bio 121- learning outcomes

Liquid water

Water acts as a solvent and a medium in which biochemical reactions can occur

Energy

Fuel for living organisms

Biogenic elements

Build up organic macromolecules that are essential for life. (Carbon, Oxygen, Hydrogen, Nitrogen, phosphor and sulfur.)

Describe the basic requirements for life and justify their role in supporting life

Liquid water, Energy, and biogenic elements.

Describe the properties of water that are critical to maintaining life

Transportation, Reactions, Regulation, Structure and support, protection.

Tranpsortation

Water can dissolve many substances and therefore allow for them to be transported inside and outside of cells. 

Reactions

(e.g. metabolism): Water allows for reactions to take place. 

Regulation

(e.g. heat): Water allows organisms to maintain a stable temperature

Structure and support

(e.g. turgor/hydrostatic pressure): Water allows cells and organisms to maintain their shape.

Protection

 Water provides cushioning for organs inside organisms. Which special properties allows water to do this?

Water acts as a solvent and a medium in which biochemical reactions can occur.

How did life start? (H.D.L.S.)

life almost certainly originated in a series of small steps, each building upon the complexity that evolved previously: Simple organic molecules formed, replicating molecules evolve & natural selection, replicating molecules became enclosed within a cell membrane, cells began to evolve metabolic processes, multicellularity evolved.

(H.D.L.S.) 1. Simple organic molecules formed

Simple organic molecules, similar to the nucleotide shown below, are the building blocks of life and must have been involved in its origin.

(H.D.L.S.) 2. Replicating molecules evolved and began to undergo natural selection

All living things reproduce, copying their genetic material and passing it on to their offspring. The ability probably first evolved in the form of an RNA self-replicator

(H.D.L.S.) 3. Replicating molecules became enclosed within a cell membrane

The evolution of a membrane surrounding the genetic material provided two huge advantages: the products of the genetic material could be kept close by and the internal environment of this proto-cell could be different than the external environment.

(H.D.L.S.) 4. Some cells began to evolve modern metabolic processes and out-competed those with older forms of metabolism.

Up until this point, life had probably relied on RNA for most jobs, But everything changed when some cell or group of cells evolved to use different types of molecules for different functions: DNA (which is more stable than RNA) became the genetic material, proteins (which are often more efficient promoters of chemical reactions than RNA) became responsible for basic metabolic reactions in the cell, and RNA was demoted to the role of messenger, carrying information from the DNA to protein-building centers in the cell.

(H.D.L.S.) 5. Multicellularity evolved

As early as two billion years ago, some cells stopped going their separate ways after replicating and evolved specialized functions. Giving rise to Earth’s first lineage of multicellular organisms.

Does life have a goal?

Life, from a biological perspective, has the innate goal of self-perpetuation and adaptation to its environment.

When did life originate?

Evidence suggests that life first evolved around 3.5 billion years ago. This evidence takes the form of microfossils and ancient rock structures in South Africa and Australia called stromatolites. 

What defines life?

order, sensitivity or response to the environment, reproduction, adaptation, growth and development, regulation/homeostasis, energy processing, and evolution.

Does life exist elsewhere in the universe?

It is likely that life does exist elsewhere in the universe, the discovery of possible ancient life on Mars, and the possibility of life on Europa are examples as to places besides Earth that life could exist within our universe. It is likely.

Why are there so many species on earth?

The diversity of life on Earth is a result of mutations, or random changes in hereditary material over time. Mutations allow organisms to adapt to a changing environment.

Identify and describe the properties of life? (I.D.P.O.L.)

All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, adaptation, growth and development, regulation/homeostasis, energy processing, and evolution.

Order (I.D.P.O.L)

Organisms are highly organized, coordinated structures that consist of one or more cells.

Sensitivity/Response to stimuli (I.D.P.O.L)

Organisms respond to diverse stimuli.

Reproduction (I.D.P.O.L.)

When reproduction occurs, DNA containing genes are passed along to an organism’s offspring.

Adaptation (I.D.P.O.L.)

Adaptations enhance the reproductive potential of the individuals exhibiting them, including their ability to survive to reproduce.

Growth & Development (I.D.P.O.L.)

Organisms grow and develop as a result of genes providing specific instructions that will direct cellular growth and development.

Regulation/Homeostasis (I.D.P.O.L.)

relatively stable internal environment required to maintain life. Two examples of internal functions regulated in an organism are nutrient transport and blood flow. Organisms are able to maintain homeostatic internal conditions within a narrow range almost constantly, despite environmental changes, by activation of regulatory mechanisms.

Energy processing (I.D.P.O.L.)

All organisms use a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert it into chemical energy in food. Others use chemical energy in molecules they take in as food.

Evolution (I.D.P.O.L.)

