Behavioural neuroscience: genetics Flashcards
What is behaviour?
Behaviour is the response of an individual, group or species to stimuli (trigger) in the environment.
Why do people (or other species) respond differently to a similar environmental trigger?
• Their genetic make-up (nature)
– Evolution (e.g., human vs bird) Evolved pattern of bvr adapted to an env
– Parental traits (colour of skin, height, intelligence, ability to sing)
• Factors in their environment (nurture/experience)
– How they are ‘feeling’ at the time (hungry, tired, happy, hot)
– Previous experiences (or taught a skill or how to behave)
– Culture
What are chromosomes?
• Chromosomes are found in every cell of our body
• Chromosomes contain our genetic material: our genes
• Genes drive the function of our cells.
It is unusual to see chromosomes as single structures as they are usually in a replicated stage. So there are two of each (sister chromatids) joined together at the centromere
Females have XX
Males have XY
Females will always contribute an X chromosome to offspring and males will give X or Y (males determine the sex of the child)
What are genes?
Genes are regions of DNA that are units of hereditary (information can be passed from one generation to another)
These are in the NUCLEUS of cells (animals & plants)
What is a nucleus?
The nucleus is a membrane bound part of a cell which contains all genetic information to promote survival of the cell (organism)
Cells are present in all body parts - groups of cells make an organism
Each cell contains a nucleus & contains chromosomes made up of genes
Why do we have genes?
• Chromosomes are made up of genes
• Particular sequences of DNA are known as genes Gene = particular squence of DNA
• DNA is essential for life: the DNA in each gene programs the manufacture of different proteins for use in the body
• Proteins are made with amino acids
• Amino acids are obtained from our diet and are the building blocks of life
What are the 9 essential amino acids?
There are 20 amino acids used to make proteins 9 of these amino acids are essential for us to make proteins which make us live (found in food)
- Histidine
- Isoleucine
- Leucine
- Lysine - beans
- Methionine
- Phenylalanine
- Threonine
- Tryptophan - can be found in turkey, sesame seeds (e.g.)
- Valine
It is very important that you include these amino acids in your diet
How does DNA make proteins?
•The sequence of amino acids to form the protein is determined by an intermediate RNA (ribonucleic acid) from DNA
DNA = Self-replicating molecule, copies itself into RNA, Each base determines one base of RNA
RNA = Copy of one strand of the DNA
A TRIPLET of bases determines one amino acid
Formation of proteins by combining amino acids Body structures or enzymes
• Genetic information gets translated into proteins for use in the body
– May become biological tissue/cells
– May become enzymes
– Enzymes(catalysts) produce chemical reactions so that our bodies function normally
What is replication?
Replication - essential in cell division when making new cells
What are mitosis and meiosis?
• Cells can be directly replicated to produce more cells with the same genetic information (Mitosis) –> Diploid cells
• Particular cells divide their genetic information - ready for recombination with another organism (Meiosis)
Chromosome pairs split and rejoin through sex –> genetic diversity
Meiosis I = Separation of Chromosome pair
Meiosis II = Division of Sister chromatids –> 4 Haploid cells/ gametes
How do chromosomes recombine?
• Sex cells can be divided and recombined to mix up the genetic information (Meiosis) - occurs with sexual reproduction
- Spermatogenesis: 4 sperm
- Oogenesis: 1 ovum +3 polar bodies
- Fertilization of eggs with sperm recombines genes
Each offsring have diff caracteristics bc they have diff combinations of genes
Same 2 ppl can make offspring with diff combinations of genes so siblings can have diff bvrs even if they have the same 2 parents
Homozygous vs heterozygous
• Recombination of genes allows for the biological expression of different characteristics (physical or psychological)
• Our genes on the chromosomes are responsible for making proteins genes
• They are also responsible for our characteristics
• If a chromosome contains two identical genes on the chromosome pair we are said to be homozygous for that gene (characteristic)
• If a chromosome contains two different genes (for the same characteristic) we are said to be heterozygous for that gene
Dominant vs recessive
• Characteristics are determined by homozygous vs heterozygous genes and if the genes are dominant or recessive
• Dominant genes only require ONE gene to be present on the chromosome to produce that characteristic
• Recessive genes require BOTH genes to be present on the chromosome to produce that characteristic
What are genetic alterations?
• Mutations: alterations or deletions of genetic sequence - may be beneficial or not
• Failure to divide properly in reproduction, get additional genes e.g., Down’s syndrome has 3 chromosomes at Chr 21
What is epigenetics?
Some genetic changes are permanent (mutations) but some aren’t, the env can temporarily change the expression of genes
• Behaviour can be influenced without mutations (permanent genetic changes)
• The same genes can be “expressed” or “activated” to different degrees
• If the chemical environment in a cell changes, histones tighten or release their grip on DNA thus regulating the expression that gene.
Same genetic mat, no permanent change but bvr changes
Experience can alter the chemical structure of cells so it can also alter how genes are expressed so can alter our bvr
