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Mpf Ap Biology Essays

AP Biology Exam Terms

AP Biology Exam Terms to know for AP Exam
contain carbon; examples include lipids, proteins, and carbs
amino (NH2), carbonyl (RCOR), carboxyl (COOH), hydroxyl (OH), phosphate (PO4), sulfhydryl (SH)
glycerol and three fatty acids
bad for you; animals and some plants have it; solidifies at room temp.
better for you, plants have it; liquifies at room temp.
lipids whose structures resemble chicken-wire fence. include cholesterol and sex hormones
glycerol + 2 fatty acids + 1 phosphate group; makes up membrane bilayers of cells; hydrophobic interiors and hydrophillic exteriors
used by cells for energy and stucture; monosaccharides (glucose), disaccharides (sucrose, maltose, lactose), storage polysaccharides (starch [plants], glycogen [animals]), structural polysaccharides (chitin [fungi], cellulose [arthropods])
made with the help of ribosomes out of amino acids; serve many functions (transport, enzymes, cell signals, receptor molecules, structural components, and channels)
catalytic proteins that react in an induced-fit fashion with substrates to speed up that rate of reactions by lowering the activation energy
inhibitor resembles substrate and binds to active site
noncompetitive inhibition
inhibitor binds elsewhere on the enzyme; alters active site so that the substrate cannot bind
logarithmic scale; <7 acidic, 7 neutral, >7 basic (alkaline); 4 is 10 times more acidic than 5
breaks down compounds by adding water
two components brought together, producing H2O
reaction that requires input of energy
reaction that gives off energy
electron transfer reactions
found in prokaryotes and plant cells eukaryotes; protects and shapes the cell
found in prokaryotes and eukaryotes; regulates what substances enter and leave a cell
found in prokaryotes and eukaryotes; host for protein synthesis; form in nucleolus
found in eukaryotes; lipid synthesis, detoxification, carbohydrate metabolism; contains no ribosomes on cytoplasmic surface
found in eukaryotes; synthesizes proteins to secrete or send to plasma membrane; contains ribosomes on cytoplasmic surface
found in eukaryotes; modifies lipids, proteins to secrete or send to plasma membrane; contains ribosomes on cytoplasmic surface
found in eukaryotes; power plant of cell; hosts major energy-producing steps of respiration
found in eukaryotes; contains enzymes that digest organic compounds; serves as cell's stomach
found in eukaryotes; control center of cell; host for transcription, replication, and DNA
found in eukaryotes; breakdown of fatty acids, detoxification of alcohol
found in plant cells eukaryotes; site of photosynthesis in plants
found in eukaryotes; skeleton of cell; consists of microtubules, microfilaments, and intermediate filaments
large in plant cells and small in animal cells; storage vaults of cells
found in animal cells eukaryote; part of microtubule separation apparatus that assits cell division in animal cells
plasma membrane is selectively permeable phosolipid bilayer with proteins of various lengths and sizes interspersed with cholesterol amoung the phospholipids
proteins implanted within lipid bilayer of plasma membrane
passive movement of substances down their concentration gradient (from high to low concentrations)
passive movement of water from the side of low solute concentration to the side of high solute concentration
assisted transport of particles across membrane (no energy input)
movement of substances against concentration gradient (low to high concentrations; requires energy input)
phagocytosis of particles into cell through the use of vesicles
process by which particles are ejected from the cell, similar to movement in a trash chute
glycolysis -> krebs cycle -> oxidative phosphorylation -> 36 ATP per glucose molecule
anaerobic respiration (fermentation)
glycolysis -> regenerate NAD+ -> 2 ATP per glucose molecule
conversion of 1 glucose molecule into 2 pyruvate, 2 ATP, and 2 NADH; occurs in the cytoplasma, and in both aerobic and anaerobic respiration; must have NAD+ to proceed
conversion 1 pyruvate molecule into 4 NADH, 1 FADH2, 1 ATP, H2O, and CO2; occurs twice for each glucose to yeild double the products above; occurs in the mitochondria
oxidative phosphorylation
production of large amounts of ATP from NADH and FADH2; occurs in the mitochrondria; requires the presence of oxygen to proceed
coupling of the movement of electrons down the ETC with the formation of ATP using the driving force provided by the proton gradient; occurs in both cell respiration and photosynthesis to produce ATP
enzyme responsible for using protons to actually produce ATP from ADP
process that regenerates NAD+ so glycolsis can begin again; occurs in absence of oxygen
occurs in fungi, yeast, and bacteria; causes conversion of pyruvate to ethanol
occurs in humans and animal muscles; causes conversion of pyruvate -> lactate; causes cramping sensation when oxygen runs low in muscles
process by which plants use the energy from light to generate sugar; occurs in chloroplasts; light reactions (thylakoid), and Calvin cycle (stroma)
self-nourishing organism that is also known as a producer (plants)
organisms that must consume other organisms to obtain energy--consmers
loss of water via evaporation through the stomata
process by which ATP is made during light reactions
process by which water is split into hydrogen ions and oxygen atoms (light reactions)
structure through which CO2 enters a plant, and water vapor and oxygen leave plant
molcule that absorbs light of a particular wavelength (chlorophyll, carotenoid, phycobilins)
plants that have adapted their photosynthetic process to more efficiently handle hot and dry conditions
process that first converts CO2 into a 4-carbon molcule in the mesophyll cells, converts that product to malate and then shuttles it to the bundle sheath cells, where the malate releases CO2 and rubisco picks it up as if all were normal
plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis
prokaryotic cell division; double the DNA, double the size, then split apart
