Mitosis and Meiosis Flashcards
(27 cards)
What types of cells are there?
Somatic Cells (Body Cells - Diploid No. Chromosomes) OR
Gametes (Sex Cells - Haploid No. chromosomes)
Explain the diploid number (2N)
The total number of chromosomes in a normal body cell of an organism
What is the DNA like in a somatic cell?
An identical copy of your DNA is found in the nucleus of every somatic cell.
Every time a cell divides through mitosis, each chromosome is copied (replicated) before the division. Each new cell gets an identical copy of that genetic information (DNA).
Explain Mitosis - Interphase
- Cells grow & carry out normal function
during this stage - Each chromosome replicates
(synthesizes) to produce sister
chromatids that become attached at
the centromere. - Chromosomes are not visible at this
stage just the nucleus
Explain Mitosis - Prophase
- The DNA in the nucleus coils & the
chromosomes become visible under a
microscope - The nuclear membrane (envelope)
disappears - The replicated chromatids pair up and
are attached by a centromere - Centrioles (used to produce spindle
fibers) move to the edges of the cell
Explain Mitosis - Metaphase
- Spindle fibers from the centrioles
attach to the pairs of chromatids and
line them up along the middle of the
cell in a single file line.
Explain Mitosis - Anaphase
- Centromeres split in two
- Centrioles drag back the spindle fibers
(like a fishing line) and the paired
chromatids are pulled apart - Each chromatid becomes a full-fledged
chromosome.
Explain Mitosis - Telophase
- The new chromosomes go to the edge
of the cell - A new nuclear membrane forms
around the nucleus of each daughter
cell - Chromosomes no longer visible.
- Spindle fibers disappear
- Mitosis is complete
Explain Mitosis - Cytokinesis
- Cytokinesis is the formation of the two
daughter cells. - The cell membrane pinches together in
the middle in order to create two new
cells. - Each of these cells has a full set of
genetic information, exactly the same
as the parent cell.
How many chromosomes in a human zygote?
46
After the first round of Meiosis, how many chromosomes do the daughter cells have?
23
Explain Meiosis - Interphase
Cell prepares for division by growing, replicating its DNA, and ensuring it’s ready to divide.
Explain Meiosis - Prophase 1
Chromosomes condense and thicken; they line up with their homologous pairs and cross over.
Explain Meiosis - Metaphase 1
Chromosomes line up in pairs, down the metaphase plate.
Explain Meiosis - Anaphase 1
The chromosomes are pulled to opposite poles of the cell by the spindle fibers.
Explain Meiosis - Telophase 1
2 newly formed nuclei and it becomes obvious you will end Meiosis with daughter cells.
Explain Meiosis - Cytokinesis 1
Cytoplasm of the parent cell divides, resulting in two daughter cells.
Explain Meiosis - Prophase 2
Chromosomes are present and spindle fibers start to form.
Explain Meiosis - Metaphase 2
Chromosomes line up in the middle, in a single file line.
Explain Meiosis - Anaphase 2
The chromatids are pulled to opposite poles by the spindle fibers.
Explain Meiosis - Telophase 2
The nuclei reform, and the overall 4 cells begin to divide.
Explain Meiosis - Cytokinesis 2
The cytoplasm completely splits, resulting in 4 daughter cells with a haploid number. Each daughter cell is different.
What is a centromere?
Part of chromosome where sister chromatids are held together.
What is crossing over?
During Prophase 1, the homologous pairs line up in a way, so that they can transfer genetic information and share it between each other. Makes for recombinant chromosomes.
