Biology Chapter: Cell - The Fundamental Unit of Life

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the basic structural and functional unit of all living organisms?

Organ

Organelle

Tissue

Cell (correct)

Which scientist is credited with observing living cells in 1674?

Anton Van Leeuwenhoek (correct)

Matthias Schleiden

Theodor Schwann

Robert Hooke

What did Rudolf Virchow propose regarding cells?

Cells do not reproduce

All plants are made up of cells

All cells arise from pre-existing cells (correct)

The cell is the basic unit of life

Which of the following is NOT a concept derived from cell theory?

All living cells come from non-living matter Signup and view all the answers

What did Felix Dujardin discover in 1835?

The fluid content of the cell Signup and view all the answers

An organism composed of only one cell is known as a?

Unicellular organism Signup and view all the answers

Who proposed that all plants are made up of cells?

Matthias Schleiden Signup and view all the answers

Which of the following statements is a part of cell theory?

All living organisms are made up of one or more cells Signup and view all the answers

What is defined as a multicellular organism?

An organism made up of more than one cell Signup and view all the answers

What is the size of the smallest known cell?

0.1 µm Signup and view all the answers

Which cell is known to be the largest in the human body?

Ovum cell Signup and view all the answers

What shape do human red blood cells take, facilitating their function?

Biconcave Signup and view all the answers

What instrument is typically used to study the detailed structure of a cell?

Compound microscope Signup and view all the answers

Which type of microscope can provide ultrastructural details of cells?

Electron microscope Signup and view all the answers

What variation of cell shape is primarily influenced by a cell's function?

Function of the cell Signup and view all the answers

What characteristics differentiate species like Euglena and Amoeba from other cells?

Ability to change their shape Signup and view all the answers

Which structure is responsible for encapsulating the cell and controlling the entry and exit of substances?

Plasma membrane Signup and view all the answers

What is the main function of the nucleus in a cell?

Genetic material storage and regulation Signup and view all the answers

Which organelle is primarily involved in protein synthesis?

Ribosomes Signup and view all the answers

What is the function of mitochondria within a cell?

Respiration and energy production Signup and view all the answers

Which cellular structure is found only in plant cells and provides structural support?

Cell wall Signup and view all the answers

Which structure helps in the digestion of waste materials in the cell?

Lysosome Signup and view all the answers

Which of the following organelles is responsible for modifying, sorting, and packaging proteins?

Golgi body Signup and view all the answers

What is the main role of the vacuole in plant cells?

Storage and maintaining turgor pressure Signup and view all the answers

What is the primary function of chromoplasts in plant cells?

Production and storage of pigments Signup and view all the answers

Which pigment is associated with tomatoes?

Lycopene Signup and view all the answers

What is the primary food product stored in leucoplasts?

Protein Signup and view all the answers

What are the two distinct regions found in chloroplasts?

Stroma and Grana Signup and view all the answers

What structure in centrosomes is primarily responsible for forming spindle fibers during cell division?

Centrioles Signup and view all the answers

What are microtubules made of?

Tubulin Signup and view all the answers

Which organelles are primarily involved in providing structural strength to the cell?

Cytoskeleton Signup and view all the answers

What function is specifically attributed to the stroma of chloroplasts?

Converting light energy into chemical energy Signup and view all the answers

Which of the following is NOT a role of centrioles?

Producing chloroplasts Signup and view all the answers

What is the main function of chlorophyll found in thylakoids?

Absorbing light energy for photosynthesis Signup and view all the answers

What is the primary function of the plasma membrane?

Regulate entry and exit of substances Signup and view all the answers

Which of the following structures is responsible for protein synthesis?

Rough Endoplasmic Reticulum Signup and view all the answers

Which cell organelle is known as the powerhouse of the cell?

Mitochondria Signup and view all the answers

What type of genetic material is primarily stored in chromosomes?

DNA Signup and view all the answers

What is the main structural component of the cell wall in plants?

Cellulose Signup and view all the answers

What does the cytoplasm primarily consist of?

80% water and various organelles Signup and view all the answers

Which part of the nucleus is responsible for synthesizing ribonucleic acid (RNA)?

Nucleolus Signup and view all the answers

What is the function of lysosomes in a cell?

Digest large molecules and destroy invaders Signup and view all the answers

Which component of the endoplasmic reticulum lacks ribosomes?

Smooth ER Signup and view all the answers

What is the primary function of vacuoles in plant cells?

Provide turgidity and rigidity Signup and view all the answers

What is a key characteristic of the Golgi body?

Modifies, sorts, and packages cellular materials Signup and view all the answers

Which part of the mitochondria is folded to form cristae?

Inner membrane Signup and view all the answers

What is the function of the nuclear pores?

