Lecture 10 - The Cell Cycle Flashcards
What are the key roles of cell division?
- reproduction = unicellular organism divide to produce more organisms
- growth and development = multicellular eukaryotes are composed of many cells which arose from a single fertilized cell
What is prokaryotic cell division?
- divide by binary fission
- simpler than mitosis
- results in creating two genetically identical daughter cells
What is the prokaryotic growth curve?
- growth is exponential
- different phases of population growth of bacterial culture
What are the phases of the growth curve?
- lag phase = cells preparing to divide
- log phase cells divide (exponential)
- stationary phase = cell division equals cell death (space and food becomes limiting)
- death phase = cell death is greater than cell division
What are the terms in the division of a eukaryotic cell?
chromatid = product of DNA replication chromatin = DNA + protein complex centromere = site of attachment of chromatids and kinetochore kinetochore = protein complex that assembles at the centromere
What are the phases of the cell cycle?
G1 (Gap 1) = normal cell activities (the cell is preparing and deciding to divide, one copy of the genome)
S phase (Synthesis) = DNA replication (two copies of genomes)
G2 (Gap 2) = normal cell activities (BUT cell is committed to eventual mitosis)
M phase (Mitosis) = separation of chromatids
What are the phases of mitosis?
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
What happens in prophase?
- chromosomal condensation (package DNA into dense mitotic chromosome)
- review to notes for diagram*
What happens in prometaphase?
- nuclear envelope breakdown
- microtubules invade the nuclear area and attach to kinetochores
- circle shape
What happens in metaphase?
- chromosomes line up at the metaphase plate
- circle shape
- chromosome movement is driven by microtubule pol/depol, kinesin, dynein
What happens in anaphase?
- separation of chromosomes
- “chromatids” becomes “chromosomes”
- oval shape
What happens in telophase?
- nuclear envelope reformation
- chromosomal dencondensation
What happens in cytokinesis?
- separation of the cytoplasm
What is cell cycle control?
- three main checkpoints = control passage through the cell cyles
What happens at restriction point/ G1-S?
- most important checkpoint
- asks… are there divide signals? is there enough space? is there enough nutrients?
