uncoiled or free chromatin (Telophase through G2)
chromatin coils up to form "X" shape (Prophase)
1. Chromatin start to condense and foil.
2. Nuclear membrane dissolves. ATP energizes proteins in nuclear envelope to vibrate so it shatters and liquifies.
3. Centroles start to migrate towards opposite poles of cell. Grow mitotic spindle.
TRANSITIONARY PERIOD. Fibers and tubules of spindle attach to proteins at centromeres. Spindle pulls chromosomes toward equatorial plate at center.
MOMENT IN TIME. All chromosomes are aligned in equator of cell.
1. Spindles attached to centromeres pull in opposite directions, pulling the chromosome part, 1/2 DNA to each pole.
Chromosomes uncoil. Nuclear envelope reforms. See remnants of mitotic spindle which pull sides of cell membrane towards each other which creates cleavage furrow.
SEPARATION. Eventually, 2 sides touch and separate. Each enter G1 of the cell cycle and repeat.
Primary growth stage. Getting closer to adult size. Cellular contents are being duplicated.
Occurs after G1. The cell is receptive to chemical stimuli (hormones), and must decide if it will differentiate (take on identity and specialize) or go through cell cycle for a generic cell.
Differentiating cells enter this. Is a resting stage in respect to reproduction.
Synthesis (S Phase)
The cell copies DNA, doubling the amount. Checkpoint afterwards.
The cell gets ready to divide, and double checks the duplicated chromosomes for error, making any needed repairs. Checkpoint afterwards.
Mitosis (M Phase)
Nuclear division. Divide chromosomes, divide cytoplasm, and ultimately makes 2 cells (cytokinesis). Both cells enter G1.
Nervous System Cells
Cannot enter the cell cycle again on their own.
Act as a spool; DNA winds around them and packs together to form nucleostomes. They then pack together to form chromosomes.
Bonds sister chromatids together.
A mass of proteins attached to the centromere that links the sister chromatid to the mitotic spindle.
The diploid form that results from two gametes coming together. Humans are sporophytes.
The haploid form that is produced from sporophytes. Sperm and ovum are gametophytes.
Alteration of Generations
A life cycle which has both haploid (gametophyte) and diploid (sporophyte) forms. In meiosis, cells divide to produce gametophytes, and in gamete production, haploid cells coming together to form a diploid cell.
Cells in the body not used for reproduction.
X and Y Chromosomes. Females are XX, Males are XY. Males give gender. Are the exception to homologous chromosomes which have the same size, shape, centromere position, and genes at same loci.
A single diploid cell with duplicated chromosomes divides to create 4 haploid cells with single chromosomes. Includes M1 and M2.
Homologues pair up and move together. Crossover occurs. Separation of homologues. Is the first division in meiosis; creates 2 cells.
Separation of sister chromatids; creates 4 haploid cells. All have the potential to become a gamete.
Meiosis 1 Stages
1. Prophase 1: Homologues condense and cross over
2. Metaphase 1: Homologues align at center
3. Anaphase 1: Homologues separate to opposite poles
4. Telophase 1: Separate into 2 cells, 23 chromosomes each
Crossing over, independent assortmant, random fertilization.
New, "shuffled" versions of our parents chromosomes; exchange of genetic material between nonsister chromatids. You only get ONE of them from each parental unit.
Homologues line up randomly on the metaphase plate in M1. This makes 8 million possible assortments of chromosomes inherited in every cell.
The unlimited number of possible sperm & egg combinations = 64 trillion possible chromosome combinations.
Meiosis 2 Stages
1. Prophase II: Spindle apparatus forms, chromosomes start to move towards center.
2. Metaphase II: Chromosomes are centered, and are not identical due to crossing over.
3. Anaphase II: The sister chromatids separate and are pulled toward opposite poles.
4. Telophase II: The chromomes begin to uncoil, cytokinesis occurs. 4 haploid cells are formed.
Disease of the cell cycle; massive cell division that is out of control.
A tumor, or solid lesion formed by abnormal cell division.
A tumor that cannot metastasize. They are harmless, but can produce negative health effects:
- Mass effect (compression of blood flow/organs)
- Functional effect (doesn't work as well)
- Pre-Malignant (only needs one more mutation to become malignant)
A condition which becomes progressively worse leading to death. 3 types:
- Anaplasia: reversion of differentiation
- Invasiveness: invades adjacent tissue
- Metastasis: leave site of origin to invade other organ systems
Type of cancer derived from epithelial cells (cells that line organs). Most common type.
Type of cancer derived from connective tissue, blood vessel, fat, muscle, bone, cartilage, etc.
A type of cancer derived from hematopoietic cells (blood forming cells).
Germ Cell Tumors
A type of cancer derived from totipotent cells (testicle/ovary). Mutated germ cells.
A type of cancer derived from tumors that assemble immature or embryonic tissues (most common in children). Failure of cells to migrate or differentiate.
Signs of Cancer
Local - Unusual lumps/swelling, hemorrhage, pain.
Metastasis - enlarged lymph nodes, enlarged liver, bone pain, neurological symptoms.
Systemic - Weight loss, poor appetite, fatigue, night sweats, anemia, etc.
Produce growth factors that tell cells to divide, causing development of cancer..
