Lab 6 Flashcards
Where does mitosis occur in the onion root tip?
Located just above the root cap is the apical meristem, which is the embryonic region where active emitotic division occurs.
Describe Interphase
The presence of a nuclear membrane, chromatin, and one or more nucleoili. During S-phase of interphae the chromosmes duplicate themselves into two sister chromatids (not visible on light microscope)
Describe Prophase
The chromatin condenses and shortens into chromosomes, first appearing as long, tangled threads. Later, the chromosomes are visible paired, composed of two parts, called chromatids. Each chromatid pair (sister chromatids) are held together at the centromere. The spindle forms, the nuclear membrane fragments and nucleoli disappear. You may not be able to see the spindle fibres (spindle microtubes)
Describe Metaphase
The chromosomes form a line across the middle of th e cell. This is the equatorial plane or plate. The chromosomes are attached to the spindle fibres at the centromets, which are aligned along the equatorial plane. The spindle fibres appear to originate from the opposite ends of the cells. Thes ends are referred to as the poles
Describe Anaphase
The two sister chromatids of each chromosome are pulled apart at he centromeres by spindle microtubules and move to opposite poles. Once the sister chromatids have separated at the centromere, they are called chromosomes once again. In Allium, there would be sixteen chromosomes at each pole. Hint: To count the number of chromosomes present at any stage of cell division, count the number of centromeres not the number of chromatids
Describe Telophase
The chromosomes have reached the poles, and the spindle begins to disappear as the nuclear membrane re-forms around each mass of uncoiling chromosomes. In plant cells, a cell plate is formed as vesicles produced by the Golgi complex/apparatus line up across the equatorial plate and begin to fuse. Cellulose accumulates in the space between the membrane of the cell plate to form the new cell walls. Eventually, the cell plate fuses with the plasma membrane and two new daughter cells are produced.
What are homologous pairs, and what are homologous chromosomes
Homologous pairs are pairs of homologous chromosomes. Homologous chromosomes are the same length, the centromeres are in the same position, and they possess the genes for the same traits.
How are homologous chromosomes passed down?
In all sexually producing organisms, one of the homologous chromosomes (of each pair) is inherited from the father and one from the mother.
When is a cell diploid or 2n?
The two members of the pairs are called homologues; having both homologues present in the same cell makes the cell diploid or 2n
Animals and plants have different proteins microtubules; what are they called
In animals = centrioles, which form star like asters
In plants, it is called spindles
What is formed during the cytokinesis of animal cells?
A clevage furrow
What is synapsis
The careful patching of the pairs of homologous chromosomes in a diploid cell during Meiosis I
Meiosis II is similar to what?
Mitosis
What is the production of sperm called? And where are they located?
The production of sperm is called spermatogenesis, located in the seminiferous tubules
What is the production of eggs called, and where are they located?
It is called oogenesis, located in the mature follicle
What is the process in which haploid spores are created
Called Sporogenesis
What is Sporangia, Sori (sorus) and Spores?
Sori is the whole cluster of Sporangani, which hold spores (Stem, peas, pods)
What structure produces sperm in a fern gametophyte, and is it what gametophyte type?
Sperm = Antheridia, Haploid
What structure produces eggs in a fern gametophyte, and is it what gametophyte type?
Egg = Archegonia
What is different between plant sperm and animal sperm?
Plant sperm have multiple flagellum, while animals are uniflagellum
