BIO 101 Exam 5: Cellular Reproduction, Meiosis, and Heredity
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Why do cells divide?
Division supports growth, maintenance, and repair in multicellular organisms. It can serve as reproduction in single-celled organisms.
DNA wraps around _________ _______ to form nucleosomes.
histone proteins
Nucleosomes and associated proteins form ______________ which condenses into _________.
chromatin, chromosomes
A ________________ arranges chromosomes by features such as size and banding pattern.
karyotype
_____________ chromosomes carry the same genes at corresponding loci, though their alleles may differ.
Homologus
Replicated chromosomes consist of ___________ ___________ joined at the centromere.
sister chromatids
Cell Cycle phases?
Interphase (G1, growth), S (DNA replication), G2 (preparation), and M phase (nuclear division and cytokinesis).
What are the mitosis stages?
Prophase, Prometaphase, Metaphase, Anaphase, Telephase, Cytokenesis
_______________ is a mitosis stage that condenses chromosomes and begins spindle formation.
Prophase
_____________ is a mitosis stage that includes breakdown of the nuclear envelope and spindle attachment to kinetochores.
Prometaphase
_________________ is a mitosis stage that aligns chromosomes.
Metaphase
___________________ is a mitosis stage that separates sister chromatids.
Anaphase
___________________ is a mitosis phase that reforms nuclei.
Telophase
_________________ step in mitosis divides the cytoplasm.
Cytokenesis
In animal cytokinesis, animal cells use an actin-based contractile ring to form a _____________ _________.
cleavage furrow
In plant cytokinesis, plant cells form a cell plate that develops into a new ______ ______.
cell wall
What is G0 phase?
A nondividing state that a cell may enter when it exits the cell cycle.
What does the G1 checkpoint assess?
Cell conditions, including whether the cell is large enough and whether DNA is damaged.
What does the G2 checkpoint check?
Whether DNA replication is complete and whether DNA is damaged.
What does the M checkpoint (spindle checkpoint) verify?
That chromosomes are properly attached to spindle fibers before they separate.
What are cyclins?
Proteins that activate CDKs to regulate and promote cell-cycle progression.
What are CDKs?
Cyclin-dependent kinases that help control progression through the cell cycle.
What happens when DNA damage activates p53?
p53 promotes the production of p21.
What is the function of p21?
It inhibits CDKs, slowing or stopping cell-cycle progression.
What is the function of p53?
It responds to DNA damage and helps prevent damaged cells from dividing.
What is the function of Rb?
It restrains E2F until conditions allow the cell to progress through the cell cycle.
What are proto-oncogenes?
Normal genes that help regulate and promote cell division.
What happens when proto-oncogenes mutate?
They can become oncogenes that promote excessive cell division.
What are oncogenes?
Mutated genes that can cause excessive or uncontrolled cell division.
What are tumor-suppressor genes?
Genes that normally slow down or prevent uncontrolled cell division.
What is a benign tumor?
A noncancerous growth that remains localized and does not invade surrounding tissues.
What is a malignant tumor?
A cancerous growth that can invade surrounding tissues.
What is metastasis?
The spread of cancer cells to distant sites in the body.
How can HPV increase the risk of cancer?
Some HPV proteins can disable p53-mediated tumor suppression, allowing abnormal cell growth.
What is p53's relationship to HPV?
Some HPV proteins interfere with p53, preventing it from properly stopping damaged cells from dividing.
What are HeLa cells?
An immortal cell line originating from cervical cancer cells taken from Henrietta Lacks.
Who was Henrietta Lacks?
A woman whose cervical cancer cells were used to create the widely used HeLa cell line.
Why is the history of HeLa cells ethically significant?
The cells were taken and used for research without Henrietta Lacks's informed consent, raising questions about research ethics and consent.
What does Taxol do as a cancer treatment?
It disrupts spindle function, interfering with chromosome separation during cell division.
What does 5FU do as a cancer treatment?
It interferes with DNA synthesis, preventing cancer cells from properly making DNA.
How does radiation treat cancer?
It damages DNA, making it difficult for cancer cells to survive and divide.
What are angiogenesis inhibitors?
Treatments that limit the growth of blood vessels that supply tumors.
Why can cancer treatments damage healthy cells?
They may also affect healthy cells that divide rapidly.
How do bacteria reproduce?
Through binary fission, not mitosis.
What is binary fission?
