Biochemistry Lipids and Membranes Quiz

A simple sugar with a single sugar unit, the basic building block of all carbohydrates.

Two monosaccharide units covalently linked together.

A long chain of many monosaccharides linked together.

A covalent bond that links monosaccharides together in disaccharides and polysaccharides.

A type of organic molecule with a long hydrocarbon chain ending in a carboxyl group (-COOH).

A glycerol molecule with three fatty acid tails attached.

A 3-carbon molecule with a hydroxyl (OH) group attached to each carbon.

A fatty acid with no double bonds between carbons.

A fatty acid with one or more double bonds between carbons.

A weak attraction between molecules due to temporary fluctuations in electron distribution.

The temperature at which a substance changes from a solid to a liquid.

A type of lipid molecule with a characteristic four-ring structure.

A type of carbohydrate that is a long, branched chain of monosaccharides.

A monosaccharide with an aldehyde group on one end.

A monosaccharide with a ketone group on one end.

Molecules that provide structure and carry out functions in the cell.

The synthesis of RNA from a DNA template.

The synthesis of proteins from an RNA template.

The central dogma outlines the flow of genetic information from DNA to RNA to proteins.

A segment of DNA that corresponds to a functional product, like a protein.

The process where DNA is copied to create two identical DNA molecules.

Errors that occur during DNA replication.

The sum of chemical reactions that occur within an organism to sustain life.

A form of energy that cells use to carry out functions.

The theory that all living organisms are composed of cells, which are the fundamental unit of life, and that all cells arise from pre-existing cells.

Simple, single-celled organisms that lack a nucleus and other membrane-bound organelles.

Complex, single or multi-celled organisms that have a nucleus and other membrane-bound organelles.

Specialized compartments within eukaryotic cells that perform specific functions.

A small, circular DNA molecule found in some bacteria that is separate from the main chromosome.

A type of lipid with a core of four fused carbon rings. It is hydrophobic and plays a crucial role in cell membranes. It also serves as a precursor for critical hormones such as estrogen and testosterone.

A type of lipid that forms the basis of cell membranes. It has a glycerol backbone, a phosphate group, and two fatty acid tails.

A molecule that has both hydrophilic and hydrophobic regions. These molecules tend to self-assemble in aqueous environments, with their polar heads facing the water and their nonpolar tails facing inwards.

Spherical structures formed by lipids with bulky heads and a single hydrophobic tail. These structures form when lipids are added to water.

A structure formed by two layers of lipids, with their hydrophobic tails facing inwards and their hydrophilic heads facing outwards. It is the primary structure of cell membranes.

Spherical structures, similar to cells, formed by phospholipids in an aqueous environment. The bilayer creates a closed structure with an internal space.

The outermost layer of a cell. It forms a barrier between the cell's internal environment and the surrounding environment, controlling what enters and leaves the cell.

They are embedded within cell membranes and play various roles in transporting molecules, signaling, and anchoring the membrane to other structures.

The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments due to the antiparallel nature of DNA strands.

An enzyme that removes RNA primers from newly synthesized DNA and replaces them with DNA nucleotides.

The process by which DNA polymerase checks for and corrects errors during DNA replication, ensuring accuracy.

A specific sequence of DNA where DNA replication begins, often rich in adenine and thymine bases.

A Y-shaped structure formed during DNA replication where the double helix is unwound, exposing the template strands for copying.

A region of DNA that is actively being replicated, marked by two replication forks moving in opposite directions.

An enzyme that helps unwind the DNA double helix during replication, relieving torsional stress caused by unwinding.

An enzyme that breaks the hydrogen bonds between the two DNA strands, separating them for replication.

Saturated fatty acids have a straight chain structure due to the absence of double bonds, leading to tighter packing and reduced mobility. Unsaturated fatty acids, containing double bonds, have kinks in their structure, resulting in looser packing and increased mobility.

Cholesterol, a major component of animal cell membranes, is amphipathic, meaning it has both hydrophobic and hydrophilic regions. This allows it to insert itself into the lipid bilayer.

At high temperatures, cholesterol interacts with phospholipids, reducing their movement and stabilizing the membrane structure. At low temperatures, cholesterol prevents tight packing of phospholipids, increasing fluidity and preventing membrane solidification.

