AP Biology: Chapter 12 Flashcards

Questions and Answers

What does MPF trigger?

It triggers the cell's passage past the G2 checkpoint into the M phase.

What happens if all the chromosome kinetochores are not attached to spindle fibers?

The sister chromatids remain together, delaying anaphase, and the M phase checkpoint is not passed.

What is a growth factor?

A protein released by cells that stimulates other cells to divide.

What is platelet-derived growth factor (PDGF)?

PDGF is made by blood cell fragments called platelets and is required for the division of cultured fibroblasts. Signup and view all the answers

How does PDGF stimulate fibroblast division?

Fibroblasts have PDGF receptors on their plasma membranes, and the binding of PDGF triggers a signal transduction pathway that allows the cell to pass the G1 checkpoint and divide. Signup and view all the answers

What is density-dependent inhibition?

It is the phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another. Signup and view all the answers

What is anchorage dependence?

It is the requirement that a cell must be attached to a substratum in order to initiate cell division. Signup and view all the answers

What is the source of the HeLa cell?

HeLa cells were originally from Henrietta Lacks in 1951, who had cervical cancer from HPV. Signup and view all the answers

What is transformation in cell biology?

The conversion of a normal animal cell to a cancerous cell. Signup and view all the answers

What is metastasis?

The spread of cancer cells to locations distant from their original site. Signup and view all the answers

What is a benign tumor?

A mass of abnormal cells that are not capable of surviving at a new site and generally remain at the site of the tumor's origin. Signup and view all the answers

What is a malignant tumor?

A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading new sites. Signup and view all the answers

What is radiation in cancer treatment?

It damages the DNA of localized cancer cells. Signup and view all the answers

What is chemotherapy?

Drugs that are toxic to actively dividing cells that are administered throughout the circulatory system. Signup and view all the answers

What are proto-oncogenes?

Genes in normal cells that stimulate cell division, turned off most of the time. In cancer cells, mutations turn these genes on continuously, now called oncogenes. Signup and view all the answers

What are tumor suppressor genes?

In normal cells, they encode proteins to inhibit cell division and are turned on most of the time. In cancer cells, they are turned off and cell division occurs constantly. Signup and view all the answers

What do out of control cancer cells do?

<ol> <li>Form tumors, 2. Lose adhesion to other cells, break away, and spread throughout the body (metastasis), 3. Live immortally until the organism dies.</li> </ol> Signup and view all the answers

What is cell division?

the reproduction of cells Signup and view all the answers

What is the cell cycle?

the ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two Signup and view all the answers

What are three key roles of cell division?

reproduction, growth and development, tissue renewal/repair Signup and view all the answers

What is a genome?

a cell's endowment of DNA Signup and view all the answers

What are chromosomes?

cellular structures carrying genetic material Signup and view all the answers

What is chromatin?

the complex of DNA and proteins that makes up eukaryotic chromosomes Signup and view all the answers

What are somatic cells?

any cell in a multicellular organism except a sperm or egg or their precursors Signup and view all the answers

What are gametes?

haploid reproductive cells, such as sperm or egg Signup and view all the answers

How many chromosomes are in a human somatic cell?

46 Signup and view all the answers

What are the two types of gametes?

sperm and eggs Signup and view all the answers

How many chromosomes are in a human gamete?

23 Signup and view all the answers

How many DNA molecules are in each of your somatic cells?

46 Signup and view all the answers

What are sister chromatids?

two copies of a duplicated chromosome attached to each other Signup and view all the answers

What are cohesins?

protein complexes that are responsible for attaching sister chromatids Signup and view all the answers

What is a centromere?

the region on each sister chromatid where they are most closely attached Signup and view all the answers

What is mitosis?

a process of nuclear division in eukaryotic cells Signup and view all the answers

What is cytokinesis?

the division of the cytoplasm to form two separate daughter cells Signup and view all the answers

Where does meiosis occur?

in the gonads, ovaries, or testes Signup and view all the answers

What process replaces damaged cells in a wound?

mitosis Signup and view all the answers

What process forms eggs?

meiosis Signup and view all the answers

Which process produces identical daughter cells?

mitosis Signup and view all the answers

Which process reduces the chromosome number of daughter cells?

meiosis Signup and view all the answers

What is the mitotic (M) phase?

the phase of the cell cycle that includes mitosis and cytokinesis Signup and view all the answers

What is interphase?

the period in the cell cycle when the cell is not dividing Signup and view all the answers

What happens during the G1 phase?

the first gap, where the cell grows before DNA synthesis Signup and view all the answers

What is the S phase?

the synthesis phase of the cell cycle where DNA is replicated Signup and view all the answers

What is the G2 phase?

the second gap where the cell prepares for mitosis Signup and view all the answers

What is a mitotic spindle?

an assemblage of microtubules involved in chromosome movement during mitosis Signup and view all the answers

What is a centrosome?

a structure that functions as a microtubule-organizing center during cell division Signup and view all the answers

What is an aster?

a radial array of short microtubules extending from each centrosome Signup and view all the answers

What are the components of the mitotic spindle?

fibers made of microtubules and associated proteins Signup and view all the answers

What is another name for the centrosome?

microtubule-organizing center Signup and view all the answers

What happens to the centrosome during interphase and prophase?

grows and copies its chromosomes in interphase; centrioles move apart in prophase Signup and view all the answers

What is a kinetochore?

a structure of proteins attached to the centromere linking each sister chromatid to the spindle Signup and view all the answers

