Interphase
Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases
G1
In interphase - cell grows rapidly, builds new organelles; also performs regular cell functions
S
In interphase- The synthesis phase of the cell cycle; DNA is replicated
G2
In interphase- Final preparation phase. Cell checks for DNA errors and prepares for mitosis.
Cell Cycle
A series of events that cells go through as they grow and divide. Consists of interphase and mitosis.
M-Phase
The stage of the cell cycle where cell division happens, consisting of mitosis and cytokinesis.
Prophase
DNA inside the nucleus condenses and the chromosomes become visible.
Metaphase
Chromosomes line up in the middle of the cell.
Anaphase
The chromosomes separate and move apart to opposite ends of the cell.
Telophase
Chromosomes uncoil, a nuclear envelope returns around the chromatin, and a nucleolus becomes visible in each daughter cell.
Cytokinesis
Division of the cytoplasm to form two separate daughter cells.
Surface Area: Volume
A factor that limits cell size.
As the cell increases in volume the ratio of surface area to volume decreases. Cells need a high surface area to volume ratio in order to exchange nutrients and wastes well. This is why cells need to remain relatively small
DNA Replication
The process in which DNA makes a duplicate copy of itself. This happens in the S phase during interphase.
Helicase
An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.
Complementary Bases
Two bases that pair together. In DNA Adenine is complementary to Thymine and Cytosine is complementary to Guanine.
DNA polymerase
Enzyme that adds new nucleotides during DNA replication
Mutations
A change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity.
Nuclear Membrane
A membrane that envelopes the nucleus and separates it from the cytoplasm; present in eukaryotes.
Chromosomes
Condensed DNA that is coiled up around histone proteins. DNA condenses into chromosomes when it's getting ready to divide.
Chromatin
During interphase: Uncoiled DNA and protein that makes up chromosomes.
Centromere
Region of a chromosome where the two sister chromatids attach.
Sister Chromatids
Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.
Cancer
A disease in which some body cells grow and divide uncontrollably, damaging the parts of the body around them.
Benign
Harmless, not cancerous. A benign tumor lacks the ability to invade neighboring tissue or metastasize.
Malignant
Cancerous. Malignant tumors invade neighboring tissues or metastasize.
Metastasize
A cancer spreading to other sites in the body.
Carcinogens
Substances that cause cancer. Chemicals, radiation, and viruses are carcinogens.
Asexual Reproduction
Reproduction that does not involve the union of gametes and in which a single parent produces offspring that are genetically identical to the parent. Example: Mitosis.
Binary Fission
A method of asexual reproduction by "division in half." In prokaryotes, binary fission does not involve mitosis.
Differentiation
Process in which cells become specialized in structure and function. Stem cells change into red blood cells, nerve cells, or muscle cells, etc.
Zygote
A fertilized egg.
Adult (Somatic) Stem Cells
Undifferentiated cells found among differentiated cells in a tissue or organ. The role of the adult stem cells is to differentiate and maintain and repair the tissue where they are found.
Embryonic Stem Cells
Undifferentiated cells found in embryos. These cells can differentiate into different cells throughout the body such as muscle cells, white blood cells, bone cells, etc.
Somatic Cell
Any diploid body cell in a multicellular organism. (Not sperm or egg cell).
Gamete
A haploid sex cell such as an egg or sperm.
Autosomes
Any chromosome that is not a sex chromosome. In a cell there are 22 pairs of chromosomes that are autosomes.
Sex Chromosomes
In a cell there is one pair of chromosomes that are sex chromosomes. In females the sex chromosomes are two X chromosomes. In males the sex chromosomes are XY chromosomes.
Karyotype
A display of the chromosome pairs of a cell arranged by size and shape.
Homologous Chromosomes
Pair of chromosomes that are the same size, same appearance and same genes.
Diploid
2n; Cell having two sets of chromosomes or twice the haploid number. In humans the diploid number is 46.
Haploid
n; A cell having only one complete set of chromosomes. In humans the haploid number is 23.
Monosomy
Chromosomal abnormality consisting of the absence of one chromosome.
Trisomy
Chromosomal abnormality consisting of the presence of an extra chromosome.
Sexual Reproduction
Process by which two gametes fuse and offspring that are a genetic mixture of both parents are produced. Example: Meiosis.
Nondisjunction
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.
PMAT 1
The phases in Meiosis 1: Prophase 1, Metaphase 1, Anaphase 1, Telophase 1.
It is the first part of meiosis.
In meiosis 1, chromosomes in a diploid cell produce 2 daughter haploid cells.
PMAT 2
The phases in Meiosis 2: Prophase 2, Metaphase 2, Anaphase 2, Telophase 2.
It is the second part of meiosis.
In meiosis 2, chromosomes in each of the 2 haploid cells produce 2 more haploid cells, resulting in a total of 4 daughter haploid cells.
Crossing Over
The exchange of genetic material between homologous chromosomes during prophase I of meiosis.
Tetrad
A paired set of homologous chromosomes, each composed of two sister chromatids. Tetrads form during prophase I of meiosis.
Oogenesis
The production of eggs.
Egg
Female sex cell.
Spermatogenesis
The production of sperm cells.
Sperm
Male sex cell.
Polar Body
In oogenesis, a small cell, containing a nucleus but virtually no cytoplasm, produced by the first meiotic division of the primary oocyte.
Cell Cycle Checkpoints
3 major checkpoints that determine whether the cell has successfully completed a specific phase of the cell cycle.
Checkpoint 1: G1 to S
Checkpoint 2: G2 to mitosis
Checkpoint 3: Metaphase to anaphase