genes, brain and behaviour

What are alleles

Two genes that control the same trait

What is homozygous

2 identical alleles (BB, ww)

What is heterozygous

2 different alleles (Bw)

What is phenotype

Observable traits

What is genotype

Traits present in the genes

True or false: if the dominant trait is present in the genotype (Bw), it will be observed in the phenotype (brown seeds)

True

Why do humans have an extended length of juvenile period

It allows time to develop a large brain and learn complexity of human society

What is the bidirectional view

Environmental and biological conditions influence each other

True or false: evolution does dictate behavior

False, it gives us bodily structures and biological potentialities

What is a limitation of evolutionary psychology

It’s deterministic and ignores the role of environment in shaping human behaviour

Functions of the prefrontal cortex

• plays the central role in forming goals and objectives

• Devising a plan of action required to attain those goals

• Selects the cognitive skills needed to implement the plans, coordinates those skills, and applies them in the correct order

• Responsible for evaluating our actions as success or failure relative to our intentions

True or false: a greatly enlarged prefrontal cortex (PFP) is a distinctively human and primate feature

True

The PFP accounts for what % of total cortex in humans

29%

Physiological explanations of behaviour

Relates a behaviour to the activity of the brain and other organs

Ontogenetic explanation of behaviour

Describes the development of a structure or behavior

Evolutionary explanation of behaviour

Reconstructs evolutionary history of a behaviour

Functional explanation of behaviour

Describes why a structure or behaviour evolved

What are exaptation or co-option

Describe a shift in the function of a trait during evolution (e.g, feathers for warmth and then flight)

What are spandrels

A phenotypic characteristic that is a byproduct of the evolution of another trait, rather than a direct product of adaptive selection

What does an adaptation represent?

a trade-off btwn different survival and reproductive needs (e.g, having a large body)

What is proximate causation

The immediate psychological, physiological, biochemical and environmental reasons

• sensory systems - need to be able to perceive danger

• Mechanisms that drive muscles that elicit behaviour - need to be able to contract muscles to run

• Cellular activities regulate development - nerve function

What is ultimate causation

The reason why it increased fitness in the evolutionary past

What are social scientists

They accept that our bodies have been sculpted by evolutionary forces e.g., we all possess sweat glands for thermoregulation

What are evolutionary psychologists

They argue that our psychological mechanisms and the resulting behaviour have also been shaped by the same forces

What is natural selection

The principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations

What are mutations

Random errors in gene replication that lead to a change in the sequence of nucleotides in the genome, resulting in changes in specific gene expressions, brain function and behaviour

What is adaptive behaviour

• an evolutionary adaptation that enhances survival and reproductive success

• Evolves as natural selection fine-tunes an animal to its environment

What is sexual selection

The creation and maintenance of features essential for attracting the opposite sex, and defending ones status

True or false: natural selection and sexual selection work together

True

What is inclusive fitness

Characteristics will be selected for that improves the chances of an individuals genes being passed directly or via relatives

Principle of variation

Individuals within a species show variation on their physical and behavioural traits

Principle of variation

Variation of physical and behavioural traits are inheritable

Principle of adaptation

Individuals are in competition with one another for scarce resources and some inherited variations will have survival advantages

Principle of evolution

Those who are better adapted to the environment will produce more offspring, who will inherit the same advantages (called fitness)

What is a karyotype

It’s the umber and appearance of chromosomes in the nucleus of a eukaryotic cell

What are sources of variability in development

1. Combining genes of both parents increases genetic variability

   • chromosomes in zygote are not exact copies

2. Identical (monozygotic) twins develop from a single zygote that splits into two

3. Fraternal (dizygotic) twins develop from separate eggs and sperm

4. Gene mutations can permanently alter segments of DNA

What are gene-linked abnormalities

Single gene disorder

• autosomal dominant

• Autosomal recessive

• X-linked dominant

• X-linked recessive

• Y-linked

• Mitochondrial

What are some examples of gene-linked abnormalities

• cystic fibrosis

• Diabetes

• Huntingtons

• Sickle cell

• Spina bifida

What are chromosomal abnormalities

• Occur when there is an error in cell division following meiosis or mitosis

• Caused by an extra, or irregular portion of chromosomal DNA

What are some examples of chromosomal abnormalities

• Down syndrome

• XYY syndrome

• Klinefelter syndrome (XXY)

What are linkage studies

They look for patterns of inheritance of genetic markers in large families

What is a genetic marker

A segment of DNA that varies among individuals

What is heritability

The statistical estimate of the proportion of the total variance in some trait that is attributable to genetic differences among individuals within a group

• expressed as a proportion (60/100)

• Max value is 1.0

What are some limits to an estimate of heritability

1. Applies only to a particular group Living in a particular environment

2. Heritability estimates do not apply to individuals, only to variations within a group

3. Even highly heritable traits can be modified by the environment

What are the three ways heritability of a behavior can be estimated

1. examining whether children more closely resemble their adoptive or biological parents

2. Comparing identical and fraternal twins

3. Examine identical twins raised in different households

What is passive gene environment (GE)-Interaction

Parents provide rearing environment

What is evocative GE-Interaction

When genotype elicits certain types of physical and social environments ex. A child with naturally difficult personality provokes parental stress and family discord

