03-Heredity & Environment

03-Heredity & Environment

Genes

DNA (deoxyribonucleic acid) The basis of heredity Chromosome

Molecule of DNA Make up chromosomes

Humans = 46 (23 pairs) of chromosomes Genes = Section of chromosomes

Allele = Slight normal variation in a gene

Genome = Code for making an individual

20,000 genes (99% in other creatures also)Genotype = The full set of genes for a

specific orgasm organism (entire genetic inheritance)

Phenotype What you look like based on your genes

Appearance, personality, intelligenceGenotype = Hidden in your genesPhenotype = Observable characteristics

based on genes – E.g. brown eyes

Beginning of life

Gamete

SpermOvum (egg)Each has23 chromosomes (one half of 46)

Zygote

Single cell from two gametes

Male or female?

23rd pair of chromosomesFemale = XXMale = XY

Twins

Monozygotic (identical) twins From one zygote Share 100% genes

Dizygotic (fraternal) twins Two sperm penetrating two ova

Share 50% of their genes

ART = Assisted Reproduction Technology

IVF = In Vitro Fertilization Sperm mixed with ova in glass dish Viable embryos implanted

ICSI (Intracytoplasmic sperm injection)

Intrafallopian sperm injection

One cell to many

How genes interactGenotype = Entire set of genes (about

20,000)Phenotype = Appearance (blue eyes) and

behavior (alcoholic)

Genotype to phenotype

How genes affect appearance and behavior Genes + Environment = Phenotype

(Appearance & behavior)E.g. Alcoholism

Genes(Varies in intensity) + Environment (Encourages or discourages drinking) = Result

Epigenetic

All characteristics are determined by both genes and environment E.g. height and nutrition

Additive heredity

Some alleles (gene variations) combine to affect appearance and behavior

Dominant – recessive heredity

Dominate genes are more influential than recessive genes.

E.g. Brown eyes (Mother-dominate) + Blue eyes (Father-recessive) = Brown eyed child

Being a carrier for blue eyes can effect this

Genetic (chromosomal) abnormalities

Most often related to age of motherExtra chromosome

E.g. Down Syndrome = 47 chromosomes

Abnormalities of the 23rd. Pair

Humans have 44 chromosomes + one X + an “X” or ”Y” Embryos do not develop without one X

Missing chromosome E.g. XO

Three sex chromosomes XXY XYY Appear normal until puberty

Genetic Counseling

Find harmful conditionsAffect insurance coverageJeopardize the marriage