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Developmental PSYC213 > Chapter 3: biological foundations, genetics and prenatal development > Flashcards

Chapter 3: biological foundations, genetics and prenatal development Flashcards

1
Q

Pre and Early Life Cells

A
  • Gametes:
    • reproductive cells: sperm and ova
    • Only contain 1⁄2 normal complement of DNA
  • Zygote: new cell formed by conception.
    • Full complement of DNA (1⁄2 from sperm + 1⁄2 from egg)
    • All other cells are derived from the zygote by Mitosis
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2
Q

Deoxyribonucleic acid (DNA):

A

Genetic information for each cell

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3
Q

Genes:

A

segments of DNA that code for individual traits

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4
Q

Chromosomes

A
  • Storage structures for DNA
  • Rod-like structures visible in cell nucleus
  • 46 chromosomes in 23 pairs

• Sex Chromosomes

  • Males = XY
  • Females = XX
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5
Q

Mitosis

A
  • Mitosis is the process that ensures that the duplicate cell is identical in genetic makeup to the original cell
    • The replication of genetic material during cell multiplication and the transfer of genetic information during reproduction are central to understanding development and growth
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6
Q

Meiosis

A
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7
Q

Genotype vs Phenotype

A

• Genotype
– The genetic code of the individual; sum of all genes
– Together with the environment determines phenotype

• Phenotype
– Traits as displayed or expressed
– Examples: height, eye colour or IQ

Phenotype = Genotype + Environment

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8
Q

Alleles

A
  • There are two alleles for each gene, one from each parent
  • Different alleles can produce variation in inherited characteristics
  • Some alleles are dominant, some are recessive, and some are co-dominant
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9
Q

Dominant and Recessive Inheritance

A

Dominant alleles

  • Always expressed in phenotype
  • e.g., brown eyes, curly hair, facial dimples, type A blood, Huntington’s disease
  • Possible genotypes: DD, Dd or dD (capitalisation indicates dominant allele)

Recessive alleles

  • Must be paired with another recessive allele (aka one from each parent) to be expressed
    e. g., blue eyes, colour-blindness, baldness, type O blood, PKU

Possible genotype: dd

Co-dominance:

• Both alleles expressed • Example of blood group

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10
Q

Homozygous alleles

Heterozygous alleles

Polygenic traits

A
  • Homozygous: alleles for a trait are identical
  • Heterozygous: alleles for a trait are different
    • Can be a carrier for a recessive allele (e.g., haemophilia)
  • Polygenic traits: many genes as well as environment influence character (most traits are polygenic)
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11
Q

Summary of concepts

A
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12
Q

Determination of sex

A
  • Ova - X; Sperm - X or Y
  • Sex of zygote determined by which type of sperm fertilises the ovum
  • 30% more male than female zygotes
  • 6% more live male births
  • Some traits are inherited in a sex linked manner
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13
Q

Genetic abnormalities

A
  • Chromosome abnormality
  • e.g., Down syndrome
  • Dominant gene disorders
  • e.g., Huntington’s disease
  • Recessive gene disorders
  • e.g., Sickle-cell disease
  • Multifactorial
  • e.g., congenital heart disease
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14
Q

Down syndrome

A
  • Trisomy 21 – an extra 21st chromosome
  • Most common autosomal disorder
  • Responsible for 40% of moderate to severe mental retardation
  • Symptoms include distinct facial features, mental retardation, speech problems, and slow motor development.
  • Incidence increases with maternal age
  • 1 in 1900 births at 20yrs; 1 in 300 at 35yrs; 1 in 30 at 45yrs
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15
Q

Phenylketonuria (PKU)

A
  • Frequently occurring recessive disorder
  • By 1 year infants are permanently retarded
  • However, if identified early, these children are given a diet low in phenylalanine and usually attain an average level of intelligence and have a normal lifespan
  • Inheriting unfavourable genes does not always lead to an untreatable condition if the environment (diet) can be adjusted
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16
Q

Abnormalities of the Sex Chromosomes

A
  • These disorders produce less severe problems and deficits usually result in fewer problems than defects of the autosomes
  • Often not recognised until adolescence
  • XO = Turner’s syndrome (Female, short, infertile)
  • XXY = Kleinfelter’s syndrome (Male, sterile, learning disorders)
  • XYY = Male, tall, low IQ (especially verbal IQ)
17
Q

Genetic counseling

A

• Helps prospective parents assess risk of bearing a child with a genetic defect

  • Especially helpful when:
  • Parents already have biological children with a defect
  • Family history
  • Ethnicity
  • Women 35 years or older
18
Q

