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Questions and Answers
What process results in the production of two new cells from one cell?
What process results in the production of two new cells from one cell?
Which type of reproduction is commonly used by unicellular organisms?
Which type of reproduction is commonly used by unicellular organisms?
What is the primary function of meiosis?
What is the primary function of meiosis?
What term describes programmed cell death that shapes organisms?
What term describes programmed cell death that shapes organisms?
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Which process occurs during the union of sperm and ova?
Which process occurs during the union of sperm and ova?
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How do multicellular organisms primarily reproduce?
How do multicellular organisms primarily reproduce?
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What occurs in the cell cycle from inception to the creation of two new cells?
What occurs in the cell cycle from inception to the creation of two new cells?
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What is a key characteristic of life related to cell function?
What is a key characteristic of life related to cell function?
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What direction does DNA replication proceed in when new nucleotides are added?
What direction does DNA replication proceed in when new nucleotides are added?
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What role does helicase play in DNA replication?
What role does helicase play in DNA replication?
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Which strand is continuously synthesized during DNA replication?
Which strand is continuously synthesized during DNA replication?
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What are Okazaki fragments?
What are Okazaki fragments?
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Which enzyme adds a short RNA primer to facilitate DNA synthesis?
Which enzyme adds a short RNA primer to facilitate DNA synthesis?
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What happens to RNA primers placed by Primase during DNA replication?
What happens to RNA primers placed by Primase during DNA replication?
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Which process is involved in reducing cell webbing between toes?
Which process is involved in reducing cell webbing between toes?
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What happens to DNA during replication?
What happens to DNA during replication?
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How are the two strands of DNA oriented in relation to each other?
How are the two strands of DNA oriented in relation to each other?
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What is the role of binding proteins during DNA replication?
What is the role of binding proteins during DNA replication?
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What is meant by the term 'antiparallel' in DNA structure?
What is meant by the term 'antiparallel' in DNA structure?
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What are the two important steps for cell reproduction mentioned?
What are the two important steps for cell reproduction mentioned?
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Which component does not belong to the nucleotide structure?
Which component does not belong to the nucleotide structure?
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What is the role of carbon atoms in the 5 Carbon sugar of DNA?
What is the role of carbon atoms in the 5 Carbon sugar of DNA?
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What occurs after DNA is replicated?
What occurs after DNA is replicated?
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Which component is specifically highlighted as cytosine in the nucleotide structure?
Which component is specifically highlighted as cytosine in the nucleotide structure?
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What role does DNA ligase perform during DNA replication?
What role does DNA ligase perform during DNA replication?
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Which mutation involves the substitution of one nucleotide for another?
Which mutation involves the substitution of one nucleotide for another?
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What is the average accuracy rate of DNA polymerase in nucleotide addition?
What is the average accuracy rate of DNA polymerase in nucleotide addition?
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What is the primary structural organization unit of chromatin?
What is the primary structural organization unit of chromatin?
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What typically happens to chromosomes after DNA replication?
What typically happens to chromosomes after DNA replication?
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Which of the following is NOT a type of mutation that DNA polymerase can make?
Which of the following is NOT a type of mutation that DNA polymerase can make?
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How many chromosomes do most humans have?
How many chromosomes do most humans have?
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What is the purpose of histones in relation to DNA?
What is the purpose of histones in relation to DNA?
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What role does the p53 protein play in cell division?
What role does the p53 protein play in cell division?
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What happens during the G1 checkpoint of the cell cycle?
What happens during the G1 checkpoint of the cell cycle?
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How does a malignant tumor differ from a benign tumor?
How does a malignant tumor differ from a benign tumor?
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At what checkpoint does the cell ensure the chromosomes are properly aligned?
At what checkpoint does the cell ensure the chromosomes are properly aligned?
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What can trigger apoptosis during the cell cycle?
What can trigger apoptosis during the cell cycle?
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What is the significance of telomeres in chromosomes?
What is the significance of telomeres in chromosomes?
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What is a common characteristic of cancer cells?
What is a common characteristic of cancer cells?
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What occurs if there are not enough nucleotides during the S phase of the cell cycle?
What occurs if there are not enough nucleotides during the S phase of the cell cycle?
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What happens to normal cells when their telomeres are lost?
What happens to normal cells when their telomeres are lost?
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Which of the following statements about telomerase is true?
Which of the following statements about telomerase is true?
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What is the effect of oncogenes when they are mutated?
What is the effect of oncogenes when they are mutated?
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What role do tumor suppressor genes play in the body?
What role do tumor suppressor genes play in the body?
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How do cancer cells differ from normal cells in terms of growth?
How do cancer cells differ from normal cells in terms of growth?
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Which of the following is NOT a known risk factor for cancer?
Which of the following is NOT a known risk factor for cancer?
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What is contact inhibition?
What is contact inhibition?
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Which statement about cellular respiration and molecular oxygen is correct?
Which statement about cellular respiration and molecular oxygen is correct?
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Study Notes
DNA Replication, Mitosis, and Cell Cycle
- Cells are the fundamental unit of life and life consists of one or more cells.
- Life reproduces because life dies.
- Cells reproduce and are replaced by other cells through cell reproduction.
- Cell cycle is the process from a cell's inception to the moment it produces two new cells.
- Bacteria reproduce asexually with binary fission.
Multicellular Reproduction
- Simple unicellular organisms reproduce asexually.
- Multicellular organisms reproduce sexually with two parents exchanging gametes (sex cells).
