1. Human Growth and Development
Day #4
Fort Omaha 12 – 1:55 p.m.
March 22, 2011

2. Agenda for Day #4
Methods
Begin genetics
7 mos
20 mos.

3. Steps in the method Identify and Define the Problem
Formulate Hypotheses
Select Methodology
Collect and Analyze Data
Draw Conclusions relevant to Hypothesis
Report Results
Expand to Future Studies

4. Formulating Hypotheses
Hypothesis = statement of the relationship presumed to exist between dependent and independent variables.
Cause and Effect implications
Must be testable; dependent variable must be measurable.

5. Sample Hypotheses
Older pregnant women are more likely to have their babies delivered by Cesarean birth than younger ones. IV DV
Babies who are picked up every time they cry will tend to cry more.

6. Common Methodologies Surveys Observations Case studies
Interviews
Questionnaires
Observations
Participant
Unobtrusive
Simulated
Case studies
Experimental Studies

7. Approaches to developmental studies
Cross- sectional studies study several age groups simultaneously
Longitudinal studies study the same subjects over a period of time
Sequential studies

8. Correlation vs. Causation
Classical Experimental
Design
Dependent
variable
Control
Group
Independent
Variable
Experimental
or Treatment
Pre -
test
Post
Correlation vs. Causation
Correlation – two events or variables appear to be related to one another
Causation – one event or variable can be shown to “cause” the other to happen
can be established only through experimental studies.

9. Ethical Issues Do not deceive, coerce or harm the subjects
Collect data using ethical procedures
Protect confidentiality of subjects
Report results accurately

10. Opening Day Survey
Hypothesis: Men and women will differ in their preference for comfort/snack foods.
Men are more likely to prefer salty or savory snacks whereas women are more likely to prefer sweet foods.
IV = sex of the individual (variables are never the people; some characteristic of the person)
DV = snack/comfort food preference; salty or sweet foods

11. Survey Results Can I support my hypotheses?
Sex
Sweet
Salty/Savory
Not scored
Male
1 (11%)
7 (77%)
Female
18 (64%)
10 (36%)
Total (N=37)
19 (51%)
17 (46%)
1 (2.7%)
Can I support my hypotheses?
If I were on a committee working with the bookstore and food service/ vending for the College, how might I use these results?

12. The Data from the Class Survey Winter 2010
N = (11 males; 43 females)
Salty/Savory Sweet
Males (27%) (63%)
Females (62%) (34%)
Abstain
Can I support my hypothesis?

13. Genetics and Human Development

14. .

15. GENETIC FOUNDATIONS OF DEVELOPMENT
Each of us carries a “genetic code” that we inherited from our parents
A fertilized human egg carries this human code
fertilized human egg cannot grow into any other species

16. Human Genetics
Each of us began life as a single cell weighing about one twenty-millionth of an ounce
This cell contained our entire genetic code

17. Chromosomes Nucleus of each human cell contains chromosomes
thread-like structures made up of deoxyribonucleic acid, or DNA.
DNA is a complex molecule that has a double helix shape, like a spiral staircase, and contains genetic information

18. DNA Molecule

21. Genes Genes - units of hereditary information
short segments of DNA
Genes direct cells to reproduce themselves and to assemble proteins
Proteins
the building blocks of cells
the regulators that direct the body’s processes
(Mader, 2008)

23. Human Genome Project Preliminary map of the human genome
the complete set of developmental instructions for creating proteins that initiate the making of a human organism
Each human has 20,000 – 30,000 genes

24. Enduring Nature of Genes
Three processes by which cells split and are formed
Mitosis
Meiosis
Fertilization.

25. Mitosis
All body cells, except the sperm and egg, have 46 chromosomes arranged in 23 pairs
These cells reproduce by a process called mitosis
During mitosis, the cell’s nucleus—including the chromosomes—duplicates itself and the cell divides
Two new cells are formed, each containing the same DNA as the original cell.

26. Meiosis Sex cell division is different type of cell division
Eggs and sperm (or gametes) are formed in meiosis
A cell of the testes (in men) or ovaries (in women) duplicates its chromosomes but then divides twice, thus forming four cells
Each of these has only half of the genetic material of the parent cell.
By the end of meiosis, each egg or sperm has 23 unpaired chromosomes.

27. Fertilization
During fertilization, an egg and a sperm fuse to create a single cell, called a zygote
In the zygote, the 23 unpaired chromosomes from the egg and sperm combine to form one set of 23 paired chromosomes
One chromosome of each pair is from the mother’s egg and the other from the father’s sperm.
Each parent contributes half of the offspring’s genetic material.

28. The 23rd Pair of Chromosomes
Ordinarily, in females the 23rd pair consists of two chromosomes called X chromosomes
In males the 23rd pair consists of an X and a Y chromosome
The presence of a Y chromosome is what makes an individual male

30. Sources of Variability
Combining genes of two parents increases genetic variability in the population
chromosomes in the zygote are not exact copies of the parents
Another source of variability comes from DNA
a mutated gene, which is a permanently altered segment of DNA

31. Genotype and Phenotype
Genotype -- all of a person’s genetic material
Phenotype -- observable characteristics
Phenotypes include
physical characteristics (such as height, weight, and hair color)
psychological characteristics (such as personality and intelligence)

32. Genetic Principles Dominant-recessive genes Sex-linked genes
Genetic imprinting
Polygenically determined characteristics

33. Dominant-Recessive Genes Principle
Dominant -- one gene of a pair always exerts its effects
Recessive gene – exerts its influence only if the two genes of a pair are both recessive
may be overridden by a dominant gene
May be carried from generation to generation but not expressed in phenotype

34. Sex-Linked Genes
X-linked inheritance -- mutated gene is carried on the X chromosome
very different implications for males than females (Turner, 2006)
males have no “backup” copy to counter the harmful gene
females have a second X chromosome, which is likely to be unchanged
Females who have one changed copy of the X gene are known as “carriers”

35. Polygenic Inheritance
Genetic transmission is usually quite complex
Few characteristics reflect the influence of only a single gene or pair of genes
polygenically determined characteristics -- determined by the interaction of many different genes

36. Chromosome Abnormalities
Down syndrome -- caused by the presence of an extra copy of chromosome 21
once in every 700 live births
Women aged are less likely to give birth to a child with Down syndrome
Sex-Linked Chromosome Abnormalities

37. Sex-Linked Chromosome Abnormalities
Klinefelter syndrome – extra X chromosome
Fragile X syndrome -- results from an abnormality in the X chromosome
X chromosome becomes constricted and often breaks
Turner syndrome -- females have either an X chromosome missing or part of one X chromosome is deleted
XYY syndrome – male has extra Y

38. Gene-Linked Abnormalities
Phenylketonuria (PKU) – individual cannot properly metabolize phenylalanine, an amino acid
once in every 10,000 to 20,000 live births
left untreated, phenylalanine builds up in the child, producing mental retardation and hyperactivity

39. Sickle-cell anemia -- genetic disorder that impairs the body’s red blood cells
most often in African Americans
red blood cell becomes a hook-shaped “sickle” that cannot carry oxygen properly
1 in 400 African American babies is affected
1 in 10 African Americans is a carrier
1 in 20 Latin Americans is a carrier

40. Other diseases that result from genetic abnormalities
cystic fibrosis
diabetes
hemophilia
Huntington disease
spina bifida
Tay-Sachs disease

41. Assignment
Genetics and Prenatal Development (finish reading Chapters 2 and 3)
Notes are on the Quia website:
Twins