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Bell Ringer What is karyotyping and how is it useful?
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Transcript of Bell Ringer What is karyotyping and how is it useful?
Bell Ringer
• What is karyotyping and how is it useful?
Nondisjunction
• The homologous chromosomes, or sister chromatids do not separate properly during cell division.
• This can happen during Meiosis 1 or Meiosis 2
Objectives
• By the end of today you should be able to- Know the difference between somatic cells and gametes- Identify the difference between a diploid cell and a
haploid cell.- Compare the processes of Mitosis and Meiosis
You have two types of cells in your body•Somatic Cells
-body cells- Make up most of your body tissues and organs
•Germ cells-Cells in your reproductive organs that develop into gametes (sex cells)
• Every species has a characteristic number of chromosomes per cell.
Examples: Humans= 46 chromosomes or 23 pairs Dog= 78 chromosomes or 39 pairs Husk Tomato= 24 chromosomes or 12 pairs
Chromosomes 1-22 make up your autosomes ( characteristics not related to your sex)
The 23rd pair of chromosomes are your sex chromosomes. (XX or XY)
Sexual Reproduction
• Involves the fusion of two gametes, resulting in offspring that are a genetic mixture of both parents.
• This fusion is called fertilization. The nuclei of the sperm and egg cell fuse together to form one nucleus.
• Since you are taking DNA from 2 cells and creating one you need half the amount of DNA
Diploid and Haploid Cells
• Diploid Cells- The cell has two copies of
each chromosome; one from the mother , and one from the father
- Body cells-represented as 2n
- Humans cells the diploid number is 46
• Haploid Cells-A cell has only one copy of
each chromosome
-Gametes (sex cells)
-Each human egg or sperm cell has 22 autosomes and 1 sex chromosome
Organism Diploid (2n) Haploid (n)Human 46 23
Chimpanzee 24
Elephant 56
Garden pea 14
Turkey 40
Polar Bear 74
Pineapple 25
Meiosis
• Germ cells in reproductive organs undergo the process of meiosis to form gametes.
• Meiosis is a form of nuclear division that divides a diploid cell into a haploid cell.
Objectives
- What is the difference between somatic cells and gametes
- Identify the difference between a diploid cell and a haploid cell.
- Compare the processes of Mitosis and Meiosis
Objectives
• Illustrate the process of meiosis 1 and describe what is happening
• Describe how crossing over can alter the composition of chromosomes
Meiosis l• Prophase l
-Chromatin Chromosomes-nuclear membrane breaks down-Homologous chromosomes pair up-Crossing over may occur
Meiosis l
• Metaphase l-Homologous chromosome pairs are randomly lined up along the middle-This mixes up the chromosomal combinations and helps create genetic diversity
Meiosis l continued
• Anaphase l-Paired homologous chromosomes separate-Sister chromatids stay together during meiosis l
Meiosis l
• Telophase l-Nuclear membrane forms again-Spindle fibers disassemble- Cell undergoes cytokinesis
End Result is two cells with unique combinations of 23 chromosomes
Objectives
• Illustrate the process of meiosis 1 and describe what is happening
• Describe how crossing over can alter the composition of chromosomes
Objectives
• Illustrate the process of meiosis and describe what is happening• Describe how nondisjunction can alter the number of chromosomes
in a cell• Distinguish between mitosis and meiosis.• Compare and contrast spermatogenesis with oogenesis.
There is no Interphase: Chromosomes do NOT duplicate
Meiosis ll
• Prophase ll-Nuclear membrane breaks downChromosomes condense-Centrioles move to opposite sides of cell-spindle fibers assemble
• Metaphase ll-Spindle fibers align the 23 chromosomes in the middle-Each chromosome still has 2 sister chromatids
Meiosis ll
• Anaphase ll-The sister chromatids are pulled apart to opposite sides of the cell
• Telophase ll-nuclear membranes reform-spindle fibers break apart-The cell undergoes cytokinesis
CytokinesisThe end result is four haploid cells with a combination of chromosomes
from both the mother and the father.
Spermatogenesis
Oogenesis
Nondisjunction- The homologous chromosomes, or sister chromatids do not separate properly during cell division.
Meiosis 1
Meiosis 2
Objectives
• Illustrate the process of meiosis and describe what is happening• Describe how nondisjunction can alter the number of chromosomes
in a cell• Distinguish between mitosis and meiosis.• Compare and contrast spermatogenesis with oogenesis.