Human Karyotypes

Name:______Period: _____ Date:______

  1. What Is AKaryotype?
  • ______= a test to identify and evaluate the size, shape, and number of chromosomes in a sample of body cells.
  • Extra, missing, or abnormal positions of chromosome pieces can cause problems with a person's growth, development, and body functions.
  • Examples:
  1. Why Is It Done?

1)Determine whether the chromosomes of an adult have an______that can be passed on to a child.

2)Determine whether a chromosome ______is preventing a woman from becoming pregnant or causingmiscarriages.

3)Determine whether a chromosome defect is present in a fetus.

4)Determine the cause of a baby's birth defects or disability.

5)Identify the ______of a person by determining the presence of the Y chromosome.

  • This may be done when a newborn's sex is not clear.
  1. How Is A Karyotype Created?

1)Human karyotypes are usually prepared from ______of chromosomes that have been spread, fixed, and stained to highlight banding patterns.

2)The chromosomes in the photograph are ______and then arranged in homologous pairs just as you will be doing in an upcoming activity.

3)Chromosomes are obtained through various tests: blood, bone marrow, amniotic fluid, or tissue from the placenta (the organ that develops during pregnancy to feed a growing baby).

  • White blood cells are used most frequently because they are easily induced to divide and grow in culture.
  • To test amniotic fluid, an______is done. A long needle is inserted through the abdomen into the uterus and amniotic fluid is withdrawn which contains cells shed by the fetus.
  • A bone marrow specimen requires a bone marrow biopsy.

4)The sample is placed into a special dish and allowed to grow in the laboratory.

5)Various ______are added to stop the cell’s growth during prophase and metaphase.

6)The cells are placed on microscope slides and treated so they swell and their chromosomes spread apart.

7)Then various ______are used to highlight banding patterns.

8)Experienced geneticists observe the karyotype for chromosomal abnormalities.

  • ______of chromosomes
  • ______chromosomes
  • ______chromosomes
  • the ______of the person

9)The treated chromosomes can then be photographed, enlarged if desired, and ______to do a karyotype.

  1. What Are Genetists Looking For?

1)Differences in ______of chromosomes

2)Differences in the position of ______

  • This is brought about by translocations.

3)Differences in basic ______of chromosomes

  1. Common Abnormalities:

1)Down Syndrome(also known as ______)

  • Cause = nondisjunction of the ______of chromosomes
  • Characteristics:
  • Happens ______in males and females since it does not involve the sex chromosomes
  • Individuals are retarded but the severity varies with the individual.
  • The probability of giving birth to a child with Down syndrome ______with age of the mother, increasing significantly after age 35.

2)Turner syndrome

  • Cause =nondisjunction of the ______during meiosis so individuals are missing one copy of the ____chromosome.
  • They have 22 pairs of autosomal chromosomes and only one X chromosome.
  • Characteristics:
  • Affects ONLY ______
  • Women are usually short, sexually underdeveloped and sterile.
  • Women with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults.

3)Klinefelter syndrome (XXY)

  • Cause =nondisjunction of the ______during meiosis so individuals have an extra ___ chromosome
  • The person has 22 autosomal chromosomes and 3 sex chromosomes (XXY).
  • Characteristics:
  • Affects ONLY ______
  • Males are often tall, sexually underdeveloped and may have slight intellectual impairment.
  • Recognition of this syndrome before puberty usually does not occur.
  • Many males with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults.

4)Jacob's syndrome(XYY)

  • Cause = occurs when a male inherits ______Y chromosomes from his father instead of one. The exact cause of why this occurs is unknown.
  • Individuals with Jacob’s syndrome have 22 autosomal chromosomes and 3 sex chromosomes (XYY).
  • He is an______male. Remember most males are XY.
  • Characteristics:
  • Affects ONLY______
  • The most common symptoms are learning problems at school and delayed emotional maturity.
  • Males are tall, thin, have acne, speech problems, and reading problems.

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