This chapter focuses on the biological foundations of development, especially genetic inheritance, prenatal development, and their effects on individual variability.
Genetics and Inheritance
Genetic Make-up at Conception
Genotype of the Zygote: The initial genetic configuration of an individual formed at conception.
Genes: Basic units of genetic information influencing phenotype traits.
Dominant Characteristics: Traits expressed when at least one dominant allele is present.
Recessive Characteristics: Traits expressed only in homozygous recessive conditions.
Chromosomes
Definition: Structures made of DNA that carry genetic information.
Types:
Autosomes: 22 pairs that are not sex chromosomes.
Sex Chromosomes: 1 pair determining an individual's sex.
Germ-cell Production: Involves genetic replication and diversity via mitosis (cell division) and meiosis (germ cell production).
Prenatal Development Stages
Stages of Prenatal Development
Germinal Stage (0-2 weeks): Initially forms a zygote and then a blastocyst; begins implantation into the uterus.
Embryonic Stage (3-8 weeks): Rapid organ development (organogenesis); major organs begin to form; the embryo is susceptible to teratogens.
Foetal Stage (9 weeks to birth): Further development and maturation of organs, alongside the establishment of body systems.
Effects of Prenatal Environment
Teratogenic Effects
Definition: Disorders caused by agents harmful to the embryo. These include:
Maternal diseases (e.g., rubella, HIV) leading to mortality or disabilities.
Drugs (e.g., thalidomide) causing deformities or other abnormalities.
Environmental factors (commonly referred to as teratogens).
Developmental Disorders
Single-gene-pair Effects
Definition: Disorders from dominant or recessive genes affecting development:
Definition: Disorders caused by abnormal chromosomes, typically affecting autosomal or sex chromosomes.
Examples: Turner Syndrome, Klinefelter’s Syndrome, and Fragile-X Syndrome.
Behavioural Genetics
Foundations of Behavioural Genetics
Definition: The study of how genetics and environment interact in shaping behaviour and psychological traits.
Research Methods:
Twin studies advocate the genetic basis versus environmental contributions.
Adoption studies help differentiate hereditary influences.
Key Concepts:
Heritability: Quantifies the genetic contribution to individual differences in behaviour traits.
Canalization: Some traits follow strong genetic pathways resistant to environmental impacts (e.g., basic language acquisition).
Niche-Picking: Individuals actively seek environments compatible with their genetic tendencies.
Prenatal Learning
Evidence of Prenatal Learning
Studies: Sedgwick et al., found foetuses exhibit response patterns (heart rate changes) showcasing learning from auditory stimuli.
Implications: Suggests experiences in utero can influence postnatal behaviours, demonstrating early capability for learning.
The Birth Process
Steps of the Birth Process
Labor Phases:
Contractions begin and the cervix dilates.
Baby moves through the birth canal (second stage).
Expulsion of placenta post-birth (third stage).
Assessing Newborns
Apgar Scale: Measurements taken 1 and 5 minutes post-birth to assess physical condition across five physiological criteria.
Adverse Effects Related to Prematurity & Low Birth Weight:
Premature infants and babies of low birth weight are at a higher risk of health complications and poorer developmental outcomes.
Mortality Rates: Lower birth weights correlate to higher mortality rates; significant disparities exist within populations.
Summary of Key Concepts
Understanding genetic inheritance and prenatal development provides insight into individual variability and developmental outcomes.Genetic factors and environmental influences interplay significantly throughout development, from conception through infancy.
Foundations of development Genetics and prenatal development Chapter 2
Chapter Overview: Foundations of Development
This chapter focuses on the biological foundations of development, especially genetic inheritance, prenatal development, and their effects on individual variability.
Genetics and Inheritance
Genetic Make-up at Conception
Genotype of the Zygote: The initial genetic configuration of an individual formed at conception.
Genes: Basic units of genetic information influencing phenotype traits.
Dominant Characteristics: Traits expressed when at least one dominant allele is present.
Recessive Characteristics: Traits expressed only in homozygous recessive conditions.
Chromosomes
Definition: Structures made of DNA that carry genetic information.
Types:
Autosomes: 22 pairs that are not sex chromosomes.
Sex Chromosomes: 1 pair determining an individual's sex.
Germ-cell Production: Involves genetic replication and diversity via mitosis (cell division) and meiosis (germ cell production).
Prenatal Development Stages
Stages of Prenatal Development
Germinal Stage (0-2 weeks): Initially forms a zygote and then a blastocyst; begins implantation into the uterus.
Embryonic Stage (3-8 weeks): Rapid organ development (organogenesis); major organs begin to form; the embryo is susceptible to teratogens.
Foetal Stage (9 weeks to birth): Further development and maturation of organs, alongside the establishment of body systems.
Effects of Prenatal Environment
Teratogenic Effects
Definition: Disorders caused by agents harmful to the embryo. These include:
Maternal diseases (e.g., rubella, HIV) leading to mortality or disabilities.
Drugs (e.g., thalidomide) causing deformities or other abnormalities.
Environmental factors (commonly referred to as teratogens).
Developmental Disorders
Single-gene-pair Effects
Definition: Disorders from dominant or recessive genes affecting development:
Definition: Disorders caused by abnormal chromosomes, typically affecting autosomal or sex chromosomes.
Examples: Turner Syndrome, Klinefelter’s Syndrome, and Fragile-X Syndrome.
Behavioural Genetics
Foundations of Behavioural Genetics
Definition: The study of how genetics and environment interact in shaping behaviour and psychological traits.
Research Methods:
Twin studies advocate the genetic basis versus environmental contributions.
Adoption studies help differentiate hereditary influences.
Key Concepts:
Heritability: Quantifies the genetic contribution to individual differences in behaviour traits.
Canalization: Some traits follow strong genetic pathways resistant to environmental impacts (e.g., basic language acquisition).
Niche-Picking: Individuals actively seek environments compatible with their genetic tendencies.
Prenatal Learning
Evidence of Prenatal Learning
Studies: Sedgwick et al., found foetuses exhibit response patterns (heart rate changes) showcasing learning from auditory stimuli.
Implications: Suggests experiences in utero can influence postnatal behaviours, demonstrating early capability for learning.
The Birth Process
Steps of the Birth Process
Labor Phases:
Contractions begin and the cervix dilates.
Baby moves through the birth canal (second stage).
Expulsion of placenta post-birth (third stage).
Assessing Newborns
Apgar Scale: Measurements taken 1 and 5 minutes post-birth to assess physical condition across five physiological criteria.
Adverse Effects Related to Prematurity & Low Birth Weight:
Premature infants and babies of low birth weight are at a higher risk of health complications and poorer developmental outcomes.
Mortality Rates: Lower birth weights correlate to higher mortality rates; significant disparities exist within populations.
Summary of Key Concepts
Understanding genetic inheritance and prenatal development provides insight into individual variability and developmental outcomes.Genetic factors and environmental influences interplay significantly throughout development, from conception through infancy.
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