Fluid Mosaic Model of Plasma Membrane Structure

Bio152 Final Exam Review
Essay Questions:
Quest 1-2:
Describe the fluid mosaic model of plasma membrane structure and list the major components of the membrane. How did scientists discover that the membrane was
“fluid”? Explain one experiment that we discussed.
• The fluid mosaic model of plasma membrane was the idea that lipids or proteins could move in the membrane laterally. The plasma membrane is made up of a phospholipid bilayer and controls a lot of what goes in and out of the membrane by the organelles from within. The bilayer is considered to be amphipathic.
There are proteins in the membrane as well. To prove that the plasma membrane was “fluid”, scientists completed an experiment known as FRAP which means
Fluorescence Recovery After Photobleaching and what they did here was that they had cells with proteins and took a section and labeled them with a fluorescent tag. They then took a beam that bleached that section white. They incubated the cell at 37 degrees Celsius and after some time they came back to see that the fluorescent section was now scattered over the whole cell. This is how they knew that proteins or lipids could move across the membrane.
Explain what happens when a red blood cell is placed in a hypertonic solution. A hypotonic solution? Be sure to mention the appearance of the cell and the reason behind it. Also give a definition for osmosis.
• The definition of osmosis is the diffusion of a fluid across a semipermeable membrane from low concentration to high concentration. When a red blood cell is placed in a hypertonic solution, the water molecules diffuse out of the cell and water is lost. This causes the cell to shrivel up. If a red blood cell is placed in a hypotonic solution the water will diffuse into the red blood cell and cause it to swell and maybe even burst.
Compare the light-dependent and light independent reactions of photosynthesis in terms of what is required, what is produced, and where it occurs in the chloroplast. Please make a table. Also, describe in a sentence or two how cyclic photophosphorylation differs from noncyclic photophosphorylation.
Light dependent (Hill)
Where it occurs?
What is required?
What is produced?

Thylakoid membranes
(grana)
Light
H2O
ATP
NADPH
O2

Light Independent
(Calvin)
Stroma
ATP
NADPH
CO2
Glucose

•

Cyclic photophosphorylation differs in that it only uses photosystem I which is sensitive to light at 700 nm. It produces only ATP and is less common that its counterpart, noncyclic photophosphorylation. During this, both photosystem I
(p700) and photosystem II (p680) are used in conjunction with each other to produce ATP and NADPH. This is more common and also where water can split.

Quest 3-6
At one time, scientists were not certain that DNA is the genetic material in cells. What was considered as an alternative to DNA? Explain two of the following experiments and how they helped to lead to DNA being identified as the genetic material. You can choose from: Griffith Bacterial Transformation in mice, Avery/MacLeod/McCarty, or Hershey and Chase. (Include the name/s of researchers, the method in 2-4 sentences, the results in 1-2 sentences, and the conclusion in 1-2 sentences.
• An alternative to DNA was protein.
• Griffith (1928) o S strain of Staphylococcus lethal in mice o R strain nonvirulent in mice o Dead S strain nonvirulent o Live R + dead S= dead mice, so something in the dead S must have 00
• Avery/MacLeod/McCarty o Biochemical purification of DNA showed that they could recapitulate
Griffith experiment, but with live R + DNA from S=dead mice
Hershey
and Chase
•
o Bacteriophage and a kitchen blender
§ Radioactively label bacteriophage with 35S (proteins) and radioactively label bacteriophage with 32P (DNA)
§ Allows the phage to infect bacteria
§ Blend to separate phage coats (outer protein “shell”) from the bacteria § Examine bacteria to determine what phage product was able to
“transduce” the bacteria into little phage-producing factories= radioactive DNA
Multiple proteins and protein complexes are needed to initiate transcription. Describe the major proteins and protein complexes discussed in class, their roles in transcription, and where they bind DNA (if they do). Be as specific as possible. Include TFIID (or TBP) and its role and binding site; TFIIA and its role and binding site; TFIIB and its role and binding site; RNA polymerase II, and how it begins transcription at the correct DNA sequence; the role of phosphorylation in initiation of transcription.
• TBP which is part of the multiprotein complex TFIID binds to the TATA box.
Additional general transcription factors TFIIA and TFIIB also bind to specific
DNA sequences in the promoter region. RNA polymerase and TFIIF then interact with (bind) the general transcription factors
Label the following diagram. Explain how air is drawn into the lungs, and how it is expelled. Describe which muscles and skeletal bones are involved, and how each

contributes to inhalation and exhalation. (3-4 sentences max) Describe how oxygen in the air is delivered to all of the tissues in the body – start with oxygen in the air in the lungs, and explain how oxygen moves to the tissues in the feet. Include the role of the lungs, hemoglobin, cells, and vessels. (5-6 sentences max)

a.
b.
c.
d.
e.

f.
g.

