66 Questions
What is the role of topoisomerase at a replication fork?
Relieves the strain caused by unwinding the DNA
What is the function of primase in DNA replication?
Synthesizes RNA primers
Which proteins are responsible for stabilizing the unwound parental strands in DNA replication?
Single-strand binding proteins
What happens to the lagging strand during DNA replication?
Forms short fragments discontinuously
What is the consequence if a cell division goes awry?
End of continuity of life
What are the two families of nitrogenous bases?
Pyrimidines and Purines
Which nitrogenous base is only found in DNA?
Thymine
What is the function of DNA?
Program protein production in the cytoplasm
What is the role of RNA in protein synthesis?
Carry genetic information for translation into proteins
How many phosphate groups can a nucleotide have?
One to three phosphate groups
What is the first stage of mitosis?
Prophase
What is the function of DNA polymerase in DNA replication?
Catalyzes the addition of nucleotides to the 3' end of an existing chain
What is the role of an origin of replication in DNA replication?
Initiates the process of DNA replication
What is the main difference between DNA and RNA?
DNA is a double helix, while RNA is a single helix
During which phase of mitosis do the daughter chromosomes move to opposite poles of the cell?
Anaphase
What is the role of a control element in gene regulation?
Helps regulate transcription of a gene by binding to RNA polymerase
In which type of operon does the repressor bind to a corepressor to stop production?
Repressible operon
What is the function of a tumor suppressor gene in the context of cancer development?
Promotes the synthesis of proteins that inhibit cell division
How do paracrine, synaptic, and endocrine signaling types initiate a response in target cells?
By interacting with specific receptors on target cells
What is the main difference between a G-protein-coupled receptor and a ligand-gated ion channel receptor?
G-protein-coupled receptors respond to signaling molecule binding by activating G proteins
What is the role of DNA Polymerase I in DNA replication?
Replaces RNA primers with DNA
Which protein binds to unpaired DNA strands during replication?
Single-stranded binding proteins (SSBs)
What is the function of an inducer in gene regulation?
Stimulates gene transcription by changing the repressor's shape
What is the main role of Topoisomerase in DNA replication?
Breaks, swivels, and rejoins DNA strands
What does the term 'Operator' refer to in bacterial and phage DNA?
A sequence of nucleotides near the start of an operon
What is the term for a small, nonprotein molecule that relays signals to a cell's interior in response to a signaling molecule bound by a receptor protein?
Second Messenger
How do ligand-gated ion channels regulate the flow of specific ions?
By changing shape in response to a ligand
What process involves a primary mechanism of homeostasis by triggering a response that counteracts the initial change?
Negative Feedback
Which type of signaling involves a nerve cell releasing neurotransmitter molecules into a synapse to stimulate target cells, such as muscles or other nerve cells?
Synaptic Signaling
In cell signaling, what occurs when a ligand binds to a receptor protein, causing it to change shape?
Reception
What is the function of a second messenger in cell signaling?
Amplifying the signal
Where are receptor proteins typically found in a cell?
In the plasma membrane
Which type of cell communication involves a hormone acting on the same cell that produced it?
Autocrine
What is the function of a ligand-gated ion channel in cell signaling?
Allowing or blocking ion flow based on ligand binding
In endocrine signaling, where do hormones typically travel to reach target cells?
By diffusion into interstitial fluid
What is negative feedback regulation in physiology?
A mechanism that slows a process by accumulating an end product
What is the role of the hypothalamus in maintaining homeostasis?
Coordinating endocrine and nervous systems
What is thermoregulation's primary purpose in mammals?
Maintenance of internal body temperature within a range
What characterizes positive feedback regulation?
A process where an end product speeds up its own production
What is the function of single-stranded binding proteins (SSBs) during DNA replication?
Stabilize and separate unpaired DNA strands
At what stage of mitosis do chromosomes align at the metaphase plate?
Prometaphase
What is the primary role of DNA polymerase III and DNA polymerase I in E.coli?
