Biology: Taxonomy and Classification Overview

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Questions and Answers

Why might taxonomy be challenging when determining species?

Taxonomy can be difficult due to variations in physical traits and the existence of species that may not fit neatly into classifications, such as asexual organisms or fossils.

Describe how morphology and anatomy differ in the context of organism classification.

Morphology refers to the structure and form of organisms, while anatomy focuses on the internal structures of organisms.

What role does DNA analysis play in phylogenetic classification?

DNA analysis helps in identifying evolutionary relationships by comparing genetic similarities and differences among species.

What distinguishes closely related species from more distantly related ones on the evolutionary time scale?

Closely related species, such as those in the same genus, split more recently than those in different families. Signup and view all the answers

Why is the classification of organisms important for species protection?

Classification helps identify newly discovered species, enabling laws to protect them from poaching. Signup and view all the answers

What is species diversity and why is it important?

Species diversity refers to the variety and abundance of different species in an area and is important because it contributes to ecosystem stability and resilience. Signup and view all the answers

How does genetic diversity aid in the survival of a species?

Genetic diversity helps species adapt to environmental changes and protects against diseases, allowing for healthier populations. Signup and view all the answers

Define a gene pool in the context of a population.

A gene pool is the total genetic variation within a population of the same species in a specific area. Signup and view all the answers

What defines a virus's dependence on host cells?

Viruses depend on host cells for survival and reproduction, as they lack the necessary cellular machinery to grow independently. Signup and view all the answers

What are the two essential components of a virus?

The two essential components of a virus are nucleic acid (either DNA or RNA) and a protective protein coat called a capsid. Signup and view all the answers

Describe the significance of the capsid in a virus.

The capsid protects the nucleic acid and plays a crucial role in the virus's ability to infect host cells. Signup and view all the answers

Explain the role of an envelope in certain viruses.

The envelope is a lipid layer that surrounds some viruses, formed from the host cell's membrane as the virus exits the cell. Signup and view all the answers

What is the significance of endospores in bacteria?

Endospores allow bacteria to survive harsh conditions by providing dormancy and resistance to extreme environments. Signup and view all the answers

How does conjugation contribute to genetic variation in bacteria?

Conjugation allows for the exchange of genetic material between two bacterial cells, leading to increased genetic variation. Signup and view all the answers

What role do cyanobacteria play in the environment?

Cyanobacteria are essential for oxygen production through photosynthesis, which transformed Earth's atmosphere billions of years ago. Signup and view all the answers

Explain the method of Gram staining and its importance.

Gram staining classifies bacteria based on their cell wall structure, with Gram-positive bacteria appearing purple and Gram-negative bacteria pink. Signup and view all the answers

What are two diseases caused by viruses in humans and their common symptoms?

HIV/AIDS and COVID-19, with common symptoms including fever and fatigue. Signup and view all the answers

Identify the main difference in the cell wall composition between bacteria and archaea.

Bacteria have peptidoglycan in their cell walls, while archaea have a different composition that lacks peptidoglycan. Signup and view all the answers

What are the shapes and common aggregation patterns of bacteria?

Bacteria can be spherical (cocci), rod-shaped (bacilli), or spiral; they can aggregate in diplo- (pairs), staphylo- (clusters), or strepto- (chains) patterns. Signup and view all the answers

Explain the process of binary fission in prokaryotes.

Binary fission is an asexual reproduction method where one cell splits into two daughter cells. Signup and view all the answers

What distinguishes gram-negative bacteria from gram-positive bacteria during gram staining?

Gram-negative bacteria appear pink due to a thin peptidoglycan layer beneath an outer membrane, while gram-positive bacteria stain purple due to a thick peptidoglycan wall. Signup and view all the answers

What role do plasmids play in bacteria and how do they affect genetic diversity?

Plasmids are small DNA loops separate from chromosomes that facilitate genetic material exchange, increasing genetic diversity. Signup and view all the answers

Explain how viruses are classified based on their host.

Viruses are classified into plant viruses, animal viruses, and bacteria viruses, with the latter known as bacteriophages. Signup and view all the answers

What is the primary distinction between the lytic and lysogenic phases in viral replication?

