Download The cell

Cellular Level of Organization
FTCE Biology 6-12
Day 1
Cell discovery
timeline
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Hooke: 1660
– Cork, used term “cells”
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Van Leeuwenhoek:
1673’s
– Wee beasties, protists
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Schleiden: 1839
– Plants made of cells
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Schwann: 1839
– Animals made of cells
Cell theory
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Rudolf Virchow -1855
The cell theory
1. Cells are the units of structure &
function in organisms.
2 . All cells come from pre-existing cells.
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Cells are 1µm to 20µm small. Why is
small better?
– 1000 µm = 1mm
– Ex. on pg. 156
Microscopes
Magnification: the ratio between the
size of the image and the object
Resolution: the smallest degree of
separation at which 2 objects appear
distinct
Resolution
(resolving power)
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The ability to see clearly
between two points.
– Limited by the wavelength of the
source of illumination
• Visible light is used for “light
microscopes”
• Beam of electrons for EM
Two types of microscopes
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Light microscope
– Visible light to see image
– Parfocal
– Highest magnification with decent resolution =
about 1000x
– Can observe living cells
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Electron microscope
– Electrons bounced off object
– Highest magnification with decent resolution =
about 1,000,000x
– Preparation is severe.
Two types of electron
microscopes
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Transmission electron
microscope
– (TEM)
– 2-D image
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Scanning electron microscope
– (SEM)
– 3-D image
Three Views of Red Blood Cells
Light Microscope
SEM
Scanning Probe
Microscope
Parts of the microscope
Eyepiece
 Arm
 Base
 Revolving
nosepiece
 Stage
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– Clips
– diaphragm
Parts of the microscope cont.
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Nosepiece
–Objective lenses
• Low (book calls it scanning)
–4x magnification
• Medium (book calls it low)
–10x magnification
• High (book calls it same thing)
–40x magnification
Overall mag. 10x (eyepiece) x lens
Parts of the microscope cont.
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Coarse focus knob
– Only when using
low power objective
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Fine focus knob
– For small
adjustments
diaphragm
 Light switch
& cord
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Two general types of cells
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Prokaryote
– No true nucleus
– No membrane- bound
organelles
– Ex. Monera /bacteria
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Eukaryotes
– True nucleus
– Membrane- bound organelles
– Ex. Protist cells, fungi cells, plant cells,
animal cells
Prokaryote structure
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Cell wall
Plasma membrane
Cytoplasm
Nucleoid
Plasmid
(some) flagellum
Bacteria Shapes
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Cocci/sphere
Bacilli/rod
Spirilla/spiral
Eurkaryotes
(Protists, Fungi, Plant, Animal)
• organelles
•plasma membrane
• cell wall of cellulose (plants)
• nucleus w/nuclear membrane
• nucleoli
• cytoplasm
amoeba
Amoeba
Paramecium
Onion skin
Elodea
Studying Cells
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Cytology: Cyto-cell –ology study of
Human body-2 types of cells
1. Sex cells: sperm (male)
oocyte (female)
2. Somatic cells: all other cells
Generalized
Animal Cell
Generalized
Plant Cell
Cell organelles
Cell Organelles
• Compartmentalize cell’s activities
• improve efficiency
• protect cell contents from harsh chemicals
• Enable cells to:
• secrete substances
• perform cellular respiration
• degrade debris
• reproduce
Cell Organelles
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Cell membrane: lipid bilayer containing
phospholipids, steroids, proteins and
carbohydrates
F-isolation: keeping proteins inside
protection:
sensitivity: receptors that allow the cell
to recognize and respond to specific
molecules.
Cell membrane (continued)
Structural support: to stabilize (skin)
Transport: control of entrance and exit of
materials (ions, glucose, elimination of
wastes)
•
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cytoplasm: entire contents of
the cell, except the nucleus,
bounded by the plasma
membrane
cytosol: gelatinlike portion of
the cytoplasm that bathes the
organelles of the cell
Organelles of Eukaryotic Cells
Organelles compartmentalize a cell’s
activities.
