T1 - Mitosis and binary fission Flashcards
What are the steps of mitosis?
DNA condenses to form chromosomes.
Chromosomes line up along the centre of the cells.
Cell fibres pull the two arms of each chromosome to opposite sides (poles) of the cell.
Cytokinesis - the entire cell divides to form two identical daughter cells.
What are the three reasons why new cells are required?
Growth, repair, development
What is the cell cycle?
The series of steps that take place as a cell grows and then divides.
How many pairs of chromosomes do human cells have?
23 pairs, 46 chromosomes in total.
When a cell divides by mitosis, how many cells are produced?
2
Cells created by mitosis are …
Genetically identical to each other and are called daughter cells.
What is the cell cycle?
Cellular growth - the cell gets
larger and produces more sub-cellular structures, such as mitochondria and
ribosomes.
DNA replication - chromosomes
duplicate, so that each consists of
two arms (copies).
Mitosis
What type of organisms divide by binary fission?
Bacteria
When bacteria divide by binary fission, is it an example of asexual reproduction or sexual reproduction?
Asexual reproduction.
Bacteria are unicellular meaning that when they divide by binary fission they’re also reproducing as each new cell is a separate organism.
Which two things must a bacterial cell do before it can divide?
Grow
Replicate it’s genetic material.
Describe the process of binary fission?
The two circular strands of DNA move to opposite sides of the cell.
A new cell wall from down the middle of the cell
The two halves pull apart to form two cells
During binary fission, are the plasmids always split equally between the two new cells?
No. The plasmids are randomly arranged, so there are often more plasmids in one cell than the other.
What is the mean division time?
The mean (average) time it takes for a bacterial cell to divide
What 3 conditions do bacteria require for fast growth?
Warm, moist, plenty of nutrients
