Mitosis & Meiosis Flashcards
What is a haploid cell?
It is a cell that contains one complete set of chromosomes. i.e. contains one member of each homologous pair of chromosomes
What is a diploid cell?
It is a cell that contains two compelte sets of chromosomes.
What is a homologous chromosome?
They are chromosomes that carry the same genes controlling the same inherited charactersitics at the same loci but may not have the same alleles.
What are sister chromatids?
They are the result of DNA replication and are genetically identical.
What is the significance of the mitotic cell cycle?
It produces genetically identical daughter nuclei with same number and type of chromosomes and the same alleles so that genetically identical daughter cells can be produced for
- Growth
- Regeneration and cell replacement
- Asexual reproduction
Why is there a need for regulation of mitotic cell cycle?
- Cell cycle is tightly regulated as it is important for normal growth & development
- Cancer occurs when dysregulation of checkpoints of cell division occur or cell escapes cell cycle control mechanism.
What are the certain points in which regulation takes place?
G1, G2 and M phase
What is the significance of the meiosis cell cycle?
- For maintenance of chromosome number in every generation
- For genetic variation in offspring in every generation
How does meiosis cell cycle maintain chromosome number?
Production of 4 haploid gametes from 1 diploid parent cell. Chromosome number halved so that chromosome number can be restored upon fertilisation
How does meiosis cell cycle result in genetic variation in offspring every generation?
- 𝗖𝗿𝗼𝘀𝘀𝗶𝗻𝗴 𝗼𝘃𝗲𝗿 𝗯𝗲𝘁𝘄𝗲𝗲𝗻 𝗻𝗼𝗻-𝘀𝗶𝘀𝘁𝗲𝗿 𝗰𝗵𝗿𝗼𝗺𝗮𝘁𝗶𝗱𝘀 𝗼𝗳 𝗵𝗼𝗺𝗼𝗹𝗼𝗴𝗼𝘂𝘀 𝗰𝗵𝗿𝗼𝗺𝗼𝘀𝗼𝗺𝗲𝘀 resulting in new combinations of alleles on chromatids
- 𝗜𝗻𝗱𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝘁 𝗮𝘀𝘀𝗼𝗿𝘁𝗺𝗲𝗻𝘁 𝗼𝗳 𝗵𝗼𝗺𝗼𝗹𝗼𝗴𝗼𝘂𝘀 𝗰𝗵𝗿𝗼𝗺𝗼𝘀𝗼𝗺𝗲𝘀 𝗮𝘁 𝘁𝗵𝗲 𝗺𝗲𝘁𝗮𝗽𝗵𝗮𝘀𝗲 𝗽𝗹𝗮𝘁𝗲 & 𝘁𝗵𝗲𝗶𝗿 𝘀𝘂𝗯𝘀𝗲𝗾𝘂𝗲𝗻𝘁 𝘀𝗲𝗽𝗮𝗿𝗮𝘁𝗶𝗼𝗻 during metaphase I and metaphase II
- 𝗥𝗮𝗻𝗱𝗼𝗺 𝗳𝘂𝘀𝗶𝗼𝗻 𝗼𝗳 𝗴𝗮𝗺𝗲𝘁𝗲 during sexual fertilisation results in variety of genotypes
When will cell cycle be halted at G1 checkpoint?
If DNA is damaged, cell cycle will be halted at G1 checkpoint, preventing cells from entering S phase during which DNA is replicated
When will cell cycle be halted at G2 checkpoint?
If DNA is damaged/ all chromosomes are not replicated properly, the cell cycle will be halted at G2 checkpoint, preventing cell from entering mitosis
When will cell cycle be halted at M checkpoint?
If all chromosomes are not attached to spindle fibres from both poles, cell cyle will be halted at M checkpoint, preventing anaphase from occuring and hence preventing the incorrect separation of sister chromatids
