2.1.6

• the cell cycle involves

  the preparation and division of a cell into 2
• the cell cycle takes

  a long time but depends on the type of cell
• mitotic phase

  the cell divides into 2, consists of mitosis and cytokinesis
• interphase

  the cell is carrying out its function or preparing to enter the mitotic phase, consists of G1, S, G2
• G1 phase

  organelles are replicated, transcription and translation occur, the size of the cell increases
• S phase

  DNA synthesis occurs as chromosomes are replicated
• G2 Phase


  energy stores are replenished from G1, transcription and translation occur, chromosomes are repaired, cell size increases
• mitosis

  chromosomes are split into 2 separate nuclei
• cytokinesis

  the whole cell has divided into 2
• cells leave the cell cycle through

  G0
• G0

  a cell leaving the cell cycle due to: fully differentiated function, senescent ( DNA damage, cannot divide), temporary - may be stimulated back into the cell cycle by a trigger ( example: pathogen)
• the cell cycle is regulated by

  checkpoints
• cell cycle checkpoints

  G1 - cell size, DNA damage

  G2 - cell size, DNA damage

  metaphase - chromosomes have been assembled correctly on the spindle fibres and they are attached
• cell cycle diagram

  A) mitosis

  B) cytokinesis

  C) G1

  D) G0

  E) S

  F) G2

  G) Interphase

  
• diploid cell

  contains chromosomes in pairs
• mitosis produces

  2 identical diploid cells
• mitosis is used for

  growth, repair, asexual reproduction
• view of a cell nucleus during interphase

  chromsomes are not visible but chromatin is
• chromatin


  when chromosomes are loose and open so DNA is accessible to allow for transcription and replication
• chromosome

  a single long molecule of DNA
• sister chromatids

  identical copies of a single chromosome produced during DNA replication in Interphase
• sister chromatid structure

  joined by a centromere

  A) chromosome

  B) centromere

  C) chromatid

  
• centromere

  a region of compressed DNA responsible for the movement of sister chromatids into daughter cells during mitosis
• a chromosome consists of

  two sister chromatids
• stages of mitosis

  prophase, metaphase, anaphase, telophase
• prophase

  chromosomes condense

  nucleolus and nuclear membrane disappear

  centrioles move to either pole

  spindle fibres attach to the centromeres
• metaphase

  all spindle fibres are formed and attached

  chromosomes are lined up along the cell equator
• anaphase

  centromeres divide into 2

  spindle fibres shorten

  sister chromatids are pulled to opposite poles
• telophase

  chromatids have reached opposite poles

  spindle apparatus breaks down

  nuclear envelope, chromatin and nucleolus reform
• cytokinesis

  the cells central / overall membrane is pulled inwards by the cytoskeleton

  the groove deepens cause the membrane to fuse and split into 2 independent cells
• mitotic phase in plants

  centrioles are not present and do not form spindle apparatus
• cytokinesis in plant cells

  the Golgi apparatus releases vesicles

  the vesicles form a membrane structure down the equator of the cell dividing the cytoplasm into 2

  a new cellulose wall forms
• prophase diagram

  A) oppposite

  B) poles

  C) spindle

  D) centromere

  E) nucleolus

  F) nuclear envelope

  G) vesicles

  
• metaphase diagram

  A) metaphase

  B) pole

  C) spindle

  D) equator

  
• anaphase diagram

  A) anaphase

  B) centromere

  C) chromatids

  D) spindles

  E) opposite

  F) centromere

  G) spindles

  
• telophase diagram

  A) nucleolus

  B) spindles

  C) interphase

  D) division

  E) nuclear envelope

  F) chromatin

  
• cytokinesis animal and plant cell diagram

  A) cleavage furrow

  B) cell membrane

  C) vesicle deposition

  D) new cellulose wall

  
• cytokinesis occurs

  at the beginning of anaphase and by the end of telophase
• centrioles


  2 protein structures containing microtubules at right angles to each other
• spindle apparatus

  a cytoskeleton structure made of microtubules and centromeres and centrioles