Lecture_4_Behavioural_Genetics_Part_1_2023-2024

Lecture Overview

Lecture Course: PS11220Brain Behavior & CognitionTopic: Brain Evolution & Introduction to Behavioral Genetics (Part 1)Instructor: Eva Balgova, PhD, AFHEAContact: evb14@aber.ac.ukOffice Hours: Mon: 11:00-12:30, Fri: 14:00-15:30Location: P5, room 1.31

Lecture Part 1 Outline

Key Topics:

1. Evolution

2. Mendelian Genetics

3. Chromosomes & Sex Chromosomes

4. DNA, RNA & Protein Synthesis

5. Genetic Mutations

Evolution Overview

Charles Darwin (1859): Introduced the concept of evolution in "On the Origin of Species."Genetic Change: Evolution involves changes in the genetic coding of organisms over generations through natural selection.Natural Selection: Traits conducive to survival are inherited.Fitness: The capacity to survive and propagate genes.

Evolution and Behavior Genetics

Gene Pool Influence: Evolution affects the availability of behavior-influencing genes in species.Neural Development: Each individual inherits a unique genetic program that guides neural growth.Role of Experience: Environmental interactions shape gene expression and neural development.Behavioral Capacities: Current behavior arises from neural activity and environmental perception.Reproductive Success: Effective behavior can enhance the likelihood of gene transmission across generations.

The Evolution of the Human Brain

Evolution has led to:

• Increased brain size correlating with intelligence.

• Brain-body ratio considerations.

• Neuron density improvements.

• The greatest growth seen in the cerebrum.

• Increased brain convolution for enhanced processing power.

Mendelian Genetics

Gregor Mendel (1822-1884): Established the foundation of genetics through pea plant experiments.Dichotomous Traits: Traits that appear in one of two forms.True Breeding Lines: Produce offspring consistent in traits.Dominant vs Recessive Traits: Understanding inheritance patterns.

Key Terms in Genetics

• Phenotype: Observable traits.

• Genotype: Genetic constitution underlying traits.

• Gene: Inherited factor determining traits.

• Alleles: Variants controlling the same trait.

• Homozygous: Identical alleles.

• Heterozygous: Different alleles.

Chromosomes

Structure: Genes are located on chromosomes, thread-like structures in the cell nucleus. Humans possess 23 pairs of chromosomes.Sex Chromosomes Types:

• Males: XY

• Females: XXSex-linked Traits: Traits determined by sex chromosomes, with implications for conditions like color blindness.

Atypical Quantities of Sex Chromosomes

• Turner’s Syndrome: Single sex chromosome, often a missing X (45X).

• Klinefelter’s Syndrome: Presence of an extra X chromosome (47, XXY).

DNA Basics

Deoxyribonucleic Acid (DNA): Double-stranded polymer with deoxyribose.Constitutes chromosomes; sequences composed of nucleotide bases (Adenine, Thymine, Guanine, Cytosine).

RNA Basics

Ribonucleic Acid (RNA): Single-stranded polymer with ribose (not deoxyribose).Replaces thymine with uracil.Involved in protein synthesis (messenger RNA, transfer RNA).

DNA Replication Process

Complexity: Involves unwinding the double helix and matching nucleotide pairs with their complements.Errors: Can cause clinical issues.

Cell Division

• Mitosis: Cell duplicates to produce two identical daughter cells.

• Meiosis: Reduction division leads to egg and sperm cells, each with 23 chromosomes.

Protein Synthesis (PS)

Definition: Process of protein production directed by genetic information.Stages:

• Transcription: Copies DNA information to mRNA.

• Translation: mRNA is read by tRNA to assemble polypeptides (proteins).

Genetic Mutations

Nature: Changes in DNA during cell division that may be inherited or acquired.Consequences: Mutations can be beneficial or harmful.

Specific Genetic Conditions

• Down Syndrome: Extra chromosome 21 leading to various health challenges.

• Proteus Syndrome: Mutation causing widespread growth issues and tumors.

Summary of Part 1

Evolution and natural selection foster advantageous traits. Genetics underpin natural selection principles, with DNA as the core of inheritance and mutation. Down Syndrome as a prevalent genetic syndrome demonstrating the impact of genetic mutations.