1. 14-1 Human Heredity Vocabulary: Karyotype Sex chromosome Autosome
Pedigree
Polygenic
Carrier
Key Concept:
How is sex determined?
How do small changes in DNA cause genetic disorders?

2. Human Chromosomes KARYOTYPE
To look at human chromosomes, biologist photograph cells in mitosis when the chromosomes are fully condensed (shrunk together)
Cut out the chromosomes from the picture and group them together in pairs
This type of picture is called a
KARYOTYPE

3. Karyotypes What a karyotype can tell you:
Sex (male or female)
Irregular numbers of chromosomes (genetic disorder)
Basically: all the chromosomes in a cell are in a picture and can be looked at by doctors for anything wrong

4. Remember… Humans have 46 chromosomes (23 pair)
2 of them are sex chromosomes  they determine what sex you are (boy or girl)
XX = female/girl
XY = male/boy
44 of them are autosomes  they do not determine what sex you are

5. Who determines the sex of a child?
The mother or the father?
THE FATHER!!!!

6. Why does the father determine the sex of the offspring???
If the mom is XX, she can donate either one X chromosome or the other X chromosome in her gametes
If the dad is XY, he can donate either an X chromosome or a Y chromosomes in his gametes
If the offspring receives the father’s X, it is female
If the offspring receives the father’s Y, it is male

7. Pedigree Chart
Shows how a trait is passed on from generation to generation
Each row is a generation
Circles represent females
Squares represent males
Shaded in: person expresses that trait (ex: has the disease)
Half shaded in: person is only a carrier (does NOT have the disease cut carries an allele for it)
Clear: person does not carry or express that trait

9. Carrier—Definition
Carrier= carries the allele for the trait in the genotype but does NOT express it in the phenotype
EX: If brown, B, is dominant over blue
The carrier’s genotype is Bb
But the carrier’s phenotype is Brown

10. You can’t always use a pedigree!
Can’t trace every human trait through a pedigree because some genes are polygenic (coded for by more than 1 gene)
Shape of your ears
Height
Eye color

11. Human Genes The human genome is ALL genetic information in people
Determines characteristics/traits like eye color and height

12. Recessive and Dominant Alleles
Some common genetic disorders are autosomal recessive
This means that you need two recessive alleles (on any of the 44 chromosomes—NOT the sex chromosomes) to express the disease
EX: Cystic Fibrosis
Other genetic disorders are autosomal dominant
Only one allele is needed for the trait to be expressed
EX: Huntington’s Disease

13. From Gene to molecule
In both cystic fibrosis and sickle cell anemia, a small change in the DNA of ONE gene affects the structure of a protein, causing a serious genetic disorder

14. Cystic Fibrosis Caused by a recessive allele on chromosome #7
It is an autosomal genetic disorder
Causes digestive and respiratory problems
Death around years of age
How does it happen?
Three bases are deleted from the protein, which removes one amino acid
The protein cannot fold properly anymore, and is destroyed
Result: airway is clogged with mucus

15. Checking for Understanding
If a person is a carrier for a trait, what does that mean?
They have the allele for the trait but do NOT express it
What is the difference between an autosome and a sex chromosome?
Sex chromosome tells the individual’s sex (2), while autosomes are the rest of the chromosomes (44)

16. Blood Groups
Human blood comes in many genetically determined blood groups
Using the wrong blood during a blood transfusion can be fatal
Blood transfusion= when you need blood and it is given it to you during an operation from someone else
Many genes work together to help determine blood type, but we will use one:
ABO blood groups

17. ABO Blood Groups This is a case of multiple alleles
There are 3 alleles for this gene—A, B, and o.
AND…A and B are codominant!
O is recessive to A and B
Alleles A and B produce antigens (which are carbohydrates) on the surface of red blood cells
O produces NO antigens

18. ABO Blood Groups
Antigens and “signs” that are recognized by your body’s immune system cause your body to react and try to defend itself.
If the wrong blood is given to a person, the body tries to fight off these strange antigens by making antibodies
Antibodies bind to the foreign molecule (the antigen on strange blood cell) and blood clumping will occur
Which leads to blood clotting, which leads to death

19. ABO Blood Groups If you have blood type A, then you have:
The “A” antigen on the surface or your RBCs
You have anti-B antibodies
You can receive type A blood and type O blood
Remember: You antibodies attack foreign (strange) antigens—so if you received type AB or type B blood then clumping would occur.

21. Blood Groups Genotype Phenotype AA, Ao Type A blood
BB, Bo Type B blood
AB Type AB blood
oo Type O blood
Why is “o” writtten as a small “o”?
Why is the genotype for AB the same as the phenotype?

22. ABO Blood Groups Try this cross
Cross a person who’s genotype is AA with a person who is AB.
Give the possible genotypes and phenotypes of their children?

