Biology Chapters 13 & 15 Part 2

13.1 - 13.11, 15. 9 - 15.16

Chapter 15.9 - 15.10, 15.14 - 15.16

Archaeal Diversity; Viruses

How are Archaea profoundly different from bacteria?

Like bacteria, archaea are prokaryotes that lack a distinct cell nucleus & nuclear membrane.

However, archaea are classified in their own domain due to their DNA sequences, plasma membranes, cell walls, and flagella

Where do archaea thrive?

Also known as extremophiles, they thrive in habitats too extreme for most other organisms- highly acidic, salty, or hot environments

What are the unique properties archaea posses that are useful in industry?

• Thermus aquaticus, an archaeon from hot springs, produces Taq polymerase which is crucial for DNA replication in the polymerase chain reaction (PCR) process

• Archaea’s ability to metabolize toxic substances & degrade hydrocarbons is valuable for environmental cleanup- ex. they play a role in breaking down oil in natural disasters, like the 2010 Gulf of Mexico oil spill

Not all archaea are extremophiles:

Many thrive in conditions comfortable to humans, such as those responsible for gas production in the intestines after consuming beans

Why are viruses not exactly living organisms?

They are not cells and don’t belong to any of the three domains of life, which classify all living organisms.

What is a virion?

It is a virus particle that consists simply of genetic material, which can be either DNA or RNA, enclosed in a protein shell called a capsid.

Viruses can be categorized based on their outer layer:

• Enveloped viruses have an additional layer made from a piece of the host cell’s membrane, like the flu or coronavirus

• Non-enveloped viruses have just the protein coat and their genetic material, such as the viruses that cause the common cold

What is the virus infection process?

1. Attachment: viruses bind to specific glycoprotein molecules on the surface of host cells, attaching to the plasma membrane

2. Entry: they insert their genetic material into the cell, initiating infection

3. Replication: viral DNA is replicated multiple times using the host’s resources

4. Protein Production: viral mRNA is translated and translated to produce viral proteins, including the coat protein

5. Assembly and Release: newly formed viral DNA and proteins assemble into progeny virions, which then exit the host cell, often causing cell damage

What are viruses known for?

Hijacking their host’s cellular machinery

What is host range?

It describes the specific species and types of cells a virus can infect

• Narrow Host Range: some viruses, like smallpox, primarily infect only humans

• Broad Host Range: other viruses, like Influenza A, can infect multiple species, including humans, birds, and pigs. This adaptability is due to specific proteins on their surface

What is Glycoproteins?

They are proteins with sugar molecules attached, found on the surface of viruses. They determine which species and types of cells the virus can infect

In Influenza A:

One glycoprotein allows the virus to attach to and enter a host cell.

Another glycoprotein helps newly formed virus particles exit the host cell to spread the infection further

Viral transmission between species:

Viruses like Influenza A can transfer between different species, initiating pandemics:

• Bird flue viruses struggle to attach to human cell glycoproteins, making direct transmission to humans rare

• Pig cells possess glycoproteins compatible with both human and bird flu viruses, allowing them to host both types simultaneously

• When a pig cell is co-infected by both human and bird flu viruses, the mixing of their RNA during viral particle formation can lead to new influenza strains

• These new strains may have the capability to infect humans, posing risks for pandemic outbreaks

DNA Viruses:

These viruses contain DNA molecules as their genetic material, leading to stable base-pair sequences due to error-checking mechanisms during replication. This stability allows for effective treatments and vaccines, such as those for smallpox and HPV

RNA Viruses:

These viruses have RNA as their genetic material, lacking error-checking mechanisms. RNA viruses mutate rapidly, continuously evolving and presenting challenges in vaccine development, as seen with influenza and coronavirus, which require new vaccines each season.

What is a pandemic?

It is a global outbreak of a disease that spreads quickly across countries and continents

How many times have influenza pandemics occurred?

They have occurred three times in the past century, with all traced to influenza viruses adapting to humans, often via intermediate hosts like pigs. The most devastating of these was the 1918-1919 Spanish influenza, which killed approximately 50 million people

What is HIV?

