cellular level of organization ftce biology 6-12 day 1
TRANSCRIPT
Cellular Level of OrganizationFTCE Biology 6-12
Day 1
Cell discovery timeline Hooke: 1660
– Cork, used term “cells” Van Leeuwenhoek: 1673’s
– Wee beasties, protists Schleiden: 1839
– Plants made of cells Schwann: 1839
– Animals made of cells
Cell theory Rudolf Virchow -1855 The cell theory
1. Cells are the units of structure & function in organisms.
2 . All cells come from pre-existing cells.
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)
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
Light microscope– Visible light to see image– Parfocal– Highest magnification with decent resolution =
about 1000x– Can observe living cells
Electron microscope– Electrons bounced off object– Highest magnification with decent resolution =
about 1,000,000x– Preparation is severe.
Two types of electron microscopes Transmission electron microscope
– (TEM)– 2-D image
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
– Clips– diaphragm
Parts of the microscope cont. 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. Coarse focus knob
– Only when using
low power objective Fine focus knob
– For small
adjustments diaphragm Light switch
& cord
Two general types of cells Prokaryote
– No true nucleus– No membrane- bound organelles– Ex. Monera /bacteria
Eukaryotes – True nucleus– Membrane- bound organelles– Ex. Protist cells, fungi cells, plant cells,
animal cells
Prokaryote structure
Cell wall Plasma membrane Cytoplasm Nucleoid Plasmid (some) flagellum
Bacteria Shapes
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
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 Generalized
Animal Cell 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
Cell membrane: lipid bilayer containing phospholipids, steroids, proteins and carbohydratesF-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)
• 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 CellsOrganelles 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)
Controls metabolism Stores and processes genetic
information Controls protein synthesis
Nucleolus
Dense region in nucleoplasm of nucleus Site of rRNA synthesis and assembly of
ribosomal units
Nucleolus
Cytoskeleton Network of protein
filaments throughout the cytosol
Functions– cell support and
shape – Site of some
chemical reactions– cell & organelle
movement Continually
reorganized
Ribosomes Packages of Ribosomal RNA & protein Free ribosomes are loose in cytosol
– make proteins used inside the cell Membrane-attached ribosomes
– attached to endoplasmic reticulum or nuclear membrane
– make proteins needed for plasma membrane and/or for export
Inside mitochondria, synthesize mitochondrial proteins
Ribosome
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.
– #/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
4. Mitochondria– double-membrane
• outer is smooth• inner is highly folded
(cristae)
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
Cilia and FlagellaDifferences– cilia
• short and multiple– flagella
• longer and single
Movement of Cilia and Flagella Cilia
– Move material over cell surface
– Respiratory tree & oviduct
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 free-living 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 Each cell must do their own basic activities
(protein synthesis, cellular respiration, cell division, etc.)
Also show a division of labor or specialization and cooperation- contribute to the well being of other cells/tissues/organs etc.
Some form of intercellular communication– Either chemical (hormone) or electrical
(nervous)
Levels of Organization Subatomic Atom Molecule Macromolecule Organelle Cell Tissue Organs System Organism Population Community Ecosystem Biosphere
Levels of Structural Organization
Chemical Level– Subatomic, atomic and molecular level
Cellular level– smallest living unit
– Tissue level– group of cells that work together on one task
Organ level– groups of 2 or more tissue types into a
recognizable structure with a specific function. Organ system
– collection of related organs with a common function
– sometimes an organ is part of more than one system
Organism level– one living individual
Levels of Structural Organization
Population– Group of same specie in a given area
Community– All specie in a given area
Ecosystem– Biotic and abiotic in a given area
Biosphere– All ecosystems combined
Levels of Structural Organization