Bio 1011; Week 3 notes
Bio 1011; Week 3 notes 1011
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This 12 page Class Notes was uploaded by Addison Guskey on Tuesday January 12, 2016. The Class Notes belongs to 1011 at University of Denver taught by Robert Dores in Winter 2016. Since its upload, it has received 50 views. For similar materials see Evolution, Heredity, and Biodiversity in Biology at University of Denver.
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Date Created: 01/12/16
Descent with Modiﬁcation -cells will replicate themselves; the processes Mitosis WHY? [ Bacterial ] Steps: - replication Signal - Replicate the DNA - Segregate - e the two copies of DNA - Cytokinesis 1. Begin replication of DNA (ori); origin of replication How does a bacterial cell increase in size? - water; osmotic process. Concentration of water in the cell > environment 2. Segregate the copies of the DNA bw the emerging offspring cells 3. Cytokinesis offspring= identical to the parents (Eukaryotes) - DNA duplexes are called chromosomes (DNA/protein complex) - chromosome is also called chromatin (rod-shaped) - HOMOLOGOUS CHROMOSOME (humans) - humans have 23 set of homologous chromosome. one set from paternal the other from maternal Homologous chromosome s are: - 2 chromosomes that contain genes for the same traits > one pair maternal, the other paternal - Alleles are tow genes in a pair of HC that code for the same trait GENES/ CHROMOSOMES/ ALLELES - chromosomes contain the blueprint for a cell - your 46 chromosomes contain the blueprint for an entire organism - How is genetic info passed on from cell to cell within an organism? > Mitosis (all cells can do mitosis) - how is genetic info passed on from organism to organism within a species? > Meiosis (only cells that are meant to be gamete cells do meiosis) Feature of a cell prior to mitosis - chromosomes I'm the nucleus - centrosome and centrioles - events in the mitochondrion( when cells divide, equal amount of mitochondrion; duplicating mitochondria CELL CYCLE - major divisions: • Interphase • M Phase after cell devision, the cell enters interphase; - stages within interphase • G1; reaches restriction point: decision that a cell makes, once they cross the line, continuous towards mitosis(some cells never reach that point) • S; chromosomes are duplicated, each duplicate DNA is unwinding • Once chromosomes are duplicated, G2 - Chromosomes become condensed - centrosome splits, releasing two centrioles (: a microtubule organizing center) (BOARD PIC) Stages of Mitosis 1. Prophase 2. Pro metaphase 3. Metaphase (shortest stage in terms of time in mitosis) 4. Anaphase 5. Telophase Nuclear envelope dissolves; G2-Centrioles separate and Spindle apparatus forms move to opposite ends of prometaphase- begin the cell -duplicated chromosome, lines up in the middle; as soon as it happens, metaphase is over then to Anaphase -one copy being pulled to one side and the other copy to the other sides = chromatids separate and are pulled to the centrosomes when the reach the app sides of the cell, enters Telophase -nuclear envelope has reformed, beings the process of cytokinesis 2 sets of homologous chromosomes : diploid total # of chromosomes: 4 Note the two chromatids for each duplicated chromosome Nuclear env is gone, spindle apparatus is forming Cells that is dicing out of control : cancer cell What do cancer cells create? > a tumor benign- grow to a certain size and stops Cell that continuously secretes a protein : cancer cell Could a cell divide out of control and be secreting a protein out of control? > YES Observations - somatic cells perform mitosis - Precursor gamete cells perform mitosis(how they multiply) gametes? > specialized cells that are used in sexual reproduction In humans: the sperm cell and the ovum Mature gamete have one set of homologous chromosome How does a somatic cells differ from a mature gamete cell? - Ploidy (# of copies of homologous chromosomes Number of complete set of chromosome in a cell Haploid vs. Diploid 1N vs. 2N MEIOSIS I Interphase (2N) Prometaphase 1 - no nuclear env - spindle apparatus formed metaphase 1 (4N) duplicated large chromosome from paternal origin is facing the maternal: synapse DIFF than mitosis FUNDAMENTAL difference bw mitosis > have not made a mature gamete yet. cytokinesis 1 Two(2N) cells MEIOSIS II if this was human, there would be 23 in each one Spermatogenesis - made in testes, in third trimester spermatogonia- constantly replaced over the years - DNA duplication (spermatogonium to spermatocyte) - meiosis does not begin until puberty 2N - not viable gametes - bc need to go under second meiotic division Mature state Oogenesis in utero all oogonia move to ovulates at age 40, primary oocyte - 40, spindle apparatus - 40 primacy oocyte; stops at prometaphase in the fallopian tube moving to uterus 2N 2N Cross over during meiosis (@synapse) - synapse - crossover - real - re-anneal Non-Disjunction Mutations - chromosome 21 - down syndrome (extra chromosome) • XXX - sterile Female > not lethal, interferes with proper development of female reproductive system • XXY - Sterile Male (Klinefelter Syndrome • __Y - nonviable • X__ - sterile female (Turner Syndrome -> can grow to maturely, but problems with reproductive • XYY - fertile Male (Jacob Syndrome) Gregor Mendel - inheritance - gardening peas Genetics is the study of inheritance of biological traits pass on from generation to generation Observation: within a species offspring tend to resemble the parents Initial theory: > blending: gametes have heritable determinants that blend together in the offspring > particulate inheritance: each determinate had a physically distinct nature OBSERVATIONS: - some pea plants produce smooth round seeds - other peas plants have sprinkled round seeds (rough skin) - if blending is correct, then the seeds of the offspring should be a mic of patches of sooth areas and wrinkled areas > ﬁrst generation: all the seeds are smooth; no apparent blending > when he crosses F1, F2 > F2: 1/4 seeds are wrinkled (particulate theory determinants within organisms that are dominant, and determinants that are recessive. ; wrinkles: recessive MONOHybrid cross -the plants are diploid -there should be a trait of paternal origin and a trait of maternal origin -One that is dominant (smooth surface) -recessive ( wrinkled ) How were the genes for seed shaped sorted? - by the law of segregation look at gametes of the F1 generation 1) alternative versions of genes account for citations in inherited traits - alleles 2) For each character, an organism inherits 2 copies of a gene, one from each parent Mendel had to do a test cross to establish that he had • a homozygous dominant plant DIHYBRID CROSS Characters Traits - Seed shape: S- smooth, s- wrinkled - color: Y- yellow, y- green > alleles for seed colors were in a different homologous site - dealing with two sets of homologous chromosomes ( seed shape; pheno: smooth dominant, seed color; pheno: yellow dominant) - duplicate of paternal and maternal homologous chromosomes menders law of independent assortment - the side that chromosomes end up on is chance - 9: 3: 3: 1 9 - dominant 3 - dominant for surface, recessive color 3 - recessive for surface, dominant color 1 - recessive Sex-linked traits in humans - dominant and recessive alleles - the ability for blood to clot quickly is a dominant - the inability for blood to clot quickly is recessive (Hemophilia)
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