Download AG-PSB-02.441-04.3p Basic_Cell_Structure

Basic Cell Structure
Modified by Georgia Agricultural
Education Curriculum Office
June, 2002
August 2008
Cells
• Basic building blocks of life
• Understanding of cell
morphology is critical to the
study of biotechnology
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Cell
• Smallest living unit of an
organism
• Grow, reproduce, use
energy, adapt, respond to
their environment
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Cell
• Many cannot be seen with the
naked eye
• A cell may be an entire
organism or it may be one of
billions of cells that make up
the organism
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Cells
• Divided and classified in many
ways
• One common classification
method is the presence or
absence of a cell nucleus
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Nucleus
• Relatively large structure
within a cell
• Directs cell activities
• Some simple single-celled
organisms lack a nucleus
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Nucleus
• Prokaryotes – have no
nucleus
• Eukaryotes – have a
nucleus
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Prokaryotes
• Single celled organism
• Kingdom Monera
• Lacks a cell nucleus
• Internal structure is less
organized than other cells
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Prokaryotes
• Genetic info needed is
within the cell
• Two most common – blue
green bacteria and true
bacteria
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Blue green bacteria
• Have ability to produce their
own food like plants
• Most bacteria get their food
from other sources
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Prokaryotes
• Less complex than
eukaryotes
• Still have many of the basic
internal characteristics
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Common prokaryote
structures
• Cytoplasm
• Chromosomal material
• Cell membrane and wall
• Ribosomes
• Some have flagellum for
mobility
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Eukaryotes
• Organism made up of cells
that have a nucleus
• May be single celled –
Kingdom Protista
• May have billions of cells like
plant and animal kingdoms
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Eukaryotes
• Single celled eukaryotes
include paramecia, euglena,
and diatoms
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Eukaryotes
• Typically are highly
organized
• Infinite number of shapes
and purposes
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Eukaryotes
• Human body has at least 85
different cell types
• All eukaryotes have a
number of structures in
common
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Common structures
• Organelles – smaller parts
of the cell with specific
functions
• Cell membrane – acts as a
gatekeeper
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Cell membrane
• Controls what enters and
leaves the cell
• Plants, algae, and bacteria
typically have a tough outer
structure known as a cell wall
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Cell wall
• Provides additional structure
and protects the cell from
pressure caused by movement
of water
• Animal cells do not have walls
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Cytoplasm
• Organelles are surrounded by
a jelly-like substance
• Primary component is water
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Nucleus
• Largest and most identifiable
part of the cell
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Other organelles
• Ribosomes
• Mitochondria
• Golgi bodies
• Endoplasmic reticulum
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Other organelles
• Lysosomes
• Vacuoles
• Chloroplasts in plants
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Nucleus
• Brain of the cell
• Site of much of the
manipulation done in
biotechnology
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Nucleus
• Controls activity of the cell
• Round or oval structure
• Typically found in the middle of
the cell
• Appears darker than
surrounding material
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Nucleus
• Surrounded by a membrane
that controls passage of
materials in and out of the
area
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Nucleus
• Contains DNA
• DNA is located on
chromosomes
• Most organisms are diploid –
have tow chromosomes for
each trait
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Diploid
• Humans – 23 pair
• Goldfish – 90 chromosomes,
45 pair
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Cytoplasmic
Organelles
• Organelles are required for proper
cell function
• Ribosome – make proteins for
cellular use and communication
• May be attached to endoplasmic
reticulum
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Endoplasmic reticulum
• Layered membraneous
• Make and transport proteins
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Vacuole
• Large organelle, without
specific shape
• Store waste or raw materials
used in synthesis of proteins
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Golgi Bodies
• Golgi apparatus
• Similar to endo. Ret.
• Look like a thick elastic band
that has been folded several
times
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Golgi Bodies
• Adds modifications to
unfinished proteins
• Makes lysosomes
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Lysosome
• Small and round
• Store enzymes that break
down food into chemical
compounds
• Destroy cell organelles and the
cell itself
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Mitochondria
• Energy factories
• Rod-shaped
• Change food into molecules
that can be used for energy
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Mitochondria
• Contain DNA
• Can replicate themselves
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Chloroplast
• Found in plants and some
other organisms
• Contain chlorophyll
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Cellular processes
• Respiration
• Osmosis
• Diffusion
• Photosynthesis
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Respiration
• Cells break down
carbohydrates and other
molecules to produce energy
• Oxidation of glucose is one of
most common forms
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Respiration
• Breaking down of sugar into
water, carbon dioxide, and
energy
• Energy is used to do the work
of the cell
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Osmosis & Diffusion
• Transportation of raw
materials, wastes, and
synthesized materials out of
the cell
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Diffusion
• Movement of molecules;
especially gases and liquids
from areas of high
concentration to areas of low
concentration
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Osmosis
• Specific type of diffusion
• Movement of water through a
membrane from areas of high
concentration to areas of low
concentration
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Equilibrium
• Diffusion and osmosis happen
to enable a cell to reach
equilibrium
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Cellular reproduction
• Three ways:
–Fission
–Mitosis
–Meiosis
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Fission
• Prokaryotes
• Cell grows larger and makes a
second copy of its DNA
• At some point the cell membrane
divides the cell by the growth of a
transverse septum
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Fission
• Two new cells are formed as the
division grows inward from either
side of the cell
• Two cells now called “daughter
cells”
• Sometimes known as “binary
fission”
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Mitosis
• Eukaryotes
• Requires 6 stages
• Interphase, prophase,
metaphase, anaphase,
telophase, cytokinesis
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Mitosis
• Creates cells that are identical
to the original cell.
• Have the entire compliment of
chromosomes existing in pairs
- diploid
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Meiosis
• Division of sex cells
• Stages of Meiosis I: Interphase
I, prophase I, metaphase I,
anaphase I, telophase I,
cytokinesis I
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Meiosis
• Meiosis II
• Interphase II, prophase II,
metaphase II, anaphase II,
telophase II, cytokinesis II
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Meiosis
• Each cell receives one
chromosome from each pair
randomly
• Resulting cells have half the
normal number of
Chromosomes - haploid
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