Transcript Chapter 3 Cell Structure - Shelbyville Central Schools

Section 3-1
Cell Size:
• Magnification: quality of making an
image appear larger than actual size
• Resolution: measure of clarity of an
image
• e- microscopes have ↑ mag/resolution
Section 3-1
Light microscopes:
•Form an image when light passes through
1 or more lenses to produce an enlarged
image of specimen
Section 3-1
Types of Microscopes:
• Electron microscopes use beam of erather than light to view specimen
• Live organisms can’t be viewed w/ emicroscope
Section 3-1
Transmission Electron Microscope:
• e- beam directed at very thin slice of
specimen stained w/metal ions
• e- that pass through strike fluorescent
screen, forming an image; can’t view live
specimen
Section 3-1
Scanning Electron Microscope:
• e- beam is focused on specimen coated
w/ very thin layer of metal
• Shows 3D details of surface of specimen;
can’t view live specimen
Neutrophil (yellow)
engulfing anthrax (orange)
Section 3-1
Scanning Tunneling Microscope:
• Needle-like probe measures differences in
voltage caused by e- that leak, or tunnel,
from surface of object being viewed
• Shows 3D details of surface of specimen
• Live specimens can be viewed
e- surrounded by 48 iron atoms
Section 3-2
Cell Size
•Small cells function more efficiently than
large cells
•If cell’s surface area–to-volume ratio is
too low, subs can’t enter/leave cell well
enough to meet cell’s needs
Section 3-2
Cell Theory has 3 parts:
1. All LT are made of 1 or more cells
2. Cells are basic units of
structure/function in organisms
3. All cells arise from existing cells
All cells have:
• Cell membrane
• Cytoplasm
• Cytoskeleton
• DNA
• Ribosome
Section 3-2
Prokaryotic cells (bacteria):
•Single-celled organisms; no nucleus or
internal compartments
•Have cell wall, may have cilia/flagella
•Have circular molecule of DNA
E. coli
bacteria cell
Section 3-2
Eukaryotic cells (all other LT):
•Nucleus contains cell’s DNA
•Other internal compartments, organelles
Typical
animal cell
Section 3-2
Cell membrane:
• Selectively permeable membrane,
determines which substances
enter/leave cell
• Selective permeability caused by the
way phospholipids interact w/ water
• Phospholipid made of phosphate group
and 2 fatty acids
Section 3-2
Proteins are embedded in the phospholipid
bilayer to help move substances across cell
membrane
“Outside of the cell”
“Inside of the cell”
Section 3-3
Nucleus:
•Internal compartment stores cell’s DNA
•Nucleus controls cell’s functions
•Nuclear envelope is double membrane
surrounding the nucleus
•Nuclear pores are small openings
scattered over surface of nuclear envelope
Section 3-3
Ribosome:
•Structure where proteins are made
Endoplasmic Reticulum (ER):
•Extensive network of internal membranes
that move proteins and other subs through
cell; acts as a highway
Section 3-3
Vesicles:
•Carry newly made proteins through
cytoplasm from ER to Golgi apparatus
Golgi apparatus:
•Set of flattened, membrane-bound sacs
that serve as packaging/distribution
center of cell
Section 3-3
Lysosome:
•Sacs of enzymes that engulf/breakdown
large substances into smaller ones
Mitochondria: (aka “powerhouse”)
•Organelles that convert food energy from
organic compounds to make ATP
ATP:
•Main energy currency of cell; “spendable”
Section 3-3
Plants have 3 structures not found in
animal cells:
1. Cell Wall: support/maintain shape of
cell; protects cells, connect cell to
adjacent cells
2. Chloroplasts: uses light energy to make
organic compds from CO2/water
3. Large Central Vacuole: stores
water, nutrients, wastes
Section 3-3
Summary of Organelles: