science 2

• the two types of cell division are the mitosis and meiosis
• mitosis is the process of nuclear division wherein two genetically identical daughter cells with the same number of chromosomes as their parent cell are produced
• in mitosis, each daughter cell id diploid that has a complete set of chromosomes (2n), which is similar ro parent cell
• karyotype shows the number of chromosomes of an organismand the corresponding characteristics, arranged in a particular patern
• xx for female
• xy for male
• meiosis another type of cell division that generates sex cells (gametes)
• mitosis has an important function in human body growth. it is responsible for replacing dead cells, repairing tissues and healing wounds
• mitosis has 2 daughter cell
• meiosis has 4 daughter cell
• chromosome are darkly stained bodies within the nucleus consisting of highly coiled and condensed strand od DNA
• cancer is the term used to describe diseases characterized by uncontrolled cell division and abnormal cellular growth
• living and actively dividing cells are passing through a regular sequence of growth, DNA replication, and division called the cell cycle
• interphase (non dividing stage) is the period of growth with DNA replication
• mitosis(dividing stage) is a period of reproduction or the actual division of the nucleus
• cytokinests is the division of the cytoplasm and the plasma membrane
• cytokinesis differ in animal and plant cells
• in animal cell it is marked by constriction of the cell membrane called cleave furrow
• in plant cell cytokinesis happens when an expanding cell plate form cross the center of the cytoplasm called phragmoplat
• three significant phases : gap 1 phase, synthesis phase, and gap 2 phase
• in gap 1 phase (g1) the newly produced daughter cells increase in size and they prepare themselves for DNA replication
• synthesis phase the most critical part of interphase. it is where the cells DNA is synthesized and replicated so that the exact copy of the DNA can be distributed to two daughter cells during cell division
• gap 2 phase (g2) the cells continue to grow and synthesize RNA and proteins
• the process in mitosis are both the nuclear and cytoplasmic divisions are involved
• four phases in mitosis : prophase, metaphase, anaphase, and telophase
• the prophase is subdivided into three substages : early prophase, middle prophase, and late prophase
• in early prophase the nuclear membrane starts to disappear and the nucleolus gradually disintegrate
• in middle prophase spindle fibers are formed
• in late prophase chromosomes move near the surface
• metaphase all chromosomes are aligned
• anaphase centromere splits
• telophase chromosomes have reached opposite poles
• after the end of mitosis the cytokinesis the division of cytoplasm follows. in animal cell cleavage furrow has formed and in plant cell a cell plate is formed turns into cell wall
• meiosis 1 known as reduction srage. synapsis and crossing over occur
• crossing over is the process wherein homologous chromatids exchange genetic material to ensure greater variety in gamete formation
• meiosis 2 similar to meiosis one but it doesn't undergo to interphase anymore
• prophase 1 sypnasis and crossing over occur in homologous chromosomes
• prophase 2 each chromosome has sister chromatids
• metaphase 1 tetrads move to the center of the cell
• metaphase 2 dyads move to the center of cell