Chapter 04 Cellular Metabolism flashcards

A set of QUESTION_AND_ANSWER style flashcards covering key concepts from cellular metabolism, energy, DNA, transcription/translation, and related topics from the lecture notes.

What is metabolism?

Metabolism is the sum of all chemical reactions in the body.

What is cellular metabolism?

Cellular metabolism is the sum of all chemical reactions occurring in a cell, usually organized into pathways or cycles.

What are the two types of metabolic reactions and their basic characteristics?

Anabolism builds small molecules into larger ones and requires energy; catabolism breaks larger molecules into smaller ones and releases energy.

Define dehydration synthesis.

A reaction where smaller molecules are bound together to form larger ones with water (H2O) produced in the process.

Define hydrolysis.

A reaction that uses water to split substances, breaking larger molecules into smaller ones; the reverse of dehydration synthesis.

What are enzymes and what do they do?

Enzymes are protein catalysts that increase the rate of chemical reactions, lower activation energy, are not consumed, and are specific to substrates.

What is activation energy in enzyme action?

The minimum energy required to start a chemical reaction, which enzymes lower to increase reaction rates.

What determines enzyme specificity?

The shape of the enzyme’s active site determines which substrate it can bind.

How are many enzymes commonly named?

Many enzymes are named after their substrate with the suffix -ase, e.g., lipase breaks down lipids.

What is a rate-limiting enzyme?

A regulatory enzyme that catalyzes a key step in a pathway and typically sets the overall rate for the sequence; often the first enzyme and can be inhibited by the end product (negative feedback).

What is a cofactor?

A non-protein substance that activates or helps enzymes, may be an ion, element, or small organic molecule (coenzyme).

What is a coenzyme?

An organic molecule that acts as a cofactor, most are vitamins essential in the diet.

What is denaturation?

Inactivation of a protein (including enzymes) due to irreversible change in its conformation, preventing substrate binding.

What is an inborn error of metabolism?

A condition where a missing or deficient enzyme blocks a metabolic pathway, causing substrate accumulation and product deficiency (e.g., PKU).

What forms of energy does ATP store and transfer?

ATP stores chemical energy in its phosphate bonds and transfers energy to drive cellular work; it is part of a cycle with ADP and phosphate (phosphorylation).

What happens to energy during cellular respiration?

Energy from nutrients is transferred to ATP; about 40% becomes chemical energy in ATP and about 60% is released as heat.

What are the three main steps of cellular respiration?

Glycolysis (anaerobic), Citric acid cycle (aerobic), and the Electron Transport Chain/oxidative phosphorylation (aerobic).

Where does glycolysis occur and what is its net ATP yield per glucose?

Glycolysis occurs in the cytosol and yields 2 net ATP per glucose (plus 2 NADH).

What happens to pyruvic acid under aerobic vs anaerobic conditions?

Under aerobic conditions, pyruvic acid enters the mitochondria to form acetyl CoA and continue to the citric acid cycle; under anaerobic conditions, it is converted to lactic acid.

What are the main outputs of the Citric Acid Cycle per glucose molecule?

Per glucose, the cycle produces ATP (1 per turn), CO2, and transfers hydrogen to NAD+ and FAD (as NADH and FADH2).

What is the role of the Electron Transport Chain (ETC)?

ETC transfers energy from NADH and FADH2 to ATP synthase to produce ATP; oxygen is the final electron acceptor and water is formed.

What is the total ATP yield from complete aerobic oxidation of glucose?

Up to 32 ATP per glucose (2 from glycolysis, 2 from the citric acid cycle, about 28 from the electron transport chain).

How is carbohydrate stored in the body?

Excess glucose can be stored as glycogen in most cells, especially liver and muscle; fats (triglycerides) are stored in adipose tissue.

What is DNA and what information does it store?

DNA is the genetic material storing information on nucleotide sequences that instructs cells on protein synthesis and protein types.

Define gene, genome, exome, and gene expression.

Gene: sequence of DNA coding for one protein; Genome: complete genetic information; Exome: part of the genome coding for proteins; Gene expression: regulation of which proteins are produced and in what amount.

What is the structure of DNA?

A double helix of two antiparallel nucleotide chains; backbone is sugar-phosphate; bases pair via hydrogen bonds (A-T, C-G).

What is a nucleotide comprised of?

A 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base (A, T, C, G).

What is DNA replication?

Process yielding an exact copy of a DNA molecule during interphase; hydrogen bonds break, strands separate, new nucleotides pair with exposed bases, and enzymes join the backbone.

What is DNA profiling used for?

DNA profiling/fingerprinting compares variable genome regions to identify remains, establish relationships, or exonerate individuals in criminal cases.

What happens during transcription?

RNA polymerase copies a gene’s DNA sequence into a complementary RNA (mRNA) strand in the nucleus, which then leaves to the cytoplasm.

What is the role of RNA polymerase?

An enzyme that catalyzes the formation of mRNA from the DNA template during transcription.

What is translation and where does it occur?

Translation is the process of converting the genetic code carried by mRNA into a sequence of amino acids to form a protein; it occurs in the cytoplasm at the ribosome.

What are tRNA and anticodons?

tRNA transports amino acids to the ribosome and binds to mRNA via anticodons, which are complementary to mRNA codons, adding amino acids to the growing polypeptide.

How many amino acids are used to make proteins and how many codons exist?

There are 20 amino acids and 64 possible mRNA codons; most codons code for amino acids, with initiation codon AUG and stop codons signaling termination.

What is the initiation codon and what does it code for?

Initiation codon is AUG, which codes for Methionine and signals the start of a protein.

What are the major steps of transcription and translation tables summarized in flashcards?

Transcription: RNA polymerase binds, unwinds DNA, copies mRNA, terminates, mRNA exits nucleus. Translation: ribosome binds mRNA, tRNAs bring amino acids, peptide bonds form, ribosome moves along, chain elongates, finished protein released.

What are mutations and how can they arise?

Mutations are changes in DNA sequences caused by replication errors (spontaneous) or exposure to mutagens (induced) such as chemicals or radiation.

Give an example of a mutation-related health effect and a potential beneficial mutation.

Sickle cell disease is caused by a single nucleotide substitution altering hemoglobin; some mutations can confer resistance to HIV, illustrating potential benefits.

What is DNA repair and why is it important?

DNA repair enzymes correct mismatches; genetic code redundancy (multiple codons for the same amino acid) and diploidy help protect against harmful mutations.

What is the role of histones and chromatin in DNA structure?

DNA wraps around histone proteins to form chromatin, which compacts the DNA into chromosomes.

What is the human metabolome and its database?

The metabolome is all small molecules involved in metabolism; the Human Metabolome Database stores vast information about metabolites and their contexts.