The diversity of life on Earth is a result of mutations, or random changes in hereditary material over time. These mutations allow the possibility for organisms to adapt to a changing environment. An organism that evolves characteristics fit for the environment will have greater reproductive success, subject to the forces of natural selection.

What is the difference between response to environment and reaction to environment?

Response is more active and intentional. (actively deciding not to crash your car into a building)

Reaction is more automatic. (a protein will react to heat)

Identify four macromolecules that build up living organisms and explain their roles

Deoxyribonucleic acid (DNA), Ribonucleic Acid (RNA), Carbohydrates, Proteins, Glucose, Fatty Acids, Amylose, Amylopectin, Starch.

Deoxyribonucleic acid (DNA)

DNA is the genetic material in all living organisms, ranging from single-celled bacteria to multicellular mammals.

Ribonucleic Acid (RNA)

RNA, is mostly involved in protein synthesis. The DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell.

messenger RNA (mRNA)

The intermediary used to communicate with rest of the cell.

Other types of RNA

like rRNA, tRNA, and microRNA—are involved in protein synthesis and its regulation.

Carbohydrates

Grains, fruits, and vegetables are all natural carbohydrate sources that provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods.

Proteins

Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of proteins, each with a unique function.They are all, however, amino acid polymers arranged in a linear sequence.

Glucose

glucose is an important source of energy. During cellular respiration, energy releases from glucose, and that energy helps make adenosine triphosphate (ATP).

Fatty Acids

Fatty acids primarily function as a dense source of energy, act as essential structural components for cell membranes, and serve as signaling molecules and precursors for bioactive lipids that regulate various physiological processes, including inflammation, immune response, and metabolism. 

Amylose

Amylose is a starch component that serves as an energy storage molecule in plants, storing glucose for later use and providing a compact way to store energy.

Amylopectin

Amylopectin's primary roles are energy storage in plants and bacteria by providing a highly branched, glucose-rich structure, and modifying food texture, acting as a thickener and stabilizer in processed foods due to its gelatinous properties and film-forming abilities

Starch

Starch primarily functions as an energy storage form for plants and a vital dietary carbohydrate for humans, providing glucose and calories. 

Explain why a cellular membrane is required for living organisms to carry out many of their functions.

A cell membrane allows a cell to:
- control what enters and exits the cell.
- maintain a constant internal environment inside the cell.
- maintain an electric potential (the difference in concentration of
ions between the inside and the outside).
- respond to external signals and communicate with other cells.

Use the characteristics of living organisms to evaluate if viruses should be considered living or not.

All viruses are parasites and need to infect a cell of a living organism to produce proteins and reproduce

Viruses cannot reproduce on there own; they use a living organism to replicate.

Most scientists agree viruses are not considered to be living organisms, but there are some grey areas.

Describe the basic components that make up a virus.

1) Nucleic acid, (genome) either DNA or RNA. The genetic material of a virus, it contains the instructions for making more viruses.

2) Protein Capsid. A shell that protects the genetic material, and plays a role in attaching to a host cell.

Explain why antibiotics do not affect viruses.

Antibiotics kill bacteria by:
• Destroying their cell wall.
• Stopping bacteria from reproducing by preventing
the production of new cell walls.
• Damaging their cell membrane.
• Binding to ribosomes and preventing protein
production.
• Blocking specific enzymes in their metabolism.

Viruses do not have a cell wall, a cell membrane, ribosomes, or metabolism so they are not affected!

Explain the purpose of a phylogenetic tree.

diagram used to reflect evolutionary relationships among organisms or groups of organisms. In other words, we can construct a “tree of life” to illustrate when different organisms evolved and to show the relationships among different organisms.

Systematics

the field that scientists use to organize and classify organisms based on evolutionary relationships

Taxonomy

the science of classifying organisms to construct internationally shared classification systems with each organism placed into increasingly more inclusive groupings.

What structure is needed for an organism to maintain homeostasis, metabolize, and respond to its environment?

A cell membrane

Why is a cell membrane essential for life?

A cell membrane allows a cell to: control what enters and exits the cell, maintain a constant internal environment inside the cell, maintain an electric potential (the difference in concentration of ions between the inside and the outside), and respond to external signals and communicate with other cells.

Describe the levels of organization among living things?

after the common beginning of all life, scientists divide organisms into three large categories called domains: Bacteria, Archaea, and Eukarya. Within each domain is a second category called a kingdom. After kingdoms, the subsequent categories of increasing specificity are: phylum, class, order, family, genus, and species.

How viruses evolved: Regressive Hypothesis

suggests that viruses evolved from free-living cells, or from intracellular prokaryotic parasites. 

How viruses evolved: Progressive Hypothesis

suggests that viruses originated from RNA and DNA molecules, or self-replicating entities similar to transposons or other mobile genetic elements, that escaped from a host cell with the ability to enter another. 

