Week 2: Biological Foundations Flashcards
(25 cards)
What are chromosomes and how many does a human have?
Chromosomes are threadlike structures in the nucleus containing genetic material.
Humans have 46 total (23 pairs).
What determines the sex of a child?
The 23rd chromosome pair. Females = XX, Males = XY.
The father “determines” the sex.
What are autosomes?
The first 22 pairs of chromosomes that are not involved in determining sex.
True or false: The human egg and sperm unite, resulting in a zygote that contains a complete set of 23 paired chromosomes (46 in total)
True
What are the four nucleotide bases in DNA?
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G).
A pairs with T, C pairs with G.
What are alleles and how do they influence traits? (4)
Alleles are different forms of the same gene found at the same location on a chromosome. Each person inherits two alleles for each gene—one from each parent. Alleles determine traits, and can be:
Dominant: Expressed when at least one dominant allele is present (e.g., Aa or AA).
Recessive: Only expressed when both alleles are recessive (e.g., aa).
Homozygous: Both alleles are the same (AA or aa).
- Ex. Both parents contribute the allele for the same-coloured eyes
Heterozygous: Alleles are different (Aa).
- Ex. One parent contributes the allele for blue eyes and the other for brown eyes
Define genotype and phenotype.
Genotype: genetic makeup.
Phenotype: observable traits from gene-environment interaction.
What is dominant-recessive inheritance?
One allele can mask another in a heterozygous pair.
Dominant is expressed; recessive is masked.
What causes Down syndrome?
An extra 21st chromosome (Trisomy 21).
Name 4 genetic disorder linked to abnormal sex chromosomes.
Klinefelter’s Syndrome (XXY): male, tall, small testicles, sterile, below-normal intelligence, passive
Turner’s Syndrome (X): female, short, limited development of secondary sex characteristics, problems perceiving spatial relations
XYY complement: male, tall, some cases apparently have below-normal intelligence
XXX syndrome: female, normal stature, delayed motor and language development
What are general prenatal risk factors? (4)
Nutrition
- lack of folate can lead to spina bifida in baby
Stress
- incr risk of making poor decisions
- immune system weakens
- hormones can incr maternal HR & decr O2 to baby
- worse in early pregnancy
Maternal age
- pregnancy should happen bw 20-35
What is a teratogen?
An agent that causes abnormal prenatal development:
1) Drugs
- Thalidomide -> a drug used to treat morning sickness in the 1950s, caused babies to develop serious abnormalities, sometimes including missing limbs
- aspirin
- coffee
- alcohol (FAS)
- drugs
2) Diseases
- AIDS
- STIs (chlamydia, genital herpes, syphilis)
- Chicken Pox
- Cytomegalovirus
- Toxoplasmosis
3) Environmental hazards
- Lead
- Mercury
- PCB Chemicals
- X-Rays
What factors determine the impact of teratogens on fetal development? (4)
Genetic Interaction:
- The effect of teratogens can vary depending on the individual’s genetic makeup.
Timing:
- Development is particularly sensitive to teratogens between weeks 3 and 8 of pregnancy.
Specific Events:
- Teratogens may cause harm during particular stages or events in development.
Dosage-Dependent Impact:
- The severity of the effects depends on the amount and duration of exposure to the teratogen.
True or false: damage from teratogens is not always evident at birth
True
What are two types of prenatal assessment?
Amniocentesis: prenatal diagnostic technique that involves withdrawing a sample of amniotic fluid through the abdomen using a syringe
- Results in 2 weeks
- 1% risk of miscarriage
- Assesses fetal cells for abnormalities
Chorionic villus sampling (CVS): prenatal diagnostic technique that involves taking a sample of tissue from the chorion
- Can be performed 9–12 weeks after conception
- Results in 7–10 days
- 2% risk of miscarriage
What is postpartum depression and what are some risk factors?
A mood disorder after childbirth. Risk factors include hormonal changes, stress, lack of support, and unplanned pregnancy.
True or false: Postpartum Depression Occurs in about 10–15% of new mothers
True
Symptoms of postpartum depression?
Irritability, feelings of low self-worth, disturbed sleep, poor appetite & apathy
What are the dangers of Postpartum Depression?
Lack of warm mothering
Less touching, cuddling, talking to the baby
Less effectiveness in dealing with feeding and sleep routines
In mothers’ long-term depression, increased risk of children’s insecure attachment and later antisocial behaviour
What is infant mortality? What are the rates in Canada?
The number of infants out of 1,000 births who die before their first birthday
Canada’s mortality rate is about 5 for every 1,000 births, but with large regional disparities
- Low in PEI and Nova Scotia (3.4)
- High in Northwest Territories (15.5) and Nunavut (14.8)
What did Gregor Mendel discover?
That traits are inherited through paired alleles, and some traits are dominant while others are recessive.
What is a Punnett Square used for?
To predict genotype and phenotype probabilities in offspring.
What is epigenetics?
The study of how chemical tags on DNA influence gene expression without changing the DNA itself.
What can influence the epigenome?
Diet, stress, chemical exposure, medication, and life experiences (e.g., trauma).
Environmentally-induced epigenetic changes are part of the reason why genetically identical twins can grow up to have different lives