- Meiosis forms gametes (sperm and ova).
- Fertilization is the union of sperm and ova.
- Mitosis results in duplicated DNA transferred from one cell to two.
Death is a Part of Life
- Development from a single cell includes cell division, resulting in two identical cells.
- Development also includes apoptosis (programmed cell death).
- Cell death shapes organisms in a similar way that chiseling shapes rocks.
- Life is a balance between cell death and cell reproduction.
DNA Replication
- Two important steps in cell reproduction are DNA replication and moving the replicated DNA to each cell.
- DNA replication occurs when DNA is opened or unzipped.
- New nucleotides are added to each old strand of DNA.
- One piece of DNA becomes two, each with a copy of the old and new material.
Nucleotide Structure
- Nucleotides have a nitrogenous base (cytosine is mentioned).
- A 5-carbon sugar.
- A phosphate.
DNA Structure
- The two strands of DNA are antiparallel.
- The 5' carbon point upwards on the right strand.
- The 3' carbon point upwards on the left strand.
How DNA Replicates
- Helicase unzips the DNA molecule.
- Binding proteins stabilize separation.
- Primase adds short RNA primers to the template DNA.
- DNA polymerase adds new nucleotides to the old strand.
DNA Built in 5' to 3' Direction
- New nucleotides are added by DNA polymerase to the 5' side.
- This creates a leading strand and a lagging strand.
Okazaki Fragments
- RNA primers are lost, creating fragments.
- Fragments on lagging strand are Okazaki Fragments.
- Gaps between fragments are fixed by ligase.
- DNA molecule construction is finalized.
Mutations
- DNA polymerase is very accurate but can make mistakes.
- Mistakes include substitutions (purine/pyrimidine), deletions, and insertions.
DNA in the Nucleus
- Chromosomes are a polymer of DNA and associated proteins.
- Humans have 46 chromosomes, while others vary.
- Chromatin is DNA and proteins.
- DNA is packaged into nucleosomes and further organized.
Chromosomes Condense After Replication
- Nucleosomes condense after DNA replication.
- Duplicated chromosomes become visible in a light microscope.
- Identical pieces of DNA are called sister chromatids.
- Sister chromatids join at the centromere.
Mitotic Division Creates Identical Cells
- Mitosis is part of the cell cycle and redistributes sister chromatids.
- The cell cycle comprises Interphase, Mitosis, and Cytokinesis.
- Interphase is a period of growth, metabolism, and protein synthesis.
- Mitosis involves splitting of the cell's cytoplasm into two.
Interphase
- 90% of cell divisions are spent in interphase.
- It's a period of growth, metabolism, and protein synthesis.
- Interphase is split into three gap phases (G1, Go, and G2).
- Chromatin is very diffuse during interphase and thus not visible.
Normal Cell Metabolism
- During G1 phase the cell grows, carries out basic metabolic functions like glycolysis, makes molecules for organelles.
- G0 phase cells are fully grown and don't divide or replicate.
- Most body cells are in G0 phase.
Preparation of Cell Division
- DNA replicates in the S phase.
- The cell makes proteins necessary for division in the G2 phase.
Mitosis
- Mitosis is the separation of sister chromatids and consists of Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.
- Mitosis functions in asexual reproduction, growth and development, and repair.
Prophase and Prometaphase
- DNA condenses, forming chromosomes visible with a light microscope.
- Spindle fibers form, and the nuclear envelope breaks down.
- Spindle fibers attach to kinetochores on the centromere.
Metaphase and Anaphase
- Duplicated chromosomes line up along the cell's equator.
- Once tension is even, the cell enters anaphase.
- Chromatids move towards opposite ends of the cell.
Telophase and Cytokinesis
- New nuclear envelopes and nucleoli form.
- Cytoplasm divides into two daughter cells.
Plant and Animal Cytokinesis
- Animal cytokinesis involves a cleavage furrow (indentation).
- Plant cytokinesis forms a cell plate.
Cells Out of Control
- Cancer is the result of cells dividing out of control.
- Cells normally have checkpoints (G1, p53) to control division.
Further Checkpoints
- G2 checkpoints ensure DNA integrity and spindle formation.
- Metaphase checkpoints ensure proper chromosome alignment.
Cancer
- Cancer cells divide uncontrollably.
- Benign tumors grow slowly, don't invade other tissues.
- Malignant tumors spread to other tissues (metastasis).
Cell Fuses
- Telomeres are DNA sequences at the ends of chromosomes.
- Telomeres shorten with each cell division.
- Telomerase is an enzyme that maintains telomere length.
- Cancer cells often have active telomerase, allowing unlimited division.
Cell Growth
- Cancer cells continue to grow, often with high growth factors.
- Normal cells have contact inhibition, stopping growth when contact is made with other cells.
- Cancer cells grow unchecked on top of each other.
Genes That Affect Cancer
- Oncogenes are mutated proto-oncogenes, accelerating cell division.
- Tumor suppressor genes (e.g., p53) block cancer.
- Mutated tumor suppressor genes lead to uncontrolled cell division.
Environment
- Factors like UV exposure, chemicals, and radiation can affect cancer risk.
- Molecular oxygen is essential for cells but is also a carcinogen.
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Description
Explore the intricate processes of DNA replication, mitosis, and the cell cycle in this quiz. Understand how cells reproduce and the significance of both asexual and sexual reproduction in unicellular and multicellular organisms. Delve into the roles of apoptosis and the lifecycle of cells.