Tumor Suppressor Genes
Tell cells to stop dividing, causing development of cancer.
Causes of Cancer
Spontaneous mutation (70%, error in DNA replication)
Chemical carcinogens (tobacco)
Mutagens (radiation, UV - light)
Alcohol (high rate of cell division, less time for G2)
Infection - Viral infection responsible for 20% of cancer worldwide
Most cancers are not genetically linked. Those that do just already have one step to it, so already have a mutated form. For example:
- Breast cancer
- Ovarian cancer
- Endocrine Neoplasia
- Turcot Syndrome
- Lynch Syndrome
Diet - no red meat
Avoid Air pollution
1-3. How much the tumor resembles surrounding tissue.
1-4. How invasive and widespread the cancer is.
Removal of cancer through surgery.
Exposure to radiation to kill the tumor or reduce pain.
Drugs that prevent cell division. Prevent the mitotic spindle from working.
Uses the patients own immune system to fight the cancer by processing antigens from tumor cell.
The development of mature oocytes (eggs).Meiosis in females. Starts with oogonium which divides through mitosis. One remains oogonia, and the other grows and differentiates (primary oocytes)
Used to get rid of unused DNA. First one is product of M1 and deteriorates, second is product of M2 and deteriorates.
Diploid cell in follicles. Goes through M1 to create first polar body and secondary oocyte (haploid). Present at birth.
The product of M1 from primary oocyte. Is released after ruptured follicle. Undergoes M2 to create second polary body and ovum (haploid).
Are born with all the ones we need; are a ball of cells. Nourish and protect the oocyte. Matures and then ruptures to release secondary oocyte. Only end up using about 500 but have millions.
Steroid hormone - regulates gametogenesis directly and indirectly.
Luteinizing hormone - surge triggers ovulation. Stimulates follicle to grow.
Follicle-stimulating hormone - Initiates ovulatory cycle and follicular maturation.
Prepares endometrial lining for implantation of blastocyst. Is secreted by the corpus luteum.
Forms from the collapsed follicle after ovulation and produces progesterone.
Secrete a viscous solution prior to ejaculation which neutralizes any acidic urine remaining in the urethra (where urine and sperm come out).
The formation and development of sperm in males. The meiosis that occurs works its way from the outside to inside of tubule (lumen). Each spermatocyte gives rise to 4 spermatids=sperm cells.
Gives semen their volume and sugar fructose (which gives sperm it's energy).
Help sperm move through testes and protects sperm from immune system which tries to destroy it.
The outer layer is made from spermatagon. Job is to continuously undergo mitosis/create sperm.
Fluid-filled cavity of the tubule where sperm are released in the last step of meiosis.
Generate spermatocytes by mitosis.
Gives rise to four spermatids through meiotic cell divisions. There is primary and secondary, just like oogenesis.
Produce testosterone. Are present in the "triangle" between the seminifrous tubules in the testes.
Happens in the upper 1/3 of the oviduct, and only one sperm is successful. A chemical change happens in ovum so no other sperm can enter it; the female immune system will try to kill the sperm. If it's too hot, a deformed tail of sperm will cause it to swim in circles.
Inner Cell Mass
Once the egg is fertilized, the blastocyst will form and the inner mass of cells becomes the baby.
Arrive specifically from meiosis.
Can occur when homologues fail to separate in M1 or failiure to separate sister chromatids in M2. End up with too many or too few chromosomes in the 4 gametes.
Trisomy 21. Autosomal. Alters the child's phenotype either moderately or severely:
-characteristic facial features
-prone to Leukemia and Alzheimer's
-70% is because of age of mother
Trisomy 13. Generally don't live more than a few months. Serious eye, brain, and circulatory defects. Autosomal.
Trisomy 18. Generally don't live more than a few months. Almost every organ system affected. Autosomal.
Klinefelter Syndrom (XXY)
Male sex organs: unusually small testes, breast enlargment, and other feminine body characteristics. Can be treated with male sex hormones. Nondisjunction at chromatids. Sex Chromosome disorder.
Individuals are somewhat taller than normal and have below normal intelligence. Sex chromosome disorder.
Trisomy X (XXX)
Rare for a live birth. Healthy and fertile, usually cannot be distinguished from normal female except by karyotype (a display of the chromosomes). Sex chromosome disorder.
Turner's Syndrome (XO)
The only viable monosomy (diploid cell that has only one copy of a chromosome instead of two) in humans. Have 45 chromosomes. Are genetically female, but do not mature sexually. Normal intelligence and short stature. 98% of fetuses die before birth. Sex chromosome disorder.
Part of chromosome 7 is missing (deletion disorder, problems with crossing over). Elfin face, delayed development, cheerful and easy.
Part of chromosome 11 is missing (deletion disorder, problems with crossing over). Heart defects, skeletal defects, facial characteristics.
Part of chromosome 15 is missing (deletion disorder, problems with crossing over). Extreme insatiable appetite, morbidly obese, low muscle mass, slight mental retardation. Feel like they're starving to death no matter how much they eat.
Part of chromosome 5 is missiong (deletion disorder, problems with crossing over). Misshapen larynx, speech and motor skills, hyperactivity, aggresion, excessive drooling.