Switcharoo

How can recombination during meiosis be explained? Explain how the processes of meiosis increase genetic variation in a population.

Recombination occurs during meiosis in prophase I when chromosomes crossover and exchange DNA. The maternal and paternal chromosomes swap specific information concerning certain traits, and this exchange leads to genetic variation as there is a new chromosome as a result of this little switcharoo of genetic coding information.

Meiosis vs Mitosis

Compare the process of meiosis to the process of mitosis.

This image effectively and efficiently summarizes both processes, showing the similarities and differences.
[To better see the chart, right click and open in a new tab]

Mastering Biology | Pearson; Campbell Biology

Stages of Meiosis

Explain the events of all stages of meiosis

• Meiosis I
• Prophase I
• Centrosome movement, spindle formation, nuclear envelope breaks down, chromosomes condense
• Chromosomes align with their homolog pair, and crossing over occurs [this is the exchange of DNA between two non-sister chromatids]
• The chiasmata is visible in this stage, this is the location where crossing over occurs
• Microtubules from the centrosomes will begin to attach to the kinetochores of the homologous chromosome pairs
• Metaphase I
• Pairs of homologous chromosomes are arranged at the metaphase plate
• Both chromatids of one homolog pair are attached to a spindle fiber on either polar side of the cell
• Anaphase I
• Homologs separate as proteins responsible for sister chromatid cohesion along the chromatid arms break down
• Homologs move towards opposite poles of the cell
• Sister chromatid stay connected to each other as they separate and move
• Telophase I and Cytokinesis
• Each half of cell now has a complete haploid set of duplicated chromosomes
• Cytokinesis divides cytoplasm and splits cell in half
• Meiosis II - NO CHROMOSOME DUPLICATION
• Prophase I
• Spindle apparatus forms
• Chromosomes begin to line up along the metaphase plate
• Metaphase I
• Microtubules attach to kinetochores and pull apart sister chromatids
• Anaphase I
• Chromosomes move up the microtubules towards opposite ends of the cell
• Telophase I and Cytokinesis
• Nuclei form, chromosomes begin to condense
• Cell divides

NOW, at the end of meiosis in an animal cell, the end result is four daughter cells [when starting with one cell]

Diversity, Evolution, and All That Jazz

Justify the effects of a change in the cell cycle mitosis and/or meiosis will have on chromosome structure, gamete viability, genetic diversity, and evolution.

A change in the cell during mitosis or meiosis can cause cell division to go awry. Chromosomes may duplicate oddly, crossover in incorrect ways, etc. The end result may create two defective daughter cells. As a result, the gamete may not be as viable. For example, down syndrome occurs when there is an extra copy of chromosome 21 created during meiosis. But, such DNA mutations can drive evolution, and explain diversity.

Evolution, by definition, is genetic mutation. These mutations occur to help a species adapt to a specific environmental factor.

As for diversity, Meiosis I & Meiosis II [See Stages of Meiosis] have events such as crossing over, reduction to haploid cells, and random chromatid assignment that can lead to creating a unique set of DNA that eventually grows into a fully formed organism. This is why there is such diversity within species, there are plenty of different combinations of DNA, and typically no DNA is the exact same.

Animal Cell Dividing Or Something That Looks Like A Butt

Compare the process of mitosis in plant-like and animal-like cells.

The procedure of cell division is the same for plant and animal cells, until cytokinesis is reached.

In animal cells, a ring of microfilaments formed along the metaphase plate line will contract inwards and pinch off the parent cell membrane, creating two daughter cells. This process is known as creating a cleavage furrow.

Plant cells cannot divide like so because of the rigid cell wall. So instead, a cell plate forms along the metaphase plate line and joins with the pre-existing cell walls, closing off two sides of the parent cell and forming two daughter cells. This cell plate is created with vesicles that contain cellulose and other materials that form the cell wall of a plant.

Mastering Biology | Pearson; Campbell Biology

Cell Division Control: MPF

Explain how cell division is controlled in cells, using examples like MPF and PDGF.

Cells must pass through three checkpoints [in red below] in order to carry out cell division. If a cell does not meet the requirements to pass the checkpoint, it will be unable to continue on to the next phases of cell division.

