CELS 191 Lecture 14 Flashcards
what is a karyotype and when do we take the image for a karyotype
an ordered, visual representation of the chromosomes in a cell - this uses an image of the cell division when it is stopped for metaphase because this is when the chromosomes are most visible
what holds sister chromatids together
a centromere - one per pair
what is a homologous pair
a pair of chromosomes with the same genes, one inherited from the father and one from the mother
what is a locus
the location of a gene on the chromosome
what is a gene
a defined region (sequence) of DNA that produces a type of RNA molecule that has some function - a gene is a unit of hereditary information
what is an allele
an alternative version of a gene
in a dividing cell the mitotic (M) phase alternates with _____, a growth period
interphase
what are the 2 stages of the mitotic phase
mitosis - distribution of chromosomes into two daughter nuclei
cytokinesis - division of cytoplasm, producing two daughter cells
what are the stages of interphase and what happens during each stage
the G1 phase involves metabolic activity and growth, the S phase involves metabolic activity, growth and DNA synthesis, the G2 phase involves metabolic activity, growth and preparation for cell division
what are duplicated chromosomes comprised of
two sister chromatids which are genetically identical - these seperate during mitosis
what does G2 of interphase consist of
the nuclear envelope is still intact
the nucleolus is visible and contains one or more nuclei (singular nucleolus)
two centrosomes form and duplicated chromosomes cannot be seen individually as they have not yet condensed
what are the 5 stages of mitosis
prophase
prometaphase
metaphase
anaphase
telophase and cytokinesis
what occurs in prophase of mitosis
the nucleoli disappear
the duplicated chromosomes condense and appear as two identical sister chromatids joined at their centromeres
mitotic spindle begins to form
microtubules lengthens dot he centrosomes move to opposite poles
what occurs in prometaphase of mitosis
the nuclear envelope breaks down and chromosomes fully condense
a kinetochore (a protein structure) forms at the centromere of each chromatid
microtubules that attach to the kinetochores are called kinetochore microtubules. nonkinetochore microtubules lengthen the cell by interacting with those from the opposite pole of the spindle
what occurs in metaphase of mitosis
centrosomes are now at the opposite poles of the cell. kinetochore microtubules are attached to the kinetochores of all sister chromatids. the duplicated chromosomes align at the metaphase plate. homologous pairs do not interact. centromere lie on the metaphase plate, an equal distance between the spindles two poles
what occurs in anaphase of mitosis
sister chromatids disjoin at the centromeres. each chromatids becomes as independent daughter chromosome. daughter chromosomes move towards opposite poles as their kinetochore microtubules shorten. the nonkinetochore microtubules lengthen and the cell elongates. anaphase ends when the two poles of the cell contain identical, and complete collections of chromosomes
what occurs in telophase of mitosis
the chromosomes become less condensed and the spinal microtubules break down. two daughter nuclei (with the nuclear envelope) form in the cell. nucleoli reappear. mitosis, the division of one nucleus into two genetically identical nuclei is now complete
what occurs during cytokinesis of mitosis
the cytoplasm divides resulting in two daughter cells. in animal cells cytokinesis involves the formation of a cleavage furrow, which pinches the cell into two. in plant cells, cytokinesis involves the formation of a cell plate between daughter cells
after mitosis each daughter cell has one copy of each duplicated _______. sister chromatids seperate during anaphase and each chromatid becomes a daughter _______.
chromosome - chromosome
