Chapter3(cell Division) Flashcards
What are the stages of cell cycle
GSM
1. Gap 1-Growth and preparation of the chromosome for replication
2.synthesis of DNA and replication of the chromosome
3.Preparation for Mitosis
4.Mitosis
What’s the longest phase in the cell cycle
Interphase: Gap1,Synthesis and Gap 2
What’s the short period of the cell cycle ?
Mitotic phase
During interphase the cell grows by producing what?
Protein and cytoplasmic organelle
The resting and the non dividing stage of cell cycle is called?
Interphase
What happens during the interphase?
- The period of synthesis and growth 2.The cell absorbs nutrients to build new cells
3.DNA replication occurs - Chromatin(a long thread-like structure)are present in this phase instead of chromosomes.
The DNA replication occur during what phase of the interphase?
during the S phase of the interphase.
The cell consists of how many chromosomes and chromatid respectively
46&92 respectively
What’s the longest phase of mitosis?
Prophase
What occurs in the mitotic prophase?
1.Nucleolus and cell membrane disappears
2.condensation of chromatin to visible chromosomes
3.centrioles move to opposite side of the cell
4.spindle are formed
Spindle are form by ?
Centromeres
Short centrioles are called
Asters
What’s the coordinating center for the cells microtubules?
Centrosome
The cell inherits how many centrosome
A single
What occurs in the metaphase;
1.Chromosome arrange themselves at the equator of the cells
2. Chromosome are attached to the spindle
The point where chromosomes attach to spindle is called?
Kinetochore
Spindle are form by
Centromere
What’s occurs in mitotic anaphase ?
1.centromere split to form chromosomes( a pair of chromatid)
2.the chromosomes move to the poles of the cell
What occurs in the mitotic telophase?
1.spindle fibres break down
2. centrioles replicate
3.nuclear membrane and nucleolus reappear
4. Chromosomes change to chromatin thread
5 division of cell membrane occur
What are the phases in prophase I and what happened in each phase?
1.leptotene: chromosomes become visible and shortened i.e chromatin turns to chromosome
2.Zygotene:Homologous chromosome pairs to form bivalent i.e synapses
3.Pachytene:Bivalents shorten and thicken to become more physical
4.Diplotene :Bivalent pull slightly apart at the chiasma
5.Diakinesis:homologous centromere move apart and chromatid begins to shorten
What’s a chiasma?
Point of attachment between 2 non- sister chromatid
What occurs in metaphase I?
Homologous chromosome pairs(Bivalents) align along the equator
What occurs in Anaphase I?
Homologous chromosomes separate and move to opposite poles.
What is the cell that is produced in telophase I?
two haploid daughter cells, each with one set of chromosomes is formed
Crossing over occurs at what phase ?
Prophase I, parchytene
General recombination during meiosis is achieved by
1.Crossing over
2.independent assortment of chromosomes
What are the significance of mitosis?
1.Genetic stability:daughter cells are genetically identical to parent cell and no variation
2.Growth:increase in number of cells is by mitosis
3.Regeneration: ability to regenerate a whole part of a body
4:Asexual reproduction
What are the significance of meiosis ?
1.Sexual reproduction
2.Genetic Variation
Nucleosome
A section of DNA wrapped around a core protein
The presence of chiasma indicates that;
The 2 chromatids are in synaptonemal complex