growth 1 -> synthesis -> growth 2 -> mitosis
physical separation of newly formed daughter cells of cell division
cell division control mechanisms
growth factors, checkpoints, density-dependent inhibition, and cyclins and protein kinases
factors then when present, promote growth, and when absent, impede growth
a cell stops growing to make sure it has the nutrients and raw materials to proceed
density-dependent inhibition
cell stops growing when certain density is reached
cyclins and protein kinases
cyclin combines with CDK to form a structure known as MPF that pushes cell into mitosis when enough is present
one copy of each chromosome
two copies of each chromosome
chromosomes that are similar in shape, size, and function
the process of male gamete formation (four sperm from one cell)
the process of female gamete formation (one ovum from each cell)
sequences of events that make up the reproductive cycle of an organism
zygote (2n) -> multicellular orgainsm (2n) -> gametes (n) -> zygote (2n)
zygote (2n) -> multicellular orgainsm (n) -> gametes (n) -> zygote (2n)
zygote (2n) -> sporophyte (2n) -> spores (n) -> gametophyte (n) -> gametes (n) -> zygote (2n)
crossover, 2^n possible gametes that can be formed, random pairing of gametes
heritable feature, such as flower color
cross involving one character (3:1 phenotype ratio)
cross involving two different characters (9:3:3:1 phenotype ratio)
the two alleles for a trait separate during the formation of gametes--one to each gamete
law of indendent assortment
inheritance of one trait does not interfere with the inheritance of another trait
if two opposite pure-breeding varieties are crossed, all offspring resemble dominant parent
heterozygous individual shows characterstics unlike either parent
Yy produces a intermediate phenotype between YY and yy
both alleles express themselves fully in a Yy individual
traits that are affected by more then one gene (eye color or skin color)
traits that correspond to more than two alleles
a gene at one locus alters the phenotypic expression of a gene at another locus
a single gene has multiple effects on an organism
males are XY, females are XX
chromosome not involved in gender
passed along the X chromosome; more common in males then females
one of two X chromosomes is randomly inactivated and remains coiled as a Barr body
trait that is inherited via the Y chromosome
genes that lie along the same chromsome and do not follow the law of independent assortment
a form of genetic recombination that occurs during prophase I of meiosis
genetic map put together using crossover frequencies
family tree used to describe genetic relationships
autosomal recessive disorders
Tay-Sachs, Cystic fibrosis, sickle cell anemia, phenylketonuria
autosomal dominant disorders
Huntington disease and achondroplasia
error in which homologous chromosomes do not separate properly
deletion, inversions, duplications, and translocations
contains A, G, C, and T; arranged in double helix of two strands held together by hydrogen bonds
contains A, G, C, and U; singled stranded
brings acids to ribosomes
occurs in S-phase, semiconservative, built in 5' to 3' direction
deletion or addition of nucleotides; shifts reading frame
subsitution of wrong nucleotide into DNA; still produces a protein
subsitution of wrong nucleotide into DNA that produces an early stop codon
process by which mRNA is synthesized on a DNA template
introns (noncoding) are spliced out, exon (coding) glued together
process by which the mRNA specified sequence of amino acids is lined up on a ribosome for protein synthesis
triplet of nucleotides that codes for a particular amino acid
base sequence that signals start site for transcription
protein that prevents the binding of RNA polymerase to promoter site
molecule that binds to and inactivates a repressor
short sequence near the promoter that assists in transcription by interacting with transcription factors
on/off switch for transcription, allows for production of genes only when needed
parastic infectious agent unable to survive outside the host; can obtain DNA or RNA, or have a viral envelope
one in which the virus is actively reproducing and kills the host cell
one in which the virus lie dormant within the DNA of the host cell
RNA virus that carries with it reverse transcriptase (HIV)
virus that converts host brain proteins into misshapen proteins
virus that infects bacteria
prokaryotic cell consists of one double strand circular DNA molecule; reproduce by binary fission
uptake of foreign DNA from the surrounding environment
movement of genes from one cell to another by phages, which incorporated by crossover
lytic cycle accidently places host DNA into a phage, which is brought to another cell
virus leaving lysogenic cycle brings host DNA with it into phage
transfer of DNA between two bacterial cell connected by sex pili
enzymes that cut DNA at a paticular sequences, creating sticky ends
mover of DNA from one source to another
somewhat slow process by which a desired sequence of DNA is copied numerous times
technique used to separate DNA according to size. DNA moves from - to +
polymerase chain reaction (PCR)
produces large quanties of sequence in short amount of time
genetic drift, gene flow, mutation, natural selection
change in allele frequencies because of chance events
change in allele frequencies as genes move from one population to another
change in allele frequencies due to random genetic change in an allele
process by which characters or traits maintained or eliminated in a population based on their contribution to the differential survival and reproductive succes of their "host" organism
differences must exist between individuals
the traits to be selected for must be able to be passed along to offspring
differential reproductive success
there must be variation amoung parents in how many offspring they produce as a result of the different traits that the parent have
a trait that, if altered, affects the fitness of an organism
directional, stabilizing, disruptive, sexual, and artifical

