Chapter 8: Mitosis and Meiosis Flashcards
Why do cells reproduce? What purpose does cell division serve?
Replaces damaged or lost cells.
Permits Growth
Allows for Reproduction
Prokaryotes reproduce by…?
Binary Fission. (dividing in half)
It is considered asexual reproduction.
Chromatin
A mixture of DNA and proteins that form the chromosomes (unorganized)
Chromosomes
Bundles of DNA molecules and proteins but organized.
When do chromosomes become visible?
when the process of cell division begins, specifically in prophase.
What is the centromere?
The centromere is the narrowed waist in the sister chromatids.
*Rememember that the number of chromosomes is determined by the number of centromeres
The cells cycle consists of two distinct phases.
Interphase and Mitotic Phase.
How much time is spent in interphase? what occurs during interphase?
90% of the time.
The cell performs its normal functions, doubles everything in its cytoplasm (chromosomes), and grows in size.
Mitosis
The division somatic cells.
Meiosis
The division of a single diploid cell into four haploid daughter cells.
Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of parents.
What are the four main phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
PMAT
What begins during telophase?
cytokinesis
Mitotic Spindle
a football-shaped structure of microtubules guides the separation of two sets of daughter chromosomes.
Centrosomes
Spindle microtubules grow from structures
Asexual reproduction
Produces offspring that are identical to the original cell or organism. Involves the inheritance of all genes from one parent. MITOSIS
Sexual Reproduction
Produces offspring that are similar to the parents but show variations in traits. Involved inheritance of unique sets of genes from two parents.
MEIOSIS
Mitosis
What occurs during prophase?
***CHROMATIDS CONDENSE SO THEY ARE VISIBLE.
NUCLEAR MEMBRANE DISSEMBLES AND NUCLEI DISAPPEAR.
MITOTIC SPINDLES FORM FROM CENTROSOMES.
CENTRIOLES WILL HELP MOVE SISTER CHROMATIDS.
Mitosis
What occurs during metaphase?
Sister chromatids are organized into a single row END TO END.
METAPHASE PLATE.
Mitosis
What occurs during anaphase?
Sister chromatids are being seperated by spindles.
Mitosis
What occurs during telophase?
Chromosomes decondense.
The nuclear membrane and nuclei now reform.
Mitotic spindles disappear.
Cytokinesis begins.
Cytokinesis in animal cells.
Begins with the appearance of a cleavage furrow and indentation at the equator of the cell known as cleavage.
Cytoplasm is divided
Cytokinesis in plants
Begins when vesicles containing cell wall material collect in the middle of the cell and then fuse, forming a membranous disk called the cell plate.
The cell plate grows outward to reach the edges dividing into two cells.
THE CELL PLATE WILL EVENTUALLY TURN INTO CELL WALL!