Elongate new DNA by adding nucleotides
Where is RNA typically created but can freely move around in a cell?
Nucleolus
What is the primary function of topoisomerase during DNA replication?
Relieve strain in the double helix ahead of the replication fork
Which stage of mitosis involves the chromatids of each chromosome separating?
Anaphase
What is the primary role of primase in DNA replication?
Make RNA primers to start replication
Which enzyme catalyzes the elongation of new DNA by adding nucleotides to the 3' end?
DNA polymerase
What is the primary function of a miotic spindle during mitosis?
Separate chromatids to opposite poles
Which of the following accurately describes the structure of RNA and DNA?
DNA is a double helix with G-C and A-T base pairs while RNA is a single helix with G-C and A-U base pairs.
Which nitrogenous base is a member of the pyrimidine family and is only found in RNA?
Uracil
What is the function of DNA during protein synthesis?
Carries genetic information that is translated into proteins
Which nucleic acid type is responsible for dictating the synthesis of messenger RNA?
DNA
What are the two main types of RNA involved in protein synthesis?
rRNA and tRNA
Which nitrogenous base is a member of the purine family and found in both DNA and RNA?
Guanine
What is the primary function of RNA during protein synthesis?
Carrying genetic information for translation into proteins
Which of the following nitrogenous bases consists of one six-membered ring of carbon and nitrogen?
Thymine
What is the function of primase in DNA replication?
Synthesizes RNA primers
In DNA replication, what is the role of topoisomerase at a replication fork?
Breaks, swivels, and rejoins the parental DNA ahead of the replication fork
What is the key feature of G2 phase checkpoint in the cell cycle?
Prevents cells from entering mitosis when DNA is damaged
What characterizes a prokaryotic genome?
Has a single circular chromosome
During which phase of the cell cycle does DNA replication occur?
S phase
What is the role of single-strand binding proteins in DNA replication?
Stabilize unwound parental strands
What does a centromere on a duplicated chromosome represent?
Region where sister chromatids are attached by proteins
What differentiates the leading strand from the lagging strand in DNA replication?
'Leading' refers to 5' to 3' direction of synthesis
'Genome' refers to:
The genetic material of an organism or virus
'Cytokinesis' involves:
'Division of cytoplasm, producing two daughter cells'
Study Notes
Cell Cycle and Mitosis
- The cell cycle consists of three stages: Interphase, Mitosis, and Cytokinesis
- Interphase consists of G1 (growth), S (synthesis), and G2 (growth) stages
- Mitosis consists of Prophase, Prometaphase, Metaphase, Anaphase, and Telophase stages
- Cytokinesis is the division of cytoplasm to form two daughter cells
Mitosis Stages
- Prophase:
- Chromatin condenses into discrete chromosomes
- Miotic spindle begins to form
- Nucleolus disappears
- Prometaphase:
- Nuclear envelope fragments
- Spindle microtubules attach to kinetochores of chromosomes
- Metaphase:
- Spindle is complete
- Chromosomes, attached to microtubules, are aligned at the metaphase plate
- Anaphase:
- Chromatids of each chromosome separate
- Daughter chromosomes move to the poles of the cell
- Telophase:
- Daughter nuclei are forming
- Cytokinesis typically begins
Checkpoints
- G1 checkpoint: ensures cell is ready for DNA replication
- G2 checkpoint: ensures DNA is undamaged before mitosis
- M checkpoint: ensures all chromosomes are attached to spindle fibers
DNA Replication
- Semi-conservative model: one new strand, one old strand
- Leading strand: continuously synthesized 5' to 3' towards the replication fork
- Lagging strand: discontinuously synthesized in short fragments (Okazaki fragments)
- RNA primers: synthesized by primase, used to initiate DNA synthesis
- Topoisomerase: relieves strain in the double helix ahead of the replication fork
- Single-strand binding proteins: stabilize and hold apart the unwound DNA strands
Cell Division
- Reasons for cell division:
- Continuity of life
- Growth and development of multicellular organisms
- Replacement of cells in tissues
- Consequences of cell division gone awry:
- Cancer
Nucleic Acids
- Structure of DNA: double helix, two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs
- Structure of RNA: single helix, two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-U base pairs
- Differences between DNA and RNA:
- Sugar component (deoxyribose vs. ribose)
- Double helix vs. single helix
- Ability to move around in the cell
Cell Signaling
- Cell signaling involves the release of signaling molecules, interaction with receptors, and response to the signal
- Three stages of cell signaling:
- Reception: signaling molecule binds to receptor
- Transduction: signal is converted into a response
- Response: cellular response to the signal
Gene Regulation
- Operons: units of genetic function found in bacteria and phages, consisting of a promoter, operator, and coordinately regulated cluster of genes
- Repressor: protein that inhibits gene transcription
- Inducer: small molecule that binds to a repressor protein and changes its shape, thus switching an operon on
- Activator: protein that binds to DNA and stimulates gene transcription
Cancer
- Oncogenes: genes involved in triggering molecular events that can lead to cancer
- Proto-oncogenes: normal cellular genes that have the potential to become oncogenes
- Tumor suppressor genes: genes whose protein products inhibit cell division, preventing uncontrolled cell growth
- Multistep model of cancer development: tumor initiation, promotion, malignant conversion, and progression- Cell Signaling and Endocrine System*
Receptors and Ligands
- Ligand: a molecule that binds to a specific receptor on the cell surface or inside the cell, initiating a signaling cascade
- Receptor: a protein that receives and interprets information from signaling molecules (ligands)
- Second messenger: a small, nonprotein, water-soluble molecule or ion that relays a signal to a cell's interior in response to a signaling molecule bound by a signal receptor protein
Types of Receptors
- Extracellular receptor: a receptor protein found on the surface of the cell membrane
- Example: Insulin receptor
- Intracellular receptor: a receptor protein found inside the cell, typically in the cytoplasm or nucleus
- Example: Steroid hormone receptors
Signal Transduction
- The process of transmitting a signal from the receptor to the effector molecule
- Often involves a cascade of molecular interactions
- Can involve G proteins, second messengers, and protein kinases
Cell Signaling Pathways
- Local signaling: short-distance signaling between cells
- Examples: paracrine signaling, synaptic signaling
- Long-distance signaling: signaling between cells over a long distance
- Examples: endocrine signaling, hormone signaling
Endocrine System
- A system of glands and hormones that regulate various bodily functions
- Hormones: chemical messengers produced by endocrine glands that travel through the bloodstream to reach target cells
- Examples: insulin, adrenaline, estrogen, testosterone
Feedback Loops
- Negative feedback: a response that counteracts the initial stimulus
- Example: Lowering body temperature in response to a fever
- Positive feedback: a response that amplifies the initial stimulus
- Example: Childbirth
Homeostasis
- The maintenance of a stable internal environment despite changes in the external environment
- Crucial for the survival of an organism
- Involves negative feedback mechanisms to maintain homeostasis
Cell Cycle and Mitosis
- Cell cycle: the sequence of events from cell growth to cell division
- Mitosis: the process of cell division that results in two daughter cells with the same number of chromosomes as the parent cell
- Checkpoints: critical points in the cell cycle where the process can be halted if DNA damage is detected
DNA Replication
- The process of making an exact copy of a DNA molecule
- Involves the unwinding of the double helix, replication fork, and the synthesis of new DNA strands
- Key enzymes involved: helicase, primase, DNA polymerase, and topoisomerase
Nucleic Acids
- DNA (deoxyribonucleic acid): a double-stranded molecule that contains the genetic instructions for an organism
- RNA (ribonucleic acid): a single-stranded molecule involved in protein synthesis and other cellular processes
Prepare for your BIO 102 exam on Specialized Cells and Cell Signaling with this study guide covering topics like cell division, nucleotides, and the molecular basis of inheritance. Includes multiple-choice questions and short answer practice. Exam Date: Thursday, April 11.
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