Date post: | 30-Dec-2015 |
Category: |
Documents |
Upload: | garey-bennett |
View: | 218 times |
Download: | 1 times |
Ch.12 Warm up 1. Define: genome, gametes, chromatin,
chromosome, centromere, kinetochore, checkpoint, Cdk, MPF
2. What is the longest part of the cell cycle? Why?
1. If the diploid number is 46, the haploid number is?
Ch. 12 Warm up 1. At the end of mitosis and cytokinesis, how
do daughter cells compare with their parent cell when it was in G1?
2. A cell’s DNA was measured at 5 picograms. DNA levels range from 3-6 pgms in the cell cycle . What stage of the cell cycle is this cell in. How do you know?
3. At metaphase, if the haploid number is 3, how many chromatids does this cell have?
Ch. 12 Warm upWhat is the correct phase of the cell cycle/mitosis for the following:A.Most cells that no longer divide or rarely divide are in this phaseB.Sister chromatids separate and move apartC.Mitotic spindle begins to formD.Cell plate or cleavage furrow formE.Chromosomes replicateF.Chromosomes line up on equatorial plateG.Nuclear membrane formsH.Chromosomes become visible
Ch. 12 Warm up 1. Describe the difference between plant
and animal cell division.2. Measurements of the DNA amount per
nucleus were taken. DNA levels ranged from 3-6 picograms per nucleus, what stage of the cell cycle are these cells in?a) One nucleus has 3 pgrmsb) One with 6 pgrmsc) 5 pgrms
3. Describe binary fission.
Ch. 12 Warm up1. How do we know the cell uses chemical
signals?
2. Summarize the cell control system.
3. Compare a cancer cell to a normal cell. What goes wrong?
What you must know: The structure of the duplicated
chromosome. The cell cycle and stages of mitosis. The role of kinases and cyclin in the
regulation of the cell cycle.
Cell Cycle: life of a cell from its formation until it divides
Functions of Cell Functions of Cell DivisionDivision: Reproduction, Growth and Tissue Repair
Cell Division
Process by which cell produces more of their kind Prokaryotes- binary fission Eukaryotes- mitosis and meiosis
Genome = all of a cell’s genetic info (DNA)
ProkaryoteProkaryote: single, circular chromosome EukaryoteEukaryote: more than one linear
chromosomesEg. Human:46 chromosomes, mouse:
40, fruit fly: 8
Chromatin Raw material that gives rise to chromosomes Long and thin during interphase Condenses and becomes visible under
microscope in mitosis
Each chromosome must be duplicated before cell division
Duplicated chromosome = 2 sister sister chromatids chromatids attached by a centromerecentromere
Categories of Cells
Somatic Cells Gametes
Body cells Diploid (2n): 2 of
each type of chromosome
Divide by mitosis Humans: 2n = 46
Sex cells (sperm/egg) Haploid (n): 1 of each
type of chromosome Divide by meiosis Humans: n = 23
Phases of the Cell Cycle The mitotic phase alternates with interphase:
G1 S G2 mitosis cytokinesis Interphase (90% of cell cycle)G1 Phase: cell grows and carries out normal functions
S Phase: duplicates chromosomesG2 Phase: prepares for cell division
M Phase (mitotic)Mitosis: nucleus divides resulting in identical complete copies of chromosomes packaged into two new nucleiCytokinesis: cytoplasm divides resulting in two daughter cells
Mitosis Continuous process with observable structural
features: Chromosomes become visible (prophase) Alignment at the equator (metaphase) Separation of sister chromatids (anaphase) Form two daughter cells (telophase &
cytokinesis)
Prophase & Prometaphase (Prepare)
• Nucleus and Nucleolus disappear
• Chromosomes appear as connected sister chromatids
• Mitotic spindle (made of microtubles) begins to form
• Centrosomes (pair centrioles) move to opposite ends of cell (plant cells do not have centrioles)
Metaphase & Anaphase(Middle) (Apart)
• Sister chromatids line up along the middle of the cell
• Ready to split
• Sister chromatids split move on microtubles to opposite poles in cell
• Spindle apparatus pulls sister chromatids to opposite poles
Telophase (Two new nuclei) & Cytokinesis Telophase Nuclei of newly split cells form Nucleoli appear Chromatin uncoils
Cytokinesis Cytoplasm of cell divided Animal Cells: cleavage furrow Plant Cells: cell plate forms
Results of Mitosis• Mitosis produces 2 daughter cells• The two daughter cells contain the exact same
