Unit 3: Carbs, Lipids, First Cells Flashcards
What are the six common functional groups and their structures and properties?
C- Carbonyl Polar
C- Carboxyl Charged to release H+ ions into concentration and are considered acidic.
H- Hydroxyl Polar
A- Amino Charged, accepts H+ to form NH3+. Remove H+ from solution (basic).
M- Methyl Nonpolar
P- Phosphate Charged to release H+ ions into concentration and are considered acidic.
What are four examples of different carbohydrates?
- Monosaccharide (“one-sugar”) monomers
- Disaccharide (“two sugars”)
- Oligosaccharide (“few sugars”) 3-10 sugars polymers
- Polysaccharide (“many sugars”) > 10 sugars large polymers
_______ are ___________.
Carbohydrates are hydrated carbons
Why are carbohydrates important? Name two reasons.
- Provide chemical energy in cells.
- Serve as building blocks for larger compounds.
____________ are simple sugars that ________ in different ways.
Monosaccharide monomers are simple sugars that structurally vary in different ways.
What’s the first thing that distinguishes one monosaccharide from another?
- Location of the carbonyl group (C=O):
- At the end = aldose
- In the middle = ketose
_______ changes have functional __________.
Structural changes have functional consequences.
What’s the second thing that distinguishes one monosaccharide from another?
- Number of carbon atoms present:
- Three = triose
- Four = tetrose
- Five = pentose
- Six = hexose
* Carbon atom may not be present in the center branch of a molecule, but it is still there.
What’s the third thing that distinguishes one monosaccharide from another?
- Spatial arrangement of atoms- such as hydroxyl groups (O-H) sticking out of pointing behind (On C-4)
- Glucose- Hydroxyl group pointing down
- Galactose- Hydroxyl group pointing up
What’s the fourth thing that distinguishes one monosaccharide from another?
- Linear and alternative ring forms (usually in water).
- The linear form of glucose can convert into two different ring forms.
- Hydrogen from the C-5 hydroxyl (O-H) bonds to the C-1 carbon (C=O), resulting in a ring structure.
- This forms either an alpha glucose (bonded to the right as C< H (top) OH (bottom)) or beta glucose (bonded to the left as C< OH top H bottom)
What’s the difference between alpha glucose and beta glucose?
Alpha glucose is readily used for energy whereas beta glucose used for structure.
When are sugars linked?
Sugars are linked when a condensation
reaction occurs between two hydroxyl
groups.
* Remember a condensation reaction is when water is released as a byproduct.
What are the three steps to how polysaccharides are formed?
- Condensation reaction occurs (H2O released from the two (C-OH hydroxyl groups) and a covalent bond called a glycosidic linkage forms.
- The C1-C4 linkage results in an alpha 1-4 glycosidic linkage (usually points downwards) or a beta 1-4 glycosidic linkage (usually points upwards).
- The linkages can be broken by hydrolysis reactions.
What is a glycosidic linkage?
A covalent chemical bond that connects two sugar molecules (monosaccharides) together. Can make larger carbohydrates such as polysaccharides or oligosaccharides.
What is a hydrolysis reaction?
A hydrolysis reaction is a chemical reaction in which a water molecule (H₂O) is added to break a covalent bond between two molecules. Opposite of a condensation reaction.
True or False: Glycosidic linkages can form between any two hydroxyl groups, but form between C1 and C4 most commonly.
True
What is the difference between hydrolysis and condensation reactions? (3 things each)
Condensation
1. Builds larger molecules
2. Water expelled
3. Energy is required
Hydrolysis
1. Breaks down molecules
2. Water consumed
3. Energy is released
What is photosynthesis?
In photosynthesis, plants harvest energy from sunlight and store it in the bond of carbohydrates.
How are sugars stored in plant for energy use at a later time?
Plants store sugars in the form of starch:
- Composed of alpha glucose
- Forms a helix
What are the two types of polysaccharide starches used to store energy later in plants?
- Amylose- Unbranched starch with only alpha 1,4 glycosidic linkages.
