1. Notes: Karyotypes, inheritance patterns, sex-linked, pedigrees
14.1: Human Heredity
Notes: Karyotypes, inheritance patterns, sex-linked, pedigrees

2. Studying human heredity
To understand human genetics, we look at the ENTIRE set of genetic information in a person
Called a GENOME
Scientists look at a picture of every chromosome, taken from a person’s nucleus
Called a KARYOTYPE
Diploid chromosomes are grouped in pairs, arranged by decreasing size

3. Types of Chromosomes Sex Chromosomes Autosomal Chromosomes 44 of 46
“Body” chromosomes
Determines everything else, basically
Majority of your traits are in autosomal chromosomes
2 of 46 in human genome
Determine sex of individual
Females have X X, males have X Y
All female eggs have 1 X
50% of male sperm have 1 X, and 50% have 1 Y
This is what makes having a boy versus having a girl, 50/50 probability

4. Genes on Sex Chromosomes
1200 genes are on the X chromosome
140 genes are on the Y, most of which deal with male sex determination and sperm development

5. Dominant & Recessive Alleles
Humans, like pea plants, also follow “normal” dominant or recessive patterns
Ex: Skin and hair color (darker colors are more dominant than lighter colors)
Recessive – red hair (2 recessive alleles)
Ex: Rhesus (Rh) factor- protein found in blood
Rh+ is dominant, Rh- is recessive

6. Codominant & Multiple Alleles
Many alleles show codominant inheritance
Ex: blood type: IA , IB , i
Type A – produces antigen A
Type B – produces antigen B
Type AB – produces both antigens (CODOMINANT)
Type i (O) – produces no antigens

7. Blood Groups:

8. Sex-Linked Inheritance
Genes found on X or Y chromosome show “sex-linked” inheritance patterns
Genes on Y are ONLY found in males
Genes on X are found in males/females, but show different patterns… hmm…….

9. For females to show recessive traits from X chromosome, BOTH chromosomes need to carry the recessive alleles
If one X has a recessive, and one X has dominant, the trait will not appear
Males only have 1 X, so if they inherit a recessive trait on it, they MUST show that trait since nothing can cover it up
Sex-Linked

10. Human Pedigrees Show how traits flow through families
Help determine the pattern in which traits are inherited (recessive, dominant, sex-linked)

11. Why we look somewhat like our parents, but not exactly.
Human Chromosomes
Why we look somewhat like our parents, but not exactly.

12. Everyone in the class is alike, but different. How are we alike
Everyone in the class is alike, but different. How are we alike? How are we different?

13. The code for traits is contained in the nucleus of each cell of our body.
Inside the nucleus are chromosomes which are made of DNA. This is the code to make you you.
Cell
Nucleus
Chromosome
DNA: One section of DNA is a gene

14. Chromosome smear

15. A karyotype is when chromosomes are grouped from largest to smallest.
They are also grouped by the centromere position and the banding patterns.

16. Compare the karyotypes for a male and a female.
A male karyotype
A female karyotype

17. Body Cells
Body cells are all cells in the body, except the egg and sperm
Lung cells
Liver cells
Bone cells
Nerve cells
Skin cells
Muscle cells, etc., etc., etc.
Remember, every cell in the body has a set of chromosomes!!!

18. Before a body cell divides it copies every one of the chromosomes.
When the body cell divides, each new body cell gets a copy of each chromosomes.
The new body cell is exactly like the original cell!! They have the same number and same type of chromosomes.

20. Scientists are finding out more about DNA each day!!!!

21. Human Molecular Genetics
This section explains how genetic engineering techniques are being used to study the genes and chromosomes in the human genome. It also describes how this information is used for gene therapy.

22. Human DNA Analysis
Biologists search the volumes of the human genome using sequences of DNA bases

23. Human DNA Analysis
Why might prospective parents decide to have genetic testing? Genetic tests can determine whether prospective parents risk passing alleles for genetic disorders to their children

24. DNA FINGERPRINTING What is DNA fingerprinting?
It is the identification of individuals by a method that analyzes sections of DNA that have little or no known function but vary widely from one individual to another.

27. The Human Genome Project
What is the Human Genome Project?
It is an ongoing effort to analyze the human DNA sequence.

29. Human Genome Project
The mRNA coding regions of most genes are interrupted by Introns.

30. Human Genome Project
List three other parts of the gene that researchers look for.
Promoter
“Start” site for transcription
“Stop” site for transcription

31. Human Genome Project
Why are biotechnology companies interested in genetic information?
They are trying to use this information to develop new drugs and treatments for diseases.

32. Gene Therapy
In gene therapy, an absent or faulty gene is replaced by a normal, working gene.

33. Gene Therapy Have all gene therapy experiments been successful? No
Attempts to treat cystic fibrosis by spraying genetically engineered viruses into breathing passages have not produced a lasting cure.

34. Gene Therapy Ethics Ethical Issues in Human Genetics
What other changes could be made to the human genome by manipulating human cells?
Biologists could try to engineer taller people or change eye color, hair texture, sex, blood group, or appearance. They could even clone human beings.

35. Gene Therapy Ethics
The goal of biology… Is to gain a better understanding of the nature of life.

36. Just for thought…..
Should Scientists be expected to make all ethical decisions regarding advances in human genetics???