Essential Knowledge to scaffold FRQ answers

Where did (some) membrane bound organelles come from?

Membrane-bound organelles evolved from once free-living prokaryotic cells via endosymbiosis.

Do prokaryotes have membrane bound organelles?

Do they have any specialized regions?

Prokaryotes generally lack internal membrane-bound organelles but have internal regions with specialized structures and functions.

T/F:

Eukaryotic cells maintain internal membranes that partition the cell into specialized regions.

True. Eukaryotic cells maintain internal membranes that partition the cell into specialized regions.

How did membrane bound organelles evolve?

Membrane-bound organelles evolved from previously free-living prokaryotic cells via endosymbiosis.

What is the major mechanism of evolution?

Natural selection is a major mechanism of evolution.

Describe natural selection.

According to Darwin's theory of natural selection, competition for limited resources results in differential survival. Individuals with more favorable phenotypes are more likely to survive and produce more offspring, thus passing traits to subsequent generations.

How is evolutionary fitness measured?

Evolutionary fitness is measured by reproductive success.

Does evolution proceed at a constant rate? Why or why not?

Biotic and abiotic environments can be more or less stable/fluctuating, and this affects the rate and direction of evolution; different genetic variations can be selected in each generation.

What type of variation does natural selection act upon?

Natural selection acts on phenotypic variations in populations, not necessarily genotypic variation.

T/F:

Environments change and apply selective pressures to populations.

True. Environments change and apply selective pressures to populations.

Does a phenotypic variation always result in higher fitness?

No, phenotypic variations may significantly increase or decrease fitness of the organism in particular environments.

Describe artificial selection.

Through artificial selection, humans affect variation in other species.

What is convergent evolution?

Convergent evolution occurs when similar selective pressures result in similar phenotypic adaptations in different populations or species.

What are some random occurrences that drive evolution?

Evolution is also driven by random occurrences such as mutation, bottleneck effect, the founder effect, and gene flow.

T/F Reduction of genetic variation within a given population can increase the differences between populations of the same species.

True: Reduction of genetic variation within a given population can increase the differences between populations of the same species.

What is the primary source if genetic variation?

Mutation results in genetic variation, which provides phenotypes on which natural selection acts.

What is hardy-weinberg equilibrium and what are the 5 conditions?

Hardy-Weinberg is a model for describing and predicting allele frequencies in a nonevolving population. Conditions for a population or an allele to be in Hardy-Weinberg equilibrium are—

(1) a large population size,

(2) absence of migration,

(3) no net mutations,

(4) random mating, and

(5) absence of selection.

How can you calculate allele frequencies in a population?

Allele frequencies in a population can be calculated from genotype frequencies.

What is the relationship between allele frequences and evidence for evolution?

Changes in allele frequencies provide evidence for the occurrence of evolution in a population.

Are small or large populations more susceptible to random environmental impact?

Small populations are more susceptible to random environmental impact than large populations.

What disciplines collectively support evolution?

Evolution is supported by scientific evidence from many disciplines (geographical, geological, physical, biochemical, and mathematical data)

Describe multiple lines of evidence for evolution.

Molecular, morphological, and genetic evidence from extant and extinct organisms adds to our understanding of evolution—

a. Fossils can be dated by a variety of methods. These include:

i. The age of the rocks where a fossil is found

ii. The rate of decay of isotopes including carbon-14

iii. Geographical data

b. Morphological homologies, including vestigial structures, represent features shared by common ancestry.

How can we use molecular data to provide evidence of common ancestry?

A comparison of DNA nucleotide sequences and/or protein amino acid sequences provides evidence for evolution and common ancestry.

What is an adaptation?

An adaptation is a genetic variation that is favored by selection and is manifested as a trait that provides an advantage to an organism in a particular environment.

What molecule(s) carry genetic information?

DNA and RNA are carriers of genetic information. (DON'T FORGET THAT THERE ARE RNA VIRUSES)

What organelle is found in ALL forms of life?

Ribosomes are found in all forms of life

What is common about the genetic code among all living things?