In the lytic phase, the virus destroys the host cell to release new viral particles, whereas in the lysogenic phase, the viral DNA integrates into the host's DNA and replicates along with it. Signup and view all the answers

What role do oncoviruses play in cancer development?

Oncoviruses can alter the host cell's DNA, leading to uncontrolled cell growth and tumor formation. Signup and view all the answers

Describe how HIV compromises the immune system.

HIV attacks T4 helper T cells, weakening the immune system and making it difficult for the body to produce antibodies and fend off infections. Signup and view all the answers

What distinguishes prions from viruses?

Prions are misfolded proteins that do not contain DNA or RNA, unlike viruses which have either DNA or RNA as their genetic material. Signup and view all the answers

How can bacteriophages be utilized in medicine?

Bacteriophages can be used as an alternative to antibiotics, particularly for treating multi-drug resistant bacterial strains. Signup and view all the answers

List two ways encephalopathy can be transmitted.

Encephalopathy can be transmitted from animal-to-animal through infected tissue or from animal-to-human by consuming infected animal tissue. Signup and view all the answers

Why are neurodegenerative diseases difficult to eliminate from the body?

Neurodegenerative diseases caused by prions are challenging to eliminate because prions resist destruction from heat and radiation. Signup and view all the answers

Study Notes

Classification of Life's Diversity

Species are groups of organisms that interbreed, producing fertile and viable offspring.
Interbreeding means two organisms of the same type mate and produce offspring.
Fertile offspring can also breed.
Viable offspring are able to live and grow.
Morphological classification measures similar characteristics of living things (simple and commonly used, especially for plants). It can be challenging to determine how much physical variation constitutes too much variation.
Biological classification identifies similar characteristics to classify organisms in the same species. It can't be used to classify species that are physically separated or asexually reproducing, or for fossils.
Phylogenetic classification focuses on the evolutionary relationships of living things. Analyzing DNA is useful to determine these relationships; this method can also be used for extinct species. Evolutionary history is mostly unknown.
Binomial Nomenclature is a scientific two-name system (genus and species) for specifying organisms. Names are based on characteristics. The first name (genus) represents the group the organism belongs to, and the second name (species) represents the specific group of organisms.

Hierarchical Classification

Taxonomy divides organisms into different levels of hierarchy based on similar characteristics or traits.
The top level is Domains, followed by Kingdom, Phylum, Class, Order, Family, Genus, and Species.
The domain is the largest group of organisms.
Levels can have subgroups for a more descriptive classification of organisms with many subgroups.
Taxonomy classifies and names organisms.

Other Features of Classification of Life's Diversity

Anatomy: The structure of organisms (internal structures).
Physiology: How living organisms function.
Proteins and Genes: Similarities in proteins and genes can be compared to relate organisms to others.
Phylogenetic Tree: Shows how species are related.
- Roots represent the oldest common ancestor.
- Branches end at present-day species..
- Forks are points where species split or evolved.
Primitive and Derived Characteristics: Primitive characteristics are traits all species share from a common ancestor. Derived characteristics are new traits that appear as a species evolves.
Time Scale and Relationship. More recently evolved species will be located closer together on the tree than species that diverged from one another a long time ago.
Importance of Classification in Medicine: Studying related species can discover similar chemical compounds or proteins, which support disease control by understanding the spread of diseases, crop improvement that leads to high yields and disease resistance, and controlling pests via biological control.
Species Protection and Prevention: Classification helps to protect newly identified species from poaching and harmful invasive species.

Seven Characteristics of Living Things

Movement
Respiration
Sensation
Growth
Reproduction
Excretion
Nutrition

Prokaryotes and Eukaryotes

Prokaryotes: Organisms without a nucleus.
- Unicellular organisms.
- Lack a nuclear membrane.
- Small.
- Simple internal structure.
Eukaryotes: Organisms with a nucleus.
- Can be single or multicellular organisms.
- Have a nuclear membrane.
- Larger than prokaryotes
- Complex internal structure.
Three Domains: Bacteria, Archaea, and Eukarya. Eukaryotes are grouped into the Eukarya domain. The Archaea and Bacteria domains are made up of prokaryotes. Bacteria and Archaea became separate domains due to major differences in their characteristics.

