B1b Cell cycle Flashcards
List the stages that occur during interphase
G1 - growth
S - synthesis of DNA
G2 - growth & preparation for mitosis
When in the cell cycle does DNA replication take place?
Interphase
S phase
Describe the structure of a chromosome at prophase.
Two identical chromatids joined by a centromere
What happens during interphase?
DNA replication
Replication of cell organelles
Store of ATP synthesised
Growth of cell
Describe what happens in prophase
DNA condenses onto histones
Chromosomes become visible
What happens during metaphase?
Chromosomes move to the equator of the cell.
Centromere attaches to the spindle fibres.
Describe what happens during anaphase.
Spindle fibres pull chromatids to opposite poles of the cell.
Describe what happens at telophase
Chromosomes/chromatids arrive at the poles of the cell.
What happens during cytokinesis?
Cytoplasm divides to form two new cells.
Which stage of mitosis is shown in the diagram?
Anaphase
Which stage of mitosis is shown in the diagram?
Metaphase
Name the stage of mitosis shown in the photograph.
Metaphase
What is the cause of tumour and cancers?
Uncontrolled mitosis.
Name the process used when eukaryotic cells divide?
Mitosis
Name the process used when prokaryotic cells divide.
Binary fission.
Describe the process of binary fission
Replication of circular DNA and plasmids.
Division of cytoplasm to form two daughter cells each with a single copy of the circular DNA and a variable number of copies of plasmids.
How do viruses make copies of themselves?
Inject DNA or RNA into host cell.
Host cell replicates DNA or RNA.
Host cell makes viral proteins.
Host cell constructs new virus particles.
Cancer is caused by uncontrolled mitosis.
How do most cancer drugs work?
Prevent DNA replication inhibiting metaphase by interfering with spindle formation
Describe the cells produced by mitosis
2 daughter cells that have the same number of chromosomes as the parent cell and each other.
Genetically identical
How much of a single cell cycle is spent in interphase?
90%
How long does a mammalian cell take to undergo 1 complete cell cycle?
Approx. 24 hours.
Why are cells taken from the root tip when studying mitosis?
Area of root growth
Meristem = place where mitosis/cell division occurs.
When studying mitosis why do you firmly squash the root tip?
To create thin layer of cells /one cell thick
Allow light to penetrate the specimen
How can you tell when a cell has undergone DNA replication?
Chromosomes become visible as X shaped structures - 2 sister chromatids joined by a centromere.
How can you make the mitotic index accurate?
Systematic method of counting a large number of cells so the sample is representative.
