Question

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1. the purpose of meiosis is to make gametes, also known as sperm and egg cells. in humans, your body cells have 46 chromosomes. how many chromosomes are in a sperm or egg cell if, when they come together to form a fertilized zygote, there are 46 chromosomes? write the correct number of chromosomes next to the sperm and egg.

images of sperm and egg cell

1. interphase must occur once before meiosis can happen. (same thing for mitosis). what would happen if interphase didn’t occur first?

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image: interphase to do list (growth, dna replication, general cell processes) with a cartoon character thinking \i need a vacation\

1. a cell that begins meiosis has 23 chromosomes inherited from the mother (shown in green in the cartoon below) and 23 chromosomes inherited from the father (shown in blue in the cartoon below). in the process of meiosis, chromosomes begin to match up in homologous pairs. how would you know if two chromosomes were homologous?

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image: two chromosomes with gene for eye color

1. crossing over is a very important event in prophase i of meiosis! what happens during crossing over and what is the significance?

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image: chromosomes with \wow! cool!\ text

1. meiosis does pmat twice! that means there is a prophase i and a prophase ii. there is a metaphase i and a metaphase ii. etc... if the cartoon below has chromosomes in the middle of the cell, how would you know whether it was in metaphase i or metaphase ii?

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image: cell with chromosomes aligned at equator

1. meiosis does not always occur without any difficulties. describe what occurs during nondisjunction and the effect on the resulting cells.

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image: cells with chromosomes, one cell saying \well howdy - do, neighbor!\
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Explanation:

1. Meiosis halves chromosome number for fertilization; 46/2 = 23 per gamete.
2. Interphase duplicates DNA; no interphase = insufficient DNA for daughter cells.
3. Homologous chromosomes have same size, shape, and gene locations (e.g., eye color gene).
4. Crossing over swaps DNA between homologous chromosomes, increasing genetic diversity.
5. Metaphase I has paired homologs; Metaphase II has single chromosomes at the cell midline.
6. Nondisjunction = chromosomes fail to separate; gametes get extra/missing chromosomes, causing genetic disorders.

Answer:

1. Sperm: 23; Egg: 23
2. The cell would lack replicated DNA, so daughter cells would have incomplete genetic material.
3. They have the same size, shape, and carry genes for the same traits (e.g., eye color) at the same locations.
4. Homologous chromosomes exchange segments of DNA; it increases genetic variation in offspring.
5. Metaphase I has homologous chromosome pairs lined up; Metaphase II has individual chromosomes lined up.
6. Chromosomes do not separate properly during division; resulting cells have abnormal chromosome numbers (extra or missing), leading to conditions like Down syndrome.