What is active GE- Interaction

When children seek out compatible and stimulating environments ex. A child who likes chess might join a chess club

What are prevalence and incidence

They’re measures of distributions of a disease in a population

• prevalence is a measure of the # of cases if a disease in a certain population for a specific period of time (both old and new cases)

• Incidence is a measure of the number of new cases of the disease

What is ore reliable, prevalence or incidence

Incidence is more reliable in determining the risk of a certain disease to a population

What are complex (or multifactorial) disorders

Disorders caused by the effects of multiple mutated genes in combo with lifestyle and environmental factors

It’s difficult to predict a persons risk of inheriting or passing on these diseases

What is missing heritability of complex disorders

The discrepancy btwn epidemiological heritability estimates and the proportion of phenotypic variation explained by DNA sequence differences

Ex. Having the recipe to a pie with basic ingredients but it doesn’t turn out the way predicted because were missing key techniques like whipping technique or what temp it should be baked at

DNAsequence differences

What are some theories to explain unaccounted heritability

• part of the heritability being hidden in numerous weakly contributing genetic risk factor patterns of linkage disequilibrium

• Heritability estimates being inflated by epistatic gene interactions - i.e genes can mask each others presence or combine to produce an entirely new trait

Factors that influence phenotypic variability during development

• passage of epileptic marks(e.g., DNA/histone modification) through the germ line

• passage of maternal RNA molecules into the embryo

• Potential passage of prion proteins (misfolded, disease causing protein) from parent to offspring

• Biochemical state of the games at the time of conception

• Transmission of nutrients, bacteria, or antibodies from maternal circulation to that of the offspring

Describe Frederick Griffith’s Transformation Experiment

• performed experiment on rats and 2 strains of bacteria that cause pneumonia

• Type R (rough) = non-encapsulated, avirulent, relatively harmless

• Type S (smooth) = encapsulated, virulent, severe pneumonia

• When injecting mice with Type R, it survived and no bacteria was recovered

• When injecting mice with encapsulated Type S, the mice died and virulent bacteria was recovered

• When heat killed encapsulated Type S was injected, the mice lived and no bacteria was recovered

• When mice was injected with Type R and heat killed Type S, mice died and bac tria was recovered

• This means that the capsule remained intact and transferred onto the R bacteria

• Conclusion: DNA (not RNA) is the transforming agent

Oswald T. Avery’s Transformation Experiment

• determined that the DNA from type S bacteria was the genetic material responsible for Griffiths results (not RNA)

Describe the Hershey-Chase Bacteriophage Experiment

• DNA (not protein) is the genetic material

• Labeled the DNA of bacteriophage with p32 and their protein coats with with s35

• Only the labeled p32 entered the host bacteria during infection while the s35 remained on the outside

• This confirmed that the DNA was injected into the bacterial cells to direct the production of new phages

Describe the blender experiment

• The virulent bacteriophage is composed of DNA and a protein shell

What are the three components of DNA and RNA

• Pentose (5-carbon) sugar

  • DNA = deoxyribose

  • RNA = ribose

• Nitrogenous base

  • Purines

    • Adenine

    • Guanine

  • Pyrimidines

    • Cytosine

    • Thymine (DNA)

    • Uracil (RNA)

• Phosphate group attached to the 5’ carbon

What is a phosphodiester bond

• covalent bond btwn the phosphate group ( attached to the 5’ carbon) of one nucleotide and the 3’ carbon of the sugar of another nucleotide

• This bond is very strong, and for this reason DNA is very stable

True or false: nucleotides are linked by phosphodiester bonds to form polynucleotides

True

What are the 6 main features of the double helix model of DNA

1. Two polynucleotide chains wound in a clockwise double helix

2. Nucleotide chains are anti parallel

3. Sugar-phosphate backbones are the outside of the double helix, and the bases are oriented towards the central axis

4. Complementary base pairs from opposite strands are bound together by weak hydrogen bonds

   1. A pairs with T (2 H-bonds) and G pairs with C (3 H-bonds)

5. One complete turn of the helix requires 10 bases

6. Sugar-phosphate backbones are not equally spaced, resulting in major and minor grooves

   1. The larger grooves bind transcription factors

   2. They can also be methylated

DNA replication (in the cell nucleus)

• to make a copy of itself, dNA unwinds and separated using helicase into two strands

• Proper base pairs are assembled on the template by DNA polymerase 5’ → 3’ direction

• Nucleotides are connected together by DNA ligase to make a new strand that is identical to the old strand

RNA characteristics

• single stranded and shorter than DNA

• Less stable than DNA

• Ribose is the 5-carbon sugar (lots of variation with them)

• Uracil replaces thymine

Key concepts of regulation of gene expression in cells

• DNA is transcribed into an mRNA molecule, which is then translated during protein synthesis

• Translation requires transfer RNAs and ribosomes

• The genetic code is no overlapping triplet code (e.g. codons)

• Special sequences signal the initiation and termination of both transcription and translation

True or false: DNA is the same in all somatic cells of an organism

True

What are some key differences btwn eukaryotes and prokaryotes

• three RNA polymerases

• Monocistronic gene structure (mRNAs encode single gene product)

• RNA processing (‘capped at 5’ end, ‘polyadenylated’ at 3’ end, ‘spliced’)

• split gene structure (genes contains introns)