A major focus of the AP Biology exam is how homeostasis is maintained at every level (organism, population and so on). Homeostasis is the ability to maintain a constant environment, even when faced with a changing external environment. When we are talking at the organism level, we are talking about how the internal environment stays constant even in a changing external environment. When we are talking at the population level, we will talk more about how these populations stabilize around a carrying capacity. In this AP Biology crash course review, we will focus on one of the ways in which the body regulates itself to maintain homeostasis: negative feedback. First, we will investigate what negative feedback is. We will go over the definition and a generic example. Then, once you have an idea of what negative feedback is we can look at some real examples of negative feedback. Finally, we will go over a question that you might see on your AP Biology exam and what your graders will be looking for in a response that earns full points. As always, if you have any questions or comments about this article leave me a comment below.

What is Negative Feedback?

First, let us pick apart what negative feedback means. During the AP Biology exam, you may see words that you cannot remember. The exam is long, and there is a lot of material. Fear not, if you can master picking apart words for meaning instead of memorizing, it may help you out in the long run. So first we will start by going over feedback. We use feedback all of the time in our everyday language. For example, you get feedback from your teachers on exams. Their feedback tells you what should change, and if you’re a good student, you will make changes so that your work will improve. A similar system takes place inside of an organism. An organism will receive feedback in their body about what changes need to happen in order for the body to keep functioning. The body’s goal is to remain at “homeostasis” but environmental changes make that impossible. Feedback can also occur at the level of the population which we will discuss a little bit later in this AP Biology crash course review.

