molecular bio

What is the function of the nucleus?

Stores the cell’s DNA and is the major site of DNA replication and transcription.

What is the function of mitochondria?

Produce ATP through cellular respiration.

What is the function of the rough ER?

Synthesizes and processes proteins associated with membranes or secretion.

What is the function of the smooth ER?

Lipid synthesis and other metabolic functions.

What is the function of the Golgi apparatus?

Modifies, sorts, and packages proteins and lipids.

What is a model organism?

An organism studied to understand biological processes that may apply to other organisms.

What does bright-field microscopy use?

Visible light passing through the specimen.

What is phase-contrast microscopy especially useful for?

Viewing living, unstained cells.

What does fluorescence microscopy detect?

Fluorescent molecules used to label specific structures or molecules.

What is the advantage of confocal microscopy?

Produces sharper optical sections and can be used to create 3D images.

What does TEM show?

Internal cellular structures at very high resolution.

What does SEM show?

Detailed surface structures of specimens.

What is FRET used to study?

Whether two molecules are very close to each other, often indicating molecular interactions.

What is STORM?

A super-resolution fluorescence microscopy technique that can visualize structures beyond the normal diffraction limit.

What is subcellular fractionation?

Separating cellular components or organelles, usually using centrifugation.

What is a primary cell culture?

Cells taken directly from tissue and grown in culture.

What is an immortalized cell line?

Cells capable of dividing indefinitely in culture.

What is a plant callus?

A mass of relatively undifferentiated plant cells grown in culture.

What is a bacteriophage?

A virus that infects bacteria.

What is a retrovirus?

An RNA virus that uses reverse transcription to produce DNA.

Why is water polar?

Oxygen attracts shared electrons more strongly than hydrogen, creating partial charges.

What does hydrophilic mean?

Having an affinity for water

usually polar or charged.

What does hydrophobic mean?

Avoiding interaction with water

usually nonpolar.

Why do phospholipids spontaneously form membranes?

Their hydrophilic heads interact with water while hydrophobic tails avoid water.

What are the four major classes of biological macromolecules?

Carbohydrates, lipids, nucleic acids, and proteins.

What is a monosaccharide?

A single sugar molecule.

What is a disaccharide?

Two monosaccharides joined together.

What is a polysaccharide?

A polymer composed of many monosaccharides.

What type of bond connects sugars?

A glycosidic bond.

What is glycogen used for?

Glucose storage in animals.

What is starch used for?

Glucose storage in plants.

What is cellulose used for?

Structural support in plant cell walls.

What is chitin used for?

Structural support, including fungal cell walls and arthropod exoskeletons.

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids have no C=C double bonds

unsaturated fatty acids contain one or more.

What is a triacylglycerol?

Glycerol attached to three fatty acids

primarily used for energy storage.

What are the major parts of a phospholipid?

A hydrophilic head group and hydrophobic fatty-acid tails.

What is sphingomyelin?

A membrane lipid classified as a sphingolipid.

What is a glycolipid?

A lipid containing a carbohydrate group.

How does cholesterol affect membranes?

It helps regulate membrane fluidity.

What type of molecule are steroid hormones derived from?

Cholesterol.

What sugar is found in DNA?

Deoxyribose.

What sugar is found in RNA?

Ribose.

Which base is found in DNA but not RNA?

Thymine.

Which base is found in RNA instead of thymine?

Uracil.

What bases pair in DNA?

A–T and G–C.

What is the central dogma?

DNA → RNA → protein.

What are proteins made from?

Amino acids.

What type of bond joins amino acids?

Peptide bonds.

What is the primary structure of a protein?

Its amino-acid sequence.

What is secondary protein structure?

Local structures such as α-helices and β-sheets.

What is tertiary protein structure?

The overall 3D structure of a single polypeptide.

What is quaternary protein structure?

The arrangement of multiple polypeptide subunits.

Which amino acid forms disulfide bonds?

Cysteine.

Which amino acids are commonly phosphorylated?

Serine, threonine, and tyrosine.

Why is proline unusual?

Its rigid structure can introduce bends or disrupt regular secondary structures.

What is a protein domain?

A structurally and/or functionally distinct region of a protein.

What is an enzyme?

A biological catalyst that increases the rate of a chemical reaction.

What is a codon?

A three-nucleotide sequence that specifies an amino acid or translation signal.

What is the usual start codon?

AUG.

What do stop codons do?

Signal termination of translation.

What does DNA replication accomplish?

Copies DNA before cell division.

What does transcription produce?

RNA from a DNA template.

What does translation produce?

Protein using information encoded in mRNA.

What is recombinant DNA?

DNA formed by combining DNA sequences from different sources.

What does gel electrophoresis do?

Separates biological molecules based largely on size and charge.

What does PCR do?

Amplifies a specific DNA sequence.

What is DNA sequencing used for?

Determining the nucleotide sequence of DNA.

What is nucleic-acid hybridization?

Complementary nucleic-acid strands binding to each other.

What does a Western blot detect?

Specific proteins.

What does immunofluorescence allow scientists to do?

Use fluorescent antibodies to locate proteins within cells or tissues.

What is ELISA commonly used to detect?

Specific proteins, antigens, or antibodies.

Why are antibodies useful experimentally?

Their specificity allows them to recognize particular molecular targets.

What is CRISPR commonly used for?

Targeted modification of DNA.

What is RNA interference?

Gene silencing mediated by small RNAs that reduce expression of a target RNA.

What is genomics?

The study of entire genomes.

What is transcriptomics?

The study of the complete set of RNAs expressed by a cell or organism.

What is proteomics?

The study of the complete set of proteins expressed by a cell or organism.

What is the microbiome?

The collection of microorganisms associated with a particular environment or organism.

What is systems biology?

Studying biological components as interacting systems rather than individually.

What is an exon?

A sequence retained in the mature RNA after splicing.

What is an intron?

A sequence removed from pre-mRNA during RNA splicing.

What is alternative splicing?

Producing different mature RNAs from the same gene by combining exons in different ways.

What is a nucleosome?

DNA wrapped around histone proteins.

What is chromatin?

DNA together with its associated proteins.

What is euchromatin?

Less condensed chromatin generally associated with greater transcriptional accessibility.

What is heterochromatin?

More highly condensed chromatin generally associated with reduced transcriptional accessibility.

What is a centromere?

A specialized chromosome region important for chromosome segregation.

What forms at the centromere?

The kinetochore.

What is the kinetochore?

A protein structure that connects chromosomes to spindle microtubules.

What are telomeres?

Specialized DNA-protein structures protecting chromosome ends.

What is telomerase?

An enzyme that extends telomeric DNA.

What is shelterin?

A protein complex associated with and protecting telomeres.

In what direction does DNA polymerase synthesize DNA?

5′ → 3′.

In what direction is the template strand read?

3′ → 5′.

What does DNA polymerase proofreading do?

Removes incorrectly incorporated nucleotides during replication.

What is the leading strand?

The DNA strand synthesized continuously toward the replication fork.