cell division Flashcards
What are the types of cell division?
meiosis, mitosis, binary fission
what is binary fission?
asexual division in bacteria, replicates circular dna and then elongates the cell forming a new membrane between causing two new cells.
what is mitosis
asexual division consisting of phases M phase which is when mitosis occurs, interphase which is when the cell gets larger and receives more cytoplasmic membrane components.
what is M phase?
this is when the cell actually divides it consists of 5 stages: prophase, prometaphase, metaphase, anaphase and telophase.
what are the stages of interphase?
G1: size and protein concentration increase.
S: DNA is replicated
G2: preparation for mitosis
G0: no active preparation for cell division (occurs in cells that do not divide)
what are centromeres
middle dot in chromosomes
What are sister chromatids
the two chromosomes that are attached to each other via centromere
what are kinetochores
miotic spindle protein structures that attach to centromeres they are little protein structures at the edge of each mitotic spindle.
what are the differences between plant cell mitosis and animal mitosis
in the middle of the dividing cells there is a cell plate in a plant instead of the cleavage and during telophase they form phragmoplast in the middle to guide vesicles containing cell wall components.
what is meiosis
sexual division, resulting in 4 daughter cells and undergoes 2 rounds of miotic division.
what happens during meiosis I
Prophase: chromosomes become visable and DNA replication is already complete. homologous chromosomes continue to condense and undergo synapsis (pairing). When this is complete each chromosome forms a bivalent (identical chromatid). then crossing over occurs.
what happens during meiosis II
there is no synapse, no crossing over, at metaphase II the sister chromatids line up in the middle then are pulled apart to the edges and 4 haploid cells are formed.
what is the difference in meiosis for men and women?
At the end of meiosis there is 4 cells, in males there is 4 sperms cells, and in females there are 4 cells where 1 is an oocyte and 3 are non-functional polar bodies.
what is a karyotype?
this is a picture of all chromosomes organized by the number and shape of the chromosomes.
What is cytokinesis?
this is the basis for asexual reproduction in single-celled eukaryotes, it is also the basis for the development and maintenance of cells, tissues and organs in multi-celled eukaryotes it is when the cleavage (contractile ring) is formed in the middle of two re-forming nuclei.
What occurs during prophase?
chromosomes condense and migrate
What occurs during prometaphase?
microtubes of the mitotic spindles attach to the chromosomes
What occurs during metaphase?
chromosomes align in the centre of the cell
What occurs during anaphase?
sister chromatids are ripped apart and pulled away from the edge.
What occurs during telophase?
the envelope reforms and chromosomes condense
what is a chiasma?
when crossing over occurs and the legs of each sister chromatid connect when they connect the connection is called the chiasma.
what happens during meiosis I
maternal and paternal homologous chromosomes cross over and separate from each other
what happens during meiosis II
sister chromatids separate (same as mitosis but at the end there are 2 single-sided chromosomes in each 4 cells (meaning haploid).
what happens in first meiosis nondisjunction?
missing chromosomes in 2/4 of the daughter cells and one extra in the remaining two
what happens in second meiosis nondisjunction?
there is missing chromosomes in one daughter cell and one extra in the corresponding second one.
