Enzymes, DNA Replication, and Cell Cycle: Key Concepts for Biology
Studied by 0 people
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/77
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
78 Terms
Q: What are enzymes?
A: Enzymes are biological catalysts that speed up chemical reactions without being consumed.
Q: Where does a substrate bind on an enzyme?
A: At the enzyme's active site.
Q: What determines enzyme-substrate specificity?
A: The shape and chemical properties of the enzyme's active site.
Q: What interactions hold substrates in the active site?
A: Weak noncovalent interactions such as hydrogen bonds.
Q: What do enzymes lower in chemical reactions?
A: The activation energy (Ea).
Q: Does the overall free energy change (∆G) change when an enzyme catalyzes a reaction?
A: No, only the reaction rate increases.
Q: What happens if an enzyme is exposed to extreme temperature or pH?
A: It may denature and lose its structure and function.
Q: What is ATP's role in cells?
A: ATP provides energy to drive endergonic reactions.
Q: Is ATP hydrolysis exergonic or endergonic?
A: Exergonic.
Q: What does ATP hydrolysis produce?
A: ADP and inorganic phosphate (Pi).
Q: How do enzymes couple reactions?
A: They link exergonic and endergonic reactions at the active site.
Q: What is reversible enzyme regulation?
A: Modifications such as phosphorylation that can quickly activate or deactivate enzymes.
Q: What is irreversible regulation?
A: Permanent activation or inactivation through covalent bond cleavage.
Q: What is a competitive inhibitor?
A: A molecule that binds to the active site and competes with the substrate.
Q: What is an allosteric inhibitor?
A: A molecule that binds to a site other than the active site, changing enzyme shape and reducing activity.
Q: What is the difference between active site and allosteric site regulation?
A: Active site regulation affects substrate binding, while allosteric site regulation changes enzyme conformation to increase or decrease activity.
Q: What is the purpose of DNA replication?
A: To create identical copies of DNA before cell division.
Q: What model describes DNA replication?
A: The semiconservative model.
Q: In what direction does DNA polymerase synthesize DNA?
A: 5′ to 3′ direction.
Q: What does helicase do?
A: Unwinds the DNA double helix at the replication fork.
Q: What do single-stranded binding proteins do?
A: Bind to separated DNA strands to prevent reannealing.
Q: What does topoisomerase do?
A: Relieves tension in DNA caused by unwinding.
Q: What does primase do?
A: Synthesizes short RNA primers complementary to DNA template strands.
Q: What does DNA polymerase do?
A: Extends primers, replaces RNA primers with DNA, and proofreads mismatches.
Q: What does DNA ligase do?
A: Joins Okazaki fragments on the lagging strand.
Q: How is the leading strand synthesized?
A: Continuously toward the replication fork.
Q: How is the lagging strand synthesized?
A: Discontinuously in Okazaki fragments away from the fork.
Q: What are Okazaki fragments?
A: Short DNA segments synthesized on the lagging strand.
Q: What is the difference between prokaryotic and eukaryotic replication origins?
A: Prokaryotes have one origin per circular chromosome; eukaryotes have multiple origins on linear chromosomes
Q: What are telomeres?
A: Repetitive DNA sequences at chromosome ends that prevent information loss.
Q: What enzyme maintains telomeres?
A: Telomerase.
Q: What is PCR used for?
A: To amplify specific DNA sequences.
Q: What are the three steps of PCR?
A: Denaturation, annealing, and extension.
Q: What enzyme is used in PCR and why?
A: Taq polymerase, because it is heat-stable.
Q: What are common causes of DNA damage?
A: UV light, X-rays, and chemical mutagens.
Q: What are two DNA repair mechanisms?
A: Mismatch repair and nucleotide excision repair.
Q: What damage does UV light cause?
A: Formation of thymine dimers.
Q: When does DNA replication occur in the cell cycle?
A: During the S phase of interphase.
Q: What is a point mutation?
A: A change in a single nucleotide base.
Q: What is a nonsynonymous (missense) mutation?
A: A base change that alters the amino acid sequence of a protein.
Q: What is a synonymous (silent) mutation?
A: A base change that does not alter the amino acid sequence.
Q: What is a nonsense mutation?
A: A mutation that introduces a premature stop codon.