Major features of the genetic code are shared by all modern living systems.

All rely on A, T,C, and G.

The codon chart can be used for all life forms.

Core metabolic pathways are conserved across all currently recognized domains. Name at least 3.

Know these:

- glycolysis in cytoplasm

- ETC exists in bacteria, they just carry it on their cell membranes rather than mitochondria or chloroplasts.

- Transcription, translation

Structural and functional evidence supports the relatedness of organisms in all domains. What is meant by structural and functional?

Know vestigial, homologous, and analogous structures

What structural evidence exists that indicates common ancestry in EUKARYOTES?

Structural evidence indicates common ancestry of all eukaryotes—

a. Membrane-bound organelles

b. Linear chromosomes

c. Genes that contain introns

Does evolution ever stop?

Populations of organisms continue to evolve.

What is some evidence that evolution continues today?

a. Genomic changes over time.

b. Continuous change in the fossil record.

c. Evolution of resistance to antibiotics, pesticides, herbicides, or chemotherapy drugs.

d. Pathogens evolve and cause emergent diseases.

What do phylogenetic trees and cladograms show?

Phylogenetic trees and cladograms show evolutionary relationships among lineages

What is the difference between phylogenetic trees and cladograms?

Phylogenetic trees and cladograms both show relationships between lineages, but phylogenetic trees show the amount of change over time calibrated by fossils or a molecular clock.

How can we construct a tree using traits?

Traits that are either gained or lost during evolution can be used to construct phylogenetic trees and cladograms

What do shared/ derived characters show?

Shared, derived characters indicate common ancestry and are informative for the construction of phylogenetic trees and cladograms.

What is the out-group?

The out-group represents the lineage that is least closely related to the remainder of the organisms in the phylogenetic tree or cladogram

What is the best type of evidence for constructing a tree?

Molecular data typically provide more accurate and reliable evidence than morphological traits in the construction of phylogenetic trees or cladograms because morphology can arise through convergent evolution.

READ THIS CARD AND MEMORIZE IT

Phylogenetic trees and cladograms represent hypotheses and are constantly being revised, based on evidence.

What is the most important factor/pre-requisite for speciation to occur?

Speciation may occur when two populations become reproductively isolated from each other.

What types of organisms does the biological species concept apply to?

The biological species concept provides a commonly used definition of species for sexually reproducing organisms.

What is the biological species concept?

It states that species can be defined as a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.

Compare punctuated equilibrium with gradualism.

Punctuated equilibrium is when evolution occurs rapidly after a long period of stasis. Gradualism is when evolution occurs slowly over hundreds of thousands or millions of years.

What is divergent evolution?

Divergent evolution occurs when adaptation to new habitats results in phenotypic diversification. Speciation rates can be especially rapid during times of adaptive radiation as new habitats become available.

What are the two types of speciation?

Speciation may be sympatric or allopatric.

Wha ttypes of mechanisms/barriers result in reproductive isolation?

Various prezygotic and postzygotic mechanisms can maintain reproductive isolation and prevent gene flow between populations.

When are extinction rates typically high?

Extinction rates can be rapid during times of ecological stress.

How do humans effect ecosystems?

Human activity (hunting, fishing, climate change, deforestation, urbanization) can drive changes in ecosystems that cause extinctions.

How is diversity of an ecosystem determined?

The amount of diversity in an ecosystem can be determined by the rate of speciation and the rate of extinction.

What is a "positive" of extinction?

Extinction provides newly available niches that can then be exploited by different species.

How is carbon used in life forms?

Carbon is used to build biological molecules such as carbohydrates, proteins, lipids, and nucleic acids. Carbon is used in storage compounds and cell formation in all organisms

What macromolecules use nitrogen? What uses phosphorous?

Nitrogen is used to build proteins and nucleic acids. Phosphorus is used to build nucleic acids and certain lipids.

How does surface area-to-volume ratio play a role in cells?

Surface area-to-volume ratios affect the ability of a biological system to obtain necessary resources, eliminate waste products, acquire or dissipate thermal energy, and otherwise exchange chemicals and energy with the environment.