- Amylopectin- Branched starch with some alpha 1,6 glycosidic linkages creating branches that occur every 30 monomers.
*Describes 3D structure
What can glycogen be broken down into?
Can be broken into glucose monomers for energy.
Where is glycogen stored?
Stored in liver and muscle cells.
What is a type of polysaccharide used to store energy later in animals?
Animals store sugar as glycogen. Glycogen is a polysaccharide that serves as the main energy storage molecule in animals and fungi.
What is the chemical structure of glycogen?
Highly branched alpha glucose polymer, nearly identical to amylopectin since alpha 1-6 branches occur in about 1 out of 8-10 glucose monomers.
What is cellulose?
Cellulose is a carbohydrate that makes up the cell walls of plants.
What is a cell wall?
Major component of the protective layer
around plant cells called the cell wall.
Where are beta-glucose monomers found?
Beta-glucose monomers are the building blocks of cellulose (beta 1,4 glycosidic linkages), a structural component of plant cell walls.
_______ gives cells and organisms ______ and ______.
Structural polymers give cells and organisms strength and elasticity.
What is the structure of a cellulose polysaccharide? (2 things)
- Every other glucose is flipped, so it generates a linear molecule rather than a helix.
- Permits hydrogen bonds to form between adjacent, parallel strands which forms strong fibers.
What is Chitin?
Chitin is a structural polymer found in cells walls of fungi and exoskeletons of insects and crustaceans.
What is the structure of a chitin polysaccharide? (3 things)
- Monomer is N-acetyl glucosamine (NAG)
- Structure is similar to cellulose as beta 1,4 glycosidic linkages form with every other monomer flipped.
- Linear strands with hydrogen bonds between them form strong fibers.
How are cellulose and chitin similar?
Cellulose and chitin only differ by functional group on C-2
Cellulose has a hydroxyl group (O-H) while Chitin has N-acetylglycosamine (NAG) (NHCOCH3)
What is peptidoglycan?
Peptidoglycan is a structural polymer found in bacterial cell wells.
What is the structure of peptidoglycan? (2 things)
- Monomer is N-acetylglucosamine (NAG) linked to N-acetylmuramic acid (NAM) by beta 1,4-glycosidic linkages.
- Note the pentapeptide on NAM (HOH2C)
Where is peptidoglycan found?
Peptidoglycan is a structural polymer found in bacterial cell walls.
What are pentapeptide amino acids?
Pentapeptide amino acids on NAM form peptide bonds between adjacent strands.
What does peptidoglycan look like in it’s 3D structure?
Parallel strands joined by peptide bonds.
What do cellulose and Chitin look like in their 3D structure?
Both have parallel strands joined by hydrogen bonds. Chitin has extra NHCOCH3 group.
What is the chemical structure of gram-negative bacteria?
In gram-negative bacteria, peptidoglycan cross-linkage occurs by a peptide bond between two glycan chains.
What is the chemical structure of gram-positive bacteria?
In gram-positive bacteria, cross-linkage may occur through a short peptide interbridge between adjacent glycan chains.
What is different in the physical appearance of gram-negative bacteria and gram-positive bacteria?
Gram-positive bacteria show blue or purple after gram-staining in a laboratory test. They have thick cell walls. Gram-negative bacteria show pink or red on staining and have thin walls.
Peptidoglycan is a good target for _____________.
antibacterial drugs
What are lysozyme enzymes?
Lysozyme enzymes in human tears, mucus, and saliva split the peptidoglycan backbone, breaking the glycosidic bonds of peptidoglycan, providing defense against bacterial infection.
What are used to display information on the outer surface of cells?
Glycoproteins and Glycolipids.
What are glycoproteins?
Proteins with attached carbohydrates.
What are glycolipids?
Lipids with attached carbohydrates
What two things are glycoproteins and glycolipids key molecules in?
- Cell-cell recognition: Identify cells as “self”
- Cell-cell signaling: Communication between cells
What are the Izumo1 and Juno glycoproteins and how is it important for reproduction? (2 things)
- Izumo1 glycoprotein on surface of sperm pairs up with Juno glycoprotein on unfertilized egg.
