Biology Cell Theory and Structure

Questions and Answers

Who is the first to observe 'small chambers' in cork and called them cells?

Robert Hooke

Who commissioned a microscopic investigation of the natural world?

King Charles II of England

Robert Hooke published his book called ___________, which contains his drawings of a section of cork as seen through one of the first microscopes.

Microraphia

Who discovered and named the nucleus?

Robert Brown Signup and view all the answers

Who helped in the development of cell theory by explaining that cells are the shared element of plants and animals?

Matthias Schleiden Signup and view all the answers

Who is considered the founder of modern histology and defined the cell as the basic unit of animal structure?

Theodor Schwann Signup and view all the answers

Who concluded that new cells could be produced only from the division of existing cells?

Rudolf Virchow Signup and view all the answers

Who discovered that the cell membrane is a defined physical structure?

Janet Plowe Signup and view all the answers

Who proposed the endosymbiotic theory related to mitochondria and chloroplasts?

Lynn Margulis Signup and view all the answers

What is the 1st Cell Postulate?

All organisms are composed of one or more cells. Signup and view all the answers

What is the 2nd Cell Postulate?

The cell is the basic unit of structure and function of all organisms. Signup and view all the answers

What is the 3rd Cell Postulate?

All cells arise only from pre-existing cells. Signup and view all the answers

What is the 4th Cell Postulate?

Heredity information (DNA) is passed on from cell to cell. Signup and view all the answers

What is the 5th Cell Postulate?

All cells have the same basic chemical composition. Signup and view all the answers

What is the 6th Cell Postulate?

Energy flow (Metabolism and Biochemistry) occurs within cells. Signup and view all the answers

What regulates what enters and leaves the cell and separates the internal environment of the cell from the external environment?

Plasma membrane (cell membrane) Signup and view all the answers

What molecules help strengthen the cell membrane making it more flexible but less fluid?

Cholesterol Signup and view all the answers

What are attached to proteins and serve as identification tags for cells?

Carbohydrates Signup and view all the answers

What is a rigid structure that surrounds the cell membrane and provides support to the cell?

Cell wall Signup and view all the answers

What is the portion of the cell outside the nucleus?

Cytoplasm Signup and view all the answers

What part of the cell contains DNA and RNA and is responsible for growth and reproduction?

Nucleus Signup and view all the answers

What is found inside the nucleus and produces ribosomes?

Nucleolus Signup and view all the answers

What organelle is responsible for protein synthesis?

Ribosomes Signup and view all the answers

What structure in the cell forms a maze of passageways for transporting materials?

Endoplasmic Reticulum (ER) Signup and view all the answers

What endomembrane system is covered with ribosomes where many proteins for transport are assembled?

Rough Endoplasmic Reticulum Signup and view all the answers

What type of endoplasmic reticulum has no ribosomes but is involved in the synthesis of lipids and some steroids?

Smooth Endoplasmic Reticulum Signup and view all the answers

What stack of membranes in the cell modifies, sorts, and packages proteins from the endoplasmic reticulum?

Golgi apparatus Signup and view all the answers

What are small membrane sacs that specialize in moving products into, out of, and within a cell?

Vesicles Signup and view all the answers

What cell organelle stores materials such as water, salts, proteins, and carbohydrates?

Vacuoles Signup and view all the answers

What organelle contains digestive enzymes?

Lysosomes Signup and view all the answers

What organelles break down fatty acids and produce hydrogen peroxide?

Peroxisomes Signup and view all the answers

What organelle is known as the powerhouse of the cell?

Mitochondria Signup and view all the answers

What organelle is found in plant and algae cells where photosynthesis occurs?

Chloroplast Signup and view all the answers

What organelles are responsible for forming and anchoring the spindle fibers?

Centrosomes and Centrioles Signup and view all the answers

What are hairlike structures that extend from the surface of the cell, assisting in movement?

Cilia and Flagella Signup and view all the answers

What is a network of fibers that holds the cell together and aids in movement?

Cytoskeleton Signup and view all the answers

What are thick hollow tubes that make up the cilia, flagella, and spindle fibers?

Microtubules Signup and view all the answers

What prevents leakage of extracellular fluid across a layer of epithelial cells?

Tight Junctions Signup and view all the answers

What junction allows cells to stretch?

Adhesion Junctions (desmosomes) Signup and view all the answers

What provide cytoplasmic channels between adjacent cells?

Gap junctions (communicating junctions) Signup and view all the answers

What type of cell lacks a membrane-enclosed nucleus and membrane-enclosed organelles?

Prokaryotic Cells Signup and view all the answers

What type of cell is larger, more complex, and contains a nucleus and membrane-bound organelles?

