Biology Chapter 27: Prokaryotes Quiz

Questions and Answers

Earth's first organisms are likely what?

Multicellular organisms

Viruses

Prokaryotes (correct)

Eukaryotes

What are the 3 most common shapes of prokaryotic cells?

spheres (cocci), rods (bacilli), and spirals

What is an important feature of nearly all prokaryotic cells?

their cell wall which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment

Which domain has peptidoglycan on their walls?

bacteria Signup and view all the answers

Which domain has membrane-bound organelles?

eukarya Signup and view all the answers

Which domain has nuclear envelopes?

eukarya Signup and view all the answers

What is peptidoglycan?

protein and sugar Signup and view all the answers

Why do scientists use the Gram stain?

to classify the bacteria by their cell wall composition Signup and view all the answers

What does Gram positive refer to?

thick layer of peptidoglycan Signup and view all the answers

What does Gram negative refer to?

thin layer of peptidoglycan Signup and view all the answers

What are endospores?

tough dormant structures that are able to survive in harsh conditions for centuries Signup and view all the answers

What is taxis?

the ability to move toward or away from a stimulus Signup and view all the answers

What is chemotaxis?

the movement toward or away from a chemical stimulus Signup and view all the answers

What is bacterial flagella composed of?

motor, hook, and filament Signup and view all the answers

What is the evolutionary origin of bacterial flagella?

flagella proteins are modified versions of proteins that perform other tasks in bacteria Signup and view all the answers

What is horizontal gene transfer?

movement of genes among individuals from different species Signup and view all the answers

What is transformation?

a prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment Signup and view all the answers

What is transduction?

the movement of genes between bacteria by bacteriophages (viruses that infect bacteria) Signup and view all the answers

What is asexual binary fission?

prokaryotes reproduce & can divide every 1-3 hours; offspring cells are generally identical Signup and view all the answers

What are some key features of prokaryotic reproduction?

they are small & reproduce by binary fission; they have short generation times Signup and view all the answers

What are three factors that contribute to genetic diversity in prokaryotes?

rapid reproduction, mutation, and genetic recombination Signup and view all the answers

What is conjugation?

genetic material transferred between 2 bacterial cells joined by sex pilus Signup and view all the answers

What is the F factor?

ability to make a sex pilus and donate DNA Signup and view all the answers

What are plasmids?

some species of bacteria also have smaller rings of DNA Signup and view all the answers

What are R plasmids?

carry genes for antibiotic resistance Signup and view all the answers

What is an autotroph?

need only an inorganic compound such as CO2 as carbon source Signup and view all the answers

What is a heterotroph?

require an organic nutrient such as glucose as carbon source Signup and view all the answers

What are chemoheterotrophs?

can function as decomposers Signup and view all the answers

What are obligate aerobes?

require O2 for cellular respiration Signup and view all the answers

What are obligate anaerobes?

are poisoned by O2 and use fermentation or anaerobic respiration Signup and view all the answers

What are facultative anaerobes?

can survive with or without O2 (do fermentation in anaerobic environment) Signup and view all the answers

What is nitrogen fixation?

convert atmospheric nitrogen to ammonium Signup and view all the answers

What is Alpha Proteobacteria?

the theory is that mitochondria evolved from aerobic alpha proteobacteria through endosymbiosis Signup and view all the answers

What is symbiosis?

an ecological relationship in which two species live in close contact: a larger host and smaller symbiont Signup and view all the answers

What is commensalism?

one symbiotic organism benefits while the other is not harmed or helped Signup and view all the answers

What is parasitism?

an organism called a parasite harms but does not kill its host Signup and view all the answers

What is mutualism?

both symbiotic organisms benefit Signup and view all the answers

Genes for the resistance to antibiotics are usually located ________

on plasmids Signup and view all the answers

Are all genomes made of DNA? What is the exception?

Yes, all genomes are made up of DNA with the exception of some viruses Signup and view all the answers

Study Notes

Prokaryotes Overview

Earth's first organisms are prokaryotes.
Prokaryotic cells exhibit three common shapes: spheres (cocci), rods (bacilli), and spirals.

Cell Structure

Nearly all prokaryotic cells possess a cell wall, which maintains shape, offers protection, and prevents bursting in hypotonic environments.
Bacteria specifically have peptidoglycan in their cell walls, distinguishing them from other domains.

Domains and Organelles

The domain Eukarya features membrane-bound organelles and nuclear envelopes, which prokaryotes lack.

Peptidoglycan and Staining

Peptidoglycan is a composite of protein and sugar, crucial for bacterial structure.
The Gram stain is used to classify bacteria based on cell wall composition, identifying Gram positive (thicker peptidoglycan) and Gram negative (thinner peptidoglycan) bacteria.

Survival Mechanisms

Endospores are tough, dormant structures that can survive extreme conditions for centuries.
Taxis refers to the movement of prokaryotes toward or away from stimuli, with chemotaxis being specifically directed toward chemical stimuli.

Flagella

Bacterial flagella are composed of three parts: motor, hook, and filament.
Evolutionarily, flagella proteins are modified versions of other bacterial proteins.

Genetic Exchange

Horizontal gene transfer allows genes to move among individuals of different species, enhancing genetic diversity.
Transformation involves prokaryotic cells incorporating foreign DNA from their environment.

Gene Transfer Methods

Transduction is the transfer of genes between bacteria via bacteriophages.
Conjugation is the transfer of genetic material between two bacterial cells connected by a sex pilus, facilitated by the F factor, which enables the formation of sex pili.

Reproduction and Diversity

Prokaryotes reproduce asexually through binary fission, leading to rapid population growth every 1-3 hours, with most offspring being genetically identical.
Key factors for genetic diversity in prokaryotes include rapid reproduction, mutations, and genetic recombination.

Metabolism Types

Autotrophs require only inorganic compounds like CO2 for carbon.
Heterotrophs need organic nutrients, like glucose.
Chemoheterotrophs can function as decomposers in ecosystems.

Oxygen Requirements

Obligate aerobes need oxygen for cellular respiration.
Obligate anaerobes are poisoned by oxygen and rely on fermentation or anaerobic respiration.
Facultative anaerobes can switch between aerobic and anaerobic conditions.

Nitrogen and Symbiotic Relationships

Nitrogen fixation converts atmospheric nitrogen to ammonium.
Symbiosis is an ecological relationship where two species exist closely, including types like commensalism (one benefits, the other is unaffected), parasitism (one benefits at the host's expense), and mutualism (both benefit).

Antibiotic Resistance

Genes responsible for antibiotic resistance are commonly found in plasmids, small rings of DNA in bacteria.
All genomes consist of DNA, except for certain viruses which have RNA genomes.

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Description

Test your knowledge on the two domains of prokaryotes: Bacteria and Archaea. This quiz covers key concepts including the shapes of prokaryotic cells and essential features like cell walls. Perfect for students seeking to understand the fundamental differences between these microorganisms.