Mitosis & Meiosis Flashcards
What is the purpose of mitosis?
Ensures growth, tissue repair and asexual reproduction by producing two genetically identical diploid daughter cells
What are the stages of mitosis?
Prophase: Chromosomes condense, spindle fibres form
Metaphase: chromosomes align at the metaphase plate
Anaphase: Sister chromatids are pulled apart
Telophase: Chromosomes de-condense, nuclear membranes re-form
Cytokinesis: Division of cytoplasm and organelles
How is mitosis regulated?
By proteins and checkpoints to ensure accurate chromosome separation and prevent errors like cancer
Why is proper alignment during metaphase important?
Ensures each daughter cell receives an identical set of chromosomes, preventing genetic errors
What is the difference between homologous chromosomes and sister chromatids?
Homologous chromosomes are pairs of chromosomes (one from each parent) with the same genes, while sister chromatids are identical copies of a single chromosome.
What are the differences between mitosis and meiosis?
Mitosis produces 2 genetically identical diploid cells for growth and repair while meiosis produces four genetically diverse haploid cells for reproduction.
What is the role of spindle fibres during cell division?
Spindle fibers attach to chromosomes at the kinetochores and help separate sister chromatids or homologous chromosomes.
Why is crossing over critical in meiosis?
Crossing over during prophase I increases genetic diversity by exchanging DNA between homologous chromosomes.
How do errors in meiosis lead to conditions like Down Syndrome?
Non-disjunction during meiosis causes an unequal distribution of chromosomes, leading to trisomy 21 (Down syndrome).
What is the purpose of meiosis?
Meiosis generates gametes and ensures genetic diversity through processes like crossing over and independent assortment.
What are kinetochores?
Protein complexes located on the centromere of chromosomes, serving as the attachment site for spindle fibres.
What are the stages of meiosis I?
Prophase I: chromosomes condense, chromosomes pair up (called synapsis), crossing over occurs
Metaphase: tetrads align along metaphase plate, chromosomes attach to spindle fibres, random alignment of homologous chromosomes
Anaphase: spindle fibres shorten, chromosomes pulled apart
Telophase: chromosomes arrive at opposite poles and nuclear envelope reforms
What are the stages of Meiosis II?
Prophase II: chromosomes condense without DNA replication
Metaphase II: chromosomes align at metaphase plate, spindle fibres attach to kinetochores
Anaphase II: Sister chromatids pulled apart
Telophase II: Chromosomes reach poles and decondense, nuclear envelope reforms
When does genetic recombination occur?
Prophase I
When does independent assortment occur?
Metaphase I
