Genetic and environmental foundations Flashcards
Heredity is?
biological transmission of traits and characteristics from one generation to another
Genetics
· the field within the science of biology that studies heredity
· Genetic foundations-genetic code:
- Cell> nucleus>chromosome>DNA> gene
Chromosomes and genes are the fundamental units of heredity
Chromosomes
23 pairs of rod-shaped structures, organized packages of DNA that carry and transmit genetic information.
Genes
· : biochemical materials that regulate the development of traits
- Segments within chromosomes
- Section of the DNA that contains a specific pattern of amines.
- DNA: Long, double-stranded molecule that looks like a ladder.
- May be transmitted by a single pair of genes, or may be polygenic ( determined by combinations)
- 20,000-25,000 genes in each cell.
Autosomes
- The 22 of the pairs are called.
- The pairs look alike and possess genetic information concerning the same set of traits.
sex chromosomes
- The 23rd pair consist of sex chromosomes.
- Different from other chromosomes and determine our sex.
- Two of the chromosomes (the X and the Y chromosome) determine your sex as male or female when you are born … Skoða mynd.
- If an egg cell is fertilized by an x-carrying sperm cell, it will be a girl: xx
Genetic foundation: multiple offspring
- Fraternal/dizygotic twins: two egg cells (ova) are fertilized by two sperm cells, resulting in two zygotes.
- Identical/monozygotic twins: one egg cell(ovum) is fertilized by one sperm cell, resulting in one zygote which divides into two individuals.
- Zygote: a new cell formed from the union of a sperm and an ovum (egg cell); a fertilized egg.
Chromosomal and genetic abnormalities
- Occur when children do not have the normal number of 46 chromosomes.
- Risk rises with age of parents.
- Father aged 40 and older are 5-6 times as likely to have children with autism spectrum disorder.
Risk of down syndrome rises with maternal age
Down Syndrome
- Mostly happens when the 21st chromosome pair fails to separate.
- So, the new individual receives 3 of those chromosomes instead of 2.
- Cause: extra Chromosomes on 21st pair.· Characteristics of children
- Distinctive facial features
- Intellectual disabilities, memory, and speech problems, limited vocabulary, slow motor development
· Adjustment problems - Other children are not sensitive to their needs and feelings.
- Parental support is critical.
Sex chromosome abnormalities
- Caused by problems with X or Y chromosome.
- Often not recognized until adolescence
- Usually involve the presence of an extra chromosome (x or Y) or the absence of x in females.
- Extra x or Y chromosome:
- Females: triple x syndrome (xxx)
- Males: Klinefelter syndrome (XXY)
- XYY syndrome (supermales)
- Absent X chromosome:
Females: turner syndrome (x)
Females: sex chromosome abnormalities
- Triple x syndrome (xxx) -à 1 female in 1.000.
- Increased incidence of infertility.
- Lower language skills and short-term memory skills.· Turner syndrome (x) à 1 female in 2.500
-ovaries are poorly developed - produce less of the female sex hormone estrogen than normal females
- shorter than average
- infertility
- underdeveloped breast, lack of menstruation.
- problems in visual-spatial skills, mathematics, and nonverbal memory.
Males: sex chromosome abnormalities
· sex chromosome abnormalities
- Klinefelter syndrome (XXY)à 1 male in 500
- Produce less of the male sex hormone testosterone than normal males.
- Nor properly developed—testes, Deeping of the voice, musculature, body hair.
- Enlarged breasts.
- Intellectual disability (language delays)
- Xxy syndrome (Jacob’s syndrome) à 1 male in 700-1.000.
- The extra Y heightens male secondary sex characteristics ( e.g., taller than average; develop heavier beards)
- Supermalesà nor superior
- Developmental delays (e.g., in language domain)
- More aggressive behavior?
Huntington disease/ Determining Genetic or Chromosomal abnormalties
- Genetic counseling:
- A communication process designed to help couples.
- Asses their chances of giving birth to a baby with a hereditary disorder.
- Choose the best course of action in the face of risk and family goals.
Individuals likely to seek genetic counseling:
- Couples have had difficulties bearing children.
- Known genetic problems that exit.
- Woman over 35.
prenatal testing
- Blood tests
- Ultrasound: used to track fetal growth and determine age, sex, and structural abnormalities.
- Amniocentesis:14-16 weeks after conception via needle withdrawing fluid from the amniotic fluid. Some risk of miscarriage can detect more than 100 chromosomal and genetic abnormalities in fetus.
Chorionic villus sampling: 9th and 12th weeks of pregnancy by inserting needle trough vagina into the uterus—from the outer membrane that envelops the amniotic sac and fetus. Risk of spontaneous abortion or miscarriage
