Chapter 5: Genetics Flashcards
exam 2 material
how can you remove the dark pigment from a rat?
the agouti gene controls the distribution of black pigment so by blocking it with BPA you can halt its expression
phenotype vs genotype
phenotype: gene expression converts the genetic instructions into features of a living cell
genotype: the genetic makeup of an individual containing adenine (A), guanine (G), cytosine (C), and thymine (T)
transcription vs translation
transcription: DNA is transcribed into a complementary strand of RNA
translation: RNA acts as a template for ribosomes to produce amino acids sequences, which form proteins
meiosis vs mitosis
meiosis: the process of gametes being formed, each containing one chromosome
mitosis: when body cells clone each other and then split
what are the sources of genetic variability that can occur during meiosis?
crossing-over: where chromosomes exchange equivalent segments of DNA that results in a unique combination of genes not seen in either parent
mutations: mostly benign errors that can occur in DNA replication
what is hemophilia?
a disorder that leads to excessive bleeding since blood cannot clot as easily, males are more likely to inherit this since it is X-linked, females have XX chromosomes so inheriting one X with hemophilia can be masked by the other chromosomes leading to hemophilia not developing
what are single nucleotide polymorphisms (SNPs)?
when there is a DNA sequence change at one nucleotide, specific SNPs on the GABAA2 can lead to an increase in alcohol use disorder
what are copy-number variations (CNVs)?
mutations resulting from duplication or deletion of sections of DNA, associated with autism spectrum disorder and schizophrenia
how do mitochondrial DNA diseases act as a source of variability?
mitochondrial diseases are inherited from your mother and occur when mitochondria fail to produce enough energy for the body to function properly, this can lead to movement disorders, sensory issues, neurological problems, dementia, etc.
what is heritability?
the contribution of genetics to the variation of a trait observed in a population, heritability always refers to a population, not to individuals
what is epigenetics?
a reversible genetic change that does not change the DNA sequence but is influenced by environmental factors
what are the two mechanisms of epigenetics?
histone modifications and DNA methylation
how does child maltreatment of mouse pups affect their hippocampus?
the pups of nurturant mothers showed high levels of glucocorticoid receptors in the hippocampus regardless of whether they were handled or not handled, however, pups of non-nurturant mothers showed nearly normal levels of gene expression when handled, but reduced levels when not handled
what does the ectoderm develop into?
ectoderm -> neural plate -> neural tube -> CNS
what does the mesoderm develop into?
connective tissue, blood vessels, muscles, bone, urogenital system
what does the endoderm develop into?
internal organs
what are the 6 stages of the development of the nervous system?
- neurogenesis
- cell migration
- differentiation
- cell growth and synapse formation
- cell death
- synaptic pruning
what happens during the neurogenesis step of development?
neurons and glia are formed from cells in the ventricular zone, progenitor cells divide by mitosis before they are specialized
what happens during the cell migration step of development?
cells in cerebral cortex arrive in an inside-out fashion after they are transported by radial glia
what happens during the differentiation step of development?
differentiation of the neural tube along the dorsal and ventral halves and along the rostral-caudal axis, organization of cerebral cortex affected by intrinsic and extrinsic factors
what happens during the cell growth and synapse formation step of development?
axons and dendrites arise from neurites, developing axons and dendrites end in growth cones that then make contact with targets cells to form specific synapses
what happens during the cell death step of development?
apoptosis takes place, access to nerve growth factors (NGFs) influence the survival of a neuron (high NGF is associated with autism)
what happens during the synaptic pruning step of development?
number of functional synapses are reduced and synapses left are myelinated, PFC isn’t fully myelinated until early adulthood
what kind of early experiences impact brain development?
the high plasticity of young brains makes social experiences important at a young age, the end of the myelination growth spurt reduces neural plasticity, environmental enrichment increases synaptic plasticity
what are some disorders of the CNS?
spina bifida: caudal portion of the neural tube fails to close normally
fragile X: intellectual disability characterized by low set ears and a
large forehead and jaw
fetal alcohol syndrome: most preventable cause of intellectual disability
what happens in the brain during puberty?
surge of gray matter development and pruning, thickening of cortex and frontal lobe, amygdala matures first which explains teen risky behavior
what happens in the brain during adulthood?
the brain is fully matured by ~age 25, neurogenesis continues in the hippocampus
*Healthy aging includes brain tissue atrophy
what is gene therapy?
technique that seeks to modify or manipulate the expression of a gene or to alter the biological properties of living cells for therapeutic use
