Chapter 3 - Genetic Bases of Child Development Flashcards
Gamete
An egg or sperm
Contains 23 individual chromosomes
Created through Meiosis
Joining of gametes = conception
Meiosis
Cell division resulting in gametes
Makes sure each gamete has only 23 chromosomes to contribute
Mitosis
Cell division resulting in bodily cells
Creates bodily cells other than gametes
Louise Brown (1978)
First person to be born after being conceived in a lab dish instead of the mother’s body
In-vitro Fertilization
Artificial form of egg fertilization
Mixing egg and sperm in a lab dish, then placing into the mother 24h later
About 20% of attempts succeed, the likelihood of twins is higher
Ectogenesis
Fertilization of an egg outside the uterus
Autosomes
First 22 pairs of chromosomes
Sex Chromosomes
23rd pair of chromosomes
X and Y chromosomes
Deoxyribonucleic Acid (DNA)
Code for specific genes
Each chromosome in a cell’s nucleus consists of one molecule of DNA
The “Rungs” of DNA
Carry the genetic code and are made up of paired chemical compounds called nucleotide bases;
Adenine is paired with Thymine
Guanine is paired with Cytosine
3 Parts of DNA
Gene
Genotype
Phenotype
Gene
A group of chemical compounds, called nucleotide bases, which generate the production of a protein or other important biological building blocks in the body
Genotype
The complete set of genes that make up a person’s heredity
Phenotype
A person’s genotype plus all other environmental influences that make up that person’s physical, behavioural, and psychological characteristics.
Results from genetic and environmental factors
Single Gene Inheritance
Dominant:
Chemical instructions are always followed
Recessive:
Will be displayed when paired with another recessive gene
Incomplete dominance:
Two heterozygous alleles expressed
Alleles
Genes come in different forms called alleles
A baby inherits one version of each gene (one allele) from each parent
Homozygous Alleles
The alleles in the pair of chromosomes are the same
Heterozygous
The alleles are different from each other
Single Nucleotide Polymorphisms (SNP)
Some disease states such as sickle-cell anemia are associated with this gene mutation
The normal nucleotide base expected in a particular position is altered
How does a genotype influence phenotype if a person is homozygous for a trait?
When both alleles are the same, and therefore have chemicals instructions for the same phenotype, that phenotype results
If a baby had alleles for normal red blood cells on both chromosomes in the eleventh pair, they would be almost guaranteed to have normal cells.
How does a genotype influence phenotype if a person is heterozygous for a trait?
Often one allele is dominant, which means the instructions are always followed and the other is recessive.
Incomplete Dominance
The phenotype that results often falls between the phenotype associated with either allele.
Clinal Variation
Continuous genetic variation observed between geographic regions
2 Ways Twins Form
Dizygotic twinning (fraternal)
Monozygotic twinning (identical)
How do genetic disorders form?
Inherited disorders
Abnormal chromosomes
eg. down syndrome
Behavioral Genetics
The branch of genetics that deals with with inheritance of behavioral and psychological traits
Either-or Traits
The traits controlled by single genes
Most important behavioral/psychological characteristics are a more broad range of outcomes
Polygenic Inheritance
When phenotypes reflect the combined activity of many seperate genes
Aa Bb Cc and Dd
Nonshared Environmental Influences
The experiences and circumstances within a family that make siblings different from one another
Most disorders are caused by which alleles?
Recessive
Genetic Reductionism
To argue that genes produce environments or directly cause particular behaviours
Reaction Range
The range of phenotypic expression possible for a genotype, considering environmental factors
Relations Between Nature and Nurture - Sandra Scarr
Passive gene-environment relation
Evocative gene-environment relation
Active gene-environment relation
Passive Gene-environment Relation
Parents pass on genotypes to their children and provide much of the early environment for their young children
Bright parents pass on bright genes and buy more books, bring them to museums, etc
Evocative Gene-environment Relation
Different genotypes evoke different responses from the environment
Children who are bright ask more questions, receive more attention
Active Gene-environment Relation
Individuals actively seek environments related to their genetic makeup
Niche-picking
Deliberately seeking environments that fit one’s heredity
