Ch. 9 Flashcards
What are two functions of cell division?
- asexual reproduction
- growth and development
What is a centromere?
the region on each sister chromatid in a duplicated chromosome where it is most closely attached to its sister chromatid
What is a kinetochore?
- a protein complex at the center of a chromosome during cell division
- functions in binding microtubules
What are sister chromatids?
two copies of a duplicatied chromosome attached to each other at the centromere
What is the cell cycle?
a series of events that takes place in a cell as it grows and divides
What is interphase?
- phase in the cell cycle where the cell is not dividing
- cellular activity is high
- chromosomes & organelles are duplicated
accounts for 90% of the cell cycle
What is the mitotic (M) phase?
cell cycle phase including mitosis and cytokinesis
What are the 3 phases of interphase?
- G1 phase
- S phase
- G2 phase
What is the G1 phase?
first gap of the cell cycle consisting of the portion of interphase before DNA synthesis begins
What is the S phase?
the synthesis phase of the cell cycle where DNA is replicated
What is the G2 phase?
second gap of the cell cycle consisting of the portion of interphase after DNA synthesis occurs
What is the G0 phase?
a non-dividing state occupied by cells that have left the cell cycle
What is mitosis?
- a process of nuclear division in eukaryotic cells
- consists of 5 phases
What are the 5 phases of mitosis?
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
What happens in prophase?
- chromatin condenses into discrete chromosomes
- mitotic spindle begins to form
- nucleolus disappears but nucleus remains intact
What happens in prometaphase?
- nuclear envelope fragments
- spindle microtubules attach to the kinetochores of chromosomes
What happens in metaphase?
- spindle is complete
- chromosomes attached to microtubules at their kinetochores are aligned at the metaphase plane
What happens in anaphase?
- chromatids of each chromosome have separated
- daughter chromosomes are moving to the poles of the cell
What happens in telophase?
- final stage of mitosis where daughter nuclei are forming
- cytokinesis has typically begun
What is cytokinesis?
the division of the cytoplasm to form two separate daughter cells immediately after mitosis
What is the mitotic spindle?
- an assemblage of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis
- forms during prophase
What is cleavage?
pinching of the plasma membrane during cytokinesis
animal cells ONLY
What is the cleavage furrow?
- a shallow groove around the cell in the cell surface near the old metaphase plate
- pinched in 2, producing completely separated cells
animal cells ONLY
What is the cell plate?
- a membrane-bounded, flattened sac located at the middle of a dividing plant cell
- enlarges until its membrane fuses w/ the plasma membrane, producing 2 daughter cells
plant cells ONLY
What is binary fission?
asexual reproduction of prokaryotes by a separation of the body into two new bodies
What are the 4 stages of binary fission?
- duplication
- elongation
- pinching
- division
What is duplication?
DNA replicates
What is elongation?
cells begins to elongate and stretch
What is pinching?
septum forms from cleavage furrow
What is division?
2 daughter cells form after the septum is complete
What are the 3 major checkpoints within the cell cycle?
- G1 checkpoint
- G2 checkpoint
- M/spindle checkpoint
What happens at the G1 checkpoint?
primary point at which a cell chooses to divide or not
What happens at the G2 checkpoint?
checks for DNA damage DNA replication completeness
What happens in the M/spindle checkpoint?
checks for chromosome attachment to the spindle at the metaphase plate
