Ch. 2 - From Conception to Birth Flashcards
Deoxyribonucleic Acid
molecule containing chemical instructions for cells to manufacture various proteins. promotes growth and sustains life.
chromosomes
molecules of DNA; 46 in the human body arranged in 23 paits.
zygote
two gametes combine and produce a new individual with 23 chromosomes orm each parent.
gametes
reproductive cells each consisting of 23 chromosomes
copy number variations
small variations, mutations, or repetitions in base pairs not always found in other versions of the same gene.
DNA and RNA surrounding the gene enhance, transcribe, connect, silence, regulate, and alter genes through…
methylation
genotype
an organism’s genetic inheritance, or genetic potential. unique for each organism.
phenotype
an organism’s observable characteristics, including appearance, personality, intelligence, and all other traits.
allele
variation of a gene or any of the possible forms in which a gene for a particular trait can occur. effects vary greatly, from causing life-threatening conditions to having no detectable effects at all.
____ distinguishes each person, allowing the human species to adapt to pressures of the environment
genetic diversity
genome
involves the full set of genes that are the instructions to make an individual member of a certain species
The Human Genome Project found only ~_____ genes in humans
20,000 - 23,000
amount of autosomes vs sex chromosomes in humans:
44 vs 2
Female vs Male sex chromosomes
XX vs XY
monozygotic twins
AKA identical twins
- 1 zygote splits apart very early in development
- if split is incomplete, leads to conjoined twins
- same genotype, but slight variations possible in phenotype
dizygotic twins
fertilization of 2 separate ova by 2 separate sperm
- 1/2 genes in common; occur 2x more than monozygotic
- incidence is genetic, varying by age and ethnicity
T/F: almost every trait is polygenic and multifactorial
True
polygenic
affected by may genes
multifactorial
influenced by many factors
regulator genes
direct the interactions of other genes, controlling their genetic expression, duplication, and transcription. Responsible for differences between species.
additive genes
add to some aspect of the phenotype; add up to make the phenotype
dominant is ___ influential than recessive gene
more
only when recessive genes ______ can they be noticed/expressed
act alone
carrier
person whose genotype includes a gene not expressed in the phenotype. occurs in 1/2 of carrier’s offspring.
what makes offspring a carrier?
inherited one unexpressed gene from parents
what makes offspring express recessive genes in phenotype?
unexpressed gene is inherited from both parents
3 main periods of prenatal development
- germinal period (conception –> 2 weeks)
- embryonic period (3 –> 8 weeks)
- fetal period (9 weeks –> birth)
Germinal period
zygote begins duplication and division within hours of conception.
- placenta develops
- implantation 10 days after conception
- organism grows rapidly
Embryonic period
- primitive streak –> neural tube –> later on brain and spine
- head takes shape
- eyes, ears, nose, mouth form
- heart begins to pulsate
fetal period
- genitals form
- sex hormones cause differentiation in fetal brain organization
period of greatest brain growth
4th, 5th, and 6th months
Age of viability
~22 weeks after conception
- preterm newborn may survive outside uterus with medical care
- brain can regulate basic body functions
only __% of all zygotes grow and survive to become living newborn babies
31%
Average duration of labour for firstborn
12 hours; usually quicker for later-born
what triggers birth?
fetal brain signals a release of hormones to trigger mother’s uterine muscles
apgar scale
quick assessment of newborn heartrate, breathing, muscle tone, colour, and reflexes.
measured 2x: 1 min and 5 min after birth
each category scores a 0, 1, or 2. Ideal score is 7+
medical interventions have led to…
- childbirth becomes safer for mothers
- infant mortality has decreased
- has disadvantages
cesarean section
surgical birth in which the fetus is removed quickly.
usually safe for mother and baby, saving lives when the fetal head is too large for the pelvis. rates vary from country to country
traditional and modern birth
increasing home births and decrease in hospital births
doulas
help with prenatal, birth, and postnatal care. helps to decrease c-section rates
Brazelton Neonatal Behavioural Assessment scale records…
46 behaviours, including 20 reflexes
reflex
an unlearned, involuntary action/movement in response to a stimulus, occurring without conscious thought
mothers and postpartum depression
many women experience significant physical problems after birth; psychological symptoms range from baby blues to postpartum psychosis. this may involve struggles with adequate baby care. varied causes
father’s role
help mother stay healthy
help mother manage stress
experiencing couvade in some cultures
Chromosomal Miscounts
1 in 200 births have 45, 47, 48, o 49 chromosomes
Down syndrome
aka trisomy-21; 47 chromosomes
how many infants are born with only one or three plus sex chromosomes?
1 in 500
most dominant gene disorders begin in…
adulthood. fatal dominant childhood conditions cannot be passed on.
___ gene disorders are more common
recessive
when is the phenotype affected in genetic disorders?
when the inherited gene is dominant
OR
when both parents carry and pass on a recessive gene.
teratogens
any agent/condition (including viruses and drugs) resulting in birth defects or complications.
behavioural teratogens
agents and conditions that can harm the prenatal brain, impairing the child’s intellectual and emotional functioning.
critical periods for body formation, body weight, brain development:
- first days/weeks critical for body formation.
- final months important or body weight
- health during entire fetal period important for brain development
threshold effect
certain teratogens are relatively harmless until exposure reaches a certain level.
fetal alcohol syndrome results from…
embryos exposed to mother’s heavy drinking
innate vulnerability
some zygotes carry genes making them vulnerable
before pregnancy, mothers should…
- plan
- take multivitamins
- avoid drinking
- update immunizations
- reach appropriate weight
- reassess prescription drugs
- develop exercise habits
what % of early pregnancy tests raise anxiety and why?
20%
- parents may not want to know
- couples argue about risks
- danger of false positives or false negatives
preterm
birth occurring at 35 weeks or fewer after conception; usually associated with LBW
small for gestational age (SGA)
birthweight significantly lower than expected, given the time since conception; suggests impairment throughout prenatal development or serious problems
low birthweight (LBW)
< 2,500 g or 5.5 lbs at birth
very low birthweight (VLBW)
< 1,500 g / 3 lbs 5 oz at birth
extremely low birthweight (ELBW)
< 1,000 g / 2 lbs 3 oz at birth
what does LBW mean for chances of survival
decreased chances of survival
maternal behaviour/malnutrition for LBW
- health/illness
- drug use before/during pregnancy
- effect of father/family and their attitudes and behaviour on malnutrition
immigrant paradox
although lower SES correlates with LBW and poor neonatal health, this is not true or some immigrant groups in the US, especially Hispanics
consequences of LBW
- high risk infants and children (early developmental accomplishments are late; cry more, pay attention less, disobey more; experience language and developmental delays
- middle childhood, former SGA (more neurological problems, smaller brain volume)
risk analysis gives…
odds, not certainties!
heritability
statistical term indicating what portion of the variation in a particular trait within a particular population is inherited.