•

a. pharynx
b. (epi)glottis
c. trachea
d. lungs
e. bronchi
f. diaphragm
g. alveoli

•

During inhalation the external intercostal muscles contract, lifting the ribs up and out and then the diaphragm contracts drawing it down. The thoracic cavity expands. During exhalation, the external intercostal muscles relax, allowing the ribs to move down and in. The diaphragm then relaxes and moves upward. The thoracic cavity contracts and the neutral elasticity of the lungs returns them to their normal volume
Air passes through the pharynx, through the glottis, into the trachea, into the right and left bronchi, which branches and rebranches into the bronchioles. Only the alveoli does actual gas exchange take place. Oxygen concentration is high in the alveoli. This oxygen moves down its concentration gradient into the tissues, including the dense network of capillaries that lie next to the alveoli. Red blood cells flowing through these capillaries contain hemoglobin molecules, which cooperatively bind 4 oxygen molecules. Oxygenated blood flows to the tissues of the body. And when the blood reaches a tissue with low oxygen concentration, the oxygen bound to hemoglobin dissociates and diffuses out of the red blood cells/

•

capillaries into the oxygen-poor tissues.
The mammalian ear is involved in hearing. There are 3 main compartments for the mammalian ear. They are the outer ear, the middle ear, and the inner ear. What are the 2 parts of the outer ear? What is the purpose of each of these parts? What are the ossicles in the middle ear? What structure is next to the ossicles called (closer the inner ear)? What are their functions? What are the two structures of the inner ear and what is their function? What is the function of the Eustachian tube?
• Outer ear consists of the pinna and the auditory canal. It is separated by the tympanic membrane. Sounds waves enter the outer ear and the tympanic membrane vibrates back and forth
• The ossicles which is the hammer, anvil, and stirrup connect to the ear drum which connects to the oval window. The ossicles transfer vibration to the oval window • The inner ear consists of the cochlea and the vestibular system. They generate signals that travel to the brain. They send pressure waves through the cochlea and then waves travel from the vestibular canal to the tympanic canal and dissipate against the round window.
• The Eustachian tube equalizes pressure between the middle ear and the atmospheric pressure.
EVOLUTION:
Chapter 22/23:
• Archaeopteryx- the first bird-like creature to appear which emerged in the
Jurassic period
• Ways in which we know the earth is old o Geological time scale o 4 eons: Hadean, Archaean, Proterozoic, Phanerozoic o Changes in living organisms due to genetic and environmental changes
• Evolution- the phenomenon that populations of organisms change over the course of many generations, As a result, some organisms become more successful at survival and reproduction
• Microevolution- changes in a populations gene pool o Could be from generation to generation o Change because there is an introduction of new genetic variation o Evolutionary mechanisms that alter the prevalence of an allele of genotype
§ Survival or reproductive success
Macroevolutionevolutionary changes that create new species and groups of
•
species
• Charles Darwin and ideas that shaped his thinking of evolution o Naturalist, but trained in theology o His theory was shaped by many different fields of study
§ Geology
§ Uniformitarism
§ Economics
§ Thomas Malthus

§ Voyage of the Beagle
• Natural Selection- the process in which beneficial traits that are heritable become more common in successive generation
• Genetics and Environmental Changes on Evolution o Genes are the hard heritability material that carry successful variation unto the next generation of organisms o The environment puts selective pressures that act on randomly-generated variants in the population
• Natural Selection and Finches o Different types of finches had different beak shapes due to the species of the finch and what they ate. It was favored that finches with bigger, shorter beaks were more favored that those of long, skinny beaks.
• Fossils
• Transitional Forms o Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants
• Chronology and Geography o Geological time table o 5 large mass extinctions o Boundaries between geologic time periods are often based on these events
• Homologous Structures o Related organisms will share similarities that are derived from common ancestors. Can be revealed by comparing the anatomies of different living things • Homologous Genes and Proteins o 2 or more genes derived from the same ancestral gene o Orthologs: homologous genes occurring in separate species o Paralogs: homologous genes in the same species due to gene duplication
Chapter 24:
• Natural selection o The process in which beneficial traits that are heritable become more common in successive generations o Positive natural selection o Negative natural selection o Neutral theory: genetic variation in which natural selection does not favor any particular genotype
• Directional selection o A pattern of spacing natural selection that favors individuals at one extreme of a phenotypic distribution
• Stabilizing selection o A pattern of natural selection that favors the survival of individuals with intermediate phenotypes
• Diversifying (disruptive) selection o A pattern of natural selection that favors the survival of two or more different genotypes that produce different phenotypes
• Balancing selection

