ap biology adapted from: kim foglia chapter 13:the cell cycle
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AP BiologyAdapted from: Kim Foglia
Chapter 13:The Cell Cycle
AP Biology
How did you get from there
to here?
And now look at you…
AP Biology
Getting from there to here… Cell division
continuity of life = reproduction of cells reproduction
unicellular organisms
growth repair & renew
Cell cycle life of a cell from
origin to division into 2 new daughter cells
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A bit about DNA DNA is organized in
chromosomes double helix DNA molecule associated proteins =
histone proteins Nucleosome = a segment of
DNA wrapped around 8 histone proteins
DNA-protein complex =chromatin organized into long
thin fiber
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Chromosome Duplicated
chromosome consists of 2 sister chromatids meet at the
centromere contain identical
copies of the chromosome’s DNA
Telomeres = repeated sequence at end of each arm
p= short arm; q= long arm
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Prokaryotic Chromosome Structure
Bacteria have a one single loop of DNA
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Types of Cells & Ploidy Levels There are two types of human cells: somatic
cells and gametes. Somatic Cells = body cells (brain, muscle, heart,
liver, skin, etc) Contain 46 chromosomes in humans Diploid (2n)= cell that contains two sets of homologous
chromosomes 23 PAIRS of homologous chromosomes = 46 TOTAL
chromosomes
Gametes = sex cells (sperm or egg) Contain 23 chromosomes in humans Haploid (n)= cell that contains one set of chromosomes
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FertilizationWhen sperm meets egg a zygote is formed. A zygote is the first cell of the embryo.
Which of the cells above are haploid (n)? Diploid (2n)?
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Homologous Chromosomes
Chromosomes containing the same type of genetic information
one comes from male parent, one comes from female parent
DAD MOM
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Homologous Chromosomes
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The chromosomes diagrammed below are arranged in a karyotype, the 46 chromosomes have been arranged in homologous pairs.
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The first 22 pairs of homologous chromosomes are called autosomes or autosomal chromosomes.
The 23rd pair of chromosomes determines the sex of the individual and are called sex chromosomes.
The sex chromosomes of a female are XX.The sex chromosomes of a male are XY.
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What’s the difference?
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Cell cycle Cell has a “life cycle”
cell is formed from a mitotic division
cell grows & maturesto divide again
cell grows & matures to never divide again
G1, S, G2, M G0
epithelial cells,blood cells,stem cells
brain nerve cells
liver cells
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Cell Division cycle Phases of a dividing
cell’s life interphase
cell grows replicates chromosomes produces new organelles & biomolecules
mitotic phase cell separates & divides chromosomes
mitosis cell divides cytoplasm & organelles
cytokinesis
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Control of Cell Cycle
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Interphase 90% of cell life cycle
cell doing its “everyday job” produce RNA, synthesize proteins
prepares for duplication if triggered
Characteristics nucleus well-defined DNA loosely
packed in long chromatin fibers
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Interphase Divided into 3 phases:
G1 = 1st Gap S = DNA Synthesis G2 = 2nd Gap
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Interphase
G1 – First stage after division Cell recovers from previous division Cell increases in size Doubles organelles Accumulates materials for DNA replication Cells do everyday jobs
G0 – Some cells don’t complete the cycle (nerve and heart muscle) Continue normal cell operations No preparation for cell division Cells will operate in this stage until organism
dies
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Interphase
S Stage – DNA synthesis occurs At the beginning it contains chromosomes containing
one DNA strand At the end each chromosome contains two identical
strands of DNA Copies chromosomes
G2 – Growth & final preparations for division Prepares for division Ends with mitosis Proteins that aid in mitosis are made in this stage
Microtubules Nucleus well-defined DNA loosely packed
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Interphase Nucleus well-defined
chromosome duplication complete
DNA loosely packed in long chromatin fibers
Prepares for mitosis produces proteins &
organelles
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Mitosis copying cell’s DNA & dividing it
between 2 daughter nuclei Mitosis – division of the nucleus
is divided into 5 phases Prophase Prometaphase metaphase anaphase telophase
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Overview
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Prophase Chromatin (DNA) condenses
visible as chromosomes chromatids
fibers extend from the centromeres
Centrioles move to opposite poles of cell
Fibers (microtubules) cross cell to form mitotic spindle actin, myosin
Nucleolus disappears Nuclear membrane breaks down
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Prometaphase Proteins attach to
centromeres creating kinetochores
Microtubules attach at kinetochores connect centromeres to
centrioles
Chromosomes begin moving
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Kinetochore Each chromatid
has own kinetochore proteins microtubules
attach to kinetochore proteins
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Metaphase Spindle fibers align
chromosomes along the middle of cell meta = middle metaphase plate helps to ensure
chromosomes separate properly so each new nucleus
receives only 1 copy of each chromosome
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Anaphase Sister chromatids
separate at kinetochores move to opposite poles pulled at centromeres pulled by motor proteins
“walking”along microtubules increased production of
ATP by mitochondria
Poles move farther apart polar microtubules
lengthen
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Separation of chromatids In anaphase, proteins holding together
sister chromatids are inactivated separate to become individual
chromosomes
2 chromosomes1 chromosome2 chromatids
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Kinetochores use motor proteins that “walk” chromosome along attached microtubule microtubule
shortens by dismantling at kinetochore (chromosome) end
Chromosome movement
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Telophase Chromosomes arrive at
opposite poles daughter nuclei form nucleoli from chromosomes disperse
no longer visible under light microscope
Spindle fibers disperse Cytokinesis begins
cell division
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Cytokinesis Animals
cleavage furrow forms ring of actin
microfilaments forms around equator of cell myosin proteins
tightens to form a cleavage furrow, which splits the cell in two like tightening a draw
string
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Cytokinesis in Animals
(play Cells Alive movie here)
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Mitosis in whitefish blastula
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Mitosis in animal cells
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Cytokinesis in Plants Plants
vesicles move to equator line up & fuse to form 2 membranes = cell plate derived from Golgi
new cell wall is laid down between membranes new cell wall fuses
with existing cell wall
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Cytokinesis in plant cell
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Mitosis in plant cell
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onion root tip
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