Cell cycle CAQ

🔄 Cell cycle Created Tags Describe the interphase events and its importance Interphase occurs before cell and nuclear division During G1/G2 phases of the interphase there is an increase in cell size There is synthesis of cellular organelles such as mitochondria, chloroplast and centrioles to allow for equal division into the daughter cells There is synthesis of ATP in preparation for the energy consuming process during cell division During S phase of interphase, semi conservative DNA replication occurs Each parental DNA strand serves as a template to form daughter DNA molecule made up of 1 parental strand and 1 newly synthesised strand/daughter strand The amount of DNA content doubles G1 and G2 checkpoints checks to ensure no error in DNA so G1 checkpoints checks for DNA damage,cell size and whether nutrients are sufficient while G2 assesses if DNA is correctly replicated Progression of cell cycle is delayed as damaged cells are arrested preventing initiation of next phase if problems are detected If there is irreparable damage to DNA at either G1 or G2, cell death induced and apoptosis occurs to prevent accumulation of mutations on a single cell lineage and ensuring that incorrectly replicated DNA is not passed down to August 14 , 2025 1152 PM Cell c y cle 1

daughter cells such as cancer-critical genes which may lead to development of cancer and uncontrolled cell division Describe checks made at cell cycle checkpoints Has 3 regulatory checkpoints to ensure cell cycle events occured normally which are G1, G2 and M checkpoints During G1 checkpoints, sufficient nutrients/growth factors are checked for and whether there is adequate cell size/ duplication of all organelles/ no DNA damage before the cell proceeds to S phase At the G2 checkpoint DNA replication is assessed for completion and that there is no DNA damage and cell size is adequate At the M checkpoint, proper attachment of all chromosomes to kinectochore microtubules Is checked for and all chromosomes are properly aligned at the metaphase plate before dividing cell is allowed to enter anaphase Cell cycle checkpoints allow cell cycle to proceed only when internal and external conditions are favourable and also provide time for errors or malfunctioning cellular machinery to he repaired that may result if the cell cycle progressed prematurely to the next stage Role of centrioles There is a pair of centrioles at each pile of the cell, determining the polarity of cells Centrioles organise the synthesis of the spindle fibres which leads to the equal separation of the sister chromatids so that resulting cells are genetically identical Describe structure of homologous chromosomes Consists of 2 homologues one of paternal and one of maternal origin Have the same size, shape centromere position and staining pattern Cell c y cle 2

They have same genes at corresponding loci Are non-identical due to presence of different alleles which are alternative versions of c