Lipid rafts are specialized areas in the cell membrane enriched with specific lipids, cholesterol, and proteins. These rafts can serve as platforms for various cellular functions.

The movement of lipids between the two layers of the membrane, called lipid flip-flop, is a rare event due to the difficulty of the hydrophilic head passing through the hydrophobic interior of the membrane.

The two layers of the cell membrane often have different lipid compositions, contributing to the membrane's asymmetric nature and specialized functions.

Integral membrane proteins are permanently embedded within the cell membrane and cannot be easily separated from it. They often have transmembrane domains, spanning the lipid bilayer.

Peripheral membrane proteins are temporarily associated with the lipid bilayer through weak non-covalent interactions, like hydrogen bonds. They can interact with lipid heads or integral membrane proteins.

Proteins often exhibit lateral movement within the cell membrane, contributing to the dynamic nature of the membrane and its ability to adapt to changing conditions.

The cell membrane is selectively permeable, allowing some molecules to pass through while restricting others. This property is essential for maintaining cellular homeostasis.

The hydrophobic interior of the lipid bilayer prevents the passage of ions and charged polar molecules. Transport proteins facilitate the movement of these molecules across the membrane.

Passive transport occurs when molecules move across the cell membrane down their concentration gradient, from a region of higher concentration to a region of lower concentration, without the expenditure of energy.

Simple diffusion is a type of passive transport where molecules move directly through the lipid bilayer, while facilitated diffusion utilizes protein channels or carriers to facilitate the movement of molecules down their concentration gradients.

Aquaporins are specialized channel proteins that facilitate the movement of water across the cell membrane, allowing water to pass through much more readily than through simple diffusion.

Osmosis is the movement of water across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration, or from a region of lower solute concentration to a region of higher solute concentration.

Active transport, unlike passive transport, requires energy, typically in the form of ATP, to move molecules against their concentration gradient, from a region of lower concentration to a region of higher concentration.

A type of amino acid with a small, nonpolar R group that is just a hydrogen atom. This makes it highly flexible and able to fit into tight spaces within proteins.

A type of amino acid with a sulfur-containing R group (SH group) that can form disulfide bonds, creating strong links within or between proteins.

A covalent bond that links amino acids together, forming a polypeptide chain. It involves the reaction between the carboxyl group of one amino acid and the amino group of the next.

A chain of amino acids linked by peptide bonds. It can consist of a few hundred amino acids and can be folded into complex 3D structures to form proteins.

The sequence of amino acids in a protein, which determines the unique primary structure of the protein. This sequence ultimately influences how the protein folds and functions.

Local, repeating structures within a polypeptide chain, such as alpha-helices and beta-sheets. These structures arise from hydrogen bonding between backbone atoms.

The overall 3D shape of a single polypeptide chain, determined by interactions between amino acid side chains. This shape is crucial for protein functionality.

The arrangement of multiple polypeptide subunits (individual proteins) that come together to form a functional protein complex.

A process where a protein loses its structure and function due to disruptions in the interactions that maintain its folded form. This can be caused by factors like heat or chemicals.

A coiled structure in a polypeptide chain stabilized by hydrogen bonds between carbonyl (C=O) and amide (N-H) groups. R groups project outwards, influencing the helix's location in the folded protein.

A sheet-like structure formed by hydrogen bonding between polypeptide chains that run parallel or antiparallel to each other. It's stabilized by hydrogen bonds between carbonyl and amide groups in adjacent chains.

The process where proteins fold into their specific 3D structures, driven by interactions between amino acid side chains. Hydrophilic and hydrophobic interactions play a major role.

The specific sequence of amino acids in a protein determines its primary structure and consequently its folding and 3D shape. This relationship is crucial for protein function.

The 3D shape of a protein determines its function because it dictates the formation of active sites where molecules can bind and react.

A coiled structure found in proteins formed by the interaction of amino acid side chains. It contributes to the protein's overall 3D shape.

A short segment of a protein made up of several amino acids that has a specific function (like binding to another molecule) and can be repeated multiple times in a protein.