1. Bellringer How many chromosomes do we get from our mom? How many chromosomes do we get from our dad? How many total chromosomes do we have in our bodies? What is a karyotype? If you’re a female, what chromosomal pairs do you have? If you’re a male, what chromosomal pairs do you have?

2. Human Heredity Human Chromosomes A picture of chromosomes arranged in pairs is knows as a karytope. Since there are 46 chromosomes we know that this is a human. This karyotype is the result of a haploid sperm, and a haploid egg carrying 23 chromosomes. The resulting diploid zygote (fertilized egg) has 46 chromosomes.

3. Human Heredity Two of those 46 chromosomes are known as sex chromosomes. They determine an individual’s sex. – Females have two large XX – Males have a large X and a small Y The remaining 44 chromosomes are known as autosomes.

4. Human Karyotyping Gizmo-Vocabulary Autosome – a chromosome that is not a sex chromosome. Humans have 22 pairs of autosomes. Chromosomal disorder – a type of genetic disorder that involves missing or extra copies of chromosomes or a change in chromosome structure. o Chromosomal disorders are typically caused when an error occurs during cell division and the chromosomes do not separate properly. o Down syndrome is one of the most common chromosomal disorders. It affects approximately 1 out of every 800 babies. Chromosome – a rod-shaped structure within a cell’s nucleus that is composed of DNA and proteins. o Chromosomes are passed from one generation to the next. o All of the chromosomes in a human cell contain around 6 million nucleotides and 30,000 genes. o Chromosomes exist in duplicated or unduplicated forms. Karyotype – a picture of a cell’s complete set of chromosomes grouped together in pairs and arranged in order of decreasing size. o Karyotypes are used to detect chromosomal disorders and to study the relationship between different species. Sex chromosome – one of two chromosomes that determine an individual’s sex. o In humans and most other mammals, the two sex chromosomes are the X chromosome and the Y chromosome. Females have two X chromosomes (XX). Males have one X chromosome and one Y chromosome (XY). o Not all animals have the same sex chromosomes as humans. For example, the sex chromosomes of birds and some lizards are the Z and W chromosomes. Female birds are ZW, and male birds are ZZ.