Chapter 12: The Cell Cycle Flashcards
Cell Division
Reproduction of cells
Cell Cycle
- Ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two
- In eukaryotic cells, it’s composed of interphase and M phase
Genome
- Genetic material of an organism/virus
- -Complete complement of an organism or virus’s genes along with its non coding nucleic acid sequences
Chromosome
Cellular structure consisting of one DNA molecule and associated protein molecules
Meiosis
- Modified type of cell division in sexually reproducing organisms
- Consists of 2 rounds of cell division but only 1 round of DNA replication
- Results in 4 daughter cells with 1/2 the number of chromosome sets as the original cell
Sexual Reproduction
Type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from both parents via the gametes
Chromatin
- Complex of DNA and protein that makes up eukaryotic chromosomes
- When the cell is not dividing, exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
Somatic Cell
Any cell in a multicellular organism except a sperm, egg, or their precursors
Sister Chromatids
- Two copies of a duplicated chromosome attached to each other by proteins at the centromere and sometimes along the arms
- While joined, two make up one chromosome
- Eventually separated during mitosis or meiosis II
Centromere
- In a duplicated chromosome, the region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences
- Close attachment causes a constriction in the condensed chromosome
Mitosis
- Process of nuclear division in eukaryotic cells divided into five stages:
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase - Conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei
Cytokinesis
Division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II
Mitotic (M) Phase
Phase of the cell cycle that includes mitosis and cytokinesis
Interphase
- Period in the cell cycle when the cell is not dividing
- Cellular metabolic activity is high
- Chromosomes and organelles are duplicated
- Cell size may increase
- Accounts for about 90% of the cell cycle
G1 Phase
- First gap or growth phase of the cell cycle
- The portion of interphase before DNA synthesis begins
S Phase
- Synthesis phase of the cell cycle
- Portion of interphase during which DNA is replicated
G2 Phase
- Second gap or growth phase of the cell cycle
- The portion of interphase after DNA synthesis occurs
Prophase
- First stage of mitosis
- Nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes
Prometaphase
- Second stage of mitosis
- Nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes
Metaphase
- Third stage of mitosis
- Spindle is complete and the chromosomes, attached to microtubules at their kinetochore, are all aligned at the metaphase plate
Anaphase
- Fourth stage of mitosis
- Chromatids of each chromosome have separated
- Daughter chromosomes are moving to the poles of the cell
Telophase
- FIfth and final stage of mitosis
- Daughter nuclei are forming and cytokinesis has typically begun
Mitotic Spindle
- Assemblage of microtubules and associated proteins
- Involved in the movements of chromosomes during mitosis
Centrosome
- Structure present in the cytoplasm of animal cells
- Functions as a microtubule-organizing center
- Important during cell division
- Has two centrioles
Aster
- Radial array of short microtubules
- Extends from each chromosome toward the plasma membrane in an animal cell undergoing mitosis
Kinetochore
Structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle
Metaphase Plate
Imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located
Cleavage
Process of cytokinesis in animal cells characterized by pinching of the membrane
Cleavage Furrow
- First sign of cleavage in an animal cell
- Shallow groove in the cell surface near the old metaphase plate
Cell Plate
Membrane-bounded, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis
Binary Fission
- Method of asexual reproduction by “division in half”
- In prokaryotes, it doesn’t involve mitosis
- In single-celled eukaryotes, mitosis is part of the process
Origin of Replication
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides
Cell Cycle Control System
Cyclically operating set of molecules in a eukaryotic cell that both triggers and coordinates key events in the cell cycle
Checkpoint
Control point in the cell cycle where stop and go-ahead signals can regulate the cycle
Cyclin
- Cellular protein that occurs in a cyclically fluctuating concentration
- Plays an important role in regulating the cell cycle
Cyclin-Dependent Kinase (CDK)
Protein kinase that is active only when attached to a particular cyclin
MPF
- Maturation-promoting factor (M-phase-promoting factor)
- Protein complex require for a cell to progress from late interphase to mitosis
- Active form consists of cyclin and a protein kinase
G0 Phase
Nondividing state occupied by cells that have left the cell cycle, sometimes reversibly
Growth Factor
- Protein that must be present in the extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells
- Local regulator that acts on nearby cells to stimulate cell proliferation and differentiation
Density-Dependent Inhibition
Phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another
Anchorage Dependence
Requirement that a cell must be attached to a substratum in order to initiate cell division
Transformation
Conversion of a normal cell into a cell that is able to divide indefinitely in a culture, thus behaving like a cancer cell
Benign Tumor
Mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor’s origin
Malignant Tumor
- Cancerous tumor that has significant genetic and cellular changes
- Capable of invading and surviving in new sites
- Can impair the functions of one or more organs
Metastasis
Development of secondary malignant growths at a distance from a primary site of cancer
