The Genetic Basis of Variability, Sample of Genetic Conditions Linked with Behaviour, Cognition Flashcards
Nature
Influences from our genetic endowment (what you are born with/genetic influences)
Nurture
Environmental influences that shape us
Theory of natural selection
- Reproductive success
- Biological evolution (genes change)
- Adaptive (helps with survival) vs. deleterious traits (leads to death)
Two components of natural selection
Variation
Competition
Variation
Genotypes and phenotypes
Competition
For limited resources
Genetics
study of genes, how they are passed on and how they differ
DNA
sugar base with phosphate and nucleotides
Genes
small units of DNA that direct the synthesis of proteins and enzymes
Genome
A total/complete set of genetic material
Heredity
Sum of inherited traits and tendencies
Alleles
Variations of a gene
- Genotype
- Phenotype
Genotype
Organism’s genetic makeup and appearance of cells
Phenotype
- Outward expression of an organism’s genotype
- Observable traits and characteristics of an organism
- Not necessarily genetic
Dominant traits
- If present = phenotype because they suppress recessive traits
- Observed phenotype when the individual is heterozygous
- Phenotype will always be represented when that allele for that gene is present
Recessive trait
- Masked by a dominant allele when a dominant and recessive allele are present for the same gene
- Will only present itself when 2 recessive alleles for a trait are present
Proteins
strings of AAs, 3 nucleotides (codon) = 1 AA
Enzymes
govern processes, control cell structure and function
Chromosomes
threadlike; in nuclei of cell, contains genes
Meiosis
ell division; new sperm and ova, randomly rearranged, contains 23 indie chromosomes when done (1/2 those found in other cells)
Mutation
Accidental alterations in a single gene (environmental or spontaneous)
Hayflick number
- Each cell can go through a limited number of divisions before death (~50 in humans)
- Number of times a normal human cell population will divide until cell division stops
Telomeres
- Every reproduction of a cell, you lose a part of the telomere (which is at the end), eventually you’ll lose DNA when the telomeres run out
* Can monitor your ageing * Variations across species * Heritability
Down syndrome
Dr. John Down
Chromosomal aberration
Trisomy 21
Mental retardation
Alzheimer’s Disease
Chromosomal aberration
Rearrangement of genes with chromosomes or change in total number of chromosomes
Trisomy 21
3 chromosomes instead of 2
Physical characteristics
Facial
Mental retardation
2 standard deviations below the mean
Alzheimer’s Disease
- Much earlier (30-40 years old)
- Is chromosome 21 related to Alzheimer’s?
Likelihood of a child born with it increases with the age of the mother
Huntington’s disease
- Dr. George Huntington
- Impairment mapped to Chromosome 4
- DNA base repeat (CAG on chromosome 4)
- More times repeated = more severe damage to basil ganglia (it dies)
- DNA base repeat (CAG on chromosome 4)
- Progressive neurodegenerative disorder
- Gets worse and worse
- Damages brain cells
- Onset around 40, time course 10-15 years
- Mothers rarely know they have it before giving birth
- Impairment mapped to Chromosome 4
Chorea
- Abnormal involuntary movement disorder
- Quick movements of feet or hands are comparable to dancing
- Brief, semi-directed, irregular movements that are not repetitive or rhythmic
- Appear to flow from one muscle to the next
Athetosis
Involuntary convoluted, writhing movements of the fingers, arms, legs, and neck
Behavioural changes of Huntington’s
Depression and mood swings
Phenylketonuria (PKU)
- Autosomal recessive disorder
* If blood levels of phenylalanine rise = severe brain damage * Inability to convert phenylalanine (found in food and artificial sweetener) to tyrosine * Build up of phenylalanine causes impaired brain development, mental retardation and seizures * Manageable if caught early; just stay away from it
