Atoms and Chemical Bonds
This particle has a positive charge and is found in the nucleus.
What is a proton?
This molecule is described in the slides as essential for life and has a partial negative charge on oxygen and partial positive charges on hydrogen.
What is water?
These four major groups of biological molecules are proteins, nucleic acids, carbohydrates, and lipids.
What are the four major groups of organic molecules?
According to cell theory, this is the fundamental unit of life.
What is the cell?
The major type of lipid found in the cell membrane has a hydrophilic head and hydrophobic tails.
What is a phospholipid?
An atom has an atomic mass of 25 and contains 13 neutrons. If it is neutral, how many electrons does it have?
What is 12 electrons?
Atomic mass = protons + neutrons → 25 − 13 = 12 protons → neutral atom = 12 electrons.
The tendency of water molecules to stick to other water molecules is called this.
What is cohesion?
Proteins are built from these monomers.
What are amino acids?
Unlike eukaryotic cells, these cells lack a nucleus and membrane-bound internal organelles.
What are prokaryotic cells?
Molecules move from an area of high concentration to an area of low concentration without the cell expending energy.
What is simple diffusion?
Two atoms share electrons equally in this type of bond.
What is a nonpolar covalent bond?
A substance requires a large amount of energy to change its temperature because hydrogen bonds must be broken. This property of water is called this.
What is high specific heat?
This part of an amino acid varies between amino acids and is responsible for distinguishing one amino acid from another.
What is the R group (side chain)?
This organelle contains the cell's DNA and is the site of RNA synthesis.
What is the nucleus?
Water moves across a selectively permeable membrane from an area of low solute concentration toward an area of high solute concentration.
What is osmosis?
Oxygen and hydrogen form a covalent bond, but oxygen attracts the shared electrons more strongly. This property of oxygen explains why the bond is polar.
What is electronegativity?
A solution changes from pH 8 to pH 7. Has the H⁺ concentration increased, decreased, or stayed the same?
What is increased?
Because pH = −log[H⁺], moving from 8 → 7 means 10× more H⁺.
A scientist finds a molecule containing a five-carbon sugar, a nitrogen-containing base, and phosphate groups. Which major biological molecule is it most likely part of?
What is a nucleic acid?
A cell is producing large amounts of proteins that will either become membrane proteins or be transported elsewhere in the cell. Which organelle would be especially important?
What is the rough endoplasmic reticulum?
Ribosomes attached to the RER synthesize proteins.
A molecule cannot cross the hydrophobic interior of the phospholipid bilayer on its own, but it needs to move from high concentration to low concentration. What process could allow this?
What is facilitated diffusion?
It uses a channel or carrier, but does not require ATP.
An atom of sodium loses an electron to chlorine. Explain what happens to each atom and why the resulting particles attract one another.
What is ionic bonding?
Sodium becomes a positive ion because it loses an electron; chlorine becomes a negative ion because it gains one. Their opposite charges attract.
A red blood cell is placed into a solution with a higher solute concentration than the inside of the cell. Predict what happens to the cell and explain why.
What is the cell shrinks because water leaves by osmosis?
Higher solute outside = hypertonic → water moves toward the higher solute concentration.
Two nucleotides are joined together through this type of bond, which forms between the phosphate group of one nucleotide and the 3′-OH of another.
What is a phosphodiester bond?
A protein is synthesized in the RER and ultimately needs to be shipped to another location in the cell. Identify the major sequence of structures it would travel through.
What is RER → vesicle → Golgi apparatus → vesicle → final destination?
The Golgi modifies, sorts, and packages proteins.
A cell uses ATP to pump protons across its membrane, creating an electrochemical gradient. Another molecule then moves against its concentration gradient using the energy stored in that proton gradient. What type of transport is this?
What is secondary active transport?
Primary active transport directly uses ATP.
Secondary active transport uses a gradient created by primary active transport.