Biology Chapter 11: Cell Growth and Division

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Questions and Answers

What is the complex of DNA and proteins referred to as?

Centromere

Nucleosome

Telomere

Chromatin (correct)

What forms when DNA slightly coils around histones?

Chromatin

Chromosome

Centrosome

Nucleosome (correct)

Which structures assist in organizing the DNA inside the nucleus by forming bead-like units?

Histones (correct)

Lysosomes

Ribosomes

Mitochondria

Which phase of the eukaryotic cell cycle involves the synthesis and replication of DNA?

S phase Signup and view all the answers

What is the final result of cell division in eukaryotic cells?

Two nearly identical daughter cells Signup and view all the answers

What are the two main reasons that a cell divides?

The cell becomes less efficient in nutrient and waste exchange and places increasing demands on its DNA. Signup and view all the answers

Which factor does NOT affect the rate of exchange of substances in and out of a cell?

The genetic material inside the nucleus. Signup and view all the answers

How does the surface area to volume ratio change as a cell grows larger?

The ratio decreases, making exchange processes less efficient. Signup and view all the answers

What primarily dictates the traffic problems faced by larger cells?

The volume and surface area ratio constraints. Signup and view all the answers

What role does DNA play in limiting cell size?

It serves as the library of information, making it difficult to meet increasing cellular demands as the cell grows. Signup and view all the answers

Which stage is characterized by the separation of sister chromatids?

Anaphase Signup and view all the answers

Which structures are responsible for organizing spindle fibers in plant cells?

Centrosomes Signup and view all the answers

What occurs during prophase in eukaryotic cells?

Genetic material condenses and duplicated chromosomes become visible Signup and view all the answers

What is the primary function of the centromere during mitosis?

Attaching sister chromatids together Signup and view all the answers

Which phase of mitosis is typically the longest and may take up half of the total time to complete mitosis?

Prophase Signup and view all the answers

In which phase do the centromeres of duplicated chromosomes line up across the center of the cell?

Metaphase Signup and view all the answers

Which structure forms in plant cells during cytokinesis to separate the two daughter cells?

Cell plate Signup and view all the answers

What happens to the cell membrane in animal cells during cytokinesis?

It is drawn inward until the cytoplasm is pinched into two parts. Signup and view all the answers

Which regulatory proteins respond to events inside the cell?

Internal regulators Signup and view all the answers

What role do growth factors play in regulating the cell cycle?

They stimulate the growth and division of cells. Signup and view all the answers

How do cells respond to tissue injury in terms of cell division?

Cells at the edge of the injury are stimulated to divide rapidly. Signup and view all the answers

What prevents a cell from entering anaphase until spindle fibers have attached to each chromosome?

An internal checkpoint Signup and view all the answers

What is an advantage of asexual reproduction?

Quick reproduction when conditions are right Signup and view all the answers

Which of the following statements is true about prokaryotic chromosomes?

They are single circular DNA molecules Signup and view all the answers

What is a disadvantage of sexual reproduction?

Requires more time to find a mate and develop offspring Signup and view all the answers

What role do histones play in eukaryotic chromosomes?

Binding tightly to DNA Signup and view all the answers

What is a key consequence of lack of genetic diversity in asexual reproduction?

Population may be unable to adapt to changing conditions Signup and view all the answers

Which organisms primarily rely on cell division as their only form of reproduction?

Single-celled organisms Signup and view all the answers

How do offspring produced by sexual reproduction differ from those produced by asexual reproduction?

They inherit genetic information from two parents Signup and view all the answers

Where is the genetic information of prokaryotic cells primarily located?

In the cytoplasm Signup and view all the answers

What role does the cell cycle play in the organism?

It is essential for embryonic development and wound healing. Signup and view all the answers

Which regulatory influence is particularly associated with the cell cycle?

External regulatory proteins Signup and view all the answers

Which mechanism can halt the cell cycle?

DNA replication errors Signup and view all the answers

During wound healing, why is the cell cycle significant?

It enables rapid cell division to replace damaged cells. Signup and view all the answers

How do other external regulatory proteins affect the cell cycle?

They can either stimulate or inhibit cell division. Signup and view all the answers

Which cell type is capable of developing into any type of cell in the body?

Totipotent cells Signup and view all the answers

At what developmental stage do human cells begin to specialize?

Blastocyst stage Signup and view all the answers

What are embryonic stem cells specifically capable of producing?