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The surface area of the plasma membrane must be large enough to adequately exchange materials—

a. These limitations can restrict cell size and shape. Smaller cells typically have a higher surface area-to-volume ratio and more efficient exchange of materials with the environment.

b. As cells increase in volume, the relative surface area decreases and the demand for internal resources increases.

c. More complex cellular structures (e.g., membrane folds) are necessary to adequately exchange materials with he environment.

d. As organisms increase in size, their surface area-to-volume ratio decreases, affecting properties like rate of heat exchange with the environment

What is an important site in enzymes?

The structure of enzymes includes the active site that specifically interacts with substrate molecules.

Why does substrate shape matter?

For an enzyme-mediated chemical reaction to occur, the shape and charge of the substrate must be compatible with the active site of the enzyme.

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The structure and function of enzymes contribute to the regulation of biological processes

What are enzymes

Enzymes (almost always proteins) are biological catalysts that facilitate chemical reactions in cells by lowering the activation energy.

How might a change in enzymatic structure alter a reaction?

Change to the molecular structure of a component in an enzymatic system may result in a change of the function or efficiency of the system

What is denaturation?

Denaturation of an enzyme occurs when the protein structure is disrupted, eliminating the ability to catalyze reactions.

What can cause denaturation?

Environmental temperatures and pH outside the optimal range for a given enzyme will cause changes to its structure, altering the efficiency with which it catalyzes reactions

Can denaturation be reversed

In some cases, enzyme denaturation is reversible, allowing the enzyme to regain activity.

This typically can only occur IN CELLS, not in a lab. It usually requires chaperone proteins.

How does pH affect enzyme efficiency?

Environmental pH can alter the efficiency of enzyme activity, including through disruption of hydrogen bonds that provide enzyme structure.

What generally determines enzyme reaction efficiency/rate?

The relative concentrations of substrates and products determine how efficiently an enzymatic reaction proceeds.

Describe the role of temperature on reaction speeds.

Higher environmental temperatures increase the speed of movement of molecules in a solution, increasing the frequency of collisions between enzymes and substrates and therefore increasing the rate of reaction. REMEMBER ON UNTIL THE ENZYME BECOMES DENATURED.

What is the difference between a competitive inhibitor and non-competitive (allosteric) inhibitor?

Competitive inhibitor molecules can bind reversibly or irreversibly to the active site of the enzyme. Noncompetitive inhibitors can bind allosteric sites, changing the activity of the enzyme.

How is energy related to life?

All living systems require constant input of energy

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Life requires a highly ordered system and does not violate the second law of thermodynamics

Describe the energy balance required for cells.

Energy input must exceed energy loss to maintain order and to power cellular processes

How do processes that require input of energy occur efficiently in a cell?

Cellular processes that release energy may be coupled with cellular processes that require energy

What happens if energy is no longer supplied?

Loss of order or energy flow results in death

How do cells typically carry out complex processes?

Energy-related pathways in biological systems are sequential to allow for a more controlled and efficient transfer of energy. A product of a reaction in a metabolic pathway is generally the reactant for the subsequent step in the pathway

Describe photosynthesis generally.

Photosynthesis captures energy from the sun and produces sugars

Where did photosynthesis first evolve?

Photosynthesis first evolved in prokaryotic organisms (cyanobacteria)

What produced the oxygen in the atmosphere on ancient earth?

Scientific evidence supports the claim that prokaryotic (cyanobacteria) photosynthesis was responsible for the production of an oxygenated atmosphere

Where did eukaryotic photosynthesis "come from?"

Prokaryotic photosynthetic pathways were the foundation of eukaryotic photosynthesis

How does the light-dependent reaction work? and what does it yield?

The light-dependent reactions of photosynthesis in eukaryotes involve a series of coordinated reaction pathways that capture energy present in light to yield ATP and NADPH, which power the production of organic molecules

What is the role of chlorophyll?

During photosynthesis, chlorophylls absorb energy from light, boosting electrons to a higher energy level in photosystems I and II

What are the photosystems?