1. Nucleus
– surrounded by a double membrane
two phospholipid bilayers (nuclear
envelope), perforated with nuclear
pores
– contains DNA & nucleolus (stores RNA
nucleotides)
– functions to separate DNA from rest of
cell
Nucleus Functions (Continued)
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Controls metabolism
Stores and processes genetic
information
Controls protein synthesis
Nucleolus
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Dense region in nucleoplasm of nucleus
Site of rRNA synthesis and assembly of
ribosomal units
Nucleolus
Cytoskeleton
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Network of protein
filaments throughout
the cytosol
Functions
– cell support and shape
– Site of some chemical
reactions
– cell & organelle
movement
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Continually
reorganized
Ribosomes
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Packages of Ribosomal RNA & protein
Free ribosomes are loose in cytosol
– make proteins used inside the cell
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Membrane-attached ribosomes
– attached to endoplasmic reticulum or nuclear
membrane
– make proteins needed for plasma membrane
and/or for export
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Inside mitochondria, synthesize
mitochondrial proteins
Ribosome
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Large + small
subunits
– made in the nucleolus
– assembled in the
cytoplasm
2. Endoplasmic reticulum (ER)
–interconnected network of
membranes extending from
nucleus to plasma membrane
Rough ER - studded with ribosomes
– site of protein production (most will be
exported out of the cell)
Free ribosomes in the cytoplasm produce
proteins that remain in cell.
Smooth ER - lacks ribosomes
– site of lipid production
– contains enzymes that detoxify drugs &
poisons
3. Golgi apparatus
–stacks of membrane-enclosed
sacs
Golgi apparatus functions:
– Forms membranes/vesicles (renews/modifies
cell membrane)
– links simple carbohydrates together to form
starch
– links simple carbohydrates to proteins
(glycoprotein) or lipids (glycolipid)
– completes folding of proteins
– temporarily stores secretions
– Storage, alteration and packaging of
secretory products and lysosomal enzymes.
Organelle interaction in a mammary
gland cell.
4. Mitochondria
– double-membrane
• outer is smooth
• inner is highly folded
(cristae)
– #/cell varies with energy demands of that cell (bone
cedll have few, muscle cell has thousands)
– contain DNA (some mitochondrial genes, rest in nuclear
DNA)
– Contains some ribosomes for own protein synthesis
– inherited only from female parent
– site of cellular respiration (production
of ATP)
– Takes in short carbon chains and oxygen to generate
carbon dioxide and ATP
Plant cells also have...
• Cell wall: made of cellulose,
provides rigidity and allows for
turgor pressure
• Vacuole: contains water and
digestive enzymes, stores
nutrients and wastes
•Chloroplast: photosynthesis
Chloroplasts #/plant cell
varies (few-hundreds)
contain DNA (some
chloroplastic genes,
rest in nuclear DNA)
–found in plants &
protists
–function
photosynthesis
6. Lysosomes (suicide sacs)
apoptosis
programmed cell death
– vesicles containing > 40 types of digestive
enzymes
– function to recycle damaged organelles, break down
cellular byproducts, destroy cell & kill invading microbes
Centrioles
Found near
nucleus
–Involved in cell
divison
 Structurally similar
to cilia and flagella
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Cilia and Flagella
Differences
– cilia
• short and multiple
– flagella
• longer and single
Movement of Cilia and Flagella
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Cilia
– Move material over cell
surface
– Respiratory tree & oviduct
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Flagella
– single flagella wiggles in a
wavelike pattern
– propels sperm forward
The Endosymbiont Theory
Lynn Margulis – eary 1960’s
Proposes that chloroplasts and
mitochondria evolved from once freeliving bacteria engulfed by larger
prokaryotes, but not digested.
Based on fact that mitochondria &
chloroplasts resemble certain bacteria
(size, shape, membrane
structure,have own DNA and
ribosomes)
Multicellular Organization
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Each cell must do their own basic
activities (protein synthesis, cellular
respiration, cell division, etc.)
Also show a division of labor or
specialization and cooperationcontribute to the well being of other
cells/tissues/organs etc.
Some form of intercellular
communication
– Either chemical (hormone) or
electrical (nervous)
Levels of Organization
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Subatomic
Atom
Molecule
Macromolecule
Organelle
Cell
Tissue
Organs
System
Organism
Population
Community
Ecosystem
Biosphere
Levels of Structural Organization
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Chemical Level
– Subatomic, atomic and molecular level
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Cellular level
– smallest living unit
– Tissue level
– group of cells that work together on one task
Levels of Structural Organization
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Organ level
– groups of 2 or more tissue types into a
recognizable structure with a specific function.
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Organ system
– collection of related organs with a common
function
– sometimes an organ is part of more than one
system
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Organism level
– one living individual
Levels of Structural Organization
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Population
– Group of same specie in a given area
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Community
– All specie in a given area
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Ecosystem
– Biotic and abiotic in a given area
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Biosphere
– All ecosystems combined