Cell Division Flashcards
Chromosomes
Packages of DNA that hold many genes
Chromatin
Complexes of DNA and protein that make up chromosomes
Somatic cells
Cells of the human body: contain 46 chromosomes
Gamete cells
Sperm/egg cells in the body; contain 23 chromosomes
Sister chromatid
One of a pair of chromatids in a duplicated chromosome
Centromere
Place where sister chromatids join, exhibits slight pinching
Mitosis
Division of genetic material within the nucleus
Cell cycle phases (excluding mitosis)
G1 phase: cell grows
S phase: DNA copies
G2 phase: cell grows more
Centrosomes
Regions in the cell that organize spindle microtubules
Prophase
Spindle fibers grow; chromosomes condense; centrosomes drift apart
Prometaphase
Microtubules drift around; some attach to kinetochores
Kinetochore
A special protein structure on the chromosome’s centromere
Metaphase
Chromosomes align at the metaphase plate
Anaphase
Sister chromatids separate, cell elongates
Telophase
Daughter nuclei form, chromosomes de-condense
Aster
Radial array of short microtubules that attaches to plasma membrane later in mitosis
Role of kinetochore microtubules
Pull sister chromatids apart
Role of non-kinetochore microtubules
Elongate the cell
Cleavage furrow
A contractile ring of proteins that pinches the cell into two daughters
Cell plate
A partly-formed barrier between two dividing plant cells
Binary fission
Process of asexual reproduction in bacteria
Origin of replication
Point on a bacterial chromosome where DNA begins replicating
Cell cycle control system
A cycle of molecules in the cell that coordinates key events in the cell cycle
Checkpoint
A stop-and-go point in the cell cycle to check whether the necessary prep for the next stage is complete
Cyclin-dependent kinases (Cdk)
Kinases that activate only when bound to cyclin
Cyclin
A protein in the cell that fluctuates its concentration
MPF
A cyclin-Cdk complex that triggers cell passage into M phase
G0 phase
A non-dividing phase, which is reached if the G1 checkpoint is not passed for a long time
PDGF
Growth factor from platelets
Growth factor
A protein released by some cells to stimulate others into dividing
Density-dependent inhibition
A halt to cell division among overcrowded cells
Anchorage dependence
A requirement of a substrate for cells to divide
HeLa cells
Cancer cells from Henrietta Lacks; have continued reproducing since 1951
Benign tumor
Mass of cancer cells that remains at the original site
Malignant tumor
Mass of cancer cells that can spread to new tissues
Metastatis
Spread of cancer cells to other sites
Asexual reproduction
Creation of clone offspring from a single parent
Sexual reproduction
Creation of unique offspring from two parents
Karyotype
Visual depiction of an organism’s chromosomes
X and Y chromosomes
Sex chromosomes; XX is female, XY is male
Autosomes
Non-sex chromosomes
Diploid cell
Has two sets of chromosomes (somatic cells)
Haploid cell
Has one set of chromosomes (gamete cells)
Zygote
A fertilized egg; union of gametes
Meiosis
Cell division for gametes; reduces cells from diploid to haploid
Sporophyte
A multicellular diploid stage in plants; meiosis of the sporophyte makes spores
Gametophyte
A multicellular haploid stage in plants; mitosis of the gametophyte makes gametes
Meiosis I
Splits a diploid parent with duplicated chromosomes into two haploid offspring with duplicated chromosomes
Crossing over
The sealing of DNA breaks by bonding homologous chromosomes to each other
Chiasmata
Regions where crossing over has occurred
Synapsis
The process of binding DNA from homologous chromosomes to each other, causing crossing over
Meiosis II
From two haploid cells with duplicated chromosomes, makes four haploid cells with unduplicated chromosomes and unique gene combos; essentially identical to mitosis
