1. Lesson Overview Lesson Overview Human Chromosomes Objectives 14.1 Human Chromosomes - -Identify the types of human chromosomes in a karotype. -Describe the patterns of the inheritance of human traits. -Explain how pedigrees are used to study human traits. Identify the types of human chromosomes in a karotype.Describe the patterns of the inheritance of human traits. Explain how pedigrees are used to study human traits.

2. Lesson Overview Lesson Overview Human Chromosomes What is a GENOME? A genome is the full set of genetic information that an organism carries in its DNA. The study of any genome starts with chromosomes.

3. Lesson Overview Lesson Overview Human Chromosomes Karyotypes To see human chromosomes clearly, biologists photograph cells in mitosis, when the chromosomes are easy to view. Scientists then create a picture known as a karyotype. The karyotype from a typical human cell, which contains 46 chromosomes and is arranged in 23 pairs.

4. Lesson Overview Lesson Overview Human Chromosomes Sex Chromosomes Two of the 46 chromosomes in the human genome are known as sex chromosomes, because they determine an individual’s sex (or gender). Females have two copies of the X chromosome. Males have one X chromosome and one Y chromosome.

5. Lesson Overview Lesson Overview Human Chromosomes Autosomal Chromosomes The remaining 44 human chromosomes are known as autosomal chromosomes, or autosomes. The complete human genome consists of 46 chromosomes, including 44 autosomes and 2 sex chromosomes.

6. Lesson Overview Lesson Overview Human Chromosomes Dominant vs Recessive Alleles Many human traits follow a pattern of simple dominance. A trait that displays simple dominance is the Rh factor on blood cells. The allele for the Rh factor comes in two forms: Rh + and Rh -. Rh + is dominant, Rh- is recessive.

7. Lesson Overview Lesson Overview Human Chromosomes Co-dominant and Multiple Alleles The alleles for many human genes display co- dominant inheritance. One example is the ABO blood group, determined by a gene with three alleles: I A, I B, and i.

8. Lesson Overview Lesson Overview Human Chromosomes Sex-Linked Inheritance The genes located on the X and Y chromosomes show a pattern of inheritance called sex-linked. The genes responsible for color vision are all located on the X chromosome. In males, a defective X chromosome for any of these genes results in colorblindness. Among females, however, colorblindness has to be on BOTH X chromosomes.

9. Lesson Overview Lesson Overview Human Chromosomes Human Pedigrees To analyze the pattern of inheritance followed by a particular trait, you can use a chart, called a pedigree. A pedigree shows the presence or absence of a trait according to the relationships between family members.

10. Lesson Overview Lesson Overview Human Chromosomes True or False 1.In humans, the mother’s gamete determines the sex of the offspring. _________________________ 2.In a human karyotype, 44 of the chromosomes are autosomes. _________________________ 3.To make a karyotype, biologists take pictures of cells during mitosis, when they are condensed and easier to view. _________________________

11. Lesson Overview Lesson Overview Human Chromosomes Answers 1.In humans, the mother’s gamete determines the sex of the offspring. False, father’s gamete 2.In a human karyotype, 44 of the chromosomes are autosomes. True 3.To make a karyotype, biologists take pictures of cells during mitosis, when they are condensed and easier to view. True