Cell Division Flashcards
What is the process before cell division?
Semi-conservative DNA replication
What does semi-conservative mean?
Each new DNA molecule contains one original strand from parent DNA and one new strand.
Why is it important for DNA to have a double helix?
So it can act as its own template through universal complementary base pairing when replication DNA.
How does DNA replication work?
Free-floating complementary nucleotides attach to each half of the exposed bases to synthesis new strands.
What does cell division enable?
Growth, Repair, Reproduction, transfer of genetic material
How do prokaryotes reproduce?
Through binary fission.
What triggers binary fission?
As the bacterial cell increases in size, the cell continues to grow and split into two daughter cells.
What is the process of binary fission?
Parent cell DNA is copied to form two identical coils of chromosomes through DNA replication.
The replicated chromosomes (two circular loops) attach to the cell membrane by proteins.
As the cell membrane grows, the loops are separated and pulled towards opposite directions.
A cleavage furrow forms and the cell membrane of the parent cell pinches inwards, forming two cells.
New cell wall is formed around each cell.
Two genetically identical daughter cells are formed, each with one circular chromosome.
What are two copies of chromosomes called?
Sister chromatids
What shape do sister chromatids look like?
An X
How many pairs of chromosomes in human cells?
23
What is a diploid cell?
When both members of a homologous pair are present (one from maternal, one paternal)
What is a haploid cell?
If it only contains one set of chromosomes.
What are the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
What happens during interphase?
Parent cell replicates DNA and increases in size.
How do eukaryotic cells divide?
Mitosis
State what happens in prophase.
The nuclear membrane breaks down and the nucleolus disappears. DNA condenses, chromosomes join with sister chromatids. Spindle fibres are assembled and move to the cell’s poles.
State what occurs in metaphase.
All the chromosomes line up the middle of the cell and attach to spindle fibres.
State what occurs in anaphase.
Sister chromatids are separated by the retracting of spindle fibres and move towards the poles (opposite directions)
What occurs in telophase?
Spindle fibres break down and the chromosomes decondensed into chromatin, cell elongates
What occurs in cytokinesis?
Cell membrane pinches inwards and two identical daughter cells are formed.
What do binary fission and mitosis have in common?
Both are asexual reproduction, both used for growth and reproduction, both result in two genetically identical daughter cells, chromosomes are repeated after DNA replication
What are some differences between mitosis and binary fission?
BF is one process, mitosis have two (mitosis and cytokinesis), chromosome attach to cell membrane in BF, spindle fibres separates in mitosis
What is a mutagen?
Chemical or physical factors that increase chances of developing cancer and tumours
Provide some examples of mutagens
UV rays, carcinogens