Q: What is a frameshift mutation?
A: Insertion or deletion not in multiples of three that shifts the reading frame.
Q: How can frameshift mutations affect proteins?
A: They often cause severe disruption of protein structure and function.
Q: How can mutations lead to cancer?
A: They can disrupt genes controlling cell cycle regulation, leading to uncontrolled growth.
Q: What are the main phases of the cell cycle?
A: G1, S, G2, and M phases.
Q: What happens during G1 phase?
A: Cell grows and prepares for DNA synthesis.
Q: What happens during S phase?
A: DNA replication occurs.
Q: What happens during G2 phase?
A: The cell prepares for mitosis by producing proteins and organelles.
Q: What happens during M phase?
A: The cell divides its chromosomes and cytoplasm into two nuclei.
Q: What is the G0 phase?
A: A nondividing, resting phase where cells perform normal functions.
Q: What do Cyclin-CDK complexes control?
A: Progression through the cell cycle by phosphorylating target proteins.
Q: What does Cyclin D-CDK control?
A: Prepares the cell for S phase (G1/S transition).
Q: What does Cyclin A-CDK control?
A: Initiates and regulates DNA replication.
Q: What does Cyclin B-CDK control?
A: Prepares the cell for mitosis (M phase).
Q: What is the G1 checkpoint?
A: Ensures DNA is undamaged before replication.
Q: What is the G2 checkpoint?
A: Ensures all DNA is replicated correctly before mitosis.
Q: What is the M checkpoint?
A: Ensures all chromosomes are properly attached to spindle fibers before separation.
Q: What is the role of p53?
A: It halts the cell cycle when DNA damage is detected and promotes repair or apoptosis.
Q: How is p53 activated?
A: By phosphorylation after DNA damage.
Q: What happens when p53 is active?
A: It inhibits Cyclin-CDK complexes and promotes transcription of repair genes.
Q: What happens if p53 is mutated?
A: Cells may divide uncontrollably, contributing to cancer development.
Q: In a human somatic cell that undergoes meiosis, the daughter cells will contain 46 chromosomes.
A: False
Q: Prokaryotic chromosomes are made of chromatin which contains DNA wrapped around histone proteins in structures called nucleosomes.
A: False
Q: During the scientific process, scientists determine an alternative hypothesis which assumes there is no significant difference between variables or populations.
A: False
Q: In prokaryotes, alternative splicing allows a single gene to encode multiple gene products.
A: False
Q: When exposed to a non-optimal temperature, the peptide bonds in proteins denature.
A: False
Q: The amino group of an amino acid gives each polypeptide monomer its distinct chemical properties.
A: False
Q: What characteristic makes eukaryotic cells different from prokaryotic cells?
A: C) Chloroplasts and mitochondria that make energy for the cell to use.
Q: Given the following description, identify the stage of eukaryotic cell division: The nuclear envelope breaks down and microtubules attach to kinetochores at the centromeres of homologous chromosomes.
A: A) Prometaphase I of meiosis I
Q: Which of the following sentences correctly states one of Mendel's laws?
A: C) The law of independent assortment states that the alleles of different genes separate independently of each other during meiosis.
Q: In eukaryotic DNA, if you made a change to the terminator sequence that affected RNA polymerase binding, what would happen?
A: B) More RNA than usual would be transcribed because RNA polymerase would not stop transcribing.
Q: Which statement is true about DNA methylation and histone acetylation?
D) Acetyl groups are added to or removed from histone proteins which causes a change in transcription.
Q: Which of the following statements about transcription is true?
: B) Incoming nucleotides (NTPs) must be oriented to form hydrogen bonds with complementary DNA bases.
Q: Suppose a drug inhibited binding of a translational release factor to the A site of the ribosome. When would this affect translation?
A: D) Termination of translation
Q: Activators are transcription factors that increase gene expression by binding to regulatory sequences. How might they function?
A: A) When an activator binds to an enhancer, it helps other activators bind to their enhancers.
Q: Which characteristic is properly matched with its translational component?
A: D) Initiation factor - Composed of nucleotides only.
Q: When DNA is heated, which bonds dissociate first?
A: D) Base stacking interactions between bases within the same DNA strand.
Note 
Flashcards (50)