Chapter 11 & 12 Flashcards
Mitosis and meiosis are eukaryotic ________
nuclear division in stem cells, the mechanisms that lead to the distribution of DNA to new nuclei in forthcoming daughter cells
Mitosis is used by multicelled organisms for _____, repair, and _____ reproduction by repeated division of somatic cells
growth; asexual
Meiosis occurs only in particular somatic cells called _____ cells.
Germ cells; they divide to form gamates (sex cells)
Somatic cells=
diploid= 2n (mitosis); for humans 2(23)= 46 chromosomes
that is they have 2 of each type of chromosome
gamates=
haploid= n (meiosis); 23 chromosomes in a sperm/egg
only 1 chromosome of each type
before division, each threadlike chromosome is duplicated to form 2 sister chromatids held together by a _____
centromere
The centromere is the region where….
duplicated chromosomes will attach to the microtubules of the spindle during nuclear division
The cell cycle is….
a reoccurring sequence of events that extends from the time of a cell’s formation until each division is completed
most of cell’s existence (90%) is in the ___
interphase
what happens during interphase ?
Cell’s mass increases, the cytoplasmic components approx. double in number, AND DNA IS DUPLICATED
Interphase has three stages: G1, S1, G2
explain what happens in each
G1: most of the carbohydrates, lipids, and proteins for a cell’s own use and for export are assembled. CELL GROWTH
S phase: the cell copies its DNA and synthesizes proteins used in organizing condensed chromosomes. DNA SYNTHESIS
G2: proteins that will drive mitosis to completion are produced. PREPARE FOR DIVISION, chromatin duplicated
Apotosis have chances to form into tumors there they….
commit cell suicide or program cell death
G= Gap for growth
S= synthesis of DNA
Stages of Mitosis:
- Prophase
- Metaphase
- Anaphase
- Telephase
-Prophase: Prepare for division! Chromatin condenses to chromosomes consisting of two sister chromatids.
Nuclear envelope disappears.
Metaphase: Meet in the midline.
Chromosomes align at equatorial plane. In this stage, chromosomes are at the most condensed
Anaphase: Alone and apart :(
Sister chromatids seprate to move to the poles, spindle fibers pull apart
Centromeres divide.
Telephase: Torn and towed away T_T
Chromatin expands. Cytoplasm divides.
Phase in which nuclear membrane reforms around the chromosomes. Chromosomes decondense and arrive @ opposite poles
spindle apparatus
is crucial to mitosis/ meiosis. Seperate and move sister chromosomes to where they need to go (which is the nuclei) to opposite pole