Lecture 4 Flashcards
What does a diversity of a biomolecule depend on
1.arrangement of carbon skeleton (can bond with other carbon atoms)
2. Other chemical groups
What are the four types of biomolecules
- Proteins
- Nucleic acids
- Carbohydrates
- Lipids
What is a polymer
Chain or ring of monomers (single unit)
What type of reaction builds polymers
Dehydration/condensation
What reaction breaks down polymers
Hydrolysis reactions
Three functions of carbohydrates
- Energy storage
- Structural support and protection (plants and mushrooms)
- Cell to cell recognition (immune function)
What are the monomers of carbohydrates
Monosaccharides
Carbohydrate is a general term for…
Sugar
Polymers of carbohydrates
Polysaccharides
Simple sugars (monosaccharides) have a C, H, O ratio of 1:2:1 like :
Glucose (C6H12O6), galactose, fructose…
What bond connects monosaccharides
Covalent bond (formation of this bond is condensation reaction)
When two monosaccharides linked together, cell wants store energy! Common disaccharides are :
Sucrose, lactose, maltose
Store energy from polysaccharides
Starch (plants) and glycogen (animals)
Glycogen is a highly branched polysaccharide stored in :
Liver and muscle cells
Glycogen in liver :
Glucagon released by pancreas when blood sugar is too low. Glucagon makes liver break down glycogen to release glucose
Glycogen in muscle cells
Glycogen stored for muscle cell itself
Other storage polysaccharides in plants :
Cellulose
Cellulose purpose
Protect themselves (plants)
Human cannot digest cellulose bc
Can’t break bonds between b-glucose
What is special about lipids
Not made of repeating monomers
Lipids are defined by shared property :
Hydrophobic
Three major types of lipids :
- Fats (neutral fate)
- Phospholipids
- Steroids
Functions of fats :
-energy storage
-insulation cold
-protection of internal organs
Fat is constructed from smaller molcules
Glycerol and fatty acids
Fatty acids molecule linked to glycerol by what reaction
Condensation/dehydration
Triaglycerol :
Lipid used for E storage
Saturated fatty acids have
Maximum nb of H atoms, no double bonds
Unsaturated fats have
One or more double bonds
Saturated FA structure
Bc form linear molecules -> easily stack, stabilizing molecules making them solid at room temp
Unsaturated FA structure
Double bonds give them a kink -> don’t stack well so liquid at room temp
Our cells can break down unsat cis or unsat trans fat?
Cis (bc exists in enviro for long so cells have enzymes that metabolizes them)
Trans fat resemble saturated fats bc
H atoms are diagonal opposite sides of double carbon bond -> more rigid and straighter than cis
Why can’t we break down trans fat
Bc artificial (food transformation) -> unnatural shape so not recognized by enzymes (accumulate in cell and tissues)
Phospholipids functions
-major constituent of cell membrane
-forms lipoproteins
Phospholipids structure
-2 fatty acids
-1 glycerol molecule
-1 phosphate molecule
Phospholipids are hydrophobic and hydrophilic?
Yes, hydrophobic tail (FA) hydrophilic head
Steroids functions
-constituents of cell membrane (cholesterol
-components of vitamins
-components of hormones
Steroids structure
-four fused carbon-ring molecules
-diff differ in nb, position, composition of side chain
How does cholesterol travel in blood
In lipoproteins
Why is cholesterol in lipoprotein
Bc lipid -> hydrophobic and blood is mostly water
LDLs (low density lipoproteins) are important for homeostasis bc
Cells have specific prot receptors that recognize prot on LDLs for cholesterol functions
What happens if there’s too much cholesterol
Excess is still in LDLs but not taken by cell -> circulate in blood
Result of circulating LDLs
Higher risk of them sticking to vessel walls -> plaque that blocks blood vessels (arteries and arterioles)
HDLs do what
Pick up excess LDL (and are synthesized by liver)
What does liver do to LDL with HDLs
Specific prot receptor for prots found on HDLs -> removes excess cholesterol -> for digestion of fat or excreted in feces
Result of high HDLs
Lower risk of cardiovascular diseases bc rid body of LDLs
What is the sugar most found in blood/most common component of larger carbohydrates
Glucose