23. Cross a person who’s genotype is AA with a person who is AB.
Gametes= A, A and A, B
Cross: A A A AA AA AB B AB

24. Genotypes= ½ AA, ½ AB
Phenotypes = ½ Type A, ½ Type AB

25. Lou Gehrig: died at 37 of ALS
14-2 Human Chromosomes
Vocabulary:
Sex-linked gene
Sex-influenced gene
Sex-limited gene
Nondisjunction
Key Concepts:
Why are sex-linked disorders more common in males than in females?
What is nondisjunction, and what problems does it cause?
Lou Gehrig: died at 37 of ALS

26. Sex Linked Genes
REMEMBER… genes on the same chromosome are LINKED together
They can be separated during meiosis through CROSSING OVER
Genes located on the sex-chromosomes are said to be sex-linked
Many sex-linked genes are found on the X-chromosome
The Y-chromosome only contains a few genes

27. Sex Linked Genes
Genes carried on the X or Y chromosome are sex linked because they are on the sex chromosomes
The X chromosome has many genes that are important for growth and development
All X-linked traits are expressed in males
WHY???????
Males only have 1 copy of the X chromosome so they express whatever is on it, while females need 2 copies of the defective gene to express it

28. Sex-Linked Gene Disorders
Colorblindness
3 human genes associated with color vision are located on the X-chromosome
In males, a recessive version of any one of these produces colorblindness
Females must receive 2 copies of the allele to be colorblind
XCXc
XCXC
XCY
XcY

29. The Test

30. Sex-Linked Gene Disorders cont.
Hemophilia
2 important genes on the X-chromosome that code for proteins control blood clotting
A recessive allele in either of these 2 genes may lead to hemophilia
“bleeders disease”= they don’t stop bleeding normally—they keep bleeding if they have a cut
Injections of normal clotting proteins prevent death

31. Sex-Influenced Genes A person’s phenotype is affected by their sex
Ex: Pattern Baldness
WOMEN: MEN:
BB: not bald BB: not bald
Bb: not bald Bb: bald
 bb: bald bb: bald

32. X-Chromosome Inactivation
Females have 2 X-chromosomes… if 1 is enough for males, how does the cell “adjust” to the extra x-chromosome in females?
One X-chromosome is randomly turned off
Condenses (shrinks) and is called a Barr body

33. Chromosomal Disorders
Most of the time, meiosis works well, but things can go wrong
The most common error: NONDISJUNCTION
The chromosomes don’t separate
The result? Abnormal numbers of chromosomes (the wrong number of chromosomes)

34. Nondisjunction Prefixes: dis = absence of / opposite of non = not
Root Word:
Junction = joining together
disjunction = the act of separating
nondisjunction = the act of not separating

39. Examples of Chromosomal Disorders
Down Syndrome
Klinefelter’s Syndrome
Turner’s Syndrome
Triple X Syndrome
                

40. Examples of Nondisjunction resulting in Chromosomal Disorders
Down's Syndrome: 47 chromosomes with 3 #21 chromosomes.
Triple-X Syndrome: 47 chromosomes caused by 3 X chromosomes.
Klinefelter's Syndrome: 47 chromosomes caused by 2 X chromosomes and 1 Y chromosomes.

41. 14-3 Human Molecular Genetics

42. DNA FINGERPRINTING
DNA fingerprinting is a technique developed to analyze sections (pieces) of DNA that have little or no known function (job).
these areas are different among different people
This technique can be used to identify individuals based on banding patterns in the resulting DNA fragments (pieces)
uses restriction enzymes
proteins that cuts DNA at specific sites along the nucleotide chain (cuts at specific base pairs).
Is used to determine paternity (who is the father) or match a suspect to a crime scene

43. THE PROCESS
human DNA is cut with restriction enzymes; this makes DNA fragments of different lengths/sizes
mix the DNA fragments with a probe(“marker”) that glows in UV light
the probe will stick to certain parts of DNA

44. **smaller pieces will travel through the gel faster
run the DNA pieces through a clear gel
negative end
DNA goes in wells at the top
DNA has a "-" charge
· DNA will move to the "+" end of the gel
positive end
**smaller pieces will travel through the gel faster

46. 4. Smaller pieces of DNA will travel through the gel faster
Large DNA
fragment
negative end
positive end
Small DNA
fragment

47. In order to see these DNA pieces, the gel is looked at under UV light.
The result: The DNA pieces with the probe will glow & you will see a banding pattern
**Because each person's DNA is different, the restriction enzyme will cut the DNA in different places for different people and every person will have a different band pattern.

48. DNA_DetectivePC.exe

49. Gene Therapy
Gene therapy is the process of changing the gene that causes a genetic disorder.
This way, the body can make the correct protein or enzyme it needs which takes away the cause of the disorder.
1st attempt to cure a genetic disorder by gene transfer: 1990
French girl apparently cured of an inherited immune disorder after cells from her bone marrow were removed, modified in the laboratory, and then placed back in her body

51. Gene therapy today remains a high risk,experimental procedure.
Ethical Questions raised as we learn more about the human genome and gene therapy:
1. If we can change genes to cure disease, does this also give us the right to change our bodies? (determine eye color, whether you are tall/short, hair color, sex, blood type...)
2. What will happen if biologists successfully clone human beings?
Science meets Hollywood:
Issues like these were the basis of the movie, GATTACA

52. Checking for Understanding
What is the purpose of gene therapy?
Gene therapy is a process designed to change the damaged (“bad”) gene with a normal gene.