Descent of Modern Humans
● Y-chromosomal Adam: most recent common ancestor from whom all living people
are descended patrilineally
● Mitochondrial Eve: the most recent woman from whom all living humans are
descended matrilineally through transmission of mitochondrial DNA
Human Genetic Variation
● All humans are 99.9% genetically identical
● There are 3 billion nucleotides (‘letters’) that
make up DNA → A-T – C-G
● Less than 2% of the DNA are functional
genes coding for proteins
Lecture 3
Neural Development
● Ampulla: place where sperm and egg meet each other (fertilization)
● Haploid number: number of chromosomes in egg cell / sperm cell → once they have
merged, there is the diploid number of chromosomes
● Zygote: fertilized egg → cell starts dividing into new cells → after 46 days =
Blastocyst
● Day 1: sperm + ovum = ootid
○ Haploid number of chromosomes of both (“n”)
, ● Zygote
○ Diploid number of chromosomes (“2n”)
● Blastocyst - 4 to 6 days
● Implantation - 14 days
● Embryo - 56 days
● Fetus - after 56 days
● Ectopic pregnancy → pregnancy inside the fallopian tube (fallopian tube might burst,
a baby can’t survive it and the mother is in a lot of pain)
● Gastrulation
○ Zygote going into a blastocyst
○ Blastocyst is pushed inwards → gets 3 layers: Invagination (ectoderm,
mesoderm, endoderm)
● Neurolation
○ Development of the neural tube → neural plates folds in on itself, closure
starts above the notochord
○ Somites: skeletal muscle
○ Next to somites: progenitor cells for spine → can differentiate into specific
type of cell, …
○ Closure of the neural tube is very im …
● Neural proliferation
○ Stem cells
○ Neurons
○ Glial cells
○ Anterior part of the neural tube increases in size → Rhombencephalon,
Mesencephalon, Prosencephalon
○ Order: caudal → rostral, medial → lateral
● Migration
● Myelination
○ Wrapping of myelin around axons to increase the speed of transmissions
between neurons
○ Starts in the spinal cord
● Arborisation
○ “Branching out”; growth of dendrites
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