Early Fetal Development:
Meiosis produces gametes/sex cells with just one member of each chromosome pair
Fertilization results in union of female gamete (egg) and male gamete (sperm)
Subsequent embryonic fetal and embryonic development by mitosis and differentation of cell types produces new individual
Meiosis- two nuclear divisions occur to make 4 haploid cells, results in gametes, has 8 phases 4 in each meiosis 1 and 2
DNA and Chromosomes:
*long DNA molecules in nucleus are called chromosomes
*each chromosome is organized, packaged or wrapped up with proteins giving it a certain shape
*total view of all 23 pairs is karyotype
Mitosis:
Why do cells divide?
*Growth so tissues and structures can become larger
*Replacement so tissues can be replaced because the are worn out (blood, skin)
*Repair tissues get damaged due to injury
Prophase- chromosomes condense and become visible, nuclear envelope fragments, nucleolus dissapears, centrosomes move to opposite poles, spindle fibers appear and attach to centromere
Metaphase- chromosomes line up at the middle of cell fully formed spindle
Anaphase- sister chromatids seperate at centromere and move towards poles
Telophase and cytokinesis- chromosomes arrive at ploles become indistict chromatic again, nucleoli reappears, spindle dissapears, nuclear envelope reassembles, 2 daughter cells are formed by a ring of actin filaments
Gene expression- DNA transcribed to to mRNA , mRNA translated to amino acid sequence, amino acid folds up into protein, protein catalyze reaction of cell metabolism
Transcription- DNA is read to make mRNA in nucleus of cell, in nucleus double DNA double helix opens up, mRNA transcript is made from DNA template
Translation- Reading mRNA to make a protein in the cytoplasm, outside the nucleus ribosomes do the translation, line up amino acids according to mRNA sequence
RNA/protein translation code- every 3 RNA bases code for 1 amino acid, code is evolutionary conservitive ( works almost the same in all forms of life)
Regulation of Gene Expression
transcription control, post transcription control, translational control, post translational control
*when regulation of gene expression goes wrong result is cancer
Charecteristics of cancer cells:
lack differentation and dont contribute to body functions, abnormal nuclei that are enlarged and may have abnormal # of chromosomes, unlimited ability to divide, form tumors, can divide without growth factors, become abnormal gradually through a multistage process, undergo angiogenesis and metastasis
3 phases in the development of cancer cells"
initiation- a single cell undergos a mutation that causes it to divide repeatidly
promotion- a tumor develops and cells within the tumor mutate
progression- a cell mutates in such a way thath allows it to invade surrounding tissue
The genetic basis for cancer:
proto-oncogenes-products promote the cell cycle and prevent cell death (apoptosis)
tumor- suppressor genes- products inhibit the cell cycle and promote apoptosis
mutation- in the genes above can cause cancer
Types of Cancer
*onocology- study of cancer
*carcinomas- cancers of the epithelial tissue
*adenocarcinomas- cancers of glandular epithelial tissue
*sarcomas- cancer of muscle and connective tissue
*leukimias- cancers of blood
*lymphoma- cancers of lymphatic tussues
Causes of Cancer
*genetics
*enviroment carcinogens
*radiation, tobacco smoke, pollutants, viruses
BRCA 1 and BRCA genes associated with breast cancer
RB genes associtiated with eye tumor
RET genes associated with thyroid cancer to your right is a picture of a cell with thyroid cancer
7 warning signs to cancer
C- change in bowel movement or bladder habits
A- a sore that does not heal
U- unusual bleeding or discharge
T- thickening or lump in breast or elsewhere
I- indegestion or difficulty swallowing
O- obvious change in wart or mole
N- nagging cough or horseness
Recombinant DNA- contains DNA from 2 or more differen sources, allows genes to be cloned
Gene cloning happens as the plasmid replicates on its own. Scientists clone genes to see differences in a mutated gene and normal gene, and to genetically modify organisms in a beneficial way
Gene cloning is very benificial in the health field. Scientist are able to find medicines that are just right for one individual eliminating side effects. Also through gene cloning we might be able to cure children before they are even born of genetic disorders by inserting a normal gene into the egg that has a mutant gene. How cool is that!
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