% genetically identical - the 0.1% genetic diff ⇒ all differences in
phenotype
- Human genome project identified the genetic makeup of humans ⇒ 20 000 genes,
which are instructions for making proteins
- 2% of DNA are functional genes coding for proteins - rest is junk DNA, tightly wrapped in
chromosomes in the nucleus of each cell
Charles Darwin → Natural Selection
- Traits become more common based on:
- Variation (within species, may be caused by mutation)
- Heritability (traits can be passed down)
- Struggle for existence/competition
- Survival and reproductive rates
- ADHD - disorder due to imbalances in Dopamine
- ADHD gene inherited? Why?
, -
- Maybe ADHD served an adaptive function, where ADHD individuals way back
were better hunters and explorers - increased cognitive and behavioral flexibility;
in today’s environmental conditions it is maladaptive - but this is just theoretical
conjecture, relative lack of evidence to support this theory
- In opposition, ADHD reduces survival and reproductive advantage because it
reduces the development of executive functions
- Adhd behaviors = spandrels = not adaptations, not reproductively beneficial,
occur linked to other beneficial adaptations
- The gene related to ADHD is more prevalent in nomadic tribes, and among
nomads, those with the gene were better nourished; ADHD traits are useful to
groups as long as the ADHD group is a minority
- Supported by evidence from:
- Biogeography (see diff in temperature and adaptations to env
- Fossil records - tracking changes in physiology in our ancestors
- Structural similarity
- Embryology - Ontogeny recapitulates phylogeny theory
- Molecular biology
Karyotypes = matching pairs of chromosomes in nucleus of cells = organised set of
chromosomes
- 23 chromosomes, 46 chromatids; centromere at the center, no genetic info there,
important for cellular division
- 22 identical pairs from mother and father, 1 set of sex chromosomes
- Karyotypes displayed schematically can help identify genetic diseases (trisomy 21,
turner syndrome etc)
- Turner syndrome is a woman with only 1 X chromosome - low estrogen,
underdeveloped
Dna in the Cell
- Histones are proteins on which the DNA folds
- Genome = whole genetic information of an organism
- Chromosome = long strand of DNA wound around
histones
- Cytogenetic bands = stripes on stained chromosomes
used to locate genes
- Telomere = repetitive region of DNA, protects the DNA
during replication and division; during every division the telomere
gets shorter, until it starts to die
- Allele = the two alternative forms of a gene found at the
same place on homologous chromosome (one allele from each
parent
- Meiosis → 23 pairs of chromosomes vellularly divided into
haploid (23 unpaired chromosomes); fertilization makes them
diploid again (zygote, which then grows through mitosis (initially,
, -
for mitosis, the cell doubles its chromosomes, which allows it to be diploid)
- Meiosis is different for sperm vs eggs - ADD diagram
- Crossing over can occur during meiosis
- Linkage = certain characteristics or alleles inherited together as they are located close
by on the chromosome
- Crossing over and
linkage ensure genetic
diversity
- autosomal dominant trait = Huntington’s
- Late onset, so the gene may have already reproduced by the
time the diseases appears - genetic counseling
- Mother is homozygous, father is heterozygous
- Here there can’t be carriers - you either have the dominant allele
and Huntington’s or you are unaffected
PKU (phenylketonuria) - recessive autosomal disease, form of delayed cognitive
maturation; small head size, hyperactivity, jerking moevements, mental
impairment, rashes, tremors; people who don’t have both recessive alleles are
carriers.
- Sons can’t be carrier - either inherited the recessive allele or
the dominant, but it is still expressed because it is X-linked
Genotype = genetic makeup of a cell
Phenotype = observed trait in the organism, based on genes and
environment
- In women one X chromosome
(either from mom or dad) is activate and
the other deactivated in some cells are
others in the embryo
, -
DNA = information for making proteins; reproduction tool
- Nucleus: transcription = a gene is copied into mRNA
- Cytoplasm: translation = mRNA is translated into a protein at the ribosome
- 3 nucleotides → codon → amino acids → proteins → enzymes or other functions
Replication
- the Dna unravels and unzips; the
free nucleotides attract
unattached bases in the nucleus
⇒ new strand of DNA
- Errors can occur, mutations like
HD and PKU, but other beneficial
ones that may be passed down
Protein Synthesis → Transcription
Lecture 1 - Evolution and Genes (Ch2)
Can you inherit depression?
- Gene → does not cause depression
- Certain combinations of genes can predispose to a particular illness, diathesis stress
model
Taxonomic categorization of evolution
Homo sapiens - current human species
- Y-chromosomal adam = most recent common ancestor from whom all currently living
people are descended patrilineally
- Mitochondrial eve = the most recent woman from whom all living humans are descended
matrilineally through transmission of mitochondrial DNA
Out of Africa Theory - homo sapiens migration 200 000 years ago
Human genetic variation
- People are 99.9% genetically identical - the 0.1% genetic diff ⇒ all differences in
phenotype
- Human genome project identified the genetic makeup of humans ⇒ 20 000 genes,
which are instructions for making proteins
- 2% of DNA are functional genes coding for proteins - rest is junk DNA, tightly wrapped in
chromosomes in the nucleus of each cell
Charles Darwin → Natural Selection
- Traits become more common based on:
- Variation (within species, may be caused by mutation)
- Heritability (traits can be passed down)
- Struggle for existence/competition
- Survival and reproductive rates
- ADHD - disorder due to imbalances in Dopamine
- ADHD gene inherited? Why?
, -
- Maybe ADHD served an adaptive function, where ADHD individuals way back
were better hunters and explorers - increased cognitive and behavioral flexibility;
in today’s environmental conditions it is maladaptive - but this is just theoretical
conjecture, relative lack of evidence to support this theory
- In opposition, ADHD reduces survival and reproductive advantage because it
reduces the development of executive functions
- Adhd behaviors = spandrels = not adaptations, not reproductively beneficial,
occur linked to other beneficial adaptations
- The gene related to ADHD is more prevalent in nomadic tribes, and among
nomads, those with the gene were better nourished; ADHD traits are useful to
groups as long as the ADHD group is a minority
- Supported by evidence from:
- Biogeography (see diff in temperature and adaptations to env
- Fossil records - tracking changes in physiology in our ancestors
- Structural similarity
- Embryology - Ontogeny recapitulates phylogeny theory
- Molecular biology
Karyotypes = matching pairs of chromosomes in nucleus of cells = organised set of
chromosomes
- 23 chromosomes, 46 chromatids; centromere at the center, no genetic info there,
important for cellular division
- 22 identical pairs from mother and father, 1 set of sex chromosomes
- Karyotypes displayed schematically can help identify genetic diseases (trisomy 21,
turner syndrome etc)
- Turner syndrome is a woman with only 1 X chromosome - low estrogen,
underdeveloped
Dna in the Cell
- Histones are proteins on which the DNA folds
- Genome = whole genetic information of an organism
- Chromosome = long strand of DNA wound around
histones
- Cytogenetic bands = stripes on stained chromosomes
used to locate genes
- Telomere = repetitive region of DNA, protects the DNA
during replication and division; during every division the telomere
gets shorter, until it starts to die
- Allele = the two alternative forms of a gene found at the
same place on homologous chromosome (one allele from each
parent
- Meiosis → 23 pairs of chromosomes vellularly divided into
haploid (23 unpaired chromosomes); fertilization makes them
diploid again (zygote, which then grows through mitosis (initially,
, -
for mitosis, the cell doubles its chromosomes, which allows it to be diploid)
- Meiosis is different for sperm vs eggs - ADD diagram
- Crossing over can occur during meiosis
- Linkage = certain characteristics or alleles inherited together as they are located close
by on the chromosome
- Crossing over and
linkage ensure genetic
diversity
- autosomal dominant trait = Huntington’s
- Late onset, so the gene may have already reproduced by the
time the diseases appears - genetic counseling
- Mother is homozygous, father is heterozygous
- Here there can’t be carriers - you either have the dominant allele
and Huntington’s or you are unaffected
PKU (phenylketonuria) - recessive autosomal disease, form of delayed cognitive
maturation; small head size, hyperactivity, jerking moevements, mental
impairment, rashes, tremors; people who don’t have both recessive alleles are
carriers.
- Sons can’t be carrier - either inherited the recessive allele or
the dominant, but it is still expressed because it is X-linked
Genotype = genetic makeup of a cell
Phenotype = observed trait in the organism, based on genes and
environment
- In women one X chromosome
(either from mom or dad) is activate and
the other deactivated in some cells are
others in the embryo
, -
DNA = information for making proteins; reproduction tool
- Nucleus: transcription = a gene is copied into mRNA
- Cytoplasm: translation = mRNA is translated into a protein at the ribosome
- 3 nucleotides → codon → amino acids → proteins → enzymes or other functions
Replication
- the Dna unravels and unzips; the
free nucleotides attract
unattached bases in the nucleus
⇒ new strand of DNA
- Errors can occur, mutations like
HD and PKU, but other beneficial
ones that may be passed down
Protein Synthesis → Transcription
