Transcript Organic Chemistry Powerpoint for Bio. I

Organic Chemistry
Why Do We Eat?
Carbohydrates
A. Atoms – C,H,O in a 1:2:1 ratio
B. Monomers – Monosaccharides
Carbs Continued
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Examples:
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Monosaccharides – glucose, fructose, galactose
Disaccharides – sucrose (glucose + fructose)
lactose (glucose + galactose)
maltose (glucose + glucose)
Polysaccharides – chains of glucose (starch, glycogen,
cellulose)
Functions: immediate energy or short term energy
storage
Structure/Function Relationships
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Contains a lot of C-H covalent bonds that store
energy
We have enzymes that can break these bonds
to release the energy
The O-H bonds make carbs very polar so they
dissolve easily and so can be move in water
easily to meet up with enzymes and can be
easily transported to cells and meet up with
enzymes there
Struc/Func Continued
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Even if molecules are polar – the larger the molecule –
the less water soluble – harder to transport and harder
for enzymes to get to and break down (also more
bonds to break)
Polysaccharides are more storable because more bonds
and bigger
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Starch is made by plants – straight chains – more “packable”
Cellulose is made by plants – used for structure since there
are no enzymes that break it down, can bind to other
cellulose chains making it stronger – called “fiber” in our
diet – important for bulking up feces and cleaning intestine
Glycogen is made by animals – branched so can break down
quicker than starch
Physiology
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When you eat monosaccharides, you just absorb them into the
blood
When you eat disaccharides and polysaccharides, you first
digest them to monosaccharides so they are small enough to
absorb
These go to the cells to be further broken down to release the
energy in them to run everything
Any extra should be taken out by the liver, chained together
into glycogen for longer storage then stored in the liver and
muscles.
Any excess carbs beyond what can be stored as glycogen get
turned into fat for long term storage.
Getting Ready for a Game or Contest?
Which would you choose?
Good Carbs vs. Bad Carbs
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Good – whole fruits, whole vegetables, whole
grains
Bad – processed carbs – white bread, pastas,
white rice, any white flour product
What Makes them Good or Bad?
It’s all about the speed of absorption from the
digestive track
The speed of absorption is determined by
packaging.
Good vs. Bad Carbs Continued
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Whole fruits and vegetables – the simple
sugars are encased in cellulose cell walls –
hard to tear the cell walls open so it slows the
absorption
Whole grains and brown rice have capsule so
same as above
Refined flour – remove
outside capsule and
germ which has vitamins
and important nutrients
so its absorbed quickly
and doesn’t have a lot of
nutrients – almost all
powdered starch
Good vs. Bad carbs
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The amount a carb shoots up the blood sugar is
called the Glycemic Index (GI). The higher
the GI, the faster your blood sugar increases
and the more unhealthy the carb is for you.
Processed carbs have a high GI because the
sugar is absorbed so fast, the liver can’t take
all of the extra out for storage. Therefore, your
blood sugar spikes.
This causes you to overproduce insulin which
leads to insulin resistant diabetes and other
problems.
Why is the Speed of Absorption
Important?
High GI: Sugar High/Sugar Low – feel tired,
hungry, and maybe shaky. Creates insulin
resistance and diabetes.
Lipids
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Atoms – C,H,O but hardly any O (non-polar)
Monomers – fatty acids (hydrocarbon chains)
Examples
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Fats – saturated and unsaturated
Cholesterol
Steroid Hormones
Wax
Mucus
Functions
Long term energy storage
 Insulation
 Cushioning
 Protection (wax, mucous)
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Structure/Function Relationships
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Has more C-H bonds than carbs so contains a
lot more energy/gram (compact energy)
Had little O and is non-polar so doesn’t
dissolve easily – hard to transport and hard for
enzymes to get to it to break it down – can be
stored for a long time
Proteins
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Atoms: C,H,O,N (sometimes S)
Monomers: amino acids
Examples/Functions
Fibrous Proteins
For Structure
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Hair, teeth, nails,
skin, muscles,
bones, tendons,
ligaments
 Internal structure
of cells
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Protein Folding Video
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Globular Proteins
Work by shape
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Enzymes – catalyze chemical
reactions
Carrier Proteins – carry oxygen to
cells, transport things across
membranes
Receptors – receive messengers
Messengers – molecules to
communicate like hormones
Antibodies – proteins that help
kill foreign invaders
Protein Channels in the cell
membrane – let only certain
things in or out of cells
Marker Proteins – on cell surface
– id’s cell as your own
Fibrous vs. Globular Proteins
Why is shape so important?
Protein Structure/Function
Relationships
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Fibrous – multiple polypeptides wound around
each other like a rope – all of the
intermolecular forces (bonds) that form
between the strands makes them super strong
which makes them good for building the
structural parts of animals
Globular – all have very intricate shapes with
specifically shaped pockets on their surface
which allow them to match by shape with
other molecules. This makes them good for…
How Proteins Fold
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Primary Structure – straight chain of aa – not
functional – hooked together by peptide bonds which
are covalent
Secondary Structure – starts to fold
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uncharged parts start of collapse together
the O of the acid groups form H bonds
with the H from the amino group
Spirals and curves start to form
Protein Folding continued
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Tertiary Structure – caused by interactions of R
groups that have now been brought closer together by
secondary folding – Functional!
