Cell Cycle Flashcards
What are the main stages of the cell cycle
The cell cycle consists of interphase (G1, S, G2), mitosis (prophase, metaphase, anaphase, telophase), and cytokinesis.
What happens during interphase?
The cell grows, carries out normal functions, and prepares for division by replicating its DNA and organelles.
What are the three phases of interphase, and what happens in each?
G1 (Gap 1): Cell growth, protein synthesis, organelle duplication.
• S (Synthesis): DNA replication occurs.
• G2 (Gap 2): Further growth, protein synthesis, checking for DNA errors.
What are the three main checkpoints in the cell cycle?
G1 Checkpoint: Ensures cell size is adequate and DNA is undamaged before S phase.
• G2 Checkpoint: Ensures DNA replication was successful before mitosis.
• Metaphase Checkpoint: Ensures chromosomes are properly aligned before anaphase.
What is mitosis?
Mitosis is a type of cell division that produces two genetically identical diploid daughter cells.
What happens during prophase?
• Chromatin condenses into visible chromosomes.
• Nuclear envelope breaks down.
• Centrioles move to opposite poles, and spindle fibers form.
What happens during metaphase?
• Chromosomes align at the metaphase plate (cell equator).
• Spindle fibers attach to centromeres of chromosomes.
What happens during anaphase?
Sister chromatids separate at the centromere.
• Chromatids are pulled to opposite poles by spindle fibers.
What happens during telophase?
• Chromosomes decondense back into chromatin.
• Nuclear envelopes reform around each set of chromosomes.
• Spindle fibers break down.
What is cytokinesis, and when does it occur?
Cytokinesis is the division of the cytoplasm to form two separate daughter cells.
• In animal cells, a cleavage furrow forms.
• In plant cells, a cell plate forms to become the new cell wall.
What are the main stages of the cell cycle?
Interphase (G1, S, G2), M phase (mitosis or meiosis), and cytokinesis.
What happens in the G1 phase of interphase?
Cell grows, organelles replicate, and proteins needed for DNA replication are made.
What happens in the S phase of interphase?
DNA is replicated, so each chromosome consists of two sister chromatids.
What happens in the G2 phase of interphase?
Cell continues to grow and prepares for division by synthesising proteins like spindle fibres.
What is the purpose of meiosis?
To produce four genetically different haploid gametes from one diploid cell.
How many divisions occur in meiosis and what are they called?
Two divisions: Meiosis I (reduction division) and Meiosis II (similar to mitosis).
What happens in Prophase I of meiosis?
Chromosomes condense, homologous chromosomes pair (synapsis), crossing over occurs, and the nuclear envelope breaks down.
What is crossing over and why is it important?
The exchange of genetic material between homologous chromosomes during Prophase I; it increases genetic variation.
What is independent assortment and when does it occur?
Random orientation of homologous pairs during Metaphase I, leading to genetic variation in gametes.
What happens in Anaphase I of meiosis?
Homologous chromosomes are pulled to opposite poles (sister chromatids stay attached).
What happens in Meiosis II?
Sister chromatids are separated, similar to mitosis, producing four haploid cells.
What is the result of meiosis?
Four genetically unique haploid cells (gametes in animals).
Why does meiosis produce genetic variation?
Due to crossing over and independent assortment.
What is cytokinesis?
The division of the cytoplasm, forming two separate cells after mitosis or four after meiosis.
What is a haploid cell?
A cell with one set of chromosomes (n), e.g., gametes.
