Exam 2 Study Guide and Terms

Question 1

What is microbial metabolism?

Answer 1

The chemical engine that drives Earth’s biosphere

Eukaryotes depend on organic molecules, while prokaryotes can use both organic and inorganic materials.

Question 2

What is metabolism?

Answer 2

All the chemical reactions that occur within a cell

Think of it as the cell’s ‘factory work’.

Question 3

Define metabolic pathways.

Answer 3

A series of interconnected chemical reactions

It functions like a step-by-step ‘assembly line’.

Question 4

What are exergonic reactions?

Answer 4

Reactions that occur spontaneously by releasing energy

Mnemonic: ‘Exit energy’.

Question 5

What are endergonic reactions?

Answer 5

Reactions that require energy to occur

Mnemonic: ‘End in energy’.

Question 6

Define anabolism.

Answer 6

Building up complex molecules, which requires energy

It is an endergonic process.

Question 7

Define catabolism.

Answer 7

Breaking down complex molecules, which releases energy

It is an exergonic process.

Question 8

What is oxidation?

Answer 8

Removal of electrons from a molecule

Mnemonic: ‘Oxygen takes electrons away’.

Question 9

What is reduction?

Answer 9

Addition of electrons to a molecule

Mnemonic: ‘Reduce means to add electrons’.

Question 10

What are energy carriers?

Answer 10

Key molecules include NAD⁺, NADP⁺, FAD, ATP

They transport high-energy electrons or phosphate groups.

Question 11

What is the role of enzymes?

Answer 11

Proteins that act as catalysts to speed up chemical reactions

They lower the activation energy required for reactions.

Question 12

Define glycolysis.

Answer 12

The breakdown of glucose into pyruvate

Occurs in the cytoplasm and is considered an ancient process.

Question 13

What is cellular respiration?

Answer 13

Involves glycolysis, the Krebs cycle, and the electron transport system

Most ATP is generated via oxidative phosphorylation.

Question 14

What is fermentation?

Answer 14

An anaerobic process that regenerates NAD⁺ from NADH

It allows glycolysis to continue when respiration fails.

Question 15

What are lipases?

Answer 15

Enzymes that break down triglycerides

They play a role in lipid catabolism.

Question 16

What is β-oxidation?

Answer 16

The process of breaking down fatty acids into acetyl groups

This occurs during lipid catabolism.

Question 17

Define photosynthesis.

Answer 17

The conversion of sunlight into chemical energy

Occurs in chloroplasts in eukaryotes.

Question 18

What is a genome?

Answer 18

The complete set of DNA in a cell

It includes all genetic material of an organism.

Question 19

What is the central dogma of molecular biology?

Answer 19

DNA → RNA → Protein

It describes the flow of genetic information.

Question 20

Define semiconservative replication.

Answer 20

Each new DNA molecule contains one original and one newly synthesized strand

This is the mechanism of DNA replication.

Question 21

What is RNA polymerase?

Answer 21

The enzyme that synthesizes RNA from DNA

It plays a key role during transcription.

Question 22

What is a codon?

Answer 22

A triplet of nucleotides that corresponds to a specific amino acid

There are 64 possible codons.

Question 23

What is a silent mutation?

Answer 23

A change in DNA that does not change the amino acid

It has no effect on the protein’s function.

Question 24

What is transduction?

Answer 24

Transfer of DNA by viruses

This is one mechanism of gene transfer in prokaryotes.

Question 25

What is transformation?

Answer 25

Uptake of free DNA from the environment ## Footnote It is another mechanism of gene transfer in prokaryotes.

Question 26

What is conjugation?

Answer 26

Direct transfer of DNA from one cell to another via physical contact ## Footnote It involves a pilus for connection.

Question 27

What is Pre-mRNA?

Answer 27

The initial RNA transcript that undergoes processing.

Question 28

What is the purpose of the 5’ Cap?

Answer 28

A modified nucleotide added to the 5’ end of pre-mRNA for protection.

Question 29

What is a Poly-A Tail?

Answer 29

A chain of adenine nucleotides added to the 3’ end of mRNA for stability.

Question 30

Define Exon.

Answer 30

A coding sequence in a gene that remains in the final mRNA.

Question 31

What is an Intron?

Answer 31

A non-coding sequence removed from pre-mRNA during processing.

Question 32

Define Codon.

Answer 32

A set of three nucleotides in mRNA that codes for an amino acid.

Question 33

What is the Wobble Position?

Answer 33

The third nucleotide in a codon with flexible base-pairing.

Question 34

What does Degeneracy refer to in genetics?

Answer 34

The redundancy of the genetic code (multiple codons per amino acid).

Question 35

What is a Stop Codon?

Answer 35

A codon that signals the end of protein synthesis.

Question 36

What is the Start Codon?

Answer 36

The codon (AUG) that initiates translation.

