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barnes bio test : mitosis
Terms in this set (27)
what causes cells to have limited cell growth?
the diameter and volume increases, causing the surface area to volume ratio to decrease. as the diameter and volume increases, the ratio decreases by the same amount.
why does a cell need limited cell growth?
1. diffusion and osmosis occur at a set rate
2. if the cell is too big, there won't be enough nutrients and gases for the entire cell.
3. it will also have difficulty getting rid of all of the cell's waste.
4. since the cell is controlled by DNA, a cell that is too big won't have enough DNA to properly control the whole cell.
how does the cell fix the growth problem?
it makes copies of its DNA and splits into 2 daughter cells.
overview of what happens during the cell cycle
1. the cell grows
2. the cell functions
3. the cell prepares for division
4. the cell divides
5. begin cycle again
stages of cycle and what happens in each stage
-gap 1// cell growth, normal cell function
-synthesis// DNA replication
-gap 2// preparation for division
-mitosis// division and separation of the chromosomes
-cytokinesis// division of the cytoplasm
what happens if cells don't divide?
they stay in the first stage forever, and this is called gap 0.
what is chromatin?
the DNA and protein that makes up chromosomes
what is a nucleosome?
DNA wound around histone proteins.
what is a chromosome's structure?
nucleosomes wound around each other to make a coiled strand, which is then "super coiled" to create a chromosome.
what happens during mitosis?
chromatin must condense into chromosomes, chromosomes line-up in the center of the cell, sister chromatids move to opposite sides of the cell, and two new nuclei form.
what is a homologous chromosome?
they are chromosomes that have genes that code for variations of the same thing.
example of a homologous chromosome
one gene may code for hair color, but one can code for red and the other for brown.
how many chromosomes do humans have? and how many pairs of chromosomes?
we have 46 chromosomes, therefore we have 23 individual chromosomes.
when do chromosomes become chromatids?
while they are still connected, yet partially split (in the shape of an X), the two parts are called chromatids.
when do chromatids become chromosomes?
once the chromatids completely split apart from each other, as individuals they are called chromosomes.
what is the thing connecting two chromatids together called?
what happens to the chromosome after they replicate?
they are hooked together to create 1 new chromosome and restarting the cycle.
what happens during interphase?
normal cell growth and activity, DNA synthesis, and preparation for cell division.
what are the phases of mitosis?
what happens during prophase?
1. this is the longest phase in mitosis
2. chromosomes condense and become visible
3. spindles form
4. nuclear envelope and nucleolus disappear
what happens during metaphase?
1. chromosomes line up on the equator of the cell
2. microtubules connect to the centromeres
what happens during anaphase?
1. centromeres separate
2. chromatids get pulled to the opposite sides of the cells, becoming chromosomes
what happens during telophase?
1. chromosomes begin to unwind
2. nuclear envelope and nucleolus reform
3. spindle falls apart
according to our experiment, how many new cells are created a day from one cell in the onion skin?
what is a spindle?
the thing that pulls chromosomes apart in mitosis.
what happens during cytokinesis in an animal cell?
the membrane moves inward and the cytoplasm is pinched in two.
what happens during cytokinesis in a plant cell?
a cell plate forms and becomes a new cell wall after it splits
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