Karyotyping Socksheadspinsmall.gif

Chromosomes can be compared to socks because they come in pairs. Chromosomes are moved from an old cell to new cells in two ways. One way is called mitosis and the other is meiosis. If socks are used as a model for chromosomes, then chromosomes do two different dances. (Dancing moves your socks.) The mitosis “dance” is how things grow and repair, while the meiosis “dance” involves genetic variation and must be understood for the breeding of animals and plants. Understanding meiosis is important for social reasons like how two brown eyed parents can have a blue eyed child. Understanding meiosis is also important for economic reason, like breeding plants and animals. In fact there might well be a food shortage in the United States today if it were not for the success in breeding crop plants for higher yields over the past 100 years. Before we can learn these two “dances” we have to get to know the “socks” or in other words the chromosomes.

For this activity, cut out these socks and put them in matching pairs from longest to shortest. Compare your sorted socks to the picture (karyotype) on page 100. Glue your pairs of socks on a sheet of paper from longest to shortest. Put the mismatched pair at the end. Read page 100.
  • Right click and print this picture.
  • Cut out the socks.
  • Glue them to a sheet of paper in matching pairs from longest to shortest.
  • Put any mismatched socks as a pair at the end.

Write up: Copy and fill in the blanks of the numbered sentences.
Karyotyping Socks:
In the karyotyping activity sock were used to model chromosomes.
Socks come in pairs because one is for each foot. Sexually produced organisms have two parents, so they get one chromosome of each kind from each parent.
1. Chromosomes come in pairs because ....
Humans have the same number of chromosomes as the number of socks used in this activity.
2. The number of chromosomes in most human cells is ....
Diploid cells have pairs of chromosomes like the pairs of socks in this activity.
3. Most human cells have ........... pairs of chromosomes.
An organisms chromosome pairs are called by a number based on length and banding. This is similar to how the socks were sorted by length and stripes.
Chromosome pairs that match are called autosomes.
4. Humans have .......... pairs of autosomes.
The two copies of each autosome are called homologous chromosomes.
In the activity socks a matching pair of socks represented homologous chromosomes.
5. ............ chromosomes have the same features and genes for the same traits.
In the sock activity there was one pair of mismatched socks. The one chromosome pair that is mismatched for human males are called sex chromosomes. The sex chromosomes of human females are not mismatched, but are still called sex chromosomes.
6. Human males have sex chromosomes that are........
7. Human females have sex chromosomes that .........
8. An X and a Y are the sex chromosomes in human .............
9. Human .......... have two X sex chromosomes.
The socks in this activity represented the chromosomes in a cell. There were pairs of socks, so the cell modeled in this activity was diploid. Most cells in the body are diploid and have two sets of chromosomes.
10. In ............. cells the chromosomes are paired, so there are two sets of chromosomes.
Some cells have only one set of chromosomes. Modeling this with sock, the cell would have only half of each pair of socks. Egg and sperm cells have only one set of chromosomes and are called haploid.
11. ............ cells have only one set of chromosomes and are sex cells like eggs and sperm.
Eggs and sperm with a haploid number of chromosomes come together to make a diploid cell. This would be like the sock from two cells coming together to make a cell with pairs of socks.
12. Haploid cells with ....... set of chromosomes come together to make diploid cells with ....... sets of chromosomes.

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