- Once fusion occurs, the egg spits out the remaining Juno glycoproteins preventing multiple sperm fertilizing the same egg.
What are lipids?
Carbon-containing compounds insoluble in water.
Why are lipids insoluable?
Insolubility due to high proportion of nonpolar hydrocarbons.
What are two types of
fatty acid lipids?
- Saturated fatty acids
- Unsaturated fatty acids
What is the chemical structure of a fatty acid? (3 things)
- Hydrocarbon chain bonded to a carboxyl (-COOH) functional group.
- Contain 14-20 carbon atoms.
- Can be saturated or unsaturated.
What is the chemical structure of a saturated fatty acid?
Saturated hydrocarbon chains consist of only single bonds between carbons.
What is the chemical structure of a unsaturated fatty acid? (3 things)
- Unsaturated hydrocarbon chains have one or more double bonds in hydrocarbon chains.
- Form “kink” in chain.
- Polyunsaturated chains have many double bonds.
Why are unsaturated fats considered healthier?
Foods that contain lipids with double bonds are said to be healthier.
Highly _______ lipids are _____ at room temperature.
Highly saturated lipids are solid at room temperature. (Butter)
Highly ____________ are ____ at room temperature.
Highly unsaturated lipids are liquid at room temperature. (Sunflower oil)
What’s the structure of steroids as lipids? (2 things)
- Distinguished by bulky, four-ring structure
- Differ from one another by functional groups attached to carbons in rings.
What are some examples of steroids? (2 things)
- Hormones estrogen and testosterone.
- Cholesterol, component of plasma membranes.
What part of the steroid is hydrophilic versus hydrophobic?
The H-O bond at the top of the lipid is polar and hydrophilic whereas the CH3 bonds and isoprenoid tail in the rest of the lipid are nonpolar hydrophobic.
What’s the primary role of triglycerides?
Triglycerides (also called triacylglycerols) primarily store energy.
How do triglycerides form?
- Fats form by dehydration reactions between hydroxyl group of glycerol and carboxyl group of a free fatty acid.
- Glycerol and fatty acid molecules become joined by an ester linkage.
What is an ester linkage?
An “ester bond” in a triglyceride is the chemical linkage that connects a glycerol molecule to each of the three fatty acid chains, forming the triglyceride molecule. Forms a C-O-C=O with each of the three fatty acid chains.
Fats store more ______ than carbohydrates.
Fats store more potential energy than carbohydrates.
What is the chemical structure of a phospholipid?
Consists of glycerol linked to a phosphate group and two hydrocarbon chains.
What are two types of tails can a phospholipid have?
- With fatty acid tails- found in domain Bacteria and Eukarya
- With Isoprenoid tails- found in domain Archaea
What is the primary role of phospholipids?
Primary role of phospholipids is to form cell membranes.
A phospholipid contains both ______ and ______ regions.
A phospholipid contains both hydrophobic and hydrophilic regions.
What three things does the hydrophilic “head” of a phospholipid contain?
- Glycerol
- Negatively charged phosphate group
- Charged or polar group such as choline
What two things does the hydrophobic hydrocarbon “head” of a phospholipid contain?
- Nonpolar and hydrophobic
- Water molecules cannot form hydrogen bonds with tail
What does amphipathic mean?
Describes a chemical compound containing both polar (water-soluble) and nonpolar (not water-soluble) portions in its structure.
Are phospholipids amphipathic? How do their heads versus tails interact with water?
Yes, phospholipids are amphipathic. Amphipathic lipids do not dissolve in water:
- Hydrophilic heads interact with water
- Hydrophobic tails do not (they interact with one another)
What is selective permeability?
Selective permeability is the ability of a membrane to control what substances can pass through it.
Do phospholipid bilayers have selective permeability?
Yes, Phospholipid bilayers have selective permeability:
- Small/nonpolar molecules move across phospholipid bilayers quickly.
- Charged or large polar substances cross slowly.
What are examples of molecules with high permeability versus low permeability?
