AP Biology Proteins/Enzymes/Cell Structures Quiz Review
Protein Review
- amino acid - molecular structure (C,H,O, and N); monomer for building proteins (functional groups - amino & carboxyl); 20 different amino acids - differ in R group (side chain) -- hydrophobic (nonpolar covalent bonds), positively or negatively charged (hydrophilic), and hydrophilic (polar covalent bonds - OH or NH2)
- Peptide bond - bond that connects amino acids together; formed by dehydration synthesis
- Primary level structure of polypeptide chain - polypeptide bonding only - polypeptide chain would be linear or a straight chain
- Secondary level of structure of polypeptide chain - hydrogen bonding only - each polypeptide chain would start folding into a shape
- Tertiary level of structure of polypeptide chain - bonding occurs only at R groups - hydrogen bonding, ionic bonding, hydrophobic interactions, disulfide bridges - polypeptide continues folding into a 3-D shape
- Quaternary level of structure - 2 or more polypeptide chains come together to form the complete protein - happens at the Golgi bodies
Enzymes Review
- most are proteins
- Substrate (any organic molecule) - reactant in an enzyme-controlled reaction
- Active site - region of enzyme where the substrate binds and where the chemical reaction occurs; enzymes can have multiple active sites
- Activation energy (or energy of activation Ea) - energy that must be absorbed in order for a chemical reaction to take place; *most common form of activation energy is heat; enzymes lower activation energy
- Induced fit model hypothesis - a slight change in the shape of an enzyme’s active site that enhances the fit between the enzyme’s active site and its substrate(s) → scientists thought originally that enzymes & their substrates have a perfect fit, but some scientists later on confirmed that enzymes must have slight adjustments to attach to their substrates
- Rate of reaction calculation y2 - y1 (remember that time goes in the denominator = x axis)
x2 - x1
- ↑Substrate concentration = effect on reaction rate (at the beginning,....10 sec, 30 sec = no effect; later time periods = ↑ in reaction rate; higher than the baseline);
- ↑ Enzyme concentration = effect on reaction rate (at the beginning, …. 10 sec, 30 sec = ↑ reaction rate; later time periods = no effect - Why? Because the substrate concentration is the same for every time period)
- Competitive inhibition - a form of enzyme inhibition where the substrate and inhibitor are both able to bind to the enzyme’s active site; (a product will form only when the substrate is at the active site).
- Noncompetitive inhibition - a form of enzyme inhibition where the inhibitor binds to an enzyme at a location (allosteric site) other than the active site; while the noncompetitive inhibitor is attached at this site, the enzyme shape changes and the enzyme is unable to bind to its substrate
- pH - most enzymes have an optimal pH range between 6-8; any pH below or above this range will cause the enzyme to denature (the enzyme will lose its shape and therefore will not be able to function); there will be a decrease in product being formed because the enzyme loses its shape and is unable to interact with substrates.
- Temperature - most enzymes have an optimal temperature range between 300 Celsius and 500 Celsius; any temperature below 300 Celsius will slow down the enzyme & substrate collision rates between each other BUT low temperatures don’t denature enzymes; any temperature above 500 Celsius will stop the enzyme from reacting with the substrate (↓ or no products formed since the extra heat denatured or changed the enzyme’s shape)
Topic 2.1 Cell Structure and Subcellular Components and Subcellular Components & Topic 2.2 Cell Structure and Function
- Know the following subcellular components & organelles (structures & functions):
- Nucleus (bounded by a nuclear membrane) - controls the structure and function of the cell
- Ribosome (made of ribosomal RNA & proteins) - site of protein synthesis
- Endoplasmic reticulum (rough - outer surface bounded by ribosomes; smooth - inner surface of ER) membranous system of tubules, vesicles, and sacs; rough ER - site of protein synthesis, smooth ER - site of lipid synthesis
- Lysosome -membrane-bound vesicle that contains hydrolytic enzymes for digesting macromolecules and bacteria; mostly found in animal cells; used to recycle worn-out cellular organelles
- Central vacuole - membrane-bound sac (larger than a vesicle); functions in storage of wastes, food, and water (central vacuole is mostly comprised of water); aids in maintaining turgor pressure for plant cells
- Chloroplast (double-membrane); also contains thylakoid disks (stacks of them are called a granum) and stroma (site of photosynthesis)
- Mitochondria (double-membrane) - also contains the matrix (fluid that resides within the inner membrane)
- Prokaryotic cells - lack membrane-bound organelles (but contain ribosomes, cytoplasm, genetic material (carried by a circular chromosome), cell wall & cell membrane) - example - bacterial cells
- Eukaryotic cells - genetic material (carried by a linear chromosome);contain membrane-bound organelles and ribosomes -- examples - plant, animal, fungi, and protist cells
- Endomembrane system - cellular system that consists of the nuclear membrane, rough endoplasmic reticulum, Golgi apparatus, vesicles, and cell membrane; these organelles are involved in the production, modification,transport and secretion of proteins.
Step 1 - mRNA travels from the nucleus to the ribosomes located on the endoplasmic reticulum
Step 2 - proteins are made at the ribosomes attached to the endoplasmic reticulum
Step 3 - proteins are enclosed within vesicles at the RER and travel to the Golgi complex to be modified
Step 4 - Golgi complex modifies proteins and repackages them into vesicles
Step 5 - the vesicles carrying proteins travel to the cell membrane where the proteins will be expelled. The secreted proteins will act as hormones (chemical signals).