Biomolecules II Flashcards
1
Q
Glycogen
A
- When fungi and animals absorb/ingest more α-glucose than they can use, they store some of the excess in the form of glycogen
- A polymer formed of α-glucose monomers linked through α1-4 glycosidic bonds
2
Q
Cellulose
A
- When plants need structural support, they produce β-glucose through photosynthesis and link them together to form cellulose
- A polymer formed of β-glucose monomers linked through β1-4 glycosidic bonds
3
Q
Chitin
A
- Fungi use β-glucose monomers and link them together to form the polymer chitin
- A chitin polymer is formed of β-glucose monomers linked through β1-4 glycosidic bonds
4
Q
Neutral Fats
A
- Major type of lipid
- Fats used for energy storage, insulation, and protecting your internal organs
- Constructed from two types of molecules: Fatty acid and Glycerol
- Fatty acid molecules can be linked to a glycerol molecule through a condensation reaction to form an ester bond
5
Q
Phospholipids
A
- Function: Major constituents of cell membranes, also forms lipoproteins
- Structure: 2 fatty acid molecules, 1 glycerol molecule, 1 phosphate molecule
- Phospholipids are amphipathic as they contain both hydrophilic and hydrophobic groups in the same molecule (hydrophilic head, hydrophobic tail)
6
Q
Steroids
A
- Function: Constituents of cell membranes (cholesterol), components of vitamins, components of hormones
- Structure: Made from sterol – four fused rings composed of 20 bonded carbon atoms bonded
7
Q
Fatty Acid
A
- One type of molecule used to construct a neutral fat
- Fatty acids are found in nature in either a saturated or unsaturated state
8
Q
Glycerol
A
- The other type of molecule used to construct a neutral fat
- A single glycerol molecule can hold either 1, 2 or 3 fatty acids
9
Q
Ester Bond
A
- When fatty acid molecules are linked to a glycerol molecule through a condensation reaction, an ester bond is formed
10
Q
Saturated Fatty Acid
A
- “Classical” one
- All carbon atoms in the hydrocarbon chain are connected to each other by single covalent bonds
- Known as “saturated” because every single carbon has a maximum number of hydrogens attached to it
- Solid at room temperature (butter)
11
Q
Unsaturated Fatty Acid
A
- Most carbon atoms in the hydrocarbon chain are linked by single bonds, but some carbon atoms are linked by double bonds
- Missing some hydrogen atoms, therefore not “saturated” with hydrogen
- Liquid at room temperature (vegetable oil)
12
Q
Lipoproteins
A
- Hydrophobic fats must be circulated through the blood by way of specialized transport proteins called lipoproteins
13
Q
High Density Lipoproteins (HDL)
A
- HDL particles remove fats and cholesterol from cells and from the circulatory system and transport it back to the liver for excretion or re-utilization
- AKA good cholesterol
14
Q
Low Density Lipoproteins (LDL)
A
- Carry cholesterol from the liver to cells of the body
- LDL particles can also transport fat molecules into the artery wall, and start the formation of plaques
- AKA bad cholesterol
15
Q
Membrane
A
- Incredibly versatile and critical structures to the function of the cell
- Found both inside the cell (in eukaryotes) and surrounding the entire cell (in both prokaryotes and eukaryotes)
- Act as the gatekeepers controlling what enters or leaves the cell
- Are how the cell senses and responds to its environment (responds to external stimuli)
- Protects themselves and maintain their internal environment (homeostasis)
- Generate electrochemical gradients that allow them to convert chemical or light energy to biological energy
16
Q
What biomolecules are important in cell membranes and why?
A
- Lipids: main structure and adjacent compounds
- Proteins: transport, electrochemical gradient, signaling
- Carbohydrates (cell to cell recognition)
17
Q
Bilayer
A
- Phospholipids are organized into a lipid bilayer
- Hydrophilic heads on the outside
- Hydrophobic tails contained within the membrane
- Within the lipid bilayer, the phospholipids are mobile (turn on their axis, move laterally in any direction over the surface of the membrane, flipping across membrane is rare)
18
Q
How are cell membranes fluid?
