Difference Between Eucaryotic and Prokaryotic Cells

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Questions and Answers

Why is it difficult to define prokaryote species?

Because prokaryotes must share many more properties with each other than with other prokaryotes (correct)

Because they have similar mol% G+C content

Because of their small size

Because they have different morphologies

What is the minimum percentage of DNA reassociation required for two organisms to be considered the same prokaryote species?

80%

60%

50%

70% (correct)

What is the primary focus of numerical taxonomy?

Phylogenetic relationships

Morphological characteristics

Biochemical tests

Phenetic relationships (correct)

What is the purpose of Bergey's Manual of Determinative Bacteriology?

To provide identification schemes for identifying bacteria and archaea Signup and view all the answers

What is the significance of mol% G+C in prokaryote species?

It is one of the characteristics shared by prokaryotes of the same species Signup and view all the answers

What is the purpose of Approved Lists of Bacterial Names?

To list species of known prokaryotes Signup and view all the answers

What is the key aspect of numerical taxonomy?

It uses a large number of tests and gives equal weight to all characteristics Signup and view all the answers

What is the first step in the process of classification in numerical taxonomy?

Collection of data Signup and view all the answers

What is the result of cluster analysis in numerical taxonomy?

A phenogram or dendrogram Signup and view all the answers

What is the principle of cluster analysis?

Searching for high values that indicate the most similar pairs of OTUs Signup and view all the answers

What is the advantage of numerical taxonomy over conventional taxonomy?

It utilizes better and more number of described characters Signup and view all the answers

What is the basis of classifications in numerical taxonomy?

Phenetic similarity Signup and view all the answers

What is the advantage of numerical taxonomy in terms of skill level?

It can be performed by workers with minimal training Signup and view all the answers

What can be inferred from the taxonomic structure of a group?

Phylogenetic conclusions and evolutionary pathways Signup and view all the answers

What is the view of taxonomy in numerical taxonomy?

As an empirical science Signup and view all the answers

What is the principle of giving equal weightage to characters?

Every character should be given equal weightage Signup and view all the answers

What is the typical size range of eucaryotic cells?

10-100 um in diameter Signup and view all the answers

Which of the following is a characteristic of prokaryotic cells?

Absence of a nucleus Signup and view all the answers

What is the main difference between the ribosomes of eucaryotic and prokaryotic cells?

Size, with eucaryotic cells having larger ribosomes Signup and view all the answers

What is the name of the domain that includes 'true bacteria'?

Eubacteria Signup and view all the answers

What is the characteristic of archaea that allows them to live in extreme environments?

Absence of peptidoglycan in their cell walls Signup and view all the answers

What is the term used to describe a population of cells with similar characteristics?

Bacterial species Signup and view all the answers

What is the name of the manual that provides a reference for identifying and classifying bacteria?

Bergey's Manual Signup and view all the answers

What is the term used to describe a subgroup of a bacterial species that has distinguishing characteristics?

Bacterial strain Signup and view all the answers

What is the purpose of calculating the similarity between strains in numerical taxonomy?

To analyze the taxonomic structure and yield groups or clusters of bacteria Signup and view all the answers

What is the term used to describe the entities that can be classified in numerical taxonomy?

Operational taxonomic units (OTUs) Signup and view all the answers

What is the minimum number of characters required for accurate estimates in numerical taxonomy?

50 Signup and view all the answers

What is a character in numerical taxonomy?

Any property that can vary between OTUs Signup and view all the answers

What is the purpose of tabulating the properties of phenons in numerical taxonomy?

For publication or further study Signup and view all the answers

What is the simplest way to analyze similarities between OTUs in numerical taxonomy?

Counting the number of characters in which they are identical Signup and view all the answers

What is the term used to describe the percentage or proportion of matches between OTUs in numerical taxonomy?

Simple Similarity Measure (SSM) Signup and view all the answers

What are the two main types of analyses used to reveal the taxonomic structure in numerical taxonomy?

Cluster analysis and ordination Signup and view all the answers

Study Notes

Differences Between Eucaryotic and Prokaryotic Cells

Prokaryotic cells: 0.2-2 um in diameter, no nucleus, no membranous organelles, cell wall is chemically complex, ribosomes are smaller (70S), DNA is single circular chromosome, cell division is binary fission.
Eucaryotic cells: 10-100 um in diameter, have a nucleus, have membranous organelles, cell wall is simple when present, ribosomes are larger (80S) in cell, 70S in organelles, DNA is multiple linear chromosomes (histones), cell division is mitosis.

The Prokaryotic Domains

There are two types of prokaryotic cells: Eubacteria and Archaea.
Eubacteria (True bacteria): cell wall contains peptidoglycan, sensitive to antibiotics.
Archaea (Ancient bacteria): cell walls lack peptidoglycan, resistant to antibiotics, live in extreme environments.
Three kingdoms of Archaea: Methanogens, Extreme Halophiles, and Thermoacidophiles.

Species Definition

Bacterial species: a population of cells with similar characteristics.
Bacterial strain: a subgroup of a bacterial species that has distinguishing characteristics.
Identified by numbers, letters, or names that follow the scientific name (e.g. Escherichia coli O157:H7).
Bergey's Manual: a reference for identifying and classifying bacteria.

Species Concept

The species concept applied to eukaryotes cannot be applied to bacteria and archaea.
Prokaryotes must share many properties with each other to be considered the same species.
They must have similar mol % G+C.
The DNA from organisms of the same species must show a minimum of 70% reassociation.

Numerical Taxonomy

Developed in the late 1950s as part of multivariate analyses and in parallel with computer development.
Concerned primarily with phenetic relationships.
A large number of tests (~100) are carried out, and the results are scored as positive or negative.
All characteristics are given equal weight, and a computer-based analysis is carried out to group bacteria according to shared properties.

Steps in Numerical Taxonomy

Collection of data: examining bacterial strains for relevant properties.
Coding and scaling the data.
Calculating similarity or resemblance between strains.
Analyzing similarities for taxonomic structure.
Tabulating properties of phenons and choosing diagnostic characters.

Operational Taxonomic Units (OTUs)

Entities that can be classified, such as strains, species, or genera.
Number of characters (n) should be 50 or more, and several hundred are desirable.
Quality of characters is important.

Similarity and Analysis

Counting the number of characters in which OTUs are identical.
Simple matching coefficient (SSM) expresses similarity as a percentage or proportion.
Two main types of analyses: cluster analysis and ordination.
Cluster analysis yields a treelike diagram or dendrogram, showing phenetic relationships.
Ordination yields an ordination diagram or taxonomic map, showing closely similar OTUs.

Principles of Numerical Taxonomy

The greater the content of information in the taxa, the better the classification system.
Every character should be given equal weightage in creating new taxa.
Similarity between any two entities is considered.
Correlation of characters differs in groups of organisms.
Phylogenetic conclusions can be drawn from taxonomic structure and character correlations.

Advantages of Numerical Taxonomy

Improves conventional taxonomy by utilizing better and more described characters.
Allows for more efficient construction of better keys and classification systems.
Reinterprets existing biological concepts.
Allows for more taxonomic work to be done by less highly skilled workers.

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Description

This quiz covers the main differences between Eucaryotic and Prokaryotic cells, including cell size, nucleus, organelles, cell wall, and ribosomes. Understanding the characteristics of these cell types is crucial in biology and microbiology.