1. 11.3 CHROMOSOMES & HUMAN HEREDITY
WHAT YOU WILL LEARN
-The role of telomeres
-How nondisjunction leads to Down syndrome and other abnormalities
-The benefits and risks of fetal testing

2. READING Q’s 1-APPLY: Examine the karyotype.
Are these chromosomes for a male or female?
-MALE

3. READING Q’s 2-DEFINE -What happens during nondisjunction?
-sister chromatids do not separate properly during cell division.

4. READING Q’s
3-EVALUATE
-Does nondisjunction during meiosis produce any normal genes?
-YES
EXPLAIN-
-nondisjunction during meiosis II produces
two normal and two abnormal gametes

5. READING Q’s
4-LABEL
-Circle the pictures that show a trisomy in the sex chromosomes

6. READING Q’s 5-STATE -The purpose of fetal testing
-to test for genetic disorders in the fetus

7. BACKGROUND INFO
-1/2 SHEET NOTES

8. KARYOTYPE -method of identification of chromosomes HOW WHY
-picture taken during mitosis
-image enlarged
-individual chromosomes cut up
-chromosomes matched based on:
-size (largest smallest)
-centromere position
-g-banding
WHY
-identify abnormalities in chromosomes
-identify abnormalities in genes
-identify sex of fetus

9. KARYOTYPE: EXAMPLE
A mess of chromosomes…

10. After karyotyping- male or female?
KARYOTYPE: EXAMPLE
After karyotyping- male or female?
NORMAL MALE
NORMAL FEMALE

11. NON-DISJUNCTION WHAT WHEN FACTS -chromosome pair fails to separate
-during meiosis
-as a result, the gamete that forms has the wrong # chromosomes
-TRISOMY: 1 extra
-MONOSOMY: 1 less
FACTS
-occurs quite often in humans
-impact so severe to zygote: miscarriage occurs very early in pregnancy
-if baby survives, develops a set of traits we call a syndrome

12. NON-DISJUNCTION

13. NON-DISJUNCTION: trisomy
Trisomy 21- Down’s Syndrome
-most commonly known trisomy
-extra chromosomes #21
-1:700 births
TRAITS
-common facial features
-short stature
-stubby fingers/toes
-large tongue: difficult speech

14. Trisomy 21

15. NON-DISJUNCTION: trisomy
Patau Syndrome
-extra chromosomes #13
-1:1500 births
TRAITS
-serious eye, brain, and circulatory defects

16. Trisomy 13

17. NON-DISJUNCTION: trisomy
Edward’s Syndrome
-extra chromosomes #18
-10% survive past 1yr
TRAITS
-many complications

18. Trisomy 18

19. NON-DISJUNCTION
These are the only known trisonomy genetic disorders that result in offspring surviving for a short period of time

20. NON-DISJUNCTION: SEX CHROMOSOMES
-can be fatal
-most survive with specific traits

21. NON-DISJUNCTION: SEX CHROMOSOMES
Klinefelter’s Syndrome
-1:500 males
-XXY
TRAITS
-tall, sterile male
-normal intelligence
-has some female characteristics

22. NON-DISJUNCTION: SEX CHROMOSOMES
Jacob’s Syndrome (super male)
-1:1000 males
-XYY
TRAITS
-taller than average
-slightly below normal intelligence
-extra testosterone

23. XYY

24. NON-DISJUNCTION: SEX CHROMOSOMES
super female
-1:1000 live births
-XXX
TRAITS
-no physical problems
-normal intelligence

25. XXX

26. NON-DISJUNCTION: monosomy
Turner’s Syndrome
-1:2700 births
-XO
TRAITS
-live normal lives
-do not mature sexually at puberty
-sterile
-short stature, short broad neck, broad chest

27. Monosomy XO

28. GROUP WORK: APPLICATION NOTES
-As a cooperative group complete the note sheet using your knowledge from the reading / discussion.
HIGLIGHT/MARK supporting info in the text
-DISCUSS ideas with group and COMPLETE
11.3 VOCAB

29. VOCABULARY REVIEW: mitosis
-cell division that results in identical cells (DNA replicated)
1- micrograph of chromosomes
-KARYOTYPE
2- abnormal number of chromosomes
-NONDISJUNCTION
3- withdrawal of tissue from the placenta
-CHRONIC VILLI SAMPLING
4- extra chromosome 21
-DOWN SYNDROME
5- protective cap at the end of a chromosome
-TELOMERE

30. KARYOTYPES EXPLAIN: how chromosomes are arranged in a karyotype
-in homologous pairs LARGEST to SMALLEST

31. KARYOTYPES SEQUENCE: how a scientists make a karyotype 1-
-chromosomes are removed from a cell in metaphase 2-
-chromosomes stained
-reveal banding patterns that mark each pair of chromosomes 3-
-chromosomes arranged in pairs by size 4-
-a microscopic picture is taken

32. KARYOTYPES
INDICATE: the parts of a karyotype of a child born with Down syndrome.
TELL: why this karyotype is called trisomy
-it has a set of THREE CHROMOSOMES on ONE KIND
RECALL:the term for failure of sister chromosomes separate
-NONDISJUNCTION
STATE: does risk increase with mothers who are younger/older
-older XX
XXX XX

33. KARYOTYPES COMPARE/CONTRAST BOTH
-used by geneticist to study genetic disorders
KARYOTYPES
-method used for VISUALIZING chromosomes
-used to DETECT abnormalities in chromosome #
PEDIGREES
-method used for STUDYING inheritance by following traits in family

34. PROTECT the chromosomes
TELOMERES
DESCRIBE
-Telomeres are made of ____________&______________.
-They are located at the _____________________________________________.
-Their function is to ________________________________________________.
HYPOTHESIZE
DNA
PROTEIN
END of chromosomes
PROTECT the chromosomes
-protection of the chromosomes during cell division & against cellular enzymes

35. NONDISJUNCTION MODEL ANALYZE -Klinefelter’s XXY
-nondisjunction in meiosis 1/2 : produce egg with two sex chromsomes
-XX or XY
-Klinefelter’s results when an XX egg is fertilized with a Y sperm.

36. FETAL TESTING SUMMARIZE the following facts about fetal testing.
-How an abnormal number of chromosomes is identified-
-four possible results of abnormal chromosome numbers
1-_________________________
2-_________________________
3-_________________________
4-_________________________
A sample of cells is taken from the individual / fetus
-amniocentesis / chronic villi sample / fetal blood sample
Embryo death
Down’s syndrome
Turner’s syndrome
Klinefelter’s syndrome

37. FETAL TESTING
INFER
What might be the benefits of fetal testing? What might be the risks?
BENEFITS RISKS
-________________ -________________
Discovery of genetic problems
Harm to fetus
Medication/surgery before birth to correct problem
infection

38. REVIEW 1- What could explain a human karyotype showing 47 chromosomes
trisomy  
2- Why dos nondisjunction occur?
The sister chromatids do not separate
3- Which statement concerning telomeres is not true?
They consist of DNA and sugars