What happens in the G2 phase and how is it controlled?

sufficient MPF accumulates; triggers passage into mitosis Signup and view all the answers

What happens in the M phase and how is it controlled?

the kinetochores must attach to spindle fibers; if not aligned, mitosis stops Signup and view all the answers

What is the G0 phase?

a nondividing state occupied by cells Signup and view all the answers

What is a protein kinase?

an enzyme that transfers phosphate groups from ATP to a protein Signup and view all the answers

What activates cyclin-dependent kinases?

attachment of a cyclin Signup and view all the answers

What is cyclin?

a cellular protein that regulates the cell cycle Signup and view all the answers

What are cyclin-dependent kinases (Cdks)?

a protein kinase active when attached to a cyclin Signup and view all the answers

What is MPF?

maturation-promoting factor, a protein complex for cell progression Signup and view all the answers

Why does the activity of cyclin-dependent kinases rise and fall?

due to fluctuations in cyclin levels Signup and view all the answers

Study Notes

Cell Division and Cycle

Cell division is essential for the reproduction of cells.
The cell cycle comprises an ordered sequence of events, including interphase (G1, S, G2) and M phase (mitosis and cytokinesis).
Key roles of cell division: reproduction, growth and development, and tissue renewal/repair.

Genomic Structures

The genome includes the complete DNA endowment of a cell, encompassing all genes and noncoding sequences.
Chromosomes are cellular structures that carry genetic material, each made of a long DNA molecule and proteins.
Chromatin is the DNA-protein complex that maintains a dispersed form when the cell is not dividing.

Somatic and Gametic Cells

Somatic cells are any body cells, excluding sperm and egg cells.
Gametes (sperm and eggs) are haploid reproductive cells that unite during fertilization to form a diploid zygote.
A human somatic cell contains 46 chromosomes, while a human gamete contains 23 chromosomes.

Chromatin and Chromosome Dynamics

Sister chromatids are identical copies of a duplicated chromosome held together at the centromere.
Cohesins are protein complexes that maintain sister chromatid attachment.
The centromere region is critical for chromatid cohesion and chromosome movement during division.

Mitosis and Cytokinesis

Mitosis occurs in five stages: prophase, prometaphase, metaphase, anaphase, and telophase, ensuring equal chromosome distribution.
Cytokinesis is the cytoplasmic division that follows mitosis, completing cell division.
In animal cells, cytokinesis involves a cleavage furrow; in plant cells, it forms a cell plate.

Specialized Cell Structures and Functions

The mitotic spindle, formed from microtubules, organizes chromosome movement during mitosis.
Centrosomes serve as microtubule-organizing centers and play a pivotal role in spindle formation.
Kinetochores are protein structures attached to centromeres linking sister chromatids to the spindle apparatus.

Checkpoints and Cell Cycle Control

The cell cycle is regulated by control systems, ensuring proper progression at checkpoints (G1, G2, M).
G1 checkpoint determines if the cell proceeds based on growth signals and DNA integrity.
G2 checkpoint assesses DNA replication completion, while the M checkpoint ensures proper chromosome alignment.

Regulatory Molecules

Cyclins and cyclin-dependent kinases (Cdks) are critical for cell cycle regulation.
MPF (maturation-promoting factor) is essential for transitioning from G2 to M phase.
Changes in cyclin concentration influence the activity of Cdks, impacting the cell cycle progression.

Growth Factors and Cell Interaction

Growth factors stimulate cell division and are critical for repair and tissue growth.
Density-dependent inhibition prevents cells from dividing when in contact with each other.
Anchorage dependence requires cells to attach to a substrate to initiate division.

Binary Fission and Prokaryotic Reproduction

Binary fission is the prokaryotic reproductive method that results in two identical cells.
Prokaryotic chromosomes are circular, contrasting with the linear chromosomes found in eukaryotes.### Hela Cells
Originated from Henrietta Lacks in 1951, derived from her cervical cancer caused by HPV.

Transformation

Refers to the conversion of a normal animal cell into a cancerous cell.

Metastasis

Involves the spread of cancer cells to distant locations away from their original site, complicating treatment.

Benign Tumor

Consists of abnormal cells that exhibit specific genetic and cellular changes.
These cells typically cannot survive at new sites and remain localized at the tumor's site of origin.

Malignant Tumor

Characterized by cancerous cells with significant genetic and cellular alterations.
Capable of invading nearby tissues and can metastasize, impairing the functions of one or more organs.

Radiation

A treatment method that damages the DNA of localized cancer cells to inhibit their growth and replication.

Chemotherapy

Involves the use of toxic drugs administered throughout the circulatory system targeting actively dividing cancer cells.

Proto-oncogenes

Normal genes found in cells that stimulate cell division; usually kept off.
Mutations can activate these genes continuously, transforming them into oncogenes associated with cancer.

Tumor Suppressor Genes

Encode proteins that inhibit cell division in normal cells, maintaining control over the cell cycle.
In cancer cells, these genes are turned off, leading to unregulated cell division.

Characteristics of Out-of-Control Cancer Cells

Form tumors that disrupt normal tissue structure and function.
Lose adhesion to other cells, allowing them to break away and proliferate throughout the body (metastasis).
Possess the ability to live indefinitely until the organism's death, contributing to the progression of cancer.

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Test your knowledge of key concepts from Chapter 12 of AP Biology with these flashcards. Focus on essential terms such as cell division and the cell cycle, including interphase and mitosis. Perfect for reviewing critical biological processes.