Unit 1 - AOS 1 - Mitosis and cell cycle Flashcards
The functions of cell division
- Asexual reproduction for unicellular organisms
- Asexual reproduction for multicellular organisms
- Sexual reproduction in multicellular organisms
- Growth and development of a multicellular organisms
- Repair and maintenance of a multicellular organism
Define Binary fission
Is cell division completed asexually by prokaryotes, that results in two genetically identical organisms.
3 types of asexual reproduction for multicellular organisms
- Budding: they produce growths from their bodies which eventually fall off and become cloned offspring (hydra)
- Autonomy: when an organism performs self amputation of one of its body parts (starfish)
- Vegetative reproduction: one way is through cell division to produce runners. Which are extensions from the parent plant that contain attached cloned offspring. (Spider and strawberry)
In sexual reproduction (multicellular) , cell division is required for two reasons …
- To make gametes like speed and ova
- To allow the multiple divisions needed to create a multicellular organism
Definition of cell cycle
This represents the processes that occur between one cell division and the next cell division in a cells life
3 main stages of the cell cycle
- interphase
- mitosis
- cytokinesis
Interphase definition
The cell spends most of its life Performing it’s specialised sunrooms and then prepares for cell division when the time comes
Parts of the interphase are …
- G1
- Synthesis
- G2
What happens in the G1 phase of the Interphase ?
- the cell grows after cell division to reach to full size (can double)
- the cell performs it’s specialised function depending on what type of cell it is.
- this is the longest part of the cell cycle for most cells
Explain what happens to cells that stop dividing
- these cells stop progressing through the cell cycle and go into the G0 (gap zero)
- they simply continue there specialised function until they die
- e.g muscle cell, heart muscle cell, Brain cell
What happens in the synthesis phase of the interphase
- the DNA is replicated creating two identical copies of each chromosome
- the centriole pair also duplicates to create two pairs
Function of centriole
They are involved in the development of spindle fibres used during cell division
What happens in the G2 phase of the Interphase
- prepares for mitosis through rapid growth of cytoplasm
- the cell increases the synthesis of the proteins needed to make the spindle fibers used in mitosis
- DNA is checked for replication errors that may have occurred during DNA replication in S phase.
Definition of mitosis
The process that sorts and divides the duplicated chromosomes into two identical sets of DNA so that each daughter cell get’s one set.
how many chromosomes do humans somatic cells have before replication and after replication?
46 –> 92