Chapter Four

• Binary fission


  The method of cell replication used by prokaryotes
• Asexual reproduction


  A method of reproduction that produces genetically identical cells without the fusion of gametes (sex cells)
• Plasmid


  A small, circular loop of DNA that is separate from a chromosome, typically found in bacteria
• Cytokinesis


  The division of the cytoplasm and formation of two daughter cells
• Septum


  A dividing wall formed during binary fission
• Interphase


  The first stage of the eukaryotic cell cycle which involves cellular growth and duplication of chromosomes
• Phases of interphase


  • G1
  • S
  • G2
• Chromosome


  A structure composed of DNA tightly wrapped around histone proteins, carries the genetic information (genes) of a cell
• Mitosis


  The second stage of the eukaryotic cell cycle, which involves the complete separation of sister chromatids and nuclei
• Sister chromatids


  The two identical halves of a replicated chromosome
• Chromatin


  Chromosomes (DNA and proteins) that have been unwound and loosely packed during interphase
• Quiescent


  Dormant cells which can re-enter the cell cycle
• Terminally differentiated


  Cells that have fully specialised and no longer replicate
• Chromatid


  One half of a double-stranded chromosome
• Centromere


  The structure which holds sister chromatids together
• Somatic cells


  Any cell that is not a reproductive cell (such as sperm and egg cells)
• Diploid


  Cells or organisms that have two sets of chromosomes (2n)
• Daughter cell


  The formation of a new cell following cell replication
• Chromosome condensation


  The shortening and thickening of chromosomes, as DNA is tightly wrapped around histone proteins
• Centrioles


  Cylindrical structures composed of protein which form the spindle fibres during mitosis and meiosis
• Spindle fibres


  Structures which aid in the movement of chromosomes to either pole of the cell during mitosis and meiosis
• Equator


  The centre line between opposite ends of the cell that the chromosomes line up on during metaphase
• Cleavage furrow


  An indentation of the plasma membrane during cytokinesis
• Cell plate


  A component involved in the formation of a cell wall
• Apoptosis


  The controlled death of cells in the body, also known as programmed cell death
• Mitochondrial pathway


  The pathway of apoptosis which is initiated by the detection of internal cellular damage, also known as the intrinsic pathway
• Death receptor pathway


  The pathway of apoptosis which is initiated by the reception of extracellular death signalling molecules, also known as the extrinsic pathway
• Caspase


  Enzymes that cleave specific intracellular proteins during apoptosis
• Cytochrome c


  A protein embedded in the inner mitochondrial membrane
• Blebbing


  The bulging of the plasma membrane to form apoptotic bodies
• Apoptotic bodies


  Vesicles containing cell contents that are released from a dying cell during apoptosis and engulfed by phagocytes
• Phagocyte


  A cell of the immune system responsible for engulfing and destroying harmful microorganisms and foreign material
• Phagocytosis


  Endocytosis of solid material or food particles
• Tumour


  A mass of abnormal cells
• Benign tumour


  A tumour that lacks the ability to spread throughout other tissues and organs
• Malignant tumour


  Abnormal cells with the ability to invade nearby tissue and migrate to other parts of the body, also known as cancerous cells
• Cancer


  A disease caused by the uncontrolled replication of cells with the ability to migrate to other parts of the body
• Metastasis


  The migration of tumour cells from the primary tumour site to distant parts of the body
• Stem cell


  Undifferentiated cells with the capability of differentiating into specialised cells
• Differentiation


  The development of a stem cell into a specialised cell with a particular function