All adult cell types Signup and view all the answers

What types of cells do adult stem cells primarily differentiate into?

Cells within the tissues where they are found Signup and view all the answers

Which of the following statements about pluripotent cells is accurate?

Pluripotent cells generally cannot form tissues surrounding the embryo Signup and view all the answers

In a Punnett square prediction of genotype frequencies for a monohybrid cross between parents with PP and Pp genotypes, what percent of the offspring is expected to be heterozygous?

50% Signup and view all the answers

Study Notes

Cell Growth, Division, and Reproduction

Limits to Cell Size
Two main reasons for cell division: + Cell becomes less efficient in moving nutrients and waste materials + As a cell grows, it places increasing demands on its own DNA
Problems of Size
Rate of exchange between food, oxygen, and water to enter and waste products to leave depends on surface area of cell
As cell grows, rate of exchange becomes less efficient, leading to cell division

Cell Division and Reproduction

Asexual
- Cell division is the only form of reproduction for many single-celled organisms
- The two cells produced are genetically identical to the cell that produced them
Sexual
- Involves fusion of two reproductive cells formed by each of two parents
- Offspring produced by sexual reproduction inherit some genetic information from each parent

Compare

Asexual
- Advantages
  - Can reproduce quickly, enabling them to compete successfully with other organisms
- Disadvantages
  - Lack of genetic diversity is a disadvantage when conditions change
Sexual
- Disadvantages
  - Requires more time to find a mate and allows for growth and development of offspring
- Advantages
  - Produces genetic diversity
  - If the environment changes, diversity in species may help ensure that the population contains the right combination of characteristics needed to survive

Process of Cell Division

Chromosomes
Genetic information is bundled into packages of DNA called chromosomes
Prokaryotic Chromosomes
DNA molecules are found in the cytoplasm
Most prokaryotes contain a single circular DNA chromosome containing all of the cell's genetic information
Eukaryotic Chromosomes
Chromosomes in eukaryotic cells contain DNA tightly bound to proteins known as histones
The complex of DNA and proteins is referred to as chromatin

The Structure of DNA and Chromosomes

DNA slightly coils around histones and together the DNA

Cell Division

G2: Preparing for cell division
- Synthesis phase: Many of the organelles and molecules required for cell division are produced
M Phase: Cell division
- Mitosis
- Cytokinesis

Mitosis

4 phases:
- Prophase:
  - Longest phase, may take up to half of total time to complete mitosis
  - Genetic material inside nucleus condenses and duplicated chromosomes become visible
  - Outside nucleus, spindle starts to form
- Metaphase:
  - Centromeres of duplicated chromosomes line up across the center of the cell
- Anaphase:
  - Sister chromatids separate and move to opposite ends of the cell
- Telophase

Cytokinesis

Division of cytoplasm to form two separate cells
- Usually occurs at the same time as telophase
- In animal cells:
  - Cell membrane is drawn inward until cytoplasm is pinched into two nearly equal parts
- In plant cells:
  - Cell plate forms halfway between divided nuclei
  - Cell plate gradually grows into cell membranes that separate the two daughter cells

Regulating Cell Cycle

Controls on Cell Division
- Cells at edges of injury are stimulated to divide rapidly
- New cells form, starting the process of healing
- When healing process nears completion, rate of cell division slows, controls on growth are restored, and normal activities return
Regulatory Proteins
- Dozens of proteins help to regulate
- Cell cycle is controlled by regulatory proteins both inside and outside the cell

Cell Differentiation

Adult Cells
- Generally reach a point at which their differentiation is complete - cannot turn into other types of cells
Stem Cells and Development
- Totipotent: Able to develop into any type of cell in the body
- Human Development:
  - After about four days of development, human embryo forms into a blastocyst
  - At this stage, cells begin to specialize
    - Outer cells form tissues that attach embryo to mother
    - Inner cells are said to be pluripotent
- Stem Cells
  - Sit at base of branching “arm” of development from which different cell types form
  - Stem cells are the unspecialized cells from which differentiated cells develop
- Adult Stem Cells
  - Pools of adult stem cells produce new cells to replace dead cells
    - Limited to replacing cells in the tissues where they are found
- Embryonic Stem Cells
  - Capable of producing every cell type

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Description

This quiz covers the limitations of cell size, the reasons why cells divide, and the problems associated with increasing cell size.