Biology Chapter 6: Domains and Lineages

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Questions and Answers

What is the function of fimbriae in bacterial cells?

To provide strong structural support

To facilitate conjugation

To enable the mutual clinging of cells in biofilms (correct)

To transfer genetic material

What is the difference between a slime layer and a capsule?

A slime layer is thicker and more rigid, while a capsule is thinner and flexible

A slime layer is composed of peptidoglycan, while a capsule is composed of lipids

A slime layer is only found in Gram-positive bacteria, while a capsule is only found in Gram-negative bacteria

A slime layer is loose and irregular, while a capsule is thick and bound tightly to the cell (correct)

What is the function of glycocalyx?

To protect the cell and help it adhere to its environment (correct)

To provide structural support to the cell

To regulate the cell's internal pH

To facilitate the exchange of genetic material

What is the purpose of the peptidoglycan layer in the bacterial cell wall?

To provide structural support to the cell Signup and view all the answers

What is the function of the cell membrane in bacterial cells?

To separate the interior of the cell from the outside environment Signup and view all the answers

What is the characteristic shape of the bacterium known as Spirillum?

Spiral or coiled Signup and view all the answers

How do prokaryotes reproduce?

Through binary fission Signup and view all the answers

What is the function of pili in Gram-negative bacteria?

To serve as channels and transfer agents Signup and view all the answers

Which of the following domains does not belong to the Eukarya lineage?

Bacteria Signup and view all the answers

What is the estimated time period when Prokaryotes first appeared on Earth?

3.5 - 3.8 Billion Years Ago Signup and view all the answers

According to the chemical evolution theory, what is the origin of life?

From non-living materials that eventually self-replicated and metabolized Signup and view all the answers

Which of the following is NOT an ecological role of prokaryotes?

Producing oxygen Signup and view all the answers

What is one of the human uses of prokaryotes in industry?

Manufacturing of dairy products Signup and view all the answers

What is the function of flagella in prokaryotic cells?

Enabling motility and sensing stimuli Signup and view all the answers

What is the characteristic of polar flagella?

Attached from one end or both ends of the cell Signup and view all the answers

Which of the following is an example of bioremediation?

Using prokaryotes to clean oil spills Signup and view all the answers

Study Notes

Domains and Lineages

There are three domains of life: Eukarya, Bacteria, and Archaea
Eukarya includes Animalia, Plantae, Fungi, and Protista
Bacteria and Archaea are both prokaryotes

Prokaryotes

First living things on Earth, appearing 3.5-3.8 billion years ago
Abundant and ubiquitous, found in extreme environments
Capable of photosynthesis, decomposition, and regulating temperature
Involved in weathering, mineral extraction, and soil formation
Form symbiotic relationships with other organisms

Human Uses of Prokaryotes

Used in manufacturing dairy products, beer, antibiotics, vaccines, and enzymes
Used in genetic engineering and bioremediation

Prokaryotic Cell Profile

Cell Structure

External parts: appendages, flagella, pili, fimbriae, and glycocalyx
Flagella: hair-like structures for motility and sensing stimuli, with polar and non-polar patterns
Pili: elongated rigid structures for conjugation, found in Gram-negative bacteria
Fimbriae: small bristle-like fibers for mutual clinging of cells in biofilms
Glycocalyx: protects the cell and helps adhere to the environment

Cell Envelope

Gram-positive bacteria: thick cell wall and cell membrane
Gram-negative bacteria: outer membrane, peptidoglycan layer, and cell membrane
Developed by Hans Christian Gram

Cell Wall

Provides shape and strong structural support
Composed of peptidoglycan layer or murein macromolecule
Can be broken down by lysozyme, found in saliva and tears

Cell Membrane

Double layer of lipids, separating the interior and outside environment
Phospholipid bilayer with a fluid mosaic pattern

Internal Parts

Cytoplasmic matrix
Ribosomes
Inclusions
Nucleoid/chromosome
Actin cytoskeleton
Endospore

Shapes, Sizes, and Colonial Arrangements

Cocci: spherical or ball-shaped, can be oval or pointed
Bacilli: rod-shaped or cylindrical, can be short and plump or slightly curved
Spirillum: spiral shape, like a spring
Colonial arrangements: singles, pairs, regular clusters, Tetris, chains, and palisade structures

Reproduction

Prokaryotes reproduce through binary fission
Do not undergo mitosis, chromosome is replicated, and cell grows
Clone cells separate and can exchange genetic material by transformation

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Description

This quiz covers the three domains of life, including Eukarya, Bacteria, and Archaea, as well as the characteristics of prokaryotes and the theory of chemical evolution. Test your understanding of the origins of life on Earth.