Now that you understand feedback, we will talk specifically about what negative feedback is. There are two types of feedback; you guessed it, negative and positive feedback. The negative and positive have to do with how the body is responding. Negative feedback is when the body is responding to a stimulus by slowing down or stopping the creation of something else. Negative feedback can be a tricky subject to explain in words so see the figure below for more explanation.

In the picture, the final product “G” is inhibiting the bonding of “C”. By inhibiting the interaction of C, there will be less G made. Think about it like this: there is so much “G” being made that it is letting the body know- don’t waste the energy creating me, save it, we have enough!

Real Examples of Negative Feedback:

Thyroxine

Now that you have an idea of what negative feedback is we are going to explore two commonly used examples. The first picture that looked at was a generic representation of a molecular level negative feedback. In order to continue your understanding of negative feedback at the molecular level, we will study the mechanism of thyroxine.

Thyroxine is a hormone that has the function of raising body temperature. If the external environment temperature drops, the internal environment temperature will drop as well. If the internal body temperature drops significantly enough, the organism could die. In order to safeguard against that, as temperature drops, the hypothalamus is activated. The hypothalamus will then activate the anterior pituitary gland which is where TSH (thyroid stimulating hormone) is produced. When the thyroid is stimulated, thyroxine will be produced, which will raise the internal temperature.

What if the organism overheats? To safeguard against overheating thyroxine is involved in a negative feedback loop. As thyroxine is produced, it feeds back to the anterior pituitary gland which makes TSH. When thyroxine gets to the anterior pituitary, it’s a signal that there has been enough stimulation of the thyroid, and we need to stop this process. If this is confusing, go back to the first example. Think about that first drawing. In the first drawing, G is thyroxine, and it is inhibiting the pituitary gland from making D.

Population Level

Though we usually think of negative feedback at the level of the organism, it is also possible to have negative feedback at the population level. This example might clarify any lingering questions that you had about negative feedback because sometimes it is just easier to understand at the “bigger” level. We are going to talk about populations of mice and hawks. The hawk population is increasing and eating more and more mice than before. As the hawks are eating more mice, there are fewer mice running around. The lower number of mice will lead to some hawks to starve and die; this establishes homeostasis of populations. You might remember this being called “carrying capacity”.

The negative feedback comes from fewer mice. As the mice population is depleting, the hawk population will be forced to get smaller as well. This type of feedback is easy to see, and you can apply the understanding of this subject to the thyroxine example and negative feedback in general!

AP Biology Exam

Finally, we should talk about what kind of question you might get on the AP Biology exam. Here is a question from 2008 for us to look at:

Regulation is an important aspect of all biological processes. Choose two processes and describe the specific role of the regulator and discuss how the process will be altered if the regulation is disrupted.

We have already talked about two types of regulation, and you can certainly use those examples for this question. The raters have also included cell cycle regulation and the ovarian cycle as acceptable answers. We will go over one of the processes that are listed, and the other should be completed for studying purposes.

The cell cycle has regulators that allow the cell to proceed with growth and mitosis or to stop growing and wait for mitosis. The regulators of the cell cycle include Cdk, concentration differences, MPF, and S-phase. (If you can’t remember any of these go back and look them up- you will need to know them for the exam) If this cycle were disrupted, you would have a decrease in cell growth like in some muscular dystrophies. It is also possible that if this system was no longer regulated you would have uncontrolled cell growth (cancer).

Wrapping Up Negative Feedback and AP Biology

Homeostasis is important both at the organism level and the population level. In order to maintain homeostasis, we need to have feedback, that tells us how to proceed. There are many molecular negative feedback examples, and the general graphic can help you understand those. We covered thyroxin and predator-prey populations in detail after that in order to help you understand the concept of negative feedback better. Finally, we wrapped up with an example from the AP Biology exam.

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