G1 phase
Normal function of cells and growth occurs
S Phase
Synthesis phase of the cell cycle where cell duplicates its DNA
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G1 phase
Normal function of cells and growth occurs
S Phase
Synthesis phase of the cell cycle where cell duplicates its DNA
G2 Phase
Second growth phase during the cell cycle where proteins are created for the mitosis process
Prophase:
DNA condenses into chromosomes and nucleus breaks down; spindle fibers also start to attach and centrioles double in animals
Metaphase:
Spindle fibers attach to centrosomes; sister chromatids are aligned at the equator
Anaphase:
Sister chromatids separate and spindle fibers shorten to pull the chromatids apart
Telophase:
DNA becomes chromatin and nucleus forms back; spindle fibers break down and centrioles become one per cell
Cell Cycle
Series of events from the time a cell forms until its cytoplasm divides
Steps:
Interphase
Prophase
Metaphase
Anaphase
Telophase and cytokinesis
Asexual reproduction
Reproductive mode of eukaryotes where offspring comes from a single parent only
Mitosis
Nuclear division mechanism that maintains the chromosome number
Cytokinesis
Division of the cytoplasm of the two new cells
Cleavage furrow
The indentation where cytokinesis occurs in a dividing animal cell
Cell plate
A disk-shaped structure that forms during cytokinesis in a plant cell; matures as a cross-wall between the two new nuclei
Centrioles
Barrel-shaped cell organelle that aids in cell division in animal cells only
Spindle Fibers
Temporary structures that move chromosomes during nuclear division; made of microtubules
Telomeres and their importance in DNA
Noncoding DNA sequences that occur in the end of eukaryotic chromosomes; protects the coding sequences from degradation.
They protect the DNA from being cut out during DNA replication (due to the way the lagging strands are formed) in mitosis
Tumor
Neoplasm that forms a lump of cancer cells
Cancer
Disease that occurs when a malignant neoplasm physically and metabolically disrupts body tissues.
Proto-oncogene
Genes that promote mitosis that can become oncogenes if mutated
Oncogene
Genes that helps transform a normal cell into a tumor cell
Checkpoint genes
Code for proteins that monitor mitosis and the condition of the cell during the cell cycle; they are also known as tumor-suppressors because in their absence, tumors form
Master genes
Gene encoding a product that affects the expression of many other genes
Homeotic Gene
Type of master gene; its expression controls formation of specific body parts during development.
Neoplasm
An accumulation of abnormally dividing cells
Carcinoma
Cancer that forms in the epithelial tissue that lines most of our bodies' organs
How do normal cells becomes cancerous cells?
They can become cancerous if carcinogens such as radiation, chemicals, viruses, or mutations infect the cells. Once the oncogenes are activated and the tumor-suppressor cells stop working, the cells uncontrollably divide and become cancerous.
Sexual reproduction
Reproductive mode by which offspring arise from two parents and inherit genes from both.
Gametes
Mature, haploid reproductive cell such as an egg or sperm
Meiosis
Nuclear division process that halves the chromosome number. Basis of sexual reproduction.
Haploid
having one of each type of chromosome (n)
Ex: gametes
Diploid
Containing two complete sets of chromosomes, one from each parent.
Ex: fertilized zygote, somatic cells
Crossing over
Process by which homologous chromosomes exchange corresponding segments of DNA during prophase I of meiosis; helps in genetic variation of gametes
Oogenesis
the production, growth, and maturation of an egg, or ovum
Spermatogenesis
the production of sperm cells
Autosomes
Any chromosome that is not a sex chromosome
Sex chromosomes
Chromosomes that determine the gender of an individual
Mitosis vs. Meiosis
Mitosis: one division forming 2 identical somatic cells;
Meiosis: two divisions forming 4 genetically different gametes
Formation of sperm vs egg
In sperm, the cytoplasm is equally distributed and all four sperm are viable for fertilization
In egg production, the cytoplasm is unequally distributed and only one egg is viable (the rest become reabsorbed polar bodies)
How does meiosis contribute to genetic variation?
Crossing over of sections of parent's homologous chromosomes in prophase 1 allow for varied and mixed chromosomes in gametes
Chromosome segregation (random stacking) of homologous chromosomes in metaphase 1 allows for gametes to have different combination of the mom and dad's chromosomes
Homologous Chromosomes
Chromosomes with the same length, shape, and genes
Zygote
Cell formed by fusion of two gametes at fertilization and is the first cell of the new individual
Germ cells
Reproductive cell that gives rise to haploid gametes when it divides
Somatic Cells
Any cells in the body other than reproductive cells
Prophase I
Metaphase I
Anaphase I
Homologous chromosomes are pulled to opposite ends of the cell.
Telophase I
-2 haploid daughter cells form and nucleus and nucleolus reforms
Prophase II
Haploid chromatin condenses into chromosomes and nucleus breaks down; spindle fibers also start to attach and centrioles double in animals
Metaphase II
Spindle fibers attach to centrosomes; sister chromatids are aligned at the equator
Anaphase II
Sister chromatids separate and spindle fibers shorten to pull the chromatids apart
Telophase II
DNA becomes chromatin and nucleus forms back; spindle fibers break down and centrioles become one per cell; Each of the two daughter cells create two new daughter cells (4 daughter cells total)