topic 2.6

• What is an acrosome?

  An organelle found in the head of sperm cells which is specialised to digest the outer coating of an egg cell during fertilisation.
• What is the anaphase in mitosis ?

  The third stage in mitosis where the chromosomesare pulled apart to the poles of the cell by the spindle fibres
• What is the first anaphase?

  The third stage of meiosis where the chromosomes that make up the bivalent are pulled apart to the poles of the cell by the spindle fibres.
• What is the second anaphase?

  The seventh stage of meiosis where the chromatids are pulled apart to opposite poles of the cell.
• What is an anucleate?

  A type of cell which does not have a nucleus.
• What is asexual reproduction?

  The production of genetically identtical offspring from one parent through the process of mitosis.
• Define bivalent?

  A pair of homologous chromosomes
• What is a cilliated epithelium?

  A type of epithelium which has many fine protrusions known as cilia

  and is specialised for sweeping dirt and debris out of the body
• What is meant by crossing over?

  The exchange of genetic material between two chromosomes in a bivalent
• What is cytokinesis?

  The division of the cytoplasm at the end of mitosis to produce two new daughter cells
• what is differentiation?

  the process where a cell develops certain features so that it is specialised to carry out a certain function
• What is a diploid?

  Cells with two copies of each chromosome.
• What is an erythrocyte?

  An anucleate cell specialised to carry oxygen from the lungs around the body (commonly referred to as a red blood cell)
• What is a gap 1 checkpoint?

  The first checkpoint in the cell cycle which occurs just before the end of Gap 1 phase and commits the cell to division under favourable conditions
• What is a gap 1 phase?

  The first growth phase in interphase where the cell synthesises proteins and RNA, duplicates its organelles and increases in size before DNA replication in S phase.
• What is a gap 2 checkpoint ?

  The second checkpoint in the cell cycle which occurs at the end of Gap 2 phase and checks that the DNA was correctly replicated during S phase before the cell enters mitosis
• what is a gap 2 phase?

  The second growth phase of interphase where the cell continues to

  increase in size and synthesize biomolecules
• What are gametes?

  sex cells that have a haploid nucleus and are produced through meioisis
• What are geme loci?

  The location of a gene on a chromosome
• What are guard cells?

  A type of cell usually found in pairs that is specialised to control the opening

  and closing of stomata
• What is a haploid?

  Cells with only one copy of each chromosome
• what are homologous chromosomes?

  Two chromosomes with similar gene loci but different alleles,

  one inherited from each parent.
• What is an independent assortment?

  A source of variation in meiosis where the bivalent chromosomes can line up either way around on the metaphase plate.
• what is an interphase?

  The largest part of the cell cycle where cells spend most of their time growing,

  synthesising biomolecules and preparing for mitosis.
• What is a metaphase checkpoint?

  The checkpoint occurring at the end of metaphase during mitosis which ensures all of the chromosomes have correctly attached to the spindle fibres and aligned at the metaphase plate
• what is meiosis?

  A type of cell division used to produce gametes that produces four genetically

  different haploid daughter cells from one parent cel
• What is meristematic tissue?

  A type of plant tissue which contains stem cells and is usually found in the growing regions of the plant
• What is a metaphase?

  The second stage in mitosis where the chromosomes attach to the spindle

  fibres and align in the centre of the cell along the metaphase plate
• What is metaphase 1?

  The second stage of meiosis where the bivalent chromosomes align along the

  metaphase plate and independent assortment occurs.
• What is metaphase 2?

  The sixth stage of meiosis where the recombinant chromosomes align on the

  metaphase plate
• What is mitosis?

  The division of a cell to produce two genetically identical daughter cells.
• What is meant by mulitpotent?

  A type of stem cell which has the ability to differentiate into any cell type within

  a certain tissue in the body.
• What is a neutrophil?

  A type of white blood cell with a multi-lobed nucleus which is specialised to

  engulf and destroy pathogens.
• What is an organ?

  A group of specialised tissues working together to carry out a specific function
• What is an organ system?

  A group of specialised organs working together to carry out a specific function
• What is a palisade cell?

  A type of cell found in the leaves of plants which contains many chloroplasts

  and is specialised to carry out photosynthesis.
• What is phloem?

  A tissue found in plants which is specialised for the transport of assimilates from their site of production to different parts of the plant where they are needed
• What is a pluripotent stem cell?

  A type of stem cell which has the ability to differentiate into any cell

  type in the body.
• What is the prophase in mitosis?

  The first stage in mitosis where the nuclear envelope breaks down, the

  centrosomes move to opposite poles of the cell, the mitotic spindle begins to form and the

  chromosomes condense.
• What is prophase 1 in meiosis?

  The first stage of meiosis where the nuclear envelope breaks down, the spindle

  fibres form and the chromosomes condense and form bivalents. This is the stage of meiosis

  where crossing over occurs