Question 37

Define Reading Frame.

Answer 37

The division of nucleotides into consecutive codons.

Question 38

What is a Silent Mutation?

Answer 38

A mutation that does not change the amino acid sequence.

Question 39

Define Missense Mutation.

Answer 39

A mutation that substitutes one amino acid for another.

Question 40

What is a Nonsense Mutation?

Answer 40

A mutation that converts a codon into a stop codon.

Question 41

Define Frameshift Mutation.

Answer 41

An insertion or deletion that shifts the mRNA reading frame.

Question 42

What is a Mutagen?

Answer 42

An agent (chemical or radiation) that causes mutations.

Question 43

Define Carcinogen.

Answer 43

A substance that can lead to cancer, often by causing mutations.

Question 44

What is Transduction?

Answer 44

Gene transfer mediated by a virus.

Question 45

Define Transformation in genetics.

Answer 45

Uptake of free DNA from the environment by a cell.

Question 46

What is Conjugation?

Answer 46

Direct DNA transfer between cells through physical contact.

Question 47

What is Metabolism?

Answer 47

All chemical reactions in a cell.

Question 48

Define Metabolic pathways.

Answer 48

Chains of reactions that build or break down molecules.

Question 49

What is Anabolism?

Answer 49

Builds complex molecules (uses energy, endergonic).

Question 50

What is Catabolism?

Answer 50

Breaks down molecules (releases energy, exergonic).

Question 51

What do Redox Reactions involve?

Answer 51

Oxidation and Reduction processes.

Question 52

What is Oxidation?

Answer 52

Loss of electrons (OIL: Oxidation Is Losing).

Question 53

Define Reduction.

Answer 53

Gain of electrons (RIG: Reduction Is Gaining).

Question 54

What are Energy Carriers?

Answer 54

NAD⁺/NADH, FAD/FADH₂ that carry electrons for energy transfer.

Question 55

What is ATP?

Answer 55

Stores energy in phosphate bonds.

Question 56

What is the role of Enzymes?

Answer 56

Catalysts that speed up reactions without being consumed.

Question 57

Define Active site.

Answer 57

Where substrates bind on an enzyme.

Question 58

What are Cofactors/Coenzymes?

Answer 58

Assist enzymes (e.g., NADH, ATP).

Question 59

What occurs during Glycolysis?

Answer 59

Splits glucose (6C) into 2 pyruvate (3C) with 2 ATP and 2 NADH produced.

Question 60

Where does the Krebs Cycle occur?

Answer 60

In mitochondria, generating NADH/FADH₂ and CO₂.

Question 61

What does the Electron Transport System (ETS) do?

Answer 61

Uses NADH/FADH₂ to create ATP via oxidative phosphorylation.

Question 62

What is Fermentation?

Answer 62

Regenerates NAD⁺ for glycolysis when oxygen is absent.

Question 63

What is Lactic Acid Fermentation?

Answer 63

Produces lactic acid (e.g., in muscle cells).

Question 64

What does Alcoholic Fermentation produce?

Answer 64

Produces ethanol (e.g., in yeast).

Question 65

What does Lipase do?

Answer 65

Breaks triglycerides into glycerol + fatty acids.

Question 66

Define β-oxidation.

Answer 66

Breaks fatty acids into acetyl-CoA.

Question 67

What do Proteases do?

Answer 67

Break proteins into amino acids.

Question 68

What is the Central Dogma?

Answer 68

DNA → RNA → Protein.

Question 69

What is Transcription?

Answer 69

RNA polymerase creates mRNA from DNA template.

Question 70

What signals the start of Translation?

Answer 70

Start codon: AUG (methionine).

Question 71

What are Stop codons?

Answer 71

UAA, UAG, UGA that signal the end of protein synthesis.

Question 72

What is Semiconservative Replication?

Answer 72

Each new DNA has one old + one new strand.

Question 73

What does Helicase do?

Answer 73

Unzips DNA strands.

Question 74

What is the role of DNA Polymerase?

Answer 74

Adds nucleotides during replication.

Question 75

What is the function of Ligase?

Answer 75

Seals gaps in DNA.

Question 76

What are Telomeres?

Answer 76

Protect chromosome ends; maintained by telomerase.

Question 77

Define Mutation.

Answer 77

Change in DNA sequence.

Question 78

What is a Genotype?

Answer 78

Genetic makeup of an organism.

Question 79

What is a Phenotype?

Answer 79

Observable traits of an organism.

Question 80

What is a Plasmid?

Answer 80

Circular extra DNA in bacteria.

Question 81

What is an Operon?

Answer 81

Cluster of genes regulated together.

Question 82

What does the Spliceosome do?

Answer 82

Removes introns from pre-mRNA.

Question 83

Fill in the blank: The central dogma of molecular biology is _______.

Answer 83

DNA → RNA → Protein.