Lecture 3 Flashcards
(15 cards)
What is the gestation period for humans, mice, and elephants?
Humans: 266 days.
Mice: 20 days.
Elephants: 645 days.
Visual Mnemonic: A race track with a human (mid-track), mouse (sprinting), and elephant (walking slowly) labeled with their respective days.
What happens during neurulation?
Formation of the spinal cord and brain, occurring after gastrulation.
Visual Mnemonic: A zipper closing up a neural tube labeled “spinal cord and brain formation.”
What developmental problem occurs when the neural tube fails to close?
Spina bifida: A condition where part of the spinal cord is exposed.
Visual Mnemonic: A cracked zipper with a spinal cord poking out.
What is organogenesis?
The formation of organs during development.
Visual Mnemonic: A blueprint showing a heart, lungs, and kidneys labeled “Organ Formation.”
What is epigenetics?
Genetic changes not involving DNA sequence changes.
Genes are switched on/off, influencing cell type.
Visual Mnemonic: A light switch labeled “Gene ON/OFF” over a DNA strand.
Who proposed and discovered epigenetics?
Proposed: Conrad Waddington (1940).
Discovered: Sir Adrian Bird (1970s).
Visual Mnemonic: A timeline showing a DNA strand with Waddington at one end and Bird at the other.
What is a homeotic mutant?
A mutation that alters development, e.g., Antennapedia mutant in fruit flies where legs replace antennae.
Visual Mnemonic: A cartoon fly with legs on its head labeled “Development Error.”
What are HOX genes?
Genes with a universal function in development.
Example: Pax-6 gene mutation causes eye defects.
Visual Mnemonic: A HOX toolbox assembling a human eye labeled “Development Blueprint.”
What is the nature vs. nurture debate?
Nature: Genetic factors (e.g., hemophilia).
Nurture: Environmental factors (e.g., rickets due to vitamin D deficiency).
Visual Mnemonic: A balance scale with DNA on one side and sunlight (environment) on the other.
How does Rhesus blood group illustrate nature and nurture?
Rh- mothers with Rh+ fetuses can have complications, especially with the second Rh+ child due to an immune response.
Visual Mnemonic: A pregnant figure with a shield (Rh- antibodies) attacking a baby labeled “Rh+.”
What is an example of a temperature-sensitive gene?
Siamese cats develop darker extremities in cooler environments as pigmentation genes are ‘switched on.’
Visual Mnemonic: A Siamese cat with its paws in snow turning dark, labeled “Cool = Dark.”
What does heritability measure?
The proportion of phenotypic variation explained by genetics, not the environment or chance.
Visual Mnemonic: A pie chart with 80% labeled “Genetics” and 20% labeled “Environment.”
What is the heritability of schizophrenia?
79% according to a 2017 Danish twin study.
Both genetic susceptibility and environmental factors (e.g., infections, nutrition) contribute.
Visual Mnemonic: A brain split between DNA strands and flu viruses labeled “Genetic & Environmental.”
What is the heritability of intelligence?
Around 50%.
Increases with age: less than 40% at age 9, up to 80% in adulthood.
Visual Mnemonic: A bar graph rising with age labeled “IQ Genetics Contribution.”
How are twin studies used to measure heritability?
Compare phenotypes in monozygotic (MZ) and dizygotic (DZ) twins to assess genetic influence.
Visual Mnemonic: Two identical twin figures holding “MZ” signs, and two fraternal twin figures holding “DZ” signs.