How viruses evolved: Virus first hypothesis

 suggests that viruses may have been the first self-replicating entities before the first cells. In all cases, viruses are probably continuing to evolve along with the cells on which they rely on as hosts.

Describe the general structure of a virus

Noncellular, meaning they lack organelles, ribosomes and plasma membrane. Contain a nucleic acid core, an outer protein coating or capsid, and sometimes an outer membrane made of protein and phospholipid membranes.

Cladistics

This system sorts organisms into clades: groups of organisms that descended from a single ancestor. All organisms in the clade or monophyletic group stem from a single point on the tree.

Maximum parsimony

means that events occurred in the simplest, most obvious way.

Taxon

 phylum, class, order, family, genus, and species. Each of these is referred to as a taxon.

What is the difference between a clade and a taxon?

A clade is a group of organisms that share a common ancestor.

Taxon’s do not always indicate common ancestry.

monophyletic group

 (also, clade) organisms that share a single ancestor

paraphyletic group

organisms that includes a common ancestor but not all of its descendants.

Horizontal Gene Transfer (HGT)

introduction of genetic material from one species to another species by mechanisms other than the vertical transmission from parent(s) to offspring.

Divergent Evolution

We call two species that evolve in diverse directions form a common point this

Homologous Structures

Over time, evolution resulted in changes in bone shape and sizes in different species, but have maintained overall layout. The synonymous parts are called this.

Convergent Evolution

Where similar traits evolve independently in species that do not share a recent common ancestry.

Adaptation

Heritable trait that helps an organism’s survival and reproduction in its present environment

Vestigial Structures

Unused structures with no function

Homologous Structures

Biological features, such as bones or organs, similar in different organisms because they originated from a common ancestor

Extremophiles

Bacteria and archaea that are adapted to grow under extreme conditions are called this.

Phototrophs

Organisms that use visible light as their primary energy source for cellular metabolism

Transformation

Recycle DNA from other prokaryotes in its evironment

Transduction

Viruses accidentally move small amounts of DNA from one bacteria to another

Conjugation

They touch tips (pilus)

What is the RNA world hypothesis?

Hypothesis that in life’s history, it occupied centre stage and performed most jobs in the cell, storing genetic information, copying itself, and performing basic metabolic functions.

What is the difference between gram-positive and gram-negative bacteria?

Main dif is the cell wal and % of peptidoglycan that makes it up.

Positive bacteria → 90% ish of peptidoglycan

Negative bacteria → 10% or less

What is the importance of differentiating gram positive/negative bacteria?

Gram positive →have thick cell walls that are easily penetrated by antibiotics, making them generally more treatable.

Gram negative → Outer membrane, making them more resistant and harder to kill.

Chemotrophs

obtain chemical energy from the oxidation of substrates in their environment (either organic or inorganic molecules).

Heterotrophs

eat/absorb carbon-rich molecules in their environment. 

Autotrophs

fix carbon from CO2 (inorganic) and convert it glucose (organic)

Give examples of several important roles that prokaryotes play in the ecosystem based on their metabolism

1. Carbon cycle: carbon fixation, decomposition

2. Nitrogen cycle: Nitrogen fixation, ammonification

3. Nutrient recycling: decomposition & nutrient release, soil formation

4. Photosynthesis: Primary producer

1. Carbon cycle: Carbon Fixation

Photosynthetic prokaryotes, such as cyanobacteria, remove carbon dioxide from the atmosphere and convert it into organic molecules, similar to how plants do. 

1. Carbon cycle: decomposition

Prokaryotic decomposers break down dead organic matter (plants and animals), returning carbon in the form of carbon dioxide to the atmosphere and making it available for reuse. 

2. Nitrogen cycle: Nitrogen Fixation

Prokaryotes, like the Rhizobium bacteria in legume roots, convert atmospheric nitrogen gas into ammonia, a form of nitrogen that plants can absorb and use to build necessary biomolecules. 

2. Nitrogen Cycle: Ammonification

During the decomposition of nitrogen-containing organic compounds, other prokaryotes release ammonium, a form of inorganic nitrogen, into the soil. 

3. Nutrient recycling: Decomposition and nutrient release

By breaking down dead organisms and waste products, prokaryotes release a variety of essential elements and inorganic molecules back into the ecosystem for plants and other organisms to reuse. 

3. Nutrient recycling: Soil formation

The breakdown of organic matter by prokaryotes helps create humus, which enriches soil and increases its fertility. 

4. Photosynthesis: Primary Producers

 Some prokaryotes, particularly in marine environments, are significant photosynthetic organisms, contributing to the ocean's primary productivity and forming a base for marine food webs

What caused the oxygen revolution?

evolution of oxygenic photosynthesis by ancient cyanobacteria, which released oxygen as a byproduct.