Biology Chapter 10 Flashcards

Questions and Answers

Compare and contrast a human somatic cell to a human gamete.

Human somatic cells have 46 chromosomes (22 pairs and 2 sex chromosomes), whereas human gametes have 23 chromosomes (one of each chromosome and one sex chromosome).

What is the relationship between a genome, chromosomes, and genes?

The genome consists of all the chromosomes of an organism, each containing hundreds to thousands of genes.

Explain how chromosomes can fit inside a eukaryotic nucleus.

DNA is wrapped around histone proteins to form nucleosomes, which are coiled into a 30-nm fiber and further condensed during cell division.

Briefly describe the events that occur in each phase of interphase.

In G1, the cell grows and assesses DNA damage; in S phase, DNA replication occurs; in G2, the cell grows, duplicates organelles, and prepares for division. Signup and view all the answers

What mitotic structure is targeted by chemotherapy drugs like vincristine and colchicine?

The mitotic spindle is targeted by these drugs. Signup and view all the answers

Describe the similarities and differences between the cytokinesis mechanisms found in animal cells versus those in plant cells.

Animal cells use an actin ring to form a cleavage furrow, while plant cells form a cell plate from Golgi vesicles. Signup and view all the answers

List some reasons why a cell that has just completed cytokinesis might enter the G0 phase instead of the G1 phase.

Cells might enter G0 until maturity, only when needed, post-injury, or never divide after maturity. Signup and view all the answers

What cell cycle events will be affected in a cell that produces mutated (non-functional) cohesin protein?

Chromosomes will not be properly packaged after DNA replication, affecting the formation of centromeric proteins. Signup and view all the answers

Describe the general conditions that must be met at each of the three main cell cycle checkpoints.

G1 checks cell growth, DNA state, and energy; G2 checks DNA duplication; M confirms spindle attachment. Signup and view all the answers

Explain the roles of positive cell cycle regulators compared to the negative regulators.

Positive regulators advance the cell cycle, while negative regulators block progression until conditions are right. Signup and view all the answers

What steps are necessary for Cdk to become fully active?

Cdk must bind to a cyclin and be phosphorylated at the correct position. Signup and view all the answers

What molecular mechanism does Rb employ to halt the cell cycle?

Rb binds to E2F and prevents transcription of genes needed for the G1/S transition when it is dephosphorylated. Signup and view all the answers

Outline the steps that lead to a cell becoming cancerous.

Mutations in regulator genes lead to non-functional proteins, accumulating damage, loss of checkpoints, and increased division rates. Signup and view all the answers

Explain the difference between a proto-oncogene and a tumor suppressor gene.

Proto-oncogenes promote cell cycle progression; tumor suppressor genes inhibit it. Signup and view all the answers

List the regulatory mechanisms that might be lost in a cell producing faulty p53.

Loss of genomic DNA quality monitoring, repair enzyme recruitment, and triggering of apoptosis. Signup and view all the answers

How does p53 triggering apoptosis benefit a multicellular organism?

It prevents damaged DNA from producing faulty proteins, protecting the organism from potential cancer. Signup and view all the answers

Name the common components of eukaryotic cell division and binary fission.

DNA duplication, segregation of chromosomes, and division of cytoplasmic contents. Signup and view all the answers

Describe how the duplicated bacterial chromosomes are distributed into new daughter cells without the direction of the mitotic spindle.

The origins of replication move apart as the membrane grows and elongates the cell. Signup and view all the answers

Study Notes

Comparison of Human Cells

Human somatic cells contain 46 chromosomes (22 pairs + 2 sex chromosomes), in a diploid (2n) state.
Human gametes have 23 chromosomes (one of each unique chromosome), in a haploid (n) state.

Relationship Between Genome, Chromosomes, and Genes

The genome is the entirety of an organism's chromosomes.
Each chromosome holds hundreds to thousands of genes, which are DNA segments coding for proteins or RNA.

Chromosome Structure and Packaging

DNA wraps around histone proteins, forming nucleosomes.
Nucleosomes coil into a 30-nm fiber and condense further during cell division with the help of packing proteins.

Interphase Events

G1 phase: Cell grows, evaluates DNA for damage, and prepares energy/resources for DNA synthesis.
S phase: Chromosomes and centrosomes duplicate.
G2 phase: Cell recovers from DNA synthesis, grows, duplicates organelles, and dismantles unnecessary organelles.

Chemotherapy Effects on Mitosis

Vincristine and colchicine disrupt microtubule assembly by binding to tubulin, targeting the mitotic spindle.
Disruption leads to inability to sort/separate chromosomes during mitosis, causing cell arrest and death.

Cytokinesis Mechanisms

Animal cells undergo cytokinesis through a contracting actin ring leading to the formation of a cleavage furrow.
Plant cells form a new cell wall via a cell plate from Golgi vesicles, which grow and fuse with the parental cell wall.

G0 Phase Entry After Cytokinesis

Cells can enter G0 for maturity, only proliferating when necessary (tissue injury) or may never divide post-maturity.

Impact of Mutated Cohesin Protein

Non-functional cohesin affects chromosome packaging post-replication, hindering formation of kinetochores and resulting in failure to sort chromosomes during mitosis.

Cell Cycle Checkpoints Conditions

G1 checkpoint: Reviews cell size, DNA integrity, energy stores for S phase readiness.
G2 checkpoint: Confirms chromosome duplication and assesses DNA for errors before proceeding.
M checkpoint: Ensures correct attachment of spindle fibers to kinetochores.

Cell Cycle Regulators

Positive regulators (cyclin, Cdk) promote progression through the cell cycle.
Negative regulators (Rb, p53, p21) halt the cycle until conditions are favorable.

Activation of Cdk

Cdk requires binding to a cyclin and correct phosphorylation to attain full activity.

Role of Rb in Cell Cycle Regulation

Active Rb binds E2F, blocking transcription necessary for G1/S transition until the cell size threshold is reached, leading to Rb's phosphorylation and E2F release.

Cancer Development Steps

Mutations in regulatory genes produce defective proteins, leading to unchecked cell cycle progression and potential cell immortality.

Proto-oncogenes vs Tumor Suppressor Genes

Proto-oncogenes code for positive cell cycle regulators; mutations can create oncogenes causing abnormal divisions.
Tumor suppressor genes code for negative regulators; mutations can inactivate them, allowing unchecked cell cycle progression.

Consequences of Faulty p53 Production

Loss of p53 may impair genomic DNA monitoring, repair enzyme recruitment, and apoptosis initiation.

p53 and Apoptosis

p53-induced apoptosis from DNA damage prevents faulty protein production in daughter cells, safeguarding the organism by controlling potential cancer formation.

Commonalities in Cell Division

Both eukaryotic cell division and binary fission involve DNA duplication, segregation of chromosomes, and cytoplasmic division.

Bacterial Chromosome Distribution

In bacteria, duplicated chromosomes attach to the cell membrane, and as the cell elongates, this assists in distributing them into daughter cells without mitotic spindle direction.

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Description

This quiz covers key concepts from Biology Chapter 10, focusing on the differences between human somatic cells and gametes, as well as the relationships between genomes, chromosomes, and genes. It is designed to help reinforce understanding of these fundamental biological principles.