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Question 1

What are the three main stages of the cell cycle?

Answer 1

Interphase, mitosis, and cytokinesis

Question 2

What happens during the G1 phase of interphase?

Answer 2

The cell grows, matures, and performs normal functions; some cells may enter a resting state called G0

Question 3

What occurs during the S phase of interphase?

Answer 3

DNA replication occurs, producing identical sister chromatids; centrosomes are also duplicated

Question 4

How do sister chromatids differ from homologous chromosomes?

Answer 4

Sister chromatids are identical copies of a chromosome joined at the centromere; homologous chromosomes are pairs of similar but non-identical chromosomes, one from each parent

Question 5

What are the key events of prophase in mitosis?

Answer 5

Chromosomes condense, nuclear envelope breaks down, and spindle fibers begin to form

Question 6

What happens during metaphase?

Answer 6

Chromosomes align at the metaphase plate (cell equator), attached to spindle fibers via kinetochores

Question 7

What occurs during telophase?

Answer 7

Chromosomes decondense, nuclear envelopes reform, and the cell prepares for cytokinesis

Question 8

What happens during translation termination?

Answer 8

Release factors bind to the ribosome, promoting release of the polypeptide and disassembly of the translation complex

Question 9

What is the wobble hypothesis?

Answer 9

Flexibility in the third codon position allows one tRNA to recognize multiple codons

Question 10

What is alternative splicing?

Answer 10

A process where different combinations of exons are joined to produce multiple protein variants from one gene

Question 11

What are the three major types of RNA and their functions?

Answer 11

mRNA (carries genetic code), tRNA (transfers amino acids), and rRNA (forms ribosomes)

Question 12

What is the function of telomerase?

Answer 12

It extends the G-rich 3’ overhang of chromosomes to prevent shortening during replication

Question 13

Why is an RNA primer needed during DNA replication?

Answer 13

DNA polymerase cannot initiate synthesis; the RNA primer provides a starting 3’-OH group

Question 14

What is the role of DNA polymerase III in replication?

Answer 14

It synthesizes new DNA strands by adding nucleotides to the 3’ end and has proofreading ability

Question 15

What is semiconservative replication?

Answer 15

Each new DNA molecule consists of one original strand and one newly synthesized strand

Question 16

What is the structure of DNA?

Answer 16

A double helix with antiparallel strands held together by complementary base pairing (A-T, G-C)

Question 17

What are the stages of translation?

Answer 17

Initiation, elongation, and termination

Question 18

What is the significance of codon-anticodon pairing?

Answer 18

It ensures the correct amino acid is added to the growing polypeptide chain during translation

Question 19

What modifications occur to mRNA before it leaves the nucleus?

Answer 19

Addition of a 5’ cap and a poly-A tail, and removal of introns via splicing

Question 20

What is the role of tRNA during translation?

Answer 20

To carry specific amino acids to the ribosome and match codons in mRNA via its anticodon

Question 21

Q: Compare and contrast anabolic and catabolic pathways.

Answer 21

A: Anabolic pathways build complex molecules from simpler ones and consume energy; catabolic pathways break down complex molecules into simpler ones and release energy.

Question 22

Q: What makes ATP useful for conserving chemical energy in cells?

Answer 22

A: ATP has high-energy phosphoanhydride bonds whose hydrolysis releases energy that can be coupled to drive endergonic reactions.

Question 23

Q: Why is ATP hydrolysis highly exergonic?

Answer 23

A: Due to charge repulsion between phosphate groups resonance stabilization of products

Question 24

Q: What type of bonds are the “high-energy” bonds in ATP?

Answer 24

A: Phosphoanhydride bonds.

Question 25

Q: How does ATP hydrolysis couple with endergonic reactions?

Answer 25

A: The exergonic hydrolysis of ATP drives otherwise unfavorable endergonic reactions making the overall coupled reaction exergonic.

Question 26

Q: What is oxidation in biological systems?

Answer 26

A: Loss of electrons often accompanied by loss of protons (hydrogen ions)

Question 27

Q: What role do NAD+ and NADH play in glycolysis?

