Class Notes (806,452)
Canada (492,253)
Psychology (6,022)

Psych 2040-Chapter 3: Hereditary Influences on Development.docx

6 Pages
Unlock Document

Western University
Psychology 2040A/B
Michael G Mac Donald

Overview  principles of hereditary transmission  how are genes expressed?  chromosomal and genetic abnormalities  behavioural genetics  determining heritability  interaction of heredity and environment Conception  father’s sperm + mother’s ovum = zygote  46 chromosomes total  23 from each parent The Chromosomes  each chromosome comes in pairs and contains genes: basic unit of heredity that builds a single protein  made up of DNA  chemical code for development  shaped like a double helix  has the ability to replicate Mitosis  begins after fertilization  zygote moves down fallopian tube and begins mitosis to become an individual with billions of cells  steps: 1. original parent cell splits, producing a duplicate 2. duplicate sets move to opposite ends of cell, which begins to divide 3. cell completes division, producing two daughter cells Meiosis & Crossing Over  steps: 1. each germ cell’s chromosomes duplicate themselves, remaining attached 2. crossing-over takes place among adjacent chromosomes  new hereditary combinations 3. original cell divides to form 2 parent cells, each with 23 duplicated chromosomes (some of which have been altered by crossing over) 4. each chromosome and its duplicate split and segregate into separate gametes  each gamete has half the chromosomes of its parent cell Multiple Births  twins  monozygotic: zygote divides to form genetically identical individuals  1/250 births  dizygotic: two ova released simultaneously and fertilized by different sperm  1/125 births Male or Female  autosomes: the 22 pairs of human chromosomes identical in males and females rd  depends on 23 pair of chromosomes  males— X and Y  females— X and X  X chromosome longer than Y chromosome  sex of child determined by father’s sperm What Do Genes Do?  production of enzymes, amino acids and other proteins necessary in forming new cells and regulate timing of development  guide cells to develop different parts of body  regulate pace and timing of development  may turn on or turn off other genes  impacted by environmental factors Gene Expression  alleles: one pairs of genes  influence many characteristics  one member from mother, one from father  polygenic inheritance: influenced by the action of many genes rather than a single pair  simple dominant-recessive inheritance  some alleles stronger than others  sex linked: recessive genes appear on X chromosomes; more likely to characterize males due to one X  homozygous alleles: both dominant or both recessive  heterozygous alleles: one dominant one recessive  codominant alleles: each heterozygous and equal  eg. AB blood Dominant Recessive  dark hair  blond hair  curly hair  straight hair  pigmented skin  albinism  type A blood  type O blood  facial dimples  no dimples  farsightedness  normal vision Congenital Problems  babies may have problems at birth due to hereditary or environmental causes  congenital problems are present at birth but not always apparent Chromosomal Abnormalities— Congenital Problems  How do chromosomal abnormalities occur?  during meiosis: uneven distribution of chromosomes  mutation  most are lethal  some babies born with +1 or -1 chromosome  sex chromosomes  female abnormalities:  Turner syndrome: XO  sterile, lack breasts, low spatial abilities  Poly-X syndrome: XXX, XXXX, XXXXX  fertile, phenotypically female, low verbal reasoning  male abnormalities:  Klinefelter syndrome: XXY or XXXY  sterile, tall, hips and breasts  Supermale syndrome: XYY, XYYY, XYYYY  very tall, fertile (low sperm count)  autosomes: first 22 pairs of chromosomes  down syndrome (trisomy 21)— most common  extra 21 chromosome  intellectual disabilities  distinctive physical features  risk increases with age of mother  genetic abnormalities  often associated with recessive traits  cystic fibrosis  diabetes  hemophilia  parents often healthy; both must be carriers Genetic Mutations as a Mechanism of Evolution  mutation: change in the chemical structure or arrangement of
More Less

Related notes for Psychology 2040A/B

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.