Exam 2 Study Guide and Terms Flashcards
What is microbial metabolism?
The chemical engine that drives Earth’s biosphere
Eukaryotes depend on organic molecules, while prokaryotes can use both organic and inorganic materials.
What is metabolism?
All the chemical reactions that occur within a cell
Think of it as the cell’s ‘factory work’.
Define metabolic pathways.
A series of interconnected chemical reactions
It functions like a step-by-step ‘assembly line’.
What are exergonic reactions?
Reactions that occur spontaneously by releasing energy
Mnemonic: ‘Exit energy’.
What are endergonic reactions?
Reactions that require energy to occur
Mnemonic: ‘End in energy’.
Define anabolism.
Building up complex molecules, which requires energy
It is an endergonic process.
Define catabolism.
Breaking down complex molecules, which releases energy
It is an exergonic process.
What is oxidation?
Removal of electrons from a molecule
Mnemonic: ‘Oxygen takes electrons away’.
What is reduction?
Addition of electrons to a molecule
Mnemonic: ‘Reduce means to add electrons’.
What are energy carriers?
Key molecules include NAD⁺, NADP⁺, FAD, ATP
They transport high-energy electrons or phosphate groups.
What is the role of enzymes?
Proteins that act as catalysts to speed up chemical reactions
They lower the activation energy required for reactions.
Define glycolysis.
The breakdown of glucose into pyruvate
Occurs in the cytoplasm and is considered an ancient process.
What is cellular respiration?
Involves glycolysis, the Krebs cycle, and the electron transport system
Most ATP is generated via oxidative phosphorylation.
What is fermentation?
An anaerobic process that regenerates NAD⁺ from NADH
It allows glycolysis to continue when respiration fails.
What are lipases?
Enzymes that break down triglycerides
They play a role in lipid catabolism.
What is β-oxidation?
The process of breaking down fatty acids into acetyl groups
This occurs during lipid catabolism.
Define photosynthesis.
The conversion of sunlight into chemical energy
Occurs in chloroplasts in eukaryotes.
What is a genome?
The complete set of DNA in a cell
It includes all genetic material of an organism.
What is the central dogma of molecular biology?
DNA → RNA → Protein
It describes the flow of genetic information.
Define semiconservative replication.
Each new DNA molecule contains one original and one newly synthesized strand
This is the mechanism of DNA replication.
What is RNA polymerase?
The enzyme that synthesizes RNA from DNA
It plays a key role during transcription.
What is a codon?
A triplet of nucleotides that corresponds to a specific amino acid
There are 64 possible codons.
What is a silent mutation?
A change in DNA that does not change the amino acid
It has no effect on the protein’s function.
What is transduction?
Transfer of DNA by viruses
This is one mechanism of gene transfer in prokaryotes.
What is transformation?
Uptake of free DNA from the environment
It is another mechanism of gene transfer in prokaryotes.
What is conjugation?
Direct transfer of DNA from one cell to another via physical contact
It involves a pilus for connection.
What is Pre-mRNA?
The initial RNA transcript that undergoes processing.
What is the purpose of the 5’ Cap?
A modified nucleotide added to the 5’ end of pre-mRNA for protection.
What is a Poly-A Tail?
A chain of adenine nucleotides added to the 3’ end of mRNA for stability.
Define Exon.
A coding sequence in a gene that remains in the final mRNA.
What is an Intron?
A non-coding sequence removed from pre-mRNA during processing.
Define Codon.
A set of three nucleotides in mRNA that codes for an amino acid.
What is the Wobble Position?
The third nucleotide in a codon with flexible base-pairing.
What does Degeneracy refer to in genetics?
The redundancy of the genetic code (multiple codons per amino acid).
What is a Stop Codon?
A codon that signals the end of protein synthesis.
What is the Start Codon?
The codon (AUG) that initiates translation.
Define Reading Frame.
The division of nucleotides into consecutive codons.
What is a Silent Mutation?
A mutation that does not change the amino acid sequence.
Define Missense Mutation.
A mutation that substitutes one amino acid for another.
What is a Nonsense Mutation?
A mutation that converts a codon into a stop codon.
Define Frameshift Mutation.
An insertion or deletion that shifts the mRNA reading frame.
What is a Mutagen?
An agent (chemical or radiation) that causes mutations.
Define Carcinogen.
A substance that can lead to cancer, often by causing mutations.
What is Transduction?
Gene transfer mediated by a virus.
Define Transformation in genetics.
Uptake of free DNA from the environment by a cell.
What is Conjugation?
Direct DNA transfer between cells through physical contact.
What is Metabolism?
All chemical reactions in a cell.
Define Metabolic pathways.
Chains of reactions that build or break down molecules.
What is Anabolism?
Builds complex molecules (uses energy, endergonic).
What is Catabolism?
Breaks down molecules (releases energy, exergonic).
What do Redox Reactions involve?
Oxidation and Reduction processes.
What is Oxidation?
Loss of electrons (OIL: Oxidation Is Losing).
Define Reduction.
Gain of electrons (RIG: Reduction Is Gaining).
What are Energy Carriers?
NAD⁺/NADH, FAD/FADH₂ that carry electrons for energy transfer.
What is ATP?
Stores energy in phosphate bonds.
What is the role of Enzymes?
Catalysts that speed up reactions without being consumed.
Define Active site.
Where substrates bind on an enzyme.
What are Cofactors/Coenzymes?
Assist enzymes (e.g., NADH, ATP).
What occurs during Glycolysis?
Splits glucose (6C) into 2 pyruvate (3C) with 2 ATP and 2 NADH produced.
Where does the Krebs Cycle occur?
In mitochondria, generating NADH/FADH₂ and CO₂.
What does the Electron Transport System (ETS) do?
Uses NADH/FADH₂ to create ATP via oxidative phosphorylation.
What is Fermentation?
Regenerates NAD⁺ for glycolysis when oxygen is absent.
What is Lactic Acid Fermentation?
Produces lactic acid (e.g., in muscle cells).
What does Alcoholic Fermentation produce?
Produces ethanol (e.g., in yeast).
What does Lipase do?
Breaks triglycerides into glycerol + fatty acids.
Define β-oxidation.
Breaks fatty acids into acetyl-CoA.
What do Proteases do?
Break proteins into amino acids.
What is the Central Dogma?
DNA → RNA → Protein.
What is Transcription?
RNA polymerase creates mRNA from DNA template.
What signals the start of Translation?
Start codon: AUG (methionine).
What are Stop codons?
UAA, UAG, UGA that signal the end of protein synthesis.
What is Semiconservative Replication?
Each new DNA has one old + one new strand.
What does Helicase do?
Unzips DNA strands.
What is the role of DNA Polymerase?
Adds nucleotides during replication.
What is the function of Ligase?
Seals gaps in DNA.
What are Telomeres?
Protect chromosome ends; maintained by telomerase.
Define Mutation.
Change in DNA sequence.
What is a Genotype?
Genetic makeup of an organism.
What is a Phenotype?
Observable traits of an organism.
What is a Plasmid?
Circular extra DNA in bacteria.
What is an Operon?
Cluster of genes regulated together.
What does the Spliceosome do?
Removes introns from pre-mRNA.
Fill in the blank: The central dogma of molecular biology is _______.
DNA → RNA → Protein.