Answer 27

A: NAD+ accepts electrons during glycolysis becoming NADH

Question 28

Q: Why is an energy investment necessary in glycolysis?

Answer 28

A: To phosphorylate glucose and intermediates making them more reactive and enabling subsequent energy-releasing steps.

Question 29

Q: Name the three phases of glycolysis.

Answer 29

A: Phase 1: Preparatory and cleavage steps; Phase 2: Oxidation and first ATP generation; Phase 3: Pyruvate formation and second ATP generation.

Question 30

Q: How does fermentation allow continuous ATP generation?

Answer 30

A: By regenerating NAD+ from NADH enabling glycolysis to continue producing ATP anaerobically.

Question 31

Q: What is the net ATP yield from fermentation per glucose molecule?

Answer 31

A: 2 ATP molecules.

Question 32

Q: What are the differences between lactic acid and ethanol fermentation?

Answer 32

: Lactic acid fermentation produces lactic acid; ethanol fermentation produces ethanol and CO2.

Question 33

Q: How are disaccharides like lactose and sucrose used in glycolysis?

Answer 33

A: They are hydrolyzed into monosaccharides which are converted into glycolytic intermediates.

Question 34

Q: What is the role of glycogen phosphorylase in carbohydrate metabolism?

Answer 34

A: It catalyzes phosphorolysis of glycogen to release glucose-1-phosphate for glycolysis.

Question 35

Q: What are the five stages of aerobic respiration?

Answer 35

Glycolysis

Question 36

Q: What enzyme converts pyruvate to acetyl CoA?

Answer 36

A: Pyruvate dehydrogenase complex.

Question 37

Q: Why is the citric acid cycle considered a cycle?

Answer 37

A: Because oxaloacetate is regenerated at the end allowing continuous processing of acetyl CoA.

Question 38

Q: Which citric acid cycle enzyme generates ATP or GTP directly?

Answer 38

Succinyl CoA synthetase

Question 39

Q: How does beta-oxidation contribute to energy metabolism?

Answer 39

It breaks down fatty acids into acetyl CoA units, which enter the citric acid cycle.

Question 40

Q: What is the function of the electron transport chain (ETC)?

Answer 40

To transfer electrons from NADH and FADH2 to oxygen, pumping protons and creating a gradient for ATP synthesis.

Question 41

Q: What is the role of the F0F1 ATP synthase?

Answer 41

To synthesize ATP using the proton gradient generated by the ETC.

Question 42

Q: Describe the structure of DNA.

Answer 42

A double helix with antiparallel strands held by complementary base pairing (A-T, G-C).

Question 43

Q: What is semiconservative replication?

Answer 43

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

Question 44

Q: What is the difference between leading and lagging strand synthesis?

Answer 44

Leading strand is synthesized continuously; lagging strand is synthesized discontinuously as Okazaki fragments

Question 45

Q: Why is an RNA primer necessary in DNA replication?

Answer 45

DNA polymerase requires a 3’-OH group to add nucleotides; the RNA primer provides this starting point.

Question 46

Q: How is replication fidelity maintained?

Answer 46

DNA polymerase proofreading removes incorrectly paired nucleotides via 3’ to 5’ exonuclease activity.

Question 47

Q: What is the function of telomerase?

Answer 47

To extend telomeres, preventing chromosome shortening during replication.

Question 48

Q: What are the main classes of RNA and their functions?

Answer 48

mRNA (carries genetic code), tRNA (transfers amino acids), rRNA (forms ribosomes).

Question 49

Q: What are the components of a transcription unit?

Answer 49

Promoter, RNA coding region, and terminator.

Question 50

Q: What is the role of the sigma factor in bacterial transcription?

Answer 50

It recognizes promoter sequences and initiates transcription by guiding RNA polymerase.

Question 51

Q: How does bacterial transcription terminate?

Answer 51

Via rho-independent termination (hairpin formation) or rho-dependent termination (rho factor unwinding RNA-DNA hybrid).

Question 52

Q: How do eukaryotic promoters differ from bacterial promoters?

Answer 52

Eukaryotic promoters have complex elements like the TATA box and require multiple transcription factors for initiation.