Biology Chapter 5 Flashcards

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Questions and Answers

What is chromatin?

Loose combination of DNA and proteins that is present during interphase

What is a chromatid?

One half of a duplicated chromosome

What is a centromere?

Region of condensed chromosome that looks pinched; where spindle fibers attach during mitosis and meiosis

What is a telomere?

Repeating nucleotide at the ends of DNA molecules that don't form genes and prevent the loss of genes Signup and view all the answers

What happens during prophase?

First phase of mitosis when chromatin condenses, nuclear envelope breaks down, nucleolus disappears, centrosomes and centrioles migrate to opposite sides of the cell Signup and view all the answers

What occurs during metaphase?

Second phase of mitosis when spindle fibers align the chromosomes along the cell equator Signup and view all the answers

What is anaphase?

Third phase of mitosis during which chromatids separate and are pulled to opposite sides of the cell Signup and view all the answers

What happens during telophase?

Last phase of mitosis Signup and view all the answers

What is the cell cycle?

Pattern of growth and cell division that occurs in a eukaryotic cell Signup and view all the answers

What is mitosis?

Process by which a nucleus divides its nucleus and its contents Signup and view all the answers

What is cytokinesis?

Process by which the cell cytoplasm divides Signup and view all the answers

What are chromosomes?

Long, continuous thread of DNA that consists of numerous genes and regulatory information Signup and view all the answers

What is a histone?

Protein that organizes chromosomes and around which DNA wraps Signup and view all the answers

What occurs during the G1 phase?

Cells increase in size and organelles in number Signup and view all the answers

What happens during synthesis?

Cell makes a copy of its nuclear DNA. In the end, the cell contains 2 complete sets of DNA Signup and view all the answers

What is Gap 2?

Cells continue to carry out their normal functions, and additional growth occurs Signup and view all the answers

What must cells pass through during the cell cycle?

Critical checkpoint during Synthesis and Mitosis Signup and view all the answers

Where does DNA synthesis happen in eukaryotic cells?

In the nucleus Signup and view all the answers

What two processes make up the M stage?

Mitosis and cytokinesis Signup and view all the answers

Among different types of cells, which stage of the cell cycle varies most in length?

The length of the G1 stage differs the most between cells Signup and view all the answers

What is G0?

The stage in which cells are unlikely to divide Signup and view all the answers

What typically increases faster as a cell grows, surface area or volume?

Surface area increases faster as the cell grows Signup and view all the answers

For cells to stay the same size from generation to generation, what two things must be coordinated?

Growth and division Signup and view all the answers

What process divides the cell's cytoplasm?

Cytokinesis Signup and view all the answers

What process divides the cell nucleus and its contents?

Mitosis Signup and view all the answers

What is a chromosome?

One long continuous thread of DNA consisting of genes and information Signup and view all the answers

Why do chromosomes condense at the start of mitosis?

So the cells can carry out all their necessary processes Signup and view all the answers

Why are chromosomes not condensed during all stages of the cell cycle?

To make sure cells get the correct amount of copies and everything in proper numbering Signup and view all the answers

How does interphase prepare the cell to divide?

It provides a critical time for organelle duplication and DNA reproduction Signup and view all the answers

In what types of cells does mitosis occur?

Mitosis occurs in all of the body cells except eggs and sperm Signup and view all the answers

Describe cytokinesis.

Divide cytoplasm between 2 daughter cells, each with genetically identical nucleus. The cells enter interphase and begin again. Signup and view all the answers

Describe prophase.

DNA and proteins condense into tightly coiled chromosomes. The nuclear envelope breaks down, the nucleolus disappears, and the centrosomes and centrioles migrate to opposite sides of the cell Signup and view all the answers

Describe metaphase.

Spindle fibers attach to each chromosome. They align the chromosome along the cell equator Signup and view all the answers

Describe anaphase.

Chromatids separate to opposite sides of the cell. Cytokinesis usually begins in late anaphase or early telophase Signup and view all the answers

Describe telophase.

Nuclear membranes start to form, chromosomes begin to uncoil and the spindle fibers fall apart Signup and view all the answers

How does cytokinesis differ between plant and animal cells?

In animal cells the membrane pinches inwards, but the plant cells cannot Signup and view all the answers

DNA wraps around organizing proteins called?

Histones Signup and view all the answers

______ is the loose combination of DNA and proteins that look like spaghetti.

Chromatin Signup and view all the answers

Sister chromatids are held together at the _______, which looks pinched.

Centromere Signup and view all the answers

The ends of DNA molecules form structures called _____ that help prevent the loss of genes.

Telomeres Signup and view all the answers

What are internal factors in cell cycle regulation?

Often triggered by external factors, include kinases and cyclins Signup and view all the answers

What are external factors in cell cycle regulation?

Include cell to cell contact and other physical signals; also include chemical signals such as growth factors Signup and view all the answers

What are carcinogens?

Substances that produce or promote the development of cancer Signup and view all the answers

List examples of carcinogens.

Tobacco smoke, air pollutants, radiation, mutated genes carried by viruses Signup and view all the answers

What characterizes cancer cells?

Characterized by uncontrolled cell division; continue to grow despite cell to cell contact or lack of growth factors Signup and view all the answers

What may cancer cells form?

Tumors Signup and view all the answers

What can kill cancer cells?

Apoptosis Signup and view all the answers

What are tumors?

Disorganized clumps of cancer cells that do not carry out specialized functions needed by the body Signup and view all the answers

What is apoptosis?

