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What is the difference between What is the difference between Chromosomes, DNA, and Genes?Chromosomes, DNA, and Genes?
Inquiry Lab: Exploring a Human Karyotype
Check out this animation to see how a karyotype is prepared in the lab!
– http://www.youtube.com/watch?v=7ShPzzrCetE
Chromosome 7 isPictured to the left.The dark/light bands represent genes onthe chromosome.
What do the What do the colored bands colored bands represent on a represent on a chromosome?chromosome?
Analyzing Karyotypes
A picture of a person’s chromosomes is called a karyotype.
A person’s body cell has 46 chromosomes in total.
However, if we look closely we can see 23 pairs of chromosomes.
23
Analyzing KaryotypesA chromosome pair has the following characteristics:
– One chromosome comes from mom and the other from dad.
– Both are roughly the same size and shape.
– Both have the same centromere location.
– Both carry the same order of genes. However, the genes on one chromosomes may be a slightly different version from the genes on the other chromosome.
– http://www.youtube.com/watch?v=xp44Dp-m1cc&list=LPe665JQlBNHg&playnext=1&feature=autoplay
23
Bb b bB B
Chromosome Pairs vs. Duplicated ChromosomesChromosome Pairs vs. Duplicated Chromosomes
Chromosome pairs
DEMO: Let’s look at how chromosome pairs can have different versions of genes!
Duplicated ChromosomesTHINK! – How are chromosome pairs different from duplicated chromosomes?– Duplicated chromosomes are exact
clones of each other.– Duplicated chromosomes are always
attached at the centromere.
Bb b bB B
Analyzing Karyotypes
In a karyotype there are 23 pairs of chromosomes.– Pairs 1-22 are called autosomes– Pair 23 is called sex chromosomes
Male & female karotypes are different.– Female’s 23rd pair = XX– Male’s 23rd pair = XY– THINK! – Is this karotype showing a
male or female?
The grey colored bands on the chromosomes represent a person’s genes. 23
NOVA VIDEO Clip
Check out this NOVA video clip titled: Personal DNA Testing_12mins
Answer the questions on your ticket slip.
Also, think about whether or not you would want to have a personal DNA test done to reveal what your genes say about your health.
Meiosis
Activity: – Take out a red & blue colored pencil. – Let’s illustrate the process on our Graphic
Organizer!
Visualizing Meiosis!
United Streaming Video Clip: Meiosis (3:48)
Meiosis Animation_Glencoe
– Pay attention to these video clips to see meiosis in action.
THINK! - Why is Meiosis so Important?
MEIOSIS Sperm = 23 chromosomes
Egg = 23 chromosomes
Zygote = 46 chromosomes
Fertilization
MITOSIS
Accidents during Meiosis
Accidents during meiosis can cause some individuals to have an extra chromosome in a pair or a missing chromosome in a pair.
– An extra chromosome is called a trisomy.
– A missing chromosome is called a monosomy.
– Down Syndrome is a disorder in which a person has an extra 21st chromosome.