Eukaryotic Cells Signup and view all the answers

What is a sticky layer that surrounds the cell walls of some bacteria?

Capsule Signup and view all the answers

What is an area of the cytoplasm that contains the single bacterial DNA molecule?

Cytoplasm Region Signup and view all the answers

What are the folding structures present inside the plasma membrane that play a role in cellular respiration?

Mesosomes Signup and view all the answers

What is a small circle of DNA that plays a role in exchanging DNA between bacterial cells?

Plasmids Signup and view all the answers

What is a highly-porous membrane that separates the nucleus from the cytoplasm?

Nuclear Membrane Signup and view all the answers

What type of cell does not have a cell wall or chloroplast and has a small vacuole?

Animal Cell Signup and view all the answers

What type of cell contains a cell wall, chloroplast, and large vacuole?

Plant Cell Signup and view all the answers

What type of tissue covers the outside of the body and lines organs and cavities?

Epithelial Tissue Signup and view all the answers

What type of epithelial tissue has cube-shaped cells?

Cuboidal Epithelium Signup and view all the answers

What is made up of a single layer of tall cells that fit closely together?

Simple Columnar Epithelium Signup and view all the answers

What consists of a single layer of flattened cells?

Simple Squamous Epithelium Signup and view all the answers

What is multilayered and regenerates quickly for protection?

Stratified Squamous Epithelium Signup and view all the answers

What type of epithelium has a single layer of cells that may look stacked because of varying height?

Pseudostratified Columnar Epithelium Signup and view all the answers

What is a body tissue that provides support for the body and connects all of its parts?

Connective Tissue Signup and view all the answers

What is a connective tissue with a fluid matrix called plasma in which cells are suspended?

Blood Signup and view all the answers

What is the type of connective tissue that includes loose and dense connective tissues?

Connective Tissue Proper Signup and view all the answers

What connective tissue is more flexible than bone and protects the ends of bones?

Cartilage Signup and view all the answers

What is mineralized connective tissue?

Bone Signup and view all the answers

What tissue is composed of long cells called muscle fibers that allow movement?

Muscle Tissue Signup and view all the answers

What is striated and allows voluntary movements?

Skeletal Muscle Signup and view all the answers

What is involuntary muscle tissue found only in the heart?

Cardiac Muscle Signup and view all the answers

What muscle tissue is non-striated and involuntary?

Smooth Muscle Signup and view all the answers

What tissue carries electrical messages between the brain and other parts of the body?

Nervous Tissue Signup and view all the answers

What allows fast cell communication by sending impulses through the nervous system?

Nerve Cells Signup and view all the answers

What are cells in the nervous system that support and protect neurons?

Glial Cells Signup and view all the answers

What is the process in reproduction and growth by which a cell divides to form daughter cells?

Cell Division Signup and view all the answers

What is the regular sequence of growth and division that cells undergo called?

Cell Cycle Signup and view all the answers

What type of cell division results in nuclei containing the same number of chromosomes?

Mitosis Signup and view all the answers

What type of cell division produces reproductive cells?

Meiosis Signup and view all the answers

What checkpoint ensures chromosomes are properly attached to the spindle fibers?

Metaphase Checkpoint Signup and view all the answers

What is considered the most important of the three major checkpoints in the cell cycle?

G1 checkpoint (restriction point) Signup and view all the answers

What checkpoint ensures DNA replication has been successfully completed?

G2 checkpoint Signup and view all the answers

What must precede mitosis so that all daughter cells receive the same complement of chromosomes?

DNA replication (S Phase) Signup and view all the answers

What phases allow the cell to grow large enough and synthesize enough organelles?

Gap Phases Signup and view all the answers

What gives the 'go-ahead' signals at the G1 and G2 checkpoints?

Kinase Signup and view all the answers

What regulates the cell cycle when bound to cyclin?

Cyclin-Dependent Kinase (CDK's) Signup and view all the answers

What phosphorylates key proteins in the mitotic sequence?

Maturation Promoting Factor (MPF) Signup and view all the answers

What is the first phase of mitosis where chromosomes become visible?

Prophase Signup and view all the answers

What phase of mitosis involves chromosomes lining up in the middle of the cell?

Metaphase Signup and view all the answers

What phase of mitosis is where chromosome pairs separate and move toward opposite poles?

Anaphase Signup and view all the answers

What is the final phase of mitosis where the cell seals off?

Telophase Signup and view all the answers

What is the division of the cytoplasm to form two separate daughter cells?

Cytokinesis Signup and view all the answers

What is the first phase of meiosis that has five substages?

Prophase I (Meiosis) Signup and view all the answers

What phase of meiosis has the spindle apparatus completely formed?

Metaphase I (Meiosis) Signup and view all the answers

What phase of meiosis involves separation of chromosomes in each tetrad?

Anaphase I (Meiosis) Signup and view all the answers

What phase of meiosis forms two nuclei and cytokinesis occurs?

Telophase I (Meiosis) Signup and view all the answers

During what stage of meiosis does the nuclear envelope break down?

Prophase II (Stage 6) Signup and view all the answers

In what stage of meiosis do spindles line up the chromosomes down the middle?

Metaphase II (Stage 7) Signup and view all the answers

In what stage of meiosis do spindles pull sister chromatids apart?

Anaphase II (Stage 8) Signup and view all the answers

What occurs after nuclear membranes start to form again in meiosis?

Telophase II (Stage 9) Signup and view all the answers

Study Notes

Cell Theory and Key Contributors

Robert Hooke first observed "cells" in cork, coining the term.
King Charles II commissioned investigations into microscopy, advancing biological studies.
Robert Brown discovered and identified the nucleus in cells.
Matthias Schleiden and Theodor Schwann contributed to cell theory, emphasizing that all organisms consist of one or more cells, and that cells are the fundamental unit of life.
Rudolf Virchow concluded that all new cells arise from the division of pre-existing cells.
Lynn Margulis proposed the endosymbiotic theory, explaining that mitochondria and chloroplasts originated from ancient bacteria.

Cell Structure and Organelles

The plasma membrane controls cellular entry and exit, maintaining internal environment.
Cholesterol in the membrane enhances flexibility while reducing permeability to water-soluble substances.
Carbohydrates attached to proteins on cell surfaces function as identification tags distinguishing cell types.
The cell wall provides structural support for plant cells, while animal cells lack a cell wall.
Cytoplasm refers to all content within a cell excluding the nucleus.

Nucleus and Genetic Material

The nucleus contains DNA and RNA, crucial for cellular growth and reproduction.
The nucleolus, found within the nucleus, is responsible for ribosome production.

Cellular Components and Functions

Ribosomes are essential for protein synthesis.
Endoplasmic Reticulum (ER) facilitates material transport within the cell; Rough ER has ribosomes for protein assembly, while Smooth ER synthesizes lipids.
The Golgi apparatus modifies and packages proteins received from the ER.
Vesicles and vacuoles aid in intracellular transport and storage of materials.
Lysosomes contain digestive enzymes, while peroxisomes are involved in fatty acid breakdown and hydrogen peroxide production.

Mitochondria and Chloroplasts

Mitochondria serve as the energy powerhouse, producing ATP.
Chloroplasts are found in plant cells and are essential for photosynthesis.

Cytoskeletal Elements

The cytoskeleton provides structural support, aiding cell shape and movement.
Microtubules are key components of cilia, flagella, and spindle fibers.

Junctions Between Cells

Tight junctions prevent leakage between cells, while adhesion junctions allow flexibility.
Gap junctions enable communication between adjacent cells.

Cell Types: Prokaryotic vs Eukaryotic

Prokaryotic cells lack membrane-bound organelles and a nucleus; they are found in Bacteria and Archaea.
Eukaryotic cells have a defined nucleus, organelles, and complex structures, including plant cells with cellulose in their walls.

Tissues and their Functions

Epithelial tissue lines surfaces, with specific types based on cell shape and arrangement (e.g., cuboidal, columnar, squamous).
Connective tissue provides structural support and includes diverse forms like blood, cartilage, and bone.
Muscle tissue enables movement, categorized into skeletal, cardiac, and smooth types.
Nervous tissue transmits electrical messages, composed of nerve cells and supportive glial cells.

The Cell Cycle

The cell cycle consists of growth (G1, S, G2) and division (mitosis or meiosis).
Mitosis is the process of nuclear division producing identical daughter cells, while meiosis results in gametes with half the chromosome number.
Checkpoints (G1, G2, Metaphase) ensure proper cell cycle progression, with kinases playing a crucial regulatory role.

Mitosis and Meiosis Phases

Mitosis includes: Prophase (chromosomes visible), Metaphase (alignment), Anaphase (separation of chromatids), Telophase (nuclear envelope re-formation), and Cytokinesis (cytoplasm division).
Meiosis involves Prophase I (with substages), Metaphase I (chromosome alignment), Anaphase I (separation of tetrads), Telophase I (nucleus formation), and similar processes in Meiosis II.

Genetic Outcomes

Meiosis produces four haploid cells: in males, four sperm; in females, one egg and three polar bodies, which are non-functional.

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Description

Explore the fundamental concepts of cell theory and the key contributors who shaped our understanding of cells. This quiz covers important discoveries related to cell structure, organelles, and their functions in living organisms.