Dichotomous Keys

Tools for identifying organisms using two-part statements of characteristics.
'Dichotomy' means divided into two parts.
The user is led through a series of yes/no questions, until the species is identified when the path stops at a specific classification. 'Key' refers to the tool used for identification.

Types of Biodiversity

Species Diversity: Variety of species in a given area.
Genetic Diversity: Variety of inherited characteristics (genes) within a species, making individuals unique. Genetic diversity leads to greater resistance to diseases.
Ecosystem Diversity: Variety of ecosystems and how different ecosystems interact. Biotic (living interactions) and Abiotic (non-living factors) elements contribute to ecosystem diversity.

Viruses and Prions

Viruses: Non-living entities that cannot survive without hosts to replicate. Viruses rely on their host for reproduction.
Viruses have a protein coat and nucleic acid (DNA or RNA). The effectiveness is dependent on this nucleic acid and protein coat abilities.
Prions: Abnormal misfolded proteins that can cause diseases by influencing others to misfold.
Can cause neurodegenerative diseases like encephalopathy.
No DNA or RNA.
Usually present, but misfolding changes shape and therefore function.

Viral Replication

Lytic Cycle: a virus infects a host cell to replicate genetic material, making new virus particles, and eventually bursting and releasing new viruses.
Lysogenic Cycle: the virus inserts its genetic material into the host's DNA, so as the cell divides the virus genetic material is replicated and carried in the new cells.

HIV

HIV is a retrovirus that weakens the immune system by infecting certain cells, such as T4 helper T cells. Reverse transcriptase converts viral RNA to DNA. The viral DNA will insert into the host cell's DNA chain. This virus forms a provirus and will remain there until the cell divides and the virus is replicated, causing more damage to the host cell.

Bacteriophages

Viruses specific for bacteria (bacteriophages) enter bacteria cells and can either destroy them (lytic cycle) or exist within cells' genetic material before destruction of the cell (lysogenic cycle).

Neurodegenerative Diseases

Rare diseases where the illness is inactive in the body for a long time, and after the exposure to radiation, the disease does not get destroyed. Prions are hard to get rid of. These prions are abnormal misfolded proteins that cause diseases. Prion diseases can spread by getting contaminated tissue.

How Viruses Affect Plants and Humans

Plants: Viruses affecting plants cause diseases and reduce crop yields/food shortages and cause crop diseases.
Humans: Viruses affect human health via various diseases.

Biotechnology

Gene Cloning: Insertion of genes into host cells for replication.
Gene Therapy: Altered viruses deliver healthy genes to treat genetic disorders.

Comparing Bacteria and Archaea

Both are prokaryotic (without cell nuclei), but their structures and functions differ.
Bacteria cell walls contain peptidoglycan and archaea do not.
Gram staining distinguishes bacteria based on cell wall thickness. Bacteria can be Gram-positive or Gram-negative.
Bacteria Shapes include spheres (cocci), rods (bacilli), and spirals.
Bacteria reproduce through binary fission, which is a rapid asexual reproduction where each cell splits into two identical cells.
Bacteria and archaea both can reproduce, have genetic material exchange or conjugation, plasmids, endospores, and different morphologies, but in their specific form and features.

Endosymbiosis

Eukaryotic cells evolved from prokaryotic cells through endosymbiosis, which is the process where one cell engulfs another cell and they form a mutually beneficial relationship.
Mitochondria evolved from aerobic bacteria, and chloroplasts evolved from photosynthetic bacteria.
These organelles have their own DNA and ribosomes.

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Description

This quiz covers fundamental concepts in taxonomy and species classification, including methods of classification, the significance of interbreeding, and the use of binomial nomenclature. Test your understanding of phylogenetic trees, the challenges in taxonomy, and the role of DNA in classifying organisms. Additionally, explore the importance of organism classification for species protection and disease control.