Programmed cell death that plays a role in normal development and ridding the body of unhealthy cells Signup and view all the answers

What are the two types of tumors?

Malignant and benign Signup and view all the answers

What characterizes malignant tumors?

Cells break away and form new tumors Signup and view all the answers

What characterizes benign tumors?

Cells remain clustered together Signup and view all the answers

What is an example of apoptosis in healthy organisms?

Cells between fingers Signup and view all the answers

What do growth factors stimulate?

Cell division Signup and view all the answers

What type of disease results if cell division isn't properly regulated?

Cancer may result Signup and view all the answers

List three ways mutations can occur in genes involved in cell cycle regulation.

Inherited, exposed to radiation, exposed to chemicals Signup and view all the answers

What does metastasize mean?

When some of the cancer cells break away Signup and view all the answers

What is a substance known to produce or promote the development of cancer?

Carcinogens Signup and view all the answers

What is the chromosome structure?

DNA double helix, chromatin, supercoiled Signup and view all the answers

Why is cell size limited?

Cells have upper and lower size limits; if too small, they couldn't contain all the necessary organelles; surface area too small could result in insufficient materials transport Signup and view all the answers

Summarize the cell cycle.

Cells have distinct phases of growth, reproduction, and normal functions. The cell cycle has four main stages: G1, S, G2, and M. The length of the cell cycle can vary, resulting in different rates of cell division. This variability is based on the body's need for different cell types. Cells also divide because they need a sufficient surface area-to-volume ratio to move materials into and out of the cell. Signup and view all the answers

Summarize mitosis and cytokinesis.

Cells divide during mitosis and cytokinesis. Mitosis divides the nucleus into two genetically identical nuclei in a four-phase process: prophase, metaphase, anaphase, and telophase. In prophase, the duplicated chromosomes condense tightly. Cytokinesis actually divides the cell cytoplasm. Signup and view all the answers

Summarize the regulation of the cell cycle.

Cell cycle regulation is necessary for healthy growth. Cell growth and division are regulated by both external factors, such as hormones and growth factors, and internal factors, such as cyclins and kinases. When proper regulation of cell growth is disrupted, a cell may become cancerous. Cancer cells grow more rapidly than do normal cells and form clumps called tumors that may metastasize to other regions of the body. Signup and view all the answers

Summarize asexual reproduction.

Many organisms reproduce by cell division. Most prokaryotes reproduce through a process called binary fission, in which a cell divides into two approximately equal parts. Some eukaryotes reproduce through mitosis. The offspring that result from asexual reproduction are genetically identical to the parent organism, except when mutations occur. Whether being identical is an advantage or a disadvantage depends on the environment. Signup and view all the answers

Summarize multicellular life.

Cells work together to carry out complex functions. Within multicellular organisms, cells form tissues, tissues form organs, and organs form organ systems. The cells differentiate to perform specific functions. Much of this specialization is determined by a cell's location within the developing embryo. Stem cells are a special type of cell that continues to divide and renew themselves for long periods. Signup and view all the answers

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Study Notes

Cell Cycle and Mitosis

Chromatin: Loose DNA and protein combination present during interphase.
Chromatid: One half of a duplicated chromosome, essential for cell division.
Centromere: Pinched region of a condensed chromosome where spindle fibers attach during mitosis/meiosis.
Telomere: Repeating nucleotide sequences at DNA ends that protect genes from loss.

Phases of Mitosis

Prophase: First stage; chromatin condenses, nuclear envelope breaks down, centrosomes move apart.
Metaphase: Chromosomes align along the cell equator, facilitated by spindle fibers.
Anaphase: Chromatids separate and move to opposite cellular poles.
Telophase: Nuclear membranes form, chromosomes decondense, and spindle fibers disassemble.

Cell Cycle Overview

G1 Phase: Cells grow and increase organelle number.
Synthesis: DNA replication occurs, doubling genetic material.
Gap 2: Cells further grow and maintain normal functions before division.
Mitosis: Process of nucleus division, followed by cytokinesis to divide the cytoplasm.

Cellular Function and Regulation

Critical checkpoints exist during synthesis and mitosis to ensure proper division.
Internal factors such as kinases and cyclins regulate cell cycle progression.
External factors include cell-to-cell contact and growth factors influencing proliferation.

Cancer and Tumor Formation

Carcinogens are substances promoting cancer development.
Cancer cells' uncontrolled division leads to tumor formation, characterized by disorganized growth.
Two tumor types: Malignant (can metastasize) and Benign (remain localized).
Apoptosis: Programmed cell death essential for normal development and eliminating unhealthy cells.

Genetic Stability and Mutations

Variations in the G1 phase length differ among cell types, indicating their roles in the organism.
Mutations in regulatory genes can arise from heredity, radiation exposure, or chemical agents.
Metastasis occurs when cancer cells spread from the original tumor site.

Asexual Reproduction

Organisms, particularly prokaryotes and some eukaryotes, reproduce via binary fission or mitosis, respectively.
Asexual offspring are typically genetically identical to parent organisms unless mutations occur.

Multicellular Organization

Multicellular organisms feature specialized cells forming tissues, organs, and systems.
Cell differentiation is influenced by location during development, exemplified by stem cells that can renew indefinitely.

Summary of Cell Cycle Segments

The cell cycle includes distinct phases that regulate growth and division.
Mitosis effectively divides the nucleus into two identical nuclei, while cytokinesis divides the cytoplasm.
Cell cycle regulation is crucial for healthy growth, preventing cancerous development and maintaining normal cellular processes.

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