- High permeability- O2, CO2, and N2 (Small nonpolar molecules)
- H2O, glycerol (Small, uncharged polar molecules
* One and two can move freely without transport protein - Glucose, sucrose (Large, uncharged polar molecules)
- Low permeability- CI-, K+, NA+ (small ions)
What are two ways substances move across lipid bilayers?
- Diffusion
- Osmosis
How do substances move across lipid bilayers through diffusion? (3 things)
- Dissolved solutes in constant random motion due to thermal energy.
- Diffusion along the concentration gradient increases entropy.
- Equilibrium occurs and molecules or ions are randomly distributed in solution.
What is diffusion?
Spontaneous movement of molecules from area of higher concentration lower concentration due to random molecular motion.
What is a concentration gradient?
The difference in the concentration of molecules between two areas.
What is net movement?
Overall movement of molecules from an area of higher concentration to an area of lower concentration.
What is entrophy?
Entropy in diffusion refers to the measure of disorder in a system. In diffusion, as molecules move from high concentration to low concentration, they spread out, increasing randomness (entropy).
What is equilibrium?
Equilibrium in diffusion is the point where molecules are evenly spread out.
- In diffusion, molecules are still moving randomly.
-But there is no more net movement.
How do substances move across lipid bilayers through osmosis? (2 things)
- Water moves quickly across lipid bilayers
- Water moves from regions of low solute concentration to regions of high solute concentration.
What is osmosis?
Water moves from regions of low solute
concentration (more water) to regions of high solute
concentration (less water) to equalize concentration on both sides of the bilayer.
What is hypertonic?
Outside solution has higher concentration of solutes than
inside of cell. Net movement of water moves out of cell causing it to shrink.
What is hypotonic?
Solution inside cell has higher concentration of solutes than outside of cell. Net movement of water moves into cell causing it to swell (or even burst).
What is isotonic?
If solute concentrations are equal on outside and inside of cell, solutions are isotonic to each other.
What are channel proteins?
Channel proteins
through membrane
facilitate diffusion
What are ion channels?
Specialized membrane proteins that form pores, or openings, in membrane. Allow ions to cross membranes.
When does an electrochemical gradient occur?
Occurs when ions build up on one side of plasma membrane.
What does an electrochemical gradient establish when ions build up? (2 things)
- Establish both concentration gradient and charge gradient.
- Ions diffuse down their electrochemical gradients.
Each channel protein permits…
Each channel protein permits only particular ion or molecules to pass through.
What is passive movement?
The movement of substances through channel proteins is passive down its concentration gradient. Passive meaning movement does not require energy
What is cystic fibrosis?
Affects cells that produce mucus, sweat, and digestive juices. Secretions become abnormally concentrated—clog
pathways
What causes cystic fibrosis?
Caused by mutations in transmembrane protein CFTR (cystic-fibrosis conductance transmembrane regulator)
How does the CFTR ion channel normally activated?
In wild-type, the CFTR ion channel is gated. When activated by ATP, the channel opens and allows chloride ions to move across the membrane.
How does a mutated CFTR channel react in cases of cystic fibrosis?
In some CFTR mutants, the channel does not open.
Prevents the movement of Cl- ions (chloride) and water. Allows mucus to build up on the lung epithelium.
How common is cystic fibrosis?
Over one thousand different mutant alleles of CFTR have been described. Any mutation that prevents CFTR from sufficiently transporting ions can lead to cystic fibrosis (CF).
What is a list of polysaccharides (carbohydrates)?
- Starch
- Amylose
- Amylopectin - Glycogen
- Cellulose
- Chitin
- Peptidoglycan
What’s a list of lipids?
- Fatty acids
- Saturated/unsaturated - Steroids
- Triacylglycerols
- Phospholipids
______ lipids with long ________ tails are ____ solids at room temperature.
Saturated lipids with long hydrocarbon tails are stiff solids at room temperature. (Beeswax)
What is the chemical structure of Triglycerides?
Composed of three fatty acids linked to glycerol (C3H8O3). Large number of high-energy bonds in fatty acid chains. Tails formed by ester linkage.
Ion channel tails facing..
Residues (tails) facing inside pore are hydrophilic.