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS). It originates from a strain of the simian immunodeficiency virus (SIV) that jumped from chimpanzees to humans in the early 1900s.

Why is HIV difficult to control?

1. HIV mutates easily: HIV’s enzyme, reverse transcriptase, makes many errors when copying its genetic material, resulting in frequent mutations that continually change it. This high mutation rate helps the virus evade treatments and vaccines

2. HIV attacks white blood cells: HIV specifically targets the immune system’s white blood cells, crucial for defending against bacteria and viruses. Over time, the virus infects and depletes these cells, leading to their failure and the onset of AIDS

3. The immune system collapses: as the virus continues to deplete white blood cells, the immune system can no longer respond effectively to HIV or any other infectious agents, leading to increased vulnerability to infections and certain cancers

Chapter 15.11 - 15.13

Eukaryotic Diversity: Protists

What were the first eukaryotes?

They were protists. Protists are a diverse group of organisms, while many are single-celled, others like seaweeds are multicellular.

What are complex organelles?

Protists were the first organisms to develop complex organelles from infoldings of the plasma membrane, enhancing material exchange between the cell and its environment.

What makes up complex organelles?

• Nucleus: encloses the cell’s DNA within a specialized membrane, first appearing in protists

• Endoplasmic Reticulum: part of the internal membrane system that assembles proteins

• Golgi Apparatus: modifies, sorts, and packages proteins for transport outside the cell

• Lysosomes: contain enzymes to break down damaged or unnecessary molecules

• Mitochondria: essential for energy production, these organelles originated from the endosymbiotic relationship with bacteria

Diversity of Protists:

Protists are spread across various branches of the Tree of Life because they do not form a monophyletic group, meaning they do not all descend from a single protist ancestor. Instead, they originate from multiple lineages, which explains their diverse forms and adaptations.

Some resemble animals, others fungi or plants, and some don’t fit any of these categories.

What characteristics do animal-like protists display?

They actively move around their environment and can appear to hunt for prey. They can be classified into several groups based on their movement and structure.

What are ciliates?

They are named for cilia tiny, hair-like structures covering the body surfaces they use to move and feed. An example is Paramecium

What characteristics do fungi-like protists display?

They are heterotrophic (consuming other organisms or organic matter), they form sheet-like colonies of cells that use spores to reproduce. An example is slime molds

What are characteristics that plant-like protists display?

They use photosynthesis and thrive in water. Commonly referred to as algae (includes seaweeds and diatoms)

Seaweeds:

They are larger, more complex multicellular organisms that grow in marine environments and are often visible to the naked eye, such as kelp, and other forms of red, green, and brown algae.

Diatoms:

They are tiny unicellular organisms with silica shells, forming a significant part of phytoplankton, crucial for photosynthetic oxygen production and serve as a primary food source in aquatic ecosystems

Some protists are very harmful to:

human health

What is Malaria caused by:

It is caused by the Plasmodium parasite, a type of organism that lives on and harms its host, transmitted by infected mosquitoes

Affects 350-500 million people worldwide, especially deadly in sub-Saharan Africa

Plasmodium continuously changes its surface proteins, making it difficult to combat effectively

What is Genetic Resistance?

Individuals with one sickle cell gene (i.e., Ss heterozygotes) show resistance to malaria, a benefit not present in those with two normal genes (SS) or two sickle cell genes (ss)

Chapter 13.1 - 13.11

Eukaryotic Diversity: Invertebrate Animals

What is an animal?

To be classified as an animal, an organism must be motile at some stage in their life cycle, consume other organisms for energy, and be multicellular

There are no ____ or ____ species

“higher”, “lower”

The terms “advanced” and “primitive” are misleading in evolution because they compare species to humans rather than assessing how well an organism is adapted to its environment

What do organisms evolve based on?

Organisms evolve based on their surroundings, not their similarity to humans. Extinct species, like the wooly mammoth, are less successful because they no longer exist, unlike species such as dermestid beetles and cheetahs, which continue to thrive

What are the four key distinctions dividing animals?

