Chemistry of Life
Type of bond where shared electrons are likely to be closer to the more electronegative atom
Polar covalent bond
Type of bond that forms between the hydrogen atom of one polar molecule and an electronegative atom of another molecule
Hydrogen bond
Name the components of a phospholipid
Phosphate, glycerol, and 2 fatty acid tails
Name the components of a DNA nucleotide
Nitrogenous base (either A, T, C, or G), 5-carbon deoxyribose sugar, and phosphate group
Name the bonds that link amino acids in a polypeptide chain and the functional groups they are found between
Peptide bonds that are found between the carboxyl and amino groups
Oxygen has 6 valence electrons. Predict how many bonds it can form and explain why
2 covalent bonds because it needs to gain 2 more electrons to fill its outer shell with 8 electrons to follow the octet rule
Predict the relative pH and hydrogen ion concentration of a strong acid like HCl, which is found in the stomach
Stomach acid has a low pH and a high concentration of hydrogen ions
Explain the difference between passive transport and active transport
In passive transport, substances move along their concentration gradient and cross the membrane through simple diffusion, facilitated diffusion, or osmosis. In active transport, ATP is used to move substances against their concentration gradients.
Explain why the sugar-phosphate backbone of DNA is linked by phosphodiester bonds and the base pairs are linked by hydrogen bonds
Phosphodiester bonds are covalent, which are strong bonds that provide stability. Hydrogen bonds are weak and can be easily broken to separate the DNA strands for transcription
Determine the tRNA anticodon if the mRNA codon is GCA
CGU
Compare hydrolysis to dehydration synthesis using the terms polymer and monomer
Hydrolysis breaks a polymer into its monomers by adding water to break a bond. Dehydration synthesis forms a polymer by removing water to join the monomers together
Explain how detergent molecules forms micelles in water
Detergent molecules are amphipathic, meaning that the hydrophilic heads face outwards towards the water and the hydrophobic tails point inwards, forming spherical micelles that trap dirt and oils
Explain what happens to a cell in a hypotonic enviornment
Water moves into the cell since there is a higher concentration of water outside, and solutes move out of the cell since there is a lower concentration outside. This causes the cell to swell.
Determine the template strand and mRNA if the coding strand is 5’ ATG CAA 3’
Template strand = 3’ TAC GTT 5’; mRNA = 5’ AUG CAA 3’
If an enzyme has an optimal temperature of 37°C (body temperature), predict what will happen if the body has a high fever
The body will experience a higher than optimal temperature, which will cause the enzyme to begin to denature and lower its activity
Glucose has many hydroxyl groups. Explain if it is hydrophobic or hydrophilic
Hydrophilic because these functional groups are polar and can form hydrogen bonds with water
Explain why oil is not soluble in water
Water is polar and can only dissolve other polar substances. Since oil is nonpolar, it is not soluble in water because water can't form hydrogen bonds with it
If there is a high concentration of glucose outside a cell, explain how it enters
Glucose enters through facilitated diffusion. It binds to a specific carrier protein in the membrane, which changes shape and transports it into the cell without ATP
Explain how 1 gene can produce multiple proteins
Genes are transcribed into pre-mRNA, which can be alternatively spliced by spliceosomes to create mRNAs with different combinations of exons. These mRNAs are translated into different proteins
If a mutation in DNA causes a stop codon in the middle of the mRNA, predict what would happen during translation
Translation would stop prematurely and the polypeptide would be shorter than it was supposed to
Explain how different functional groups in the side chains of amino acids influence protein folding in water
Side chains with polar and charged functional groups face outward and interact with water, while side chains with nonpolar functional groups are folded inward away from water
Explain how sweating lowers body temperature and predict if the body cools down faster in a humid or dry environment
Sweat absorbs heat from the body, turning it into a vapor that carries the heat away when it evaporates. Your body cools down faster in a dry environment because there is less water vapor in the air
Predict what would happen to plant cells if you watered a plant with salt water
The plant cells would shrivel since the salt concentration would be higher outside the cell, causing water to diffuse out
Predict what would happen if a mutation prevents RNA polymerase from binding to the promoter
The gene would not be transcribed to mRNA and no protein would be produced, which could prevent a cell from performing its function
Explain how protein structure and function would be affected if a mutation changed a polar amino acid in the polypeptide chain to a nonpolar one
The tertiary structure would be affected because the nonpolar R-group will want to fold inward. This would alter the protein’s 3D structure and prevent it from functioning normally