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Chapter 3
From a Cell to an Organism
Cell Cycle - Most cells in an organism go through
a cycle of growth, development, and
division.
Phases of the Cell Cycle
Interphase - part of the cell cycle that
includes
the cell’s growth and development
A cell spends most of the time in
Interphase
Interphase has 3 stages
1. rapid growth and replication of the organelles
2. copying of DNA
3. preparation for cell division
During interphase DNA of the cell is copied.
Sister chromatids - two identical chromosomes,
that make up a duplicated
chromosome
Centromere - the center structure that holds the
sister chromatids together
Mitotic Phase - cell reproduces during this stage
● mitosis - nucleus divides
● cytokinesis - cytoplasm divides
At the end of this stage, 2 new identical cells
called Daughter Cells
Phases of Mitosis
Prophase - DNA forms chromosomes
Metaphase - chromosomes line up
Anaphase - chromatids separate
Telophase - two nuclei form
Cytokinesis - last phase of mitosis
the cell’s cytoplasm divides
Results of Cell Division
Reproduction - cell division is a form of
reproduction in some unicellular organisms
Growth - organisms grow from one cell to
many
Replacement - organisms replace any cells that
wear out or are damaged.
Repair - Cell division is important for repairing
damage.
Lesson 2 Levels of Organization
Unicellular Organisms
Prokaryotes - organisms without a
membrane bound nucleus,
smaller than eukaryotic cells,
and fewer cell structures
Found at the bottom of the 7.800 ft. deep Homestake ‘gold Mine in S.D.
Deinococcus peraridilitoris in the soil of
Chili’s Atacoma Desert
Maybe extreme bacteria living under Europa’s ice
Stromatolites
Eukaryotes - specialized organelles
membrane bound nucleus
Multicellular Organisms
many eukaryotic cells working together
Cell Differentiation - the process by which cells
become different types of cells
Stem Cells - unspecialized cells that are able to
develop into many different cell types
Plants have unspecialized cells located in
meristems - tips of roots and stems
Tissues - groups of similar types of cells that
work together to carry out specific tasks.
Four main types of tissue in animal cells
1.
2.
3.
4.
Muscle - cause movement
Connective - provides structure, support
Nervous - carries messages to/from the brain
Epithelial - protective outer layer of skin, lining
of organs
Plants have 3 main types of tissues
1. Dermal - protection, reduces water loss
2. Vascular - transports water, nutrients
3. Ground - storage, support, location of
photosynthesis
Organs - groups of different tissues working
together to perform a particular job.
Plants also have organs
Organ Systems - groups of different organs that
work together to complete a series of tasks.
Plants have 2 major organ systems
1. Shoot system includes leaves, stems, &
flowers
Job - transports food and water
Plant organ system:
2. Root System which anchors the plant and
takes in food and nutrients
Cells - Tissues - Organs - Organ Systems Organisms
Organisms are made up of many organ systems
that work together.