number of chromosomes as the original parent cell• Daughter cells are DIPLOID
The Mitotic Spindle: A Closer Look The mitotic spindle is an apparatus of microtubules
that controls chromosome movement during mitosis Assembly of spindle microtubules begins in the
centrosome, the microtubule organizing center The centrosome replicates, forming two
centrosomes that migrate to opposite ends of the cell, as spindle microtubules grow out from them
• The spindle includes the centrosomes, the spindle microtubules, and the asters (a radial array of short microtubules)
• Some spindle microtubules attach to the kinetochores of chromosomes and move the chromosomes to the metaphase plate
During anaphase
Chromosomes walked to poles by motor proteins
Kinetochore microtubules shorten at ends as they depolymerize
Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell
Prokaryote (Bacteria & Archaea) Division
Simple single-celled organism without nucleus
Genetic material single circular chromosome of DNA, anchored
to cell membrane Duplicated before division
The Evolution of Mitosis
Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission
Certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis
Bacterialchromosome
Chromosomes
Microtubules
Prokaryotes
Dinoflagellates
Intact nuclearenvelope
Kinetochoremicrotubules
Kinetochoremicrotubules
Intact nuclearenvelope
Diatoms
Centrosome
Most eukaryotes
Fragments ofnuclear envelope
Major Checkpoints1.1. GG11 checkpoint checkpoint (Most important!)
Controlled by cell size, growth factors, environment “Go” completes whole cell cycle “Stop” cell enters nondividing state (G0 Phase)
Nerve, muscle cells stay at G0; liver cells called back from G0
2.2. GG22 checkpoint checkpoint Controlled by DNA replication completion, DNA Controlled by DNA replication completion, DNA
mutations, cell sizemutations, cell size
3.3. M-spindle (Metaphase) checkpointM-spindle (Metaphase) checkpoint Check spindle fiber (microtubule) attachment to
chromosomes at kinetochores (anchor sites)
M-spindle Checkpoint:Mitotic spindle at metaphase
Kinetochore = proteins associated with DNA at centromere
Kinetochore = proteins associated with DNA at centromere
Internal Regulatory Molecules
• Kinases (cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active when connected to cyclin
• Cyclins: proteins which attach to kinases to activate them; levels fluctuate in the cell cycle
Internal Regulatory Molecules
MPF = maturation-promoting factor• specific cyclin-Cdk complex which allows cells
to pass G2 and go to M phase
Growth Factor: proteins released by other cells to stimulate cell division
Example: For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture
Density-Dependent Inhibition: crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth
Anchorage Dependence: cells must be attached to another cell or ECM to divide
External Regulatory Factors
Cancer CellsCancer: disorder in which cells lose the ability to
control growth by not responding to regulation. multistep process of about 5-7 genetic changes
(for a human) for a cell to transform loses anchorage dependency and density-
dependency regulation Cancer Cells
Lack differentiation Have abnormal nuclei Form tumors Undergo metastasis
Normal Cells
Cancer Cells
Tumors = mass of abnormal cells Benign tumor: lump of cells remain at
original site Malignant tumor: invasive - impairs
functions of 1+ organs (called cancer) Metastasis: cells separate from tumor and
travel to other parts of body
Cancer Prevention
Anyone can get cancer but there are ways to minimize risk:
Don’t smoke, legal or illegal (includes hookahs, chew, 2nd-hand smoke)
Use sun protection Exercise and keep weight at ideal level Eat 5-7 servings of fruit and veggies a day Use screening/preventative
measures-breast/testicle/mole checks Practice abstinence or use condoms Vaccines (eg. HPV)
10. In humans, each cell (except sex cells) has how many chromosomes? ______11. After mitosis, how many daughter cells are produced? _______12. After mitosis (in a human cell), each daughter cell has how many chromosomes? _____13. How many phases are in MITOSIS? ___________14. Which phase of the cell cycle is the longest? _________
15. During which phase does cytokinesis begin? __________