Behavioural genetics

A

• Behaviour genetics: study of the nature/ nurture interaction

  • Remembering that:
  • Nature = genetics
  • Nurture = environment

Phenotype = Genotype + Environment

19
Q

Examples of behavioural genetics

A

Examples of how behavioural genetics can be analysed in humans:

Adoption studies: dissimilar nature, similar nurture

Twin studies: identical or fraternal, raised separately or together

20
Q

Prenatal development

Gestation

Gestational age

A

• Gestation: The approximately 38-week period of development between conception and birth

• Gestational Age: Age of unborn baby, usually dated from the first day of an expectant mother’s last menstrual cycle

21
Q

Stages of prenatal development (4)

A
  • Conception
  • Germinal (0 - 2 weeks)
    • Blastocyst implants in uterus wall
  • Embryonic (3 - 8 weeks)
    • Umbilical cord connects embryo to placenta
    • Amniotic sac develops
  • Foetal
    • Week 9 to birth
22
Q

Germinal stage of development

A
23
Q

Foetal Stage Development: 8 Weeks to Birth

A

• Organs and body become more complex

  • “Finishing touches” – toenails, eyelids
  • Appearance of bone
24
Q

Two types of multiple births

A
  • Monozygotic (MZ)
    • One egg – one sperm cell
    • Identical twins
    • Share 100% of genes
  • Dizygotic (DZ)
    • Two eggs – two sperm cells
    • More common
    • Fraternal twins
    • Share 50% of genes – just like non-twin siblings
25
Q

Prenatal influences on the child

A
26
Q

Teratogens (prenatal hazards) examples

A

• Medicinal drugs
–Prescription of drugs such as thalidomide

• Non-medicinal drugs
–Foetal alcohol syndrome, foetal alcohol effect

• Maternal disease
–Viruses, bacteriological and parasitic diseases, STIs, HIV/AIDS

• Environmental hazards
–Physical, biological, chemical, radiation

27
Q

Maternal and environmental factors that Impact on Prenatal Development

A
  • Age of mothers
    • > 35 years – higher risk of infertility and Down syndrome infant
    • Teenage – higher risk for low birth weight babies, stillbirths, birth complications
  • Domestic violence
    • Stress, family dysfunction, may be deliberate to terminate pregnancy
28
Q

Paternal Factors that Impact on Prenatal Development

A

• May affect quality of sperm:

  • Exposure to lead
  • Marijuana or tobacco smoke

• Alcohol or radiation

  • Pesticides
  • Paternal age
29
Q

Risks to prenatal health

A

• Risks:
• Weight gain

  • Cigarettes, alcohol, drugs
  • Signs of pregnancy complication

• Need for:
• Rest, exercise, personal hygiene

  • Preparation for labour and birth
  • Effective use of health care system
30
Q

Childbirth settings

A
  • Until 1800s home births most common
  • Rising power of medicine saw delivery moved to hospitals by 1900s
  • Hospital births account for 90%

–Birthing rooms and rooming in

• Non-hospital

–Birth centres

–Home births

31
Q

Birth process

Difference between Parturition and Labour

A
  • Parturition – (before childbirth) brings on labour 2 weeks before delivery
    • Uterine contractions
    • Cervix becomes flexible
    • Stimulated by rising estrogen levels
  • Labour refers to uterine contractions that affect dilation of cervix and forces the fetus through birth canal
32
Q

Birth

Feotal presentation

Stages of labour

A
  • Foetal presentation
    • Cephalic (head first)
    • Breech (bottom and feet first)
    • Transverse (sideways)
  • Stages of labour
    • First stage – up to 10cm cervix dilation
    • Transition to full dilation
    • Second stage – culminates in birth
    • Third stage – expulsion of placenta and umbilical cord
33
Q

Different methods of prepared childbirth

A
  • Read method
  • Lamaze method
  • Leboyer technique
34
Q

Midwives and doulas

A
  • Important role served by the two
  • Support from doulas linked to shorter labours and fewer delivery complications
35
Q

Medication for deliveries

A
36
Q

Problems during labour

A
  • Faulty power (uterus doesnt contract strongly enough)
    • Oxytocin can induce labour
  • Faulty passageway
    • Placenta Previa (cervix covered by placenta)
  • Faulty passenger
    • Breech
    • cephalopelvic disproportion (baby is too big)
  • Caesarean section
    • When vaginal delivery is unsafe

Developmental PSYC213 (11 decks)

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