Mastering Biology | Pearson; Campbell Biology

MPF for example, uses cyclins and cyclin-dependent kinases [Cdks] that come together to form a complex which triggers a cell’s passage past the checkpoints. Cyclin and Cdks concentration gradually increases, peaking at M-phase and fusing together here. After the cell divides, cyclin degrades and is recycled to be used again to create MPF.

Mastering Biology | Pearson; Campbell Biology

Stages of Mitosis

Explain the events of all stages of mitosis and track chromosome and chromatid number through all stages of mitosis.

[To better see the chart, right click and open in a new tab]

https://en.wikibooks.org/wiki/Cell_Biology/Cell_division/Mitosis

Mastering Biology | Pearson; Campbell Biology

4 Stages of the Cell Cycle

Explain the events of all stages of the cell cycle.

There are four parts of the cell cycle:

G₁- “first gap”: growth period, first part of interphase.

S - synthesis: DNA is copied, chromosomes duplicate

G₂ - “second gap”: growth period AFTER DNA has duplicated, second part of interphase

M - Mitosis and Cytokinesis: distribution of genetic material and cytoplasm to form two daughter cells. [See "Stages of Mitosis" under Ch 12 & 13 for more information on Mitosis]

A cell spends most of its life growing in interphase, and only a short amount of time in mitosis.

https://en.wikibooks.org/wiki/Cell_Biology/Cell_division/Mitosis

Chapter 11

Cellular Communication

Also, a little on Apoptosis and Cell Communication Regulation

Receptor Tyrosine Kinase

ATP Production in Cellular Respiration

Create a visual representation to describe the structure of cell membranes and how membrane structure leads to the establishment of electrochemical gradients and the formation of ATP.

Take a look at this simplified drawing of the Electron Transport Chain, and how it creates ATP through the movement of H+ ions across the membrane.

Photosynthetic Animals

Pose scientific questions about what mechanisms and structural features allow organisms to capture, store, and use free energy (e.g., autotrophs versus heterotrophs, photosynthesis, chemosynthesis, anaerobic versus aerobic respiration).

Is it possible for animals to photosynthesize? Why or why not?

A Look At Photosynthesis

Refine or revise a visual representation to more accurately depict the light-dependent and light-independent (i.e., Calvin cycle) reactions of photosynthesis and the dependency of the processes in the capture and storage of free energy.

Light-dependent reactions occur in Photosystem II, and light-independent reactions occur in Photosystem I. The two pictures below show the interactions between the two.

Mastering Biology | Pearson; Campbell Biology

Fish are Cooler Than Humans

Describing 2–3 different strategies that organisms employ to obtain free energy for cell processes (e.g., different metabolic rates, physiological changes, variations in reproductive and offspring-rearing strategies).

1. Regulation of body temperature: Tuna fish are able to regulate their internal body temperature better than some other sea life. This allows them to swim in a varying range of temperatures. This mobility gives them access to a greater amount of resources.

   

   http://www.fao.org/fishery/topic/16082/en

2. Consumption of other organisms: We humans obtain practically ALL of our energy through eating plants and other animals. Because we are unable to photosynthesize, or hunt stealthily for our food, we have had to improvise and become a species that farms and raises animals for food.

   

   http://veganfeministnetwork.com/tag/food/

Mustard Plants

Propose experimental designs by which the rate of photosynthesis and respiration can be measured and studied.

Plants go through both photosynthesis and cellular respiration, so they would be perfect subjects to use in an experiment that measures the rate of the two processes. Mustard plants [these plants are easy to grow, and grow quite rapidly] can be grown under lights with different colored filter, and their growth will be monitored to see how photosynthesis is impacted by different colored waves of light. To study the rate of respiration, a separate set of mustard plants can be grown in containers that vary in the amount of oxygen they allow in for the plant to use. Light is required for photosynthesis, and oxygen is required for respiration, so these are the two independent variables that will be changed, and the dependent variable, growth of plant, will provide rates of photosynthesis and respiration.

http://www.vegetablegardener.com/item/3477/how-to-grow-mustard/page/all

The Canadia Goose

Explain how energetic requirements contribute to the adaptations of organisms.  Provide examples to support your statements.

