1. Chapter 14:
The Human
Genome

2. 14-1 Human Heredity
How many chromosomes does an adult human cell contain?
Autosomes – any chromosomes that are not sex chromosomes.
Sex Chromosomes – X and Y
determine sex of individual.
22 pairs of homologous chromosomes

3. 14-1 Human Heredity Notations used to describe individuals
Normal Individuals represented as
Males  46, XY
Females  46, XX
22 pairs of homologous chromosomes

4. Human Cell sperm carries an X or Y 22 pairs of homologous chromosomes
called autosomes
1 pair of sex chromosomes
23rd pair
Gametes
What sex chromosomes are carried by egg and sperm cells?
N chromosomes
egg only carries an X
sperm carries an X or Y

5. ID-ing Chromosomes Chromosomes are identified by 1. SIZE
2. CENTROMERE LOCATION
3. BANDING PATTERNS

6. Karyotype a picture of chromosomes
homologous chromosomes paired together.
What are they?
Numbered 1-22 in order of size
What is the 23rd pair?
What does the size of the chromosome indicate?

7. Which of the karyotypes represent Normal Individuals?

10. CONCEPT CHECK Apr 28 1. What is an autosome?
2. Explain the significance of the size of different chromosomes.
3. Interpret the following notation.
45, XX

11. CONCEPT CHECK
1. Any one of the numbered chromosomes (1-44) that are not sex chromosomes
2. Chromosome size determines the numbers of genes within a chromosome.
Larger chromosomes contain more genes
and are most necessary for normal growth
and development.
3. 45, XX identifies the individual as a female having 45 chromosomes.
Missing an autosome
Presence of a genetic disorder

12. Question of the DAY
Which statement is not true regarding homologous chromosomes?
A. Specific genes are found at the same loci
B. They have the same size
C. Genes will express identical traits
D. They are joined at the same centromere locations

13. Factors Affecting Phenotypes
Traits are determined by our genes.
Do other factors have an impact on our characteristics?

14. Genes and the Environment
All of our inherited characteristics are governed by our genes.
Many traits are polygenic.
Other factors influence our phenotypes.
Nutrition and Exercise
Average height has increased 10 cm in the last 200 years  3.93 inches
U.S. and Europe

15. Alleles Figure 14-6
Dominant – Some genetic disorders are expressed through these alleles
Only requires one allele
Recessive – Most genetic disorders are transmitted through these alleles
Codominant – Sickle Cell Disease

16. Pedigree Analysis
rely on family histories and medical records to study humans
pedigree: diagram that follows the inheritance of a single trait through several generations

17. Pedigrees record and trace the occurrences of traits within a family.

18. British Royal Family

19. The Story of Anastasia

20. Concept Check May 3
Explain why males cannot be carriers for sex-linked disorders.
Support your explanation with evidence.

21. 14-2: Sex-linked Inheritance
sex determination
XX female
XY male
sex-linked genes: genes located on the sex chromosomes
almost always on the X chromosome
Y chromosome contains a few genes for male development

22. Sex-linked Inheritance
males inherit these disorder much more often
gets passed from father to daughters, then daughters to their sons
examples are hemophilia, colorblindness, Duchenne’s muscular dystrophy

23. Human Genetic Disorders
autosomal genetic disorders
albinism
recessive allele on chromosome 11
can’t produce melanin
cystic fibrosis
recessive allele on chromosome 7
heavy mucus clogs lungs and breathing passageways

24. recessive allele on chromosome 15
tay sachs
recessive allele on chromosome 15
suffer from breakdown of the nervous system
sickle cell disease
recessive allele on chromosome 11
produces an alternate form of hemoglobin that causes the red blood cells to become a sickle shape
one DNA base changed
Glutamic acid for Valine

25. Sickle Cell Disease Allele very prominent in African Americans
Carried by many individuals
Connected to malaria – a parasitic disease that affects red blood cells
Individuals who are heterozygous for sickle cell are resistant to malaria
When body destroys sickled cells, parasite causing malaria also destroyed.
Low oxygen = sickle shape = cells clump together

26. PKU: phenylketonuria
recessive allele on chromosome 12
causes mental retardation
Huntington’s disease
dominant allele on chromosome 4
lose muscle control and nervous system breaks down

27. Chromosome Number Disorders
occurs by nondisjunction: when abnormal number of chromosomes are produced in the sex cells due to them not separating correctly

28. Turner’s Syndrome
either a sperm or an egg is produced without a sex chromosome
XO genotype
O means sex chromosome is missing
sex organs are not fully developed
can not have children
only in females

29. Klinefelter Syndrome have an extra X chromosome
XXY genotype
causes mental retardation
can not reproduce
only in males

30. Down Syndrome
trisomy 21
means 3 copies of chromosome #21
causes heart and circulatory problems, mental retardation, and a weakened immune system

31. Other Causes of Disorders
deletions: can occur from pieces of chromosomes breaking off and getting lost in meiosis
translocation: when pieces of chromosomes break off and become reattached to another

32. Prenatal Diagnosis want to detect if unborn child will have a disorder
two ways
amniocentesis: withdraw fluid from sac around fetus
chorionic villus sampling: tissue surrounding fetus is removed and examined

33. Special Topics in Human Genetics
barr body: dense region in the nucleus of most cells in human females
condensed turned-off X chromosome
not found in males because their one X chromosome is active
happens in some tissues and in some cells

34. 14-3 Testing for Alleles
DNA probes – specific DNA base sequences that detect the complementary base sequences found in disease causing alleles
Cystic Fibrosis and Tay Sachs are examples that use DNA probes.

35. DNA Fingerprinting
Repeats are specific sequences of DNA unique to every individual
Do not code for proteins
Repeats cut with restriction enzymes
Gel electrophoresis separates fragments
Labeled with radioactive probes
Forensics, detection of inherited diseases, and paternity cases

36. Human Genome Project
Sequencing of all of the genes within an organism.
Human genome sequencing completed in 2003.
Included sequencing of other organisms including E. coli, multiple strains of yeast, the fruit fly, the mosquito, the honey bee, the cow, the dog, the horse, and the rat.