Photosystems I and II are embedded in the internal membranes of chloroplasts and are connected by the transfer of higher energy electrons through an electron transport chain (ETC)

What is generated by the electron transport chain i both photosynthesis and cellular respiration?

When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC, an electrochemical gradient of protons (hydrogen ions) is established across the internal membrane.

What is the point of the proton gradient in both photosynthesis and cellular respiration?

The formation of the proton gradient is linked to the synthesis of ATP from ADP and inorganic phosphate via ATP synthase

What are the ATP and NADPH in the light reactions used for? Where do those subsequent reactions occur?

The energy captured in the light reactions and transferred to ATP and NADPH powers the production of carbohydrates from carbon dioxide in the Calvin cycle, which occurs in the stroma of the chloroplast

Where does the energy come from to make ATP from fermentation and cellular respiration?

Fermentation and cellular respiration use energy from biological macromolecules to produce ATP. Respiration and fermentation are characteristic of all forms of life.

What is cellular respiration?

Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that capture energy from biological macromolecules.

What does the electron transport chain do?

The electron transport chain transfers energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes

Where can you find electron transport chains?

Electron transport chain reactions occur in chloroplasts, mitochondria, and prokaryotic plasma membranes

What is the final electron acceptor in the cellular respiration ETC?

What about the final electron acceptor in the photosynthetic ETC?

In cellular respiration, electrons delivered by NADH and FADH2 are passed to a series of electron acceptor as as they move toward the terminal electron acceptor, oxygen. In photosynthesis, the terminal electron acceptor is NADP+

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The transfer of electrons is accompanied by the formation of a proton gradient across the inner mitochondrial membrane or the internal membrane of chloroplasts, with the membrane(s) separating a region of high proton concentration from a region of low proton concentration. In prokaryotes, the passage of electrons is accompanied by the movement of protons across the plasma membrane.

How is ATP formed via the proton gradient in both CR and Photosynthesis?

The flow of protons back through membrane-bound ATP synthase by chemiosmosis drives the formation of ATP from ADP and inorganic phosphate. This is known as oxidative phosphorylation in cellular respiration, and photophosphorylation in photosynthesis

Define oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

What would happen if you decoupled oxidative phosphorylation?

In cellular respiration, decoupling oxidative phosphorylation from electron transport generates heat. This heat can be used by endothermic organisms to regulate body temperature. (BROWN FAT IN BABIES)

What is glycolysis?

Glycolysis is a biochemical pathway in the cytoplasm that releases energy in glucose to form ATP from ADP and inorganic phosphate, NADH from NAD+, and pyruvate.

How many pyruvates are made from glucose and where are they transported to?

2 Pyruvate is transported from the cytosol to the mitochondrion, where further oxidation occurs.

What is released during the Kreb Cycle? What is produced? What is being stockpiled?

In the Krebs cycle, carbon dioxide is released from organic intermediates, ATP is synthesized from ADP and inorganic phosphate, and electrons are transferred to the coenzymes NADH and FADH2

What are the electron donors to the ETC in CELULLAR RESPIRATION?

Electrons extracted in glycolysis and Krebs cycle reactions are transferred by NADH and FADH2 to the electron transport chain in the inner mitochondrial membrane.

What is the electron donor to the ETC in Photosynthesis?

Water

Why is ATP used in biological reactions?

The conversion of ATP to ADP releases energy, which is used to power many metabolic processes

How is body temperature regulated in different organisms?

Organisms use different strategies to regulate body temperature and metabolism. i. Endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures. ii. Ectotherms lack efficient internal mechanisms for maintaining body temperature, though they may regulate their temperature behaviorally by moving into the sun or shade or by aggregating with other individuals.

What is the relationship between metabolic rate and size?

There is a relationship between metabolic rate per unit body mass and the size of multicellular organisms—generally, the smaller the organism, the higher the metabolic rate.

If there is excess energy i.e. too much food, what happens?

A net gain in energy results in energy storage or the growth of an organism