A form of asexual reproduction in which a bacterium divides into two daughter cells.
What is FtsZ?
A bacterial protein that helps organize the division site and septum formation during binary fission.
What is the function of FtsZ in bacterial division?
It helps form the division ring that organizes the separation of the bacterial cell.
What are plasmids?
Small DNA molecules in bacteria that are separate from the main bacterial chromosome.
What types of genes can plasmids carry?
Genes such as antibiotic-resistance genes.
Why are plasmids important in antibiotic resistance?
They can carry and transfer genes that allow bacteria to resist antibiotics.
What is a genome?
A cell's complete DNA.
What is a histone?
A protein around which DNA winds.
What is a nucleosome?
DNA wrapped around histone proteins.
What is chromatin?
DNA and associated proteins in a compact but accessible form.
What is a karyotype?
An organized display of chromosomes.
What are homologous chromosomes?
A chromosome pair with the same genes at corresponding locations.
What are sister chromatids?
Replicated copies of a chromosome joined at the centromere.
What is the cell cycle?
The sequence of growth, DNA replication, and cell division.
What is cytokinesis?
Division of the cytoplasm into daughter cells.
What is G0?
A state in which a cell is not actively progressing through the division cycle.
What is a checkpoint?
A control point that can pause the cell cycle if conditions are not met.
What is a cyclin?
A regulatory protein that binds and activates a CDK.
What is a CDK?
A kinase activated by cyclins that helps regulate cell-cycle progression.
What is p53?
A tumor-suppressor protein that responds to DNA damage and can halt the cell cycle.
What is p21?
A protein that inhibits CDKs.
What is Rb?
A tumor-suppressor protein that restrains E2F activity.
What is E2F?
A transcription factor involved in activating genes needed for DNA synthesis.
What is a proto-oncogene?
A normal gene that can promote cell-cycle progression.
What is an oncogene?
A mutated or overactive gene that can drive excessive cell division.
What is a tumor-suppressor gene?
A gene whose product helps restrain cell division or prevent abnormal growth.
What does benign mean?
Noncancerous and generally localized.
What does malignant mean?
Cancerous and capable of invading nearby tissues.
What is metastasis?
The spread of malignant cells to distant locations.
What is binary fission?
Prokaryotic cell division that copies DNA and separates one cell into two.
What is FtsZ?
A bacterial protein that helps organize the division site.
What is a plasmid?
A small DNA molecule separate from the main chromosome.
What does diploid mean?
A cell that has two sets of chromosomes (2n).
What does haploid mean?
A cell that has one set of chromosomes (n).
What happens to chromosome number during meiosis?
It is reduced from diploid (2n) to haploid (n).
What are homologous chromosomes?
Chromosomes that carry the same genes at corresponding locations.
What are sister chromatids?
Replicated copies of one chromosome joined together.
When does DNA replication occur before meiosis?
During the S phase of interphase.
How many times is DNA replicated before meiosis?
Once.
How many cell divisions occur during meiosis?
Two divisions: meiosis I and meiosis II.
Does DNA replication occur between meiosis I and meiosis II?
No, there is no additional round of DNA replication.
What happens during prophase I?
Homologous chromosomes pair through synapsis, forming tetrads, and crossing over can occur.
What is synapsis?
The pairing of homologous chromosomes during prophase I.
What is a tetrad?
A structure consisting of two homologous chromosomes and four chromatids.
What is crossing over?
The exchange of genetic material between nonsister chromatids of homologous chromosomes.
Between which chromatids does crossing over occur?
Nonsister chromatids of homologous chromosomes.
What are chiasmata?
Visible points where homologous chromosomes remain connected after crossing over.
What happens during metaphase I?
Homologous chromosome pairs line up randomly at the cell's equator.
What is independent assortment?
The random alignment and separation of homologous chromosome pairs during meiosis I.
What happens during anaphase I?
Homologous chromosomes separate while sister chromatids remain together.
Why is meiosis I called the reductional division?
Because it reduces the chromosome number from diploid to haploid.
What happens during metaphase II?
Chromosomes line up individually at the cell's equator.
What happens during anaphase II?
Sister chromatids separate and move to opposite poles.
What is the final result of meiosis?
Typically, four genetically distinct haploid cells.
What are the four sources of genetic variation?
Crossing over, independent assortment, mutation, and fertilization.
How does crossing over create genetic variation?
It exchanges DNA between nonsister chromatids, creating new combinations of alleles.