Genetics Basics

• An Individuals genotype is the genetic information.
• An Individuals phenotype is the directly observable characteristics.

Genetic Foundations

• Chromosomes are the rodlike structures within cells that store and transmit genetic information.
• DNA is the chemical substance that makes up chromosomes as deoxyribonucleic acid.
• Gene is segment of DNA along the length of the chromosome.

Mitosis vs Meiosis

• Mitosis is the process by which DNA duplicates itself.
• Mitosis produces new body cells containing the same genetic information.
• Meiosis the process by which gametes, or sex cells, are formed.
• Meiosis halves the number of chromosomes normally present.
• Meiosis leads to genetic variability

Chromosome and Cell Types

• Autosomes have 22 matching pairs of chromosomes.
• Sex chromosomes are the 23rd pair of chromosomes with XX being female and XY being male.
• Gametes are sex cells- sperm and ovum.
• A Zygote forms when sperm and ovum unite

Twins

• Fraternal/Dizygotic twins result from release and fertilization of two ova.
• Identical/Monozygotic twins result when a single zygote separates to form two individuals.

Alleles

• Alleles are two forms of same gene, one inherited from each parent.
• Homozygous: both alleles are alike.
• Heterozygous: alleles differ.
• Alleles occur at the same place on both chromosomes in a pair.

Dominant-Recessive Inheritance

• Only dominant allele affects children's phenotypic characteristics.
• Carriers are heterozygous, have one recessive allele and can pass recessive trait to their children.
• Many serious diseases are product of recessive alleles.

Incomplete Dominance

• Both alleles are expressed in the phenotype.
• This can results in combined traits
• Can also result in traits that is intermediate between the two
• Sickle cell anemia is an example.

X-Linked Inheritance

• A normal father with XY chromosomes can pass the Y chromosome to his sons creating normal males. Also can pass the X chromosome to his daughters creating a normal female if the recessive is a Y

Genomic Imprinting, Mutation, and Polygenic Inheritance

• Genomic imprinting: a chemical marker activates one allele in a pair.
• Genomic imprinting: is often temporary and may not occur in all the individuals.
• Mutation is a sudden, permanent change in a segment of DNA
• This can also affect one, two, or many genes.
• Polygenic inheritance: characteristics are influenced by many genes.

Chromosomal Abnormalities

• Down syndrome: is caused by problems with 21st chromosome.
• Sex chromosome abnormalities are caused by problems with X or Y chromosome and are often not recognized until adolescence.

Reproductive Choices

• Genetic counseling is an option.
• Prenatal diagnosis and fetal medicine are available.
• Reproductive technologies.
• Adoption is an option

Reproductive technologies

• Donor insemination
• In vitro fertilization
• Surrogate motherhood
• New technologies are being researched

Genetic Counseling

• Genetic counseling helps couples assess chances of hereditary disorders.
• Counseling can help to choose best course of action in view of risks and family goals. Genetic counseling is recommended when
• There are difficulties bearing children
• When there are known genetic problems exists
• When woman is over 35

Prenatal Diagnostic Methods

• Amniocentesis
• Chorionic villus sampling
• Fetoscopy
• Ultrasound
• Maternal blood analysis
• Ultrafast magnetic resonance imaging
• Preimplantation genetic diagnosis

Adoption

• Adoption trends include international adoption as well as older children or that have known developmental problems.
• Children typically exhibit difficulties but fare well.

Environmental Contexts for Development

• Some environmental contexts for development are family, socioeconomic status and family functioning, Neighborhoods, towns, and cities plus cultural context.

Family influence on development can be due to:

• Direct influences
• Indirect influences such as effects of third parties.
• Also adaptation to changes within and outside the family.

Socioeconomic Status (SES)

• Social status consist of years of education and prestige of one's job and skill it requires.
• Economic status is generally income.

Socioeconomic Status and Family Functioning

SES is linked to:

• Timing of marriage and parenthood
• Family size
• Values and expectations for children
• Parents' education and economic security
• Communication and discipline styles
• Investment in children's cognitive development

Poverty

• 46 million Americans are under the poverty level = 15%
• Those hit hardest are parents under age 25 especially single mothers.
• Older adults who live alone especially women.
• Children, especially African- American, Native-American, and Hispanic children.

Homelessness

• Most homeless families are women with children under age 5.
• Homeless children suffer from developmental delays and chronic emotional stress.
• 25% to 30% of school-age homeless children do not attend school.

Affluence risks include:

• Alcohol and drug use
• High levels of anxiety and depression
• Unavailable parents, lack of emotional closeness and supervision, excessive demands for achievement

Importance of Regularly Eating Dinner as a Family

• This is associated with less anxiety and depression as well as less delinquency and substance abuse and better poor school grades.

Benefits of Strong Community Ties

• Neighborhoods: resources and social ties that promote development
• Towns and cities: mold children's and adults' daily lives
• Small towns: promote connection and participation.

Cultural Values

• Cultural values and practices shape daily life within and outside the family
• Subcultures cooperate family structures help protect members from harmful effects of poverty.

Individualistic and Collectivist Societies

• Individualistic groups define themselves as separate entities with Interdependent selves.
• Collectivist groups define themselves as part of a group with Interdependent selves.

Behavioral Genetics vs Heritability Estimates

• Obtained from kinship studies
• Provide an estimate of proportion of individual differences in a trait attributable to heredity
• Range from 0 to 1.00

Gene-Environment Interaction

• Individuals respond differently to same environment because of genetic makeup.
• Similar responses can result from different gene-environment combinations.

Canalization

• Tendency of heredity to restrict development of some characteristics to just one or a few outcomes.
• Ensures development of species-typical skills under many rearing conditions.

Gene-Environment Correlation

• Passive correlation
• Evocative correlation
• Active correlation: niche-picking

Epigenesis

• Development results from bidirectional exchanges between heredity and all levels of environment
• Genes affect behavior and experiences
• Experiences and behavior affect gene expression

Test your knowledge of core genetics concepts. Questions cover genotype, phenotype, DNA replication, meiosis, autosomes, sex chromosomes, fertilization, and inheritance patterns. Explore the fundamentals of heredity.