Transcript Macromolecules

Chapter 3
Intro,3.1,3.2
Spider Webs and Carbon
Orb-Weaving Spider Web
• Contains carbon
Polymer Science U. of A.
Orb Spider Web
Spiders secrete their silk from glands
located on their lower side
• Silk being
secreted
from
glands in
the spigots
• (SEM x3,740)
Spinnerets
Web
Design
Straight Strands
• Radial
• Dry
• Inelastic
proteins
Radial Strands
• “Spiraling strand”-captures
insects
• Wet
• Sticky
• Highly elastic
(stretch up to 4X’s)
The web is started with a horizontal
thread stretched between two supports.
The spider lets out a thread that is carried
to another support by a breeze or air
current. The spider then pulls in the
excess to stretch the thread taut.
Dragline being silked from
spinnerets
• The spider then
moves to the center
of the sagging,
loose thread, and
drops, letting out
another thread and
forming a ‘Y’.
• When the spider
reaches the anchor
point, it walks down
the support to affix the
new thread to another
support point. The
spider will spin
threads between
anchor points to give
the web a frame.
• The spider makes
the non-sticky
scaffolding, from
the outer edge to
the center, attaching
sticky threads that
form the trap.
• The spider cuts
away the non-sticky
scaffolding as it
progresses toward
the center. The
whole
process of
• building a
web takes about
a half hour.
Web Design
largest spigot produces the
spider's safety line, called the
dragline.
•The smaller
spigots produce lots
of short sticky
threads that make a
strong attachment
point for other silk
lines.
Coils..then straightens
• Normal –
Stretched 5X - Stretched 20X
Spider web glue droplets
• SEM
• on a strand of spider silk
Why is there so little sag?
• Coiling and uncoiling of silk
fibers
• When the prey is no longer
pressing against the strand…the
fluid’s surface tension “beads”
and rewinds the fiber
The spider uses its rear legs to pull
and stretch the coagulated silk from
the spinnerets
What is Web Silk Made Of?
• the primary constituents of
spider silk turn out to be the
two simplest amino acids,
glycine and alanine
• "Dragline spider silk is actually
stronger than Kevlar synthetic
fiber- and Kevlar is several
times stronger than steel"
Spider Silk
• Dragline silk
• at least 5X’s stronger than steel,
• 2X’s more elastic than nylon
waterproof and
stretchable.
Why don't spiders
stick to their webs?
Only
a don't
tiny spiders
area
• Why
of its
body
in webs?
stick
to their
•
contact
with the
line (the
with middle
silkSilk
lines
claw and bristles.
tips of its legs) +
has a secretory
lubrication on
the claws
Spider Silk Research
• January 2002 spliced DNA
from spiders into cells taken
from hamsters and cows
• These cells produced spider silk
proteins
Make Artificial Silk for:
•
•
•
•
•
Artificial tendons and ligaments
Surgical sutures
Bulletproof vests
Space Station Coatings
Fishing line
USES
-wear-resistant shoes and clothes
-stronger ropes, nets, seatbelts, and parachutes
-rust-free panels and bumpers for automobiles
-improved sutures and bandages, artificial
tendons and ligaments, and supports for
weakened blood vessels.
-soldiers and police long for bulletproof vests
Organic Compounds
• Contain carbon and
synthesized by cells
Carbon
6p
6n
6 e-
Carbon can bond to 4 e-
• Total of 6 electrons
• 4e- in outer shell
Can bond to 4 H
Hydrocarbons
• Contain hydrogen and
carbon
METHANE
• One carbon
Carbon Skeleton
• Carbon Chain
• Here with 6 carbons (hexane)
Unbranched
Can be branched
• Like here with isooctane
• (8 carbons)
Rings
• Cyclohexane
Note
the
ring
Aspirin
Aspirin
• These are the same
• Single bond (ethane)
• Double bond (ethene)
• Triple bond (ethyne)
Single, Double, Triple Bonds
Isomers
• Same molecular
formula but
different
structure
(orientation)
• All C5H12
Functional Groups
•Groups of atoms
that usually
participate in
chemical reactions
Functional Groups
• hydroxyl
or
• Carbonyl
• (double bond to C)
Functional Groups
• Carboxyl
• Amino
–COOH
-NH2
or
Which functional group?
•Amino
•carbonyl
Which functional group?
• carbonyl
Which functional group?
• carbonyl
Which functional group?
•carboxyl