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80 Cards in this Set
- Front
- Back
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Roles of Mitosis in Multicellular Organisms
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-growth
-cell replacement : tissue renewal |
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Roles of Mitosis in Unicellular Organisms
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-asexual reproduction (binary fission)
-reproduction of some protists and yeast |
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Binary Fission
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the process whereby bacteria copy their chromosomes and then divide into two different cells
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Somatic cells vs. Gametes
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-stretched out, the DNA from one human somatic (body) cell would be more than two meters long
-human somatic cells each contain 46 chromosomes in the nucleus -gametes ( reproductive cells) contain 23 chromosomes |
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chromosome
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a condensed single strand of DNA along with its associated structural proteins
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Cell division vs. mitosis
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-cell division includes entire division of cell : mitosis and cytokinesis
-mitosis is only prophase, metaphase, anaphase, telephase NOT cytokinesis |
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Organization of Chromosome
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-chromatin :: long and thin strands of DNA (uncoiled) ; difficult to divide
-chromosomes :: DNA only coils into chromosomes when cell division is about to take place -chromatid :: chromsomes that are attached with their replica by the centromere |
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Organization of Chromosome 2
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-nucleotide
-DNA -DNA wraps twice around a group of histone proteins to coil -DNA condenses further into chromosome |
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histone complex
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group of 8 histone proteins
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genome
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all of the genes possible in an organism
-humans have 22 somatic chromosome that code for genes plus 2 sex chromosome (XX or XY) |
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chromatin
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the relaxed form of DNA during non-dividing stages of the cell cycle
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centromere
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region of DNA where the chromatids are closely attached
-in the beginning, chromatids are attached everywhere with cohesons but the enzyme separase separates the chromatids everywhere but at the centromere |
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sister chromatid
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a replica of a chromosome
-term is typically used while the chromosomes are attached |
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homologous chromosomes
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chromosomes that code for the same thing
-ex. mom and dad each give a copy of their chromosomes :: the chromosomes that code for the same traits pair up and are called homologous chromosomes |
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maternal
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mother
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paternal
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father
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karyotype
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22 pairs of autosomes and 1 pair of sex chromosomes that makes up a human genome
-karyotype includes homologoues chromosomes from mom and dad (total of 92 chromatids :: each chromosome from mom and dad are replicated :: 23 replicated chromosomes from mom and 23 replicated chromosomes from dad) |
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The cell cycle
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Interphase
Mitosis Cytokinesis |
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Interphase
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Cell is growing and chromosomes are replicated
-made up of several phases G1 S G2 |
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G1 phase
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"1st gap"
cell grows |
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S phase
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-cell continues to grow
-chromosomes replicate as well as other organelles, and proteins |
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G2
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cell grows even more as it prepares to go through mitosis
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M phase
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cell divides
-includes mitosis and cytokinesis |
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Stages of Mitosis
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Prophase
Prometaphase Metaphase Anaphase Telephase |
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Chromosome Walking
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In Anaphase, the chromosomes move to opposite poles of the cell
-kinetochore proteins at the centromere depolymerize the microtubule attached to the chromosome into tubulin -as the microtubles shorten, the chromosomes move closer to the spindle poles -tublin attaches to nonkinetochore microtubules at the centrosomes to elongate the cell for cytokinesis |
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Cytokinesis in Animals
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occurs through cleavage
-cleavage furrow is the 1st sign of cleavage ~begins as a shallow groove in the surface of cell near th old metaphase plate -in the cytoplasm, a ring of actin filiments form along with myosin proteins ~the actin filaments contract and pull like a drawstring until until cell is "pinched" in two |
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Cytokinesis in Plants
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-no cleavage furrow
During telephase, vescicles from the golgi form and gather in the middle of the cell -they form a cell plate when they combine -cell wall materials are carried into vescicles and they collect in cell plate as it grows -cell plate enlarges until its surrounding membrane fuses with the cells plasma membrane -a new cell wall has emerged from the contents of the cell plate |
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Regulation of the Cell Cycle
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nutrients
temperature pH growth factors (like hormones) density and anchorage dependence length *cancer involves a los of control over the cell cycle |
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PDGF
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Platelet derived growth factor
-increase the WBC and platelet formation when you have an open wound |
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Checkpoints
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*assist with regulation of cell cycle
G1 checkpoints -Go -Restriction G1 check point : growth point after which the cell is committed to cell division G2 checkpoints : check point that commits to mitosis M checkpoint : ensures chromosome attachment prior to anaphase ; moving past it allows cytokinesis |
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Go (G not) Checkpoint
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state of arrest for cells :: during most of your life, most of cells are in this phase :: some cells, like nerve, stomach, and fat cells are permanently in this phase once they've reached maturity
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cyclin dependent kinase
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kinase protein requires the prescense of cyclin to activate
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cyclin
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concentration of it flucuates in the cell curing cell cycle
-when cyclin levels rise, kinase levels rise |
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kinase
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a MPF : mitosis promoting factor
-when it attaches to cyclin, it pushes cell towards going through cell division EX. of cell regulation |
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cancerous cells
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-escaped cell cycle controls
-divide excessively and invade other tissue -do not exibit density-dependent or anchorage dependent inhibition |
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tumor
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a mass of abnormal cells
-benign -malignant |
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benign
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remains at the site of tumor
-does not spread to other tissue |
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malignant
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invasive, cancerous
-moves through tissues |
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totipotent
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stem cells that can become anything
~4 days of totipotent stem cells |
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pluripotent
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can still become anything bit cannot become any organism
-lost the ability to fice rise to the nourishing cells for the embryo |
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multipotent
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can make more than one type of tissue but not all
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adult
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specific type of tissue
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Where does mitosis occur?
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in normal body cells or “somatic” cells – diploid cell (2n)
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Where does meiosis occur?
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in germ cells or sex cell production – haploid cell (1n)
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Sexual vs. Asexual
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-Sexual reproduction requires meiosis to produce gametes.
-Asexual reproduction only requires mitosis. (no sex cells involved) |
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Sexual Reproduction
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-Chromosomes are duplicated in germ cells (diploid - 2n cells located in ovaries & testes)
-Germ cells undergo meiosis and cytoplasmic division to produce haploid (1n) cells -Cellular descendents of germ cells become gametes -Gametes (1n)meet at fertilization to produce zygotes (2n) |
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Sexual Reproduction
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Involves:
-Meiosis -Gamete production -Fertilization Produces genetic variation among offspring |
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Asexual Reproduction
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-Single parent produces offspring
-All offspring are genetically identical to one another and to parent |
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Sexual Reproduction Shuffles Alleles
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-Through sexual reproduction, offspring inherit new combinations of alleles, which leads to variations in traits
-This variation in traits is the basis for evolutionary change |
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Chromosome Number
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Sum total of chromosomes in a cell
-Germ cells are diploid (2n) -Gametes are haploid (n) Meiosis halves chromosome number -Sum total of chromosomes in a cell Somatic cells -Chromosome number is diploid (2n) -Two of each type of chromosome Gametes -Chromosome number is haploid (n) -One of each chromosome type |
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Haploid
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(1n) cells have a single copy of each chromosome
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Diploid
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(2n) cells have two copies of each type of chromosome
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Human Chromosome Number
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-Diploid chromosome number (2n) = 46
-Two sets of 23 chromosomes each One set from father One set from mother -Mitosis produces cells with 46 chromosomes --two of each type -Meiosis produces cells with 23 chromosomes – one of each type |
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Homologous Chromosomes
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-Carry Different Alleles
-Cell has two of each chromosome -One chromosome in each pair comes from mother, other from father -Paternal and maternal chromosomes carry different alleles |
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Tetrad
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Replicated homologous chromosomes physically pair together & located near one another in preparation for meiosis.
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Meiosis: Gametes Formation
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Gametes are sex cells (sperm, eggs)
Arise from germ cells |
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ALTERNATION OF GENERATION
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Plants & some algae: Diploid stage called sporophyte produces haploid spores called gametophyte stage
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Meiosis
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-Two consecutive nuclear divisions
Meiosis I Meiosis II -DNA is NOT duplicated between divisions -Four haploid nuclei are formed |
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Crossing Over
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-Each chromosome becomes zippered to its homologue
-All four chromatids are closely aligned -Non-sister chromosomes exchange segments |
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Effect of Crossing Over
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After crossing over, each chromosome contains both maternal and parental segments
Creates new allele combinations in offspring |
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Principal of Independent Assortment
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The tetrads will line up at the equator independently of each other (in terms of maternal and paternal chromosomes)
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Factors Contributing to Variation Among Offspring
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-Random alignment of chromosomes at metaphase I (Independent Assortment – 8 million different combinations of chromosomes
-Crossing over during prophase I -Random combination of gametes at fertilization |
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Random fertilization
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Any of the telophase II combinations can be selected to form the child.
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Prophase vs. Prophase I
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Prophase (Mitosis)
-Homologous pairs do not interact with each other Prophase I (Meiosis) -Homologous pairs become zippered together and crossing over occurs |
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Advantages of asexual reproduction
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makes more, more quickly
-if organism can survive, then this helps populate :: perpetuation of successful combo of genes/alleles less energy is required |
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Disadvantages of asexual reproduction
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-fewer offspring
-no genetic variation :: all cells die if exsposed to an environment not conductive to their survival |
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2 Types of Sister Chromatid Cohesions
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-between homologous = chiasmata - separates in AI
-between chromatids = centromere - separates in AII |
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chiasmata
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where hologous chromosomes cross over
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Law of Segregation
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2 alleles for a trait, one on each chromosome, separate during gamete formation adn end up in fifferent gametes
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metastasis
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when cancer cells have spread to other parts of the body
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carcinogens
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substances that cause cancer
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symptoms of cancer
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fatigue, unexplained weight loss, night sweats, cough, blood found in vomit, urine feces, persistent pain, sores in mouth, painless sores, and growths on the skin
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causes of cancer
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genetic mutations, exposure to carcinogens, overexposure to radiation, and toxic substances
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Diagnosis of cancer
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biopsy, MRI, CT scan, Xray
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biopsy
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removal of part of a tumor which is then studied for signs of cancer in a lab
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MRI
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the use of magnets and radiation to view the structure and function of organs and detect abnormalitiees
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CT scan
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cross section views using small amounts of radiation to view particular organd to detect abnormalities
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X-ray
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picture of hard tissues of the body using low doses of radiation to see if abnormalities exist
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radiation therapy
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uses x-rays, gamma rays, or other rays directed at the tumor in high doses to shrink the tumor for surgery
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chemotherapy
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use of drugs to kill cancer cells
-more useful when the cells have spread to other tissues |
