Chapter 2: Biological and Environmental Foundations and Prenatal Development Flashcards
What is a dominant gene?
gene that is always expressed regardless of the gene it is paired with
What is a recessive gene?
gene that is expressed only if paired with another recessive gene
Genetic Disorders
Name 2 dominant-recessive disorders.
Huntington’s Disease (dominant)
Phenylketonuria (PKU) (recessive)
Genetic Disorders
What are X-linked disorders?
genetic disorder carried on the X chromosome
Genetic Disorders
Who is more likely to get X-linked disorders?
males are more likely because they only have one X chromosome, and there is no other chromosome to override the disorder on their X chromosome
Genetic Disorders
Name 2 X-linked disorders.
Hemophilia
Color Blindness
Genetic Disorders
What are chromosomal abnormalities?
result from cell reproduction (mitosis and meiosis), or from damage after reproduction
Genetic Disorders
Name 3 chromosomal abnormalities.
Down Syndrome (3rd chromosome on 21st pair)
Turner Syndrome (only females, only one X chromosome)
Klinefelter Syndrome (only males, have an extra X chromosome)
Genetic Disorders
What are mutations?
sudden change or abnormality in structure of the gene that occurs spontaneously or due to exposure to environmental factors
Genetic Disorders
How might a mutated chromosome affect pregnancy?
- about half of all fertilized eggs have some level of mutated chromosomes
- the developing zygote or embryo is miscarried because the level of mutation is so severe that they embryo won’t survive the pregnancy, or won’t survive after its born
What is genetic counselling?
constructing family history of heritable genetic disorders to determine risk of genetic defects and chromosomal abnormalities
- have the opportunity to make a decision if they want to proceed with having the biological child, or use another method
What is prenatal diagnosis?
testing done after a women is pregnant, to assess for genetic defects and chromosomal abnormalities
When is CVS or amniocentesis conducted? (2)
- when genetic counselling determines there’s a risk for genetic abnormalities
- when mother is over age 35 (high risk of birth defect)
What is prenatal treatment?
therapies administered prenatally to reduce effects of genetic abnormalities
- done when we know that there’s a genetic disorder in the child
- drugs, medication, surgery can be used as treatment
What does behavioural genetics study? (4)
- examines how genes and experience combine to influence human traits, abilities, and behaviours
- studies of families (twins, adoption)
- examines how the genetic and environmental influences compare
- compare people who have varying degrees of relatedness (ie. similar environment but dissimilar DNA, comparison between identical and fraternal twins, regular siblings with adoptive siblings)
What is range of reaction?
wide range of potential expressions of genetic trait, depending on environmental opportunities and constraints
ie. severe lack of nutrition can alter person’s growth even though they have certain traits and genes that suggest otherwise
What is canalization?
heredity narrows range of development to only one or a few outcomes
ie. humans are biologically programmed to start walking at around 12 months regardless of minor influences, however, if there is some level of severe deprivation the child experiences, they might not start walking until later
What are gene-environment correlations?
many traits are supported by both genes and environment
ie. parent has a genetic musical ability and they pass it on to their child, then they raise the child in a musical environment
What are passive gene-environment correlations?
child doesn’t do anything, but parent provides gene and environment
What are active gene-environment correlations?
niche-picking:
child actively seeks out activities and experiences in their environments that are supportive of their genetic tendencies
When is the embryonic period?
3rd–8th week after conception
What happens during the embryonic period?
most rapid growth in prenatal development: all organs are functioning
What happens if defects occur during the embryonic period?
result in miscarriage or abortion (because organs are not functioning)