Held together by:
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Hydrogen bonds - form between two polar R groups (most
numerous)
Hydrophobic interactions (water pushing non-polar groups to the
inside
Ionic bonds – form between a positive and a negative R group
Covalent bonds – very few – form between R groups of 1 amino
acid type
Quarternary Structure – when more than one
polypetide binds together to make the final shape of
the protein (ex. Hemoglobin) – Functional!
Nucleic Acids: DNA
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Structure?
 base pairing
(purine/pyrimidine,
A-T, G-C, covalent
bonding of backbone, H bonding between
bases
Function?
 Code for proteins
 Copy itself before cell
division
Structure/function
relationships?
Structure/Function
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Why covalent bonds in backbone?
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In order to code for proteins – order of the bases is most
imp. The order is maintained by the backbone which
cannot fall apart or DNA is useless
Why H bonds between base pairs?
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Enough to hold the 2 strands together but easy enough to
sep. for replication and transcription
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Why purine-pyrimidine pairs
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Purines double ringed, pyr single ringed by pairing, all along
the DNA is the same width so the covalent bonds of the
backbone aren’t strained
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Why do we need base pairing?
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Ensures exact copying
Structure/Function
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Why covalent bonds in backbone?
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In order to code for proteins – order of the bases is most
imp. The order is maintained by the backbone which
cannot fall apart or DNA is useless
Why H bonds between base pairs?
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Enough to hold the 2 strands together but easy enough to
sep. for replication and transcription
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Why purine-pyrimidine pairs
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Purines double ringed, pyr single ringed by pairing, all along
the DNA is the same width so the covalent bonds of the
backbone aren’t strained
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Why do we need base pairing?
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Ensures exact copying
Structure/Function
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Why covalent bonds in backbone?
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In order to code for proteins – order of the bases is most
imp. The order is maintained by the backbone which
cannot fall apart or DNA is useless
Why H bonds between base pairs?
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Enough to hold the 2 strands together but easy enough to
sep. for replication and transcription
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Why purine-pyrimidine pairs
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Purines double ringed, pyr single ringed by pairing, all along
the DNA is the same width so the covalent bonds of the
backbone aren’t strained
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Why do we need base pairing?
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Ensures exact copying
Enzymes
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Chemical reactions will not happen in living
things without enzymes because we can’t
produce enough energy available to get them
to happen!
Enzymes lower the activation energy of a
chemical reaction so that it can happen at body
temperature.
This makes enzymes catalysts because they
speed up chemical reactions
How do Enzymes Work
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Each enzyme is different – The each have a
specially shaped pocket on their surface that
matches the substrate
Each enzyme can only catalyze one type of
chemical reaction
It works basically
like a lock and key
Motion model of
enzyme action
Why are enzymes important?
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Because each enzyme can only catalyze one
type of chemical reaction, reactions can only
happen in the body where those enzymes are
located.
Enzymes control what chemical reactions
happen where and how fast in the body so they
generally run the body.
Enzymes can either catalyze
chemical reactions to make bonds
or to break bonds
“Making Reaction”
The substrates go into the active site of the enzyme – it
changes shape in such a way as to smash the two substrates
together – they are now so close that it takes less energy to
form the bond
The bond now forms at regular body temperature
“Breaking” Reaction
The substrate goes into the active site – the enzyme changes
shape in such a way as to twist the substrate out of shape – this
strains one of the bonds (the one that is supposed to break) by
making the atoms bonded together farther apart
Now body heat is enough to finish breaking the bond
How do Enzymes and Substrates
Meet?
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Both are in motion – so random collision
If they match by shape and the substrate goes
into the active – the reaction will happen
Things that affect enzyme activity
and therefore all of the chemical reactions in a
cell or body
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Enzyme Concentration
Substrate Concentration
Temperature
pH
Co-enzymes – vitamins – large organic molecule – fit into active site
and makes the substrate fit better
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Co-factors – ions – fit into active site and make the substrate fit better
Inhibitors
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Competitive – fit into active site and block the real substrate from
getting in – no reaction when inhibitor is in active site
Allosteric – fits into a site other than active site – changes shape of
active site so it no longer works
Cell signaling – signals a shape change in the enzyme so that it now
becomes the right shape and activates
Role of Coenzymes
Allosteric Inhibitors
Cell signaling and Activation of Enzymes
The “Big Picture”
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Body makes chemical reactions optimal by maintaining the
temperature and pH within the body
It can make reactions happen in certain places by having
enzymes there or not
It can make reactions go faster by making more enzymes
It can make reactions happen based on signals by signaling to
make enyzmes in a certain place or to activate enzymes that
are already there but not the right shape yet.
If cofactor or coenzymes are needed for a reaction, they won’t
work well without them
If an inhibitor is present, the reaction will slow down or may
not work at all