All animals share a common ancestor probably originating from an ancestral protist.

1. Does the animal have specialized cells that form specific tissues?

2. How is the animal’s body symmetry?

3. Which part of the digestive system develops first?

4. How does the animal grow?

Does the animal have specialized cells that form specific tissues?

Some animals, like sponges, do not have specialized tissues, meaning their cells perform similar functions and lack coordination. However, most animals, including humans, have cells that form specific tissues with specialized functions, such as muscles, nerves, and skin.

How is the animal’s body symmetry?

Some animals are symmetrical around a central point (jellyfish, corals) known as radial symmetry, while others have a left and right side that mirror each other (humans, frogs), which is called bilateral symmetry. Animals with bilateral symmetry are typically more mobile, allowing them to actively search for food and avoid predators.

Which part of the digestive system develops first?

In protostomes, the mouth forms first during early growth, while in deuterostomes, the anus forms first (e.g., insects and mollusks are protostomes, while vertebrates like humans are deuterostomes). This split is an early and fundamental distinction in animal evolution.

How does the animal grow?

Some animals, like lobsters and insects, grow by molting or shedding their outer layer (exoskeleton), while others, like clams and octopuses, grow continuously, adding to the size of their body without shedding

What are invertebrates?

More than 95% of the animal kingdom is made up of invertebrates. They lack a backbone.

Almost all invertebrates are protostomes, except for echinoderms (like sea stars and sea urchins), which are deuterostomes and the closest relatives to vertebrates

____ are animals that lack tissues and organs

Sponges

More about Sponges:

Sponges are unique because they can reproduce both sexually (by eggs and sperm), and asexually (by budding)

Sponges have remarkable regenerative abilities- if you break a piece of sponge into tiny pieces, each piece can reassemble to form a new sponge

Common characteristics: no tissues or organs, body consist of a hollow tube or network of canals with pores in their walls, they feed by pumping in water, along with bacteria, algae, and small particles of organic material, through their pores, free-swimming larvae, sessile as adults

What are Cnidarians?

Some cnidarians are among the most poisonous animals in the world. They can exist in two body forms: stationary (sessile) polyps, (e.g., corals, sea anemones) or free-floating medusa.

Some species switch between these forms during their life cycle, while others remain as one form throughout their lives (jellyfish)

What are/is corals and coral bleaching?

Corals live as small polyps in large colonies, building giant calcium carbonate skeletons that form coral reefs.

Coral bleaching occurs when corals expel their symbiotic algae (zooxanthellae) due to stress from high temperatures (exacerbated by global warming). This leads to a loss of color and vital nutrients, often resulting in coral death if these conditions persist

Invertebrates: “Worms”

The term “worm” can refer to various animals like flatworms, roundworms, and segmented worms, all of which have a long, slimy body without a backbone.

Many worms are parasites that can cause diseases in humans and animals.

Worms have bilateral symmetry, allowing them to move forward efficiently.

Examples: flatworms, roundworms, and segmented worms which belong to different groups and have evolved independently

Flatworms:

They lack a body cavity, have a simple digestive system, and are often parasites, like tapeworms

Roundworms:

Abundant and often parasitic, they grow by molting, with some causing significant diseases like elephantiasis

Segmented Worms:

Include earthworms, which benefit soil health, and leeches, some of which feed on blood

Invertebrates: Mollusks

Mollusks are diverse, bilaterally symmetrical animals that grow by adding tissues; most have a protective shell and a radula for feeding.

Members: bivalve mollusks, cephalopods, and gastropods

Bivalve Mollusks (Clams, Scallops, Oysters):

Protected by two hinged shells. They are filter feeders, drawing in water to capture food particles.

Cephalopods (Squids and Octopuses):

Known for their tentacles, which they use for movement and capturing prey. Squids are fast predators with small internal shells, and octopuses have no shell and can squeeze through small spaces

Gastropods (Snails and Slugs):

Have a “belly foot” used for movement. Snails have a protective shell, while slugs have reduced or no shell. Some slugs use slime as a defense mechanism.