•

•
•

o A type of natural selection that maintains genetic diversity in a population
Sexual selection o A type of natural selection that is directed at certain traits of sexuality reproducing species that make it more likely for individuals to find or choose a mate and or engage in successful mating
Intrasexual selection o Sexual selection between members of the same sex
Intersexual selection o Sexual selection between members of the opposite sex

Chapter 25:
• Speciation: the formation of new species o Allopatric speciation
§ A form of speciation that occurs when a population becomes geographically isolated from other populations and evolves into one or more new species o Sympatric speciation
§ A form of speciation that occurs when members of a species that initially occupy the same habitat within the same range diverge into two or more different species
Traits
used to characterize species and species concepts
•
o Genetic drift: changes in allelic frequency due to random chance o Bottleneck: population reduces dramatically and then rebuild. Allele frequencies can drift substantially when population is small. New population likely to have less genetic variation o Founder Effect: small group of individuals separate from a larger population and established a new colony. Relatively small founding population expected to have less genetic variation than original population. Allele frequencies in founding population may differ markedly from original population
• Prezygotic Isolating Mechanisms o A mechanism that stops interbreeding by preventing the formation of a zygote Postzygotic
Isolating Mechanisms
•
o A mechanism that prevents interbreeding by blocking the development of a viable and fertile individual after fertilization has taken place
• Punctuated Equilibrium o A concept that suggests that the tempo of evolution is more sporadic than gradual. Species rapidly evolve into new species followed by long periods of equilibrium with little evolutionary change
Essays:
1. Evidence for evolution (transitional forms in the fossil records, homology, chronology and geology, ecology)

•
•

•

•

Transitional forms in the fossil records o Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants
Homology
o Related organisms will share similarities that are derived from common ancestors. Can be revealed by comparing the anatomies of different living things, looking at cellular similarities and differences, studying embryological development, and vestigial structures
Chronology and Geology o Relative dating: places fossils in a temporal sequence by noting their position in layers of rocks. The deeper they are in the layers, the older they are. o Numerical dating: relies on the decay of radioactive elements o 4 eons
§ Hadean, Archaean, Proterozoic, Phanerozoic: the first three are called “Precambrian”
§ Changes in living organisms are the result of genetic changes and environmental changes o 5 large mass extinctions
§ Near the end of Ordovician, Devonian, Permian, Triassic, and
Cretaceous periods
§ Boundaries between geologic time periods are often based on these events Ecology o Populations evolve in response to their surroundings o Organisms either have the genetic tools to take advantage of those opportunities or they do not.

2. Terminology-use the terms to correctly describe evolutionary theory: function vs. purpose, adaptation vs. design, evolution vs. development, accept vs. believe, evidence vs. proof, randomness vs. intentionality, ancestor vs. relative, ancestral vs. derived, evidence vs. causation, theory vs. hypothesis
• Function vs. Purpose o The purpose of a hammer is to pound nails, but the function of a hand is to grasp or grip
• Adaptation vs. Design o How is an aardvark designed to eat ants? BUT it is to be said: How is an aardvark adapted to eating ants, or what structures and behaviors aid an aardvark in eating plants?
• Evolution vs. Development o The girl developed into a strong young woman, but the population evolves due to genetic changes over time
Accept
vs. Believe
•
o One accepts the theory of evolution because of the evidence supporting the idea • Evidence vs. Proof

•

•

•

•
•

o Scientists gather evidence to support or falsify hypotheses. Hypotheses and theories may be well supported by evidence but never proven.
Randomness vs. Intentionality o Variation is random, but selection is not. Selection of favorable traits within a population occurs when living things meet all the challenges presented to them. These pressures are not random, but rather intentional. Ancestor vs. Relative o You and your cousin are related because you share a common ancestor.
You do not evolve from a cousin. Humans and chimps are related but humans did not evolve from chimps.
Ancestral vs. Derived o Neither primitive nor advanced; derived is when a trait shows up that was not present in ancestors. Ancestral characteristics were present at the time the ancestors were present.
Evidence vs. Causation o Having similar features does not cause relatedness. Relatedness is due to common ancestry (evidence of ancestry).
Theory vs. Hypothesis o A theory is an explanation. Theories can be supported, rejected, or modifies based on new evidence. A hypothesis is a testable idea. You do not prove hypotheses, instead they are tested.