Regulate the exchange of substances between nucleus and cytoplasm Signup and view all the answers

In which type of cells are contractile vacuoles typically found?

Animal cells Signup and view all the answers

Study Notes

Cell: The Fundamental Unit of Life

Cells are the basic structural and functional units of all living organisms.
All known living organisms are made up of one or more cells.
The cell theory states that all living cells arise from pre-existing cells by division.

Key Figures in Cell Theory

1674: Anton Van Leeuwenhoek observed the first living cells.
1665: Robert Hooke discovered the cell.
1835: Felix Dujardin discovered fluid content in cells.
1839: J.E. Purkinje named the fluid content protoplasm.
1838: Matthias Schleiden proposed that all plants consist of cells.
1845: Carl Heinrich Braun suggested that the cell is the basic unit of life.
1855: Rudolf Virchow proposed that all cells arise from pre-existing cells.

Types of Organisms

Unicellular organisms consist of a single cell (e.g., Euglena, Paramecium, Yeast).
Multicellular organisms are composed of multiple cells (e.g., Plants, Animals, Fungi).

Cell Sizes

Smallest cell: Mycoplasma, measuring 0.1 µm.
Largest cell: Ostrich egg, measuring 18 cm.
Human cells vary:
- Smallest: Sperm cell, 5 µm.
- Largest: Ovum cell, 120 µm.
- Longest: Nerve cell, 1 m.

Cell Shape

Human red blood cells are circular and biconcave for efficient capillary passage.
Nerve cells have branched shapes to conduct impulses.
Some cells can alter their shape, while others maintain a fixed structure.

Cell Structure

Common features in most cells: plasma membrane, nucleus, and cytoplasm.
Plasma membrane is semi-permeable, maintaining cell homeostasis and protecting contents.
Cell wall (non-living) provides structure, strength, and rigidity in plants and bacteria.

Nucleus

Central dense body, usually 10-25 µm in diameter, found in most cells.
Contains nuclear membrane with pores, nucleoplasm, nucleolus, and chromatin fibers (DNA and proteins).
Controls cell activities, including metabolism, growth, and replication, through gene expression.

Cytoplasm

jelly-like substance made of 80% water, containing cytosol and various organelles.
Organelles include ribosomes, endoplasmic reticulum (smooth and rough), Golgi body, lysosomes, vacuoles, and mitochondria.

Organelles

Endoplasmic Reticulum (ER): Network linked to the nuclear and cell membranes, includes rough ER (with ribosomes for protein synthesis) and smooth ER (involved in lipid synthesis and detoxification).
Golgi Body: Stacks of membranes modifying and sorting materials from the ER for transport within or outside the cell.
Lysosomes: Membrane-bound sacks filled with enzymes for digesting large molecules, pathogens, and worn-out organelles.
Vacuoles: Storage sacs for liquids; larger in plant cells for turgidity, smaller and temporary in animal cells.
Mitochondria: Double membrane-bound organelles involved in energy production (ATP synthesis).

Plastids

Double membrane-bound organelles found in plants and certain algae, involved in storage and photosynthesis.### Plastids
Plastids are organelles responsible for the synthesis and storage of food.
Chromoplasts produce pigments affecting the color of cells.
- Example: Carrots contain carotene; mangoes contain xanthophyll; tomatoes contain lycopene.
Leucoplasts are colorless plastids that store food such as starch, protein, and oil.
- Found in organs like tubers and seeds (e.g., potato tubers, maize grains, castor seeds).

Chloroplasts

Chloroplasts are double membrane-bound organelles predominantly in plant cells.
- Characterized by a spherical or discoidal shape with two distinct regions: grana and stroma.
- Grana consist of stacks of thylakoids, which house chlorophyll molecules essential for photosynthesis.
- Stroma is the dense, colorless fluid where important reactions occur.
Functions include:
- Converting light energy into chemical energy stored as food.
- Providing the green color in leaves, stems, and vegetables.

Centrosome

The centrosome is a membrane-bound organelle located near the nucleus.
- Contains two centrioles arranged perpendicularly, made of microtubules.
Functions:
- Forming spindle fibers that facilitate chromosome movement during cell division.
- Assisting in the development of cilia and flagella.

Cytoskeleton

The cytoskeleton is composed of microtubules and microfilaments.
- Microtubules are hollow tubes made of tubulin, while microfilaments are thin rods made of actin.
Functions include:
- Determining and maintaining cell shape.
- Providing structural strength.
- Enabling cellular movements.

Cell Types

Prokaryotic cells lack a membrane-bound nucleus and organelles.
Eukaryotic cells possess a membrane-bound nucleus and complex organelles.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fascinating world of cells, the building blocks of life. This quiz covers key figures in cell theory, types of organisms, and the significance of cells in living organisms. Test your knowledge of cellular structure and function.