the cell cycle - mcccblinderl/documents/thecellcyclech12_postpdf.pdf · have 1 set = haploid...
TRANSCRIPT
C H A P T E R 1 2
The Cell Cycle
The Key Roles of Cell Division
cell division = reproduction of cells
All cells come from pre-exisiting cells
Omnis cellula e cellula
Unicellular organisms division of 1 cell reproduces organism
Binary fission
Why cells reproduce Development/Growth
Replacement
Repair
Multicellular organisms
100 µm 200 µm 20 µm
(a) Reproduction (b) Growth and development
(c) Tissue renewal
Cellular Organization of Genetic Material
chromosome = strand of DNA
2 sets of 23 chromosomes in humans = 46
genome = All DNA in a cell
20 µm
chromatin complex of DNA and protein
Somatic cells= body cells (2 trillion in adult)
two sets of chromosomes (pairs= diploid)
Produced by mitosis - 1 diploid cell 2 identical diploid cells
Gametes sperm and eggs have 1 set = haploid
Produced by meiosis– 1 diploid cell 4 unique cells
Occurs only in ?
Gametes
Identical cells Unique cells
Diploid Haploid
Concept check
1. start with a fertilized egg 5 cell divisions produce how an embryo of ______ cells
2. a chicken has 78 chromosomes in a somatic cell. How many chromosomes in a chicken sperm?
Human Arabidposis
The cell cycle = time from new cell to when it divides
Interphase – 90% of time
Mitosis 4o min
S (DNA synthesis)
G1
G2
Cell Division
Mitosis = division of the nucleus
Cytokinesis = division of cytoplasm
INTERPHASE
G1 phase – cell grows, gets ready
S phase – DNA replicates
G2 phase – cell grows, gets ready
S (DNA synthesis)
G1
G2
If cycle is 24
hrs, how long
each phase?
Signs of interphase?
S phase of Interphase
Chromosomes (DNA) replicate
Sister chromatids = 2
Centromere = constricted region
0.5 µm Chromosomes
Chromosome duplication (including DNA synthesis)
Chromosome arm
Centromere
Sister chromatids
DNA molecules
Separation of sister chromatids
Centromere
Sister chromatids
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis by late telophase
MITOSIS video
Chromosomes condense
Mitotic spindle forms from centrioles
Nuclear membrane breaks apart
I. Prophase
The mitotic spindle (formation begins in prophase)
Prophase G2 of Interphase
Aster Centrosomes
Aster = radial array of microtubules
Prophase
II. Metaphase
chromosomes (sister chromatids) line up at the metaphase plate
midway between spindle’s two poles
Microtubules Chromosomes
Sister chromatids
Aster
Metaphase plate
Centrosome
Kineto- chores
Kinetochore microtubules
Overlapping nonkinetochore microtubules
Centrosome 1 µm
0.5 µm
Prophase Prometaphase G2 of Interphase
Prometaphase Prophase G2 of Interphase
Nonkinetochore microtubules
Fragments of nuclear envelope
Aster Centromere Early mitotic spindle
Chromatin (duplicated)
Centrosomes (with centriole pairs)
Nucleolus Nuclear envelope
Plasma membrane
Chromosome, consisting of two sister chromatids
Kinetochore Kinetochore microtubule
Metaphase Anaphase Telophase and Cytokinesis
Metaphase Anaphase Telophase and Cytokinesis
Cleavage
furrow
Nucleolus
forming
Metaphase
plate
Centrosome at
one spindle pole Spindle
Daughter
chromosomes Nuclear
envelope
forming
III. Anaphase
sister chromatids separate
microtubules shorten – depolymerize to move chromosomes toward opposite ends of cell
IV. Telophase
Identical nuclei form at opposite ends of cell
Chromosomes less condensed
Cytokinesis
Division of cytoplasm
animal cells cleavage furrow
plant cells cell plate
Text animation mitosis and cytokinesis
Bioflix animation
Animal mitosis time lapse
Cleavage furrow
100 µm
Daughter cells
(a) Cleavage of an animal cell (SEM)
Contractile ring of microfilaments
Daughter cells
(b) Cell plate formation in a plant cell (TEM)
Vesicles forming cell plate
Wall of parent cell
New cell wall Cell plate
1 µm
Nucleus
Prophase 1
Nucleolus
Chromatin
condensing
Prometaphase 2
Chromosomes
Metaphase 3
Anaphase 4
Telophase 5
Cell plate 10 µm
Text animation mitosis and
cytokinesis
Bioflix animation
Animal mitosis time lapse
S G1
M checkpoint
G2 M
Control system
G1 checkpoint
G2 checkpoint
Cancer cells lose control of the cell cycle
Lose contact inhibition
Lose anchorage dependence
Cells normally attached to a substrate in order to divide
Breast cancer cells dividing
Contact inhibtion
Anchorage dependance
Cancer cells
May not need growth factors
May make own growth factor
Transformed Immortal
Abnormal chromosomes
Cancer cells
necrotic
Mucus lake
Abnormal
nucleus
Lung cancer
Tumor mass of abnormal cells
Benign tumor – abnormal cells do not invade other tissues
Malignant tumors - invasive
can metastasize and form secondary tumors
Angiogenesis - tumor gets a blood supply
Metastasis – tumor spreads to other locations
Tumor
A tumor grows
from a single
cancer cell.
Glandular tissue
Lymph vessel
Blood vessel
Metastatic tumor
Cancer cell
Cancer cells
invade neigh-
boring tissue.
Cancer cells spread to other parts of the body.
Cancer cells may survive and
establish a new
tumor in another
part of the body.
1 2 3 4
Treatments
Radiation destroys fast growing cells (target site)
Chemotherapy
Excision