A
- The type of fatty acid chains in the phospholipid
- Increasing the number of saturated fatty acids will decrease membrane fluidity
- Increasing the number of unsaturated fatty acids will increase membrane fluidity - The presence of cholesterol
- Cholesterol is amphipathic, with both hydrophobic and hydrophilic parts
- The hydrophilic group binds to the phospholipid head and the hydrophobic tail binds to the hydrophobic tail of the adjacent phospholipid
- Helps maintain the integrity of membranes by preventing membranes from becoming either too fluid or too rigid
19
Q
Fluid Mosaic Model
A
- Current understanding of membrane structure is referred to as the fluid mosaic model
- Emphasizes the movement of phospholipids in the membrane
20
Q
Cell Membrane Carbohydrates
A
- Membrane bound carbohydrates are involved in cell-to-cell recognition
- Types of membrane carbohydrates are differentiated based on what they are attached to in the membrane
- Glycolipids and glycoproteins
- Membrane carbohydrates are shaped to bind to specific compounds (like a lock and key)
20
Q
Glycolipids
A
- Lipid with carbohydrate attached
- Carbohydrates covalently bonded to lipids
21
Q
Glycoproteins
A
- Protein with carbohydrate attached
- Carbohydrates covalently bonded to proteins
22
Q
Cell Membrane Proteins
A
- Proteins associate with membranes in one of two ways: peripheral membrane proteins and integral membrane proteins
- Proteins in cell membranes act as transporters, receptors, enzymes, and anchors
23
Q
Peripheral Membrane Proteins
A
- Temporarily associated with integral membrane proteins through hydrogen bonds
- Easily separated from the membrane
- Play a role in transmitting information received from external signals
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Integral Membrane Proteins
- These proteins cross the membrane, lead from extracellular space to intracellular space
- Composed of three regions: 2 hydrophilic regions and 1 hydrophobic region
- Hydrophobic region is embedded in the membrane
- Hydrophilic regions extend outside the membrane
25
Receptor Proteins
- Accept (binds) a signal outside the membrane
- Causes a change in protein shape by alerting the cell of the reception of the signal
26
Enzyme Proteins
- Membrane proteins which facilitate a chemical reaction
27
Anchor Proteins
- Anchor lipids found outside (extracellular) or inside (intracellular) the cell
28
Transport Proteins
- Regulate movement of ions and small molecules across the membrane
- This is the most complex and important function of the membrane
29
Passive Transport
- Form of movement across the membrane
- No energy is invested in order to move molecules across the cell membrane
- Takes advantage of diffusion and osmosis
30
Active Transport
- Form of movement across the membrane
- Energy must be invested in order to move molecules across the cell membrane
- Cannot take advantage of diffusion or osmosis
- Moves solutes against a concentration or electrochemical gradient
31
Diffusion
- Form of movement across the membrane
- Energy must be invested in order to move molecules across the cell membrane
- Cannot take advantage of diffusion or osmosis
- Moves solutes against a concentration or electrochemical gradient
32
Osmosis
- Water in cells contains dissolved solutes
- When water has dissolved solutes and a semi-permeable membrane, it results in osmosis
33
Facilitated Transport
- Method of passive transport
- Many polar or large molecules cannot pass freely through the plasma membrane (ex: water, proteins, sugars, ions)
- They require membrane bound proteins to open a path through the hydrophobic region of the lipid bilayer
- Compounds are transported across the membrane through integral membrane proteins
- Two types of proteins involved: channel proteins and carrier-mediated proteins
34
Concentration Gradients
- Passive transport generally depends on concentration gradients
- Items move across in the membrane from an area of higher concertation to lower concentration
35
Electrochemical Gradient
- The spaces on either side of a membrane in the cell usually have different net charges
- One side will be more positive than the other
- The differences in charges is called an electrochemical gradient
- Electrochemical gradients influence the movement of ions and charged molecules during passive transport (move from region of high charge to low charge)
36
Channel Proteins
- Molecules (mainly ions) move down their concentration gradient or electrochemical gradient)
- Proteins can exclude the passage of molecules based on size (too large) or charge
- However, any molecule that fits the size and charge requirements flows freely through
37
Carrier Proteins
- Much more specific than channel proteins
- Contains a specific binding site (lock and key) for a specific compound
- Binding that compound causes a change in protein shape
- The change in shape moves the chemical to the other side of the membrane
38
Semi-Permeable
- Allowing certain substances to pass through it but not others, especially allowing the passage of a solvent but not of certain solutes
39
Aquaporins
- Water molecules cross the cell membrane through special channel proteins called “aquaporins”
- Water molecules move from an area of low solute concentration to high solute concentration
- Aquaporins ONLY allow for the passage of water molecules
- The presence of aquaporins in a membrane creates a semi-permeable membrane for water transport
40
Primary Active Transport
- Directly spends energy to move solutes across the membrane (energy source: ATP)
- Uses integral membrane proteins
- Generally binds compounds for transport (similar to carrier proteins of passive transport)
- Reinforces existing electrochemical gradients across the plasma membrane
- Results in stored potential energy across the membrane (this energy is then used in secondary active transport)
41
Secondary Active Transport
- Uses a pre-existing electrochemical gradient (ATP or other energy molecules = not involved)
- Defined by the cotransport of two different solutes through the same transport protein (one solute is moving with its concentration gradient, one solute is moving against its concentration gradient)
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3 Domains of Life
Bacteria, Archaea, Eukarya
