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Bio 190 Exam #2 Study Guide
Topics:
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Diffusion/ Osmosis
Surface Area to Volume Ratio
Photosynthesis
Respiration
Evolution/ Adaptation
Speciation/ Phylogeny/ Taxonomy
Features of Prokaryotes and Eukaryotes

● Phototrophs- capture energy from the sun (ex
...
Sugars
such as glucose contain energy in their chemical bonds that can be used to synthesize ATP,
which in turn can power the work of the cell
...
animals)
Ingest organic molecules such as glucose that they break down in the presence of oxygen to
produce co2 and water
...

● Autotrophs- “self-feeders” make their own organic carbon using inorganic carbon as
starting material
● Heterotrophs- “other-feeders” rely on other organisms for their organic forms of carbon

Diffusion/ Osmosis:
● Diffusion leads to net movement of a substance when there is a conc gradient
● Facilitated diffusion- a molecule moves through a membrane protein and bypasses the
lipid bilayer
● In salt solutions, etc
...
elephant’s big ears)

Photosynthesis
● Photic zone- place where sunlight can penetrate to enable photosynthesis
● Pigment absorbs sunlight → sunlight energy drives e- through transport chain → produce
ATP and NADPH → synthesize carbs using CO2 (Calvin cycle)

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Photosynthetic e- transport chain is located in the thylakoid membrane
Grana- sacs connected by membrane bridges
Lumen- an enclosed compartment surrounded by the grana
Stroma- “cytoplasm” of the chloroplast

● Photosynthetic organisms need a constant supply of ATP to meet each cell’s energy
requirements
●
1)
2)
3)

Calvin cycle consists of 15 chemical reactions that synthesize carbs from CO2
Carboxylation- CO2 is added to a 5-carbon molecule
Reduction- energy and e- transferred to the compounds formed in step 1
Regeneration of the 5-carbon molecule

● 3-PGA is the first stable product of the Calvin cycle
● Rubisco is responsible for the addition of C atoms needed to form carbs
● NADPH- reducing agent of the Calvin cycle, transfers e- that allow carbs to be
synthesized from CO2
● ATP donates a phosphate group to 3-PGA , and NADPH transfers 2 e- and 1 H+ to the
phosphorylated compound, which releases one P group
● Triose phosphates- true products of the Calvin cycle, principle form in which carbs are
exported from the chloroplast during photosynthesis
● The regeneration of RuBP requires ATP
● Starch formation provides the chloroplasts with a way of storing carbs that will not allow
water to enter the cell by osmosis
● Photosystems- absorb light energy and
use it to drive e- transport
● Accessory pigments- absorbs light from
regions not easily absorbed by
chlorophyll, ex
...
the probability
of creating highly reactive forms of O2 (reactive oxygen species)
● Cold temps
...
within carbs and lipids)
● 1 molecule glucose yields 32 molecules of ATP
● Substrate-level phosphorylation- generating ATP by the addition of a phosphate group to
ADP from an enzyme substrate (an organic molecule)
● In this case, chemical energy of organic molecules is transferred to electron carriers
(move electrons from on set of reactions to another) → to the respiratory electron
transport chain
● Oxidative phosphorylation- in aerobic respiration, O2 is the final electron acceptor,
resulting in the formation of water
● Redox reactions- reactions in which electrons are transferred between atoms/molecules

● Oxidation = loss of electrons (ex
...
neutral molecule becomes a - ion in a compound)
● In redox reactions involving organic molecules, gain or loss of electrons is often
accompanied by the gain or loss of protons (H+)
● In aerobic respiration, glucose is oxidized to release CO2 and oxygen is reduced to form
water
● Glucose is a good electron donor bc its oxidation to CO2 releases a lot of energy,
whereas O2 is a good acceptor bc it has a high electron affinity
● Energy is released in a controlled manner bc glucose is oxidized to CO2 slowly in a
series of reactions rather than all at once
● Glycolysis (stage 1)- process in which glucose is broken down to make pyruvate and
energy is transferred to ATP and reduced electron carriers
● Stage 2- pyruvate is oxidized to another molecule called acetyl-CoA to produce electron
carriers and release CO2
● Citric acid cycle (stage 3)- acetyl group is oxidized to CO2 and and energy is transferred
to ATP and reduced electron carriers (this stage transfers more energy than the first 2
stages combined)
● Oxidative phosphorylation (stage 4)- reduced electron carriers donate electrons to the
electron transport chain and a large amount of ATP is produced
● In eukaryotes, glycolysis is in the cytoplasm and the other stages are in the mitochondria
● In some bacteria, reactions take place in cytoplasm and electron transport chain is in the
plasma membrane
● Change in free energy is much greater for the steps that generate reduced electron carriers
than for those that produce ATP directly
● Fermentation- extracts energy from glucose in the absence of O2
● Lactic acid fermentation- in animals and bacteria, electrons from NADH are transferred
to pyruvate to produce lactic acid and NAD+
● Ethanol fermentation- in plants and fungi, pyruvate releases CO2 to form acetaldehyde,
and electrons from NADH are transferred to acetaldehyde to produce ethanol and NAD+
● NADH and NAD+ do not appear in final equation bc there is no net loss or gain

● Fermentation yields only 2 molecules of ATP bc the end products (lactic acid and
ethanol) are not fully oxidized and still contain a lot of energy in their bonds
● Fermentation occurs in the cytoplasm and does not require membrane embedded proteins
● The first life forms on earth used anaerobic respiration bc they could not use O2
● With evolution, aerobic respiration built off of the anaerobic pathway so that bigger
organisms could harness more energy using atmospheric O2
● Excess glucose is stored as glycogen in animals and starch in plants
● Carbs are broken down into sugars and circulate in the bloodstream
● The level of glucose in the blood is tightly regulated; if levels are high, glucose molecules
are linked together to form glycogen in the liver and muscle
● Glycogen stored in muscle is used to provide ATP for muscle contraction
● Liver can release glucose into the bloodstream when it is needed elsewhere
● Hydrolysis of disaccharides (maltose, lactose, sucrose) produces glucose that enters
glycolysis directly
● Monosaccharides are converted into intermediates of glycolysis that enter later in the
pathway
● Fatty acids in triacylglycerols are an important form of energy storage in cells

Evolution/ Adaptation
● Phenotype- an organism’s exposed traits
● Genotype- info in an organism’s DNA
● Genomes contain chromosomes contain genes
● Populations evolve, individuals do not
● Evolution = change in allele frequency in a population
● Mutations- generate new alleles
● Genetic drift- coincidental change in allele frequency
● Natural selection requires a sufficiently large population of individuals that reproduce
and have genetic variation in which some alleles confer higher reproductive success than
others on average

● Individuals with “better” alleles tend to have more offspring and better alleles become
more common
● Genetic drift in pathogen populations is not in response to drug exposure
● Natural selection can only act on existing genetic variation, only acts on things that
influence lifetime reproductive success, and is constrained by trade-offs
● Trade off: how long an organism will live vs

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