cell bio

Selectively Permeable Membrane

A membrane that allows certain molecules to pass through while blocking others, providing a barrier between the inside and outside of the cell.

Passive Diffusion

The movement of molecules across the cell membrane without the need for energy, often involving small, nonpolar substances such as steroid hormones.

Protein Folding

The process that involves intermolecular forces, including hydrogen bonding, ionic bonding, van der Waals interactions, and hydrophobic interactions, to ensure proper structure.

Hydrolysis

A reaction that removes monomers from polymers.

Self-Assembly

The process by which molecules organize themselves into structured arrangements, which does not only occur in protein structures.

R Group

The variable side chain of an amino acid that determines its chemical nature.

DNA Stability

The stability of the DNA double helix is contributed by hydrophobic interactions between aromatic bases.

Hydrogen Bonds in DNA

The two strands of DNA are held together by hydrogen bonds, allowing separation at high temperatures.

Organic Molecules Formation

Experiments by Stanley Miller demonstrated that the first organic molecules could form abiotically in conditions present on early Earth.

Cell Size

Most plant and animal cells typically range from 50-100 mm in size.

Eukaryotic Cells

Cells that are characterized by a membrane-bounded nucleus.

Endosymbiont Theory

Proposes that mitochondria and chloroplasts were once free-living prokaryotic cells engulfed by ancestral eukaryotic cells.

Covalent Bond

A type of chemical bond that involves the sharing of electrons between atoms, which can be polar or nonpolar.

Hydrogen Bond Example

An example of a hydrogen bond in biology is the bond between complementary base pairs in DNA, such as adenine and thymine.

Hemoglobin Structure

Hemoglobin consists of two pairs of alpha and beta chains, defining its quaternary structure.

Archaea and Eukaryotes

Transcription and translation processes in Archaea are more similar to Eukaryotes than to Bacteria.

RNA World Hypothesis

The hypothesis suggesting that RNA was the first molecule to perform both genetic and catalytic functions in early life forms.

Triglycerides Function

The primary function of triglycerides in the body is providing energy storage.

Phospholipid Hydrophilic Component

The phosphate group of a phospholipid is hydrophilic.

Cholesterol Role

Cholesterol modulates membrane fluidity and stability.

Energy Storage Efficiency

Lipids are more efficient for energy storage compared to glycogen as they provide more energy per gram and can be stored with minimal associated water.

Carbon Backbone

Carbon is considered the backbone of organic molecules because it can form four stable covalent bonds.

Water as Universal Solvent

Water's polarity allows it to dissolve a wide variety of solutes.

Water and Biostructure

Water helps maintain the structure of biomolecules like proteins and nucleic acids through hydrogen bonding.

Chirality Significance

Chirality determines how molecules interact with biological systems, including enzymes and receptors.

L-amino Acids

L-amino acids are predominantly found in proteins as the synthesizing enzymes are specific for them.

DNA Polymerization

DNA molecules are polymerized with 5' and 3' orientations, similar to the amino and carboxyl terminus of proteins, representing polymer directionality.

Phospholipid Monolayer

If a polar group was added to the nonpolar tail of phospholipids, they would more likely form a lipid monolayer instead of a bilayer.

Complementary Base Pairing

In DNA, the percentage of adenine (A) should be equal to the percentage of thymine (T).

Protein A vs. Protein B

Protein A, which contains many polar amino acids, is likely a cytoplasmic protein, while Protein B, rich in hydrophobic amino acids, is likely a membrane-associated protein.

Monomer-Polymer Pair

Nucleotides are the monomers that form nucleic acids.

RNA vs. DNA

RNA contains ribose and uracil, while DNA contains deoxyribose and thymine.

Biomolecule Structure Trend

The order and bonding of monomers in biomolecules establish the basis for their secondary and tertiary structures.