Over time, organisms evolve according to the amount of energy available for their consumption in the environment they habitat. Birds, for example, migrate during colder seasons to warmer areas where their food is more readily available. If Canadian geese were to stay up north during winter, they would die from the extreme cold temperatures before they would starve. Even if they were able to survive the winter cold, they still would starve as there is no vegetation available to feed on.

http://www.walkingmountains.org/2015/03/reintroduction-of-the-canada-goose/

Siblings, Not Twins.

Explain the relationship between photosynthesis and cellular respiration at the molecular, organismal, and ecosystem levels of organization.

Photosynthesis and cellular respiration are very similar because they are essentially the reverse process of one another. Photosynthesis uses energy to create sugar, and cellular respiration breaks down sugar to create energy.

Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆+ 6O₂

Cellular Respiration: C₆H₁₂O₆+ 6O₂ → 6CO₂ + 6H₂O + energy

So on the molecular level, these two are palindromes of each other.

The only organisms that have photosynthesis are plants, other organisms only have cellular respiration. So in an ecosystem, trees and other plants would use photosynthesis to create food for themselves. In the process, they would expel oxygen, which powers the animal kingdom’s ability to breath and ability to go through cellular respiration.

Chemiosmosis

Describe the process of chemiosmosis and compare its function in photosynthetic and respiratory pathways.

Chemiosmosis is the movement of ions across a membrane, following the concentration gradient. In photosynthetic and respiratory pathways, H+ ions are pumped through the electron transport chain to create ATP. In respiratory pathways, ATP is produced almost at every step of the process, with the most being produced at the ETC. In photosynthetic pathways, ATP is mainly formed in photosystem II where the ETC in the thylakoid membrane produces ATP.

Photosynthesis: Prime Sightseeing Locations

Match all photosynthetic processes to their location in a typical eukaryotic, autotrophic cell.

Light-dependent reactions - thylakoids within chloroplasts

Calvin Cycle - stroma of chloroplasts

Tracking Energy & Matter in Photosynthesis

Trace the movement of energy and matter through all photosynthetic processes.

Energy enters as light in the chloroplast, where it is utilized to create ATP and NADPH [in light-dependent reactions] which will aid in the formation of sugar in the calvin cycle. It then is cycled back into light-dependent reactions as ADP and NADP+ where it is formed back into ATP and NADPH with light energy.

Water is the first substance to enter the photosynthetic process, but it leaves as oxygen. Carbon dioxide enters next, and exits as sugar. These two processes occur simultaneously, the first in thylakoids, and the second in the stroma of the chloroplast in the calvin cycle.

Light Reactions and Calvin Klein Cycle

Explain the inputs, major processes, and outputs of the light reactions and the Calvin Cycle.

Light Reactions

Input: H₂O, Light

Output: O₂, ATP, NADPH
Here, Light energy and water is utilized to create ATP and NADPH which will go into the Calvin Cycle and power it to create sugar the plant can use as food.

Calvin Cycle

Input: CO₂, ATP, NADPH

Output: Glyceraldehyde 3-phosphate [G3P]
This is an anabolic action that uses ATP’s energy and NADPH’s reducing power [gain of electrons, storage of energy] to build sugar. Carbon dioxide enters the cycle and is fixated by the enzyme rubisco, then reduction occurs as the carbon dioxide becomes sugar. But, this must occur three times for one G3P to be formed. So, once carbon dioxide is fixated and reduced,the CO₂ acceptor RuBP is regenerated so that the next carbon dioxide entering the cycle can be fixated. Once this process occurs thrice, a sugar [G3P] is created.

https://biologycieri.wikispaces.com/Week+15  AND   http://www.adweek.com/adfreak/gif-shows-you-just-how-photoshopped-justin-biebers-calvin-klein-ads-were-162280  →but there is really no need for you to visit this site.

p.s. It's not called the 'Calvin Klein Cycle'. It's just Calvin.

Cellular Respiration: Prime Sightseeing Locations

Match all cellular respiratory processes to their locations in a typical eukaryotic cell.

Glycolysis - cytosol outside of mitochondria

Pyruvate Oxidation - occurs during the movement of pyruvate from cytosol to matrix. Pyruvate is oxidized to Acteyl CoA.

Citric Acid Cycle - matrix of the mitochondria

Oxidative Phosphorylation & Electron Transport Chain - cristae of mitochondria

https://www.studyblue.com/notes/note/n/bisc-103-midterm-i/deck/1084064

Tracking Energy & Matter in Cellular Respiration

Trace the movement of energy and matter through all cellular respiratory processes.

Energy enters as Glucose and through glycolysis it is broken down to create ATP, pyruvate, and NADH. NADH now carries energy to the electron transport chain where the most ATP is created with the help of the proton-motive force. The PTM ‘powers’ the ETC as it uses the electrochemical gradient and ratio of protons & electrons provided by electron carriers [such as NADH] to push the actions of the ETC to create ATP. 
So based off of the movement of energy, matter moves through the mitochondria starting outside the organelle in the cytosol. The products of glycolysis move into the mitochondria where they undergo further break down and oxidation of energy, finally moving to the ETC in the cristae of the mitochondria. Here, the most ATP is created and this energy material is used to power the cell.

Glycolysis, Fermentation, Death and Aerobic Cellular Respiration

Explain the inputs, major processes, and outputs of glycolysis, fermentation, and aerobic cellular respiration.
Glycolysis

Input: Glucose, ADP, NAD+

Output: Pyruvate, ATP, NADH

After a glucose molecule enters the cell, it is broken down in the cytoplasm. It is oxidized [loss of electrons, loss of energy] to 2 pyruvate, 2 ATP, and 2 NADH. NADH carries electrons to the electron transport chain, where most the most ATP is made in cellular respiration. The pyruvate enters the mitochondria and enters the citric acid cycle after it is oxidized into Acetyl CoA.

Fermentation

Input: Glucose, ADP

Output: Lactate OR Alcohol and CO₂, ATP

Fermentation occurs when there is no oxygen available for cellular respiration. Oxygen helps create the most ATP, but ATP still needs to be made even if oxygen is not available. ATP keeps organisms running. Because fermentation does not create as much ATP, I guess this may explain why oxygen-breathing organisms die when their supply of air is cut off. Fermentation uses phosphorylation to enzymatically create ATP. This results in the production of lactate [animals produce this] OR alcohol and CO₂ [bacteria produce this] which is harmful for organisms as the buildup can cause fatigue.

Aerobic Cellular Respiration

Input: Oxygen, Glucose, ADP, NAD+

Output: ATP

Aerobic respiration is complete cellular respiration, with glycolysis being the first step. Once 1 molecule of glucose has been broken down to 2 ATP, 2 NADH [this goes directly to the electron transport chain (ETC)], and 2 pyruvate, the pyruvate is oxidized [loss of electrons, loss of energy] and turns into Acetyl CoA. This enters the citric acid cycle, where every turn produces 2 CO₂, 3 NADH, 1 FADH, and 1 ATP. This gives us a total of 4 CO₂, 6 NADH, 2 FADH, and 2 ATP. The FADH and NADH, which contain the energy of the process, move to the ETC. Here, at the ETC, FADH and NADH are utilized to create the most ATP, about 30-32 to be exact.

Experimental Design

Propose experimental designs by which the rate of enzyme function can be measured and studied.

The rate of enzyme function can be measured and studied by having an enzyme catalyze reactions in different temperatures, in different pH, in different concentrations of substrates, etc. to see how the enzyme functions if one variable is changed slightly. These are all variable that impact an enzyme’s productivity, so picking any one of these variables ]or some other variable that impacts enzyme functioning] and modifying it slightly as you measure the change in productivity can help study the rate at which an enzyme functions. Depending on the enzyme and variable used/ manipulated, different equipment will be needed for the experiment. If I were measuring the rate of enzymatic activity in different pH, I would need to add acid or base to an enzyme in it’s natural environment, then measure the change in time, or change in production of the product.

Demented PAC-MAN and Competitive Interactions

Describe how enzyme-mediated reactions can be controlled through competitive and noncompetitive interactions.

The following is a helpful little video that explains competitive and noncompetitive interactions through animation:

Enzymes are Serial Huggers

Describe the relationship between the structure and function of enzymes.

Substrates are reactants that attach to enzymes, and detach as a product of the reactants. The structure of an enzyme dictates what reactants it can help catalyze. When reactants enter and bond with an enzyme, the enzyme will reshape itself slightly around the substrate, to create a more snug hold. This allows the reactants to be in very close proximity, forcing the reaction to run faster.

Traffic Jam on Metabolic Lane

Explain how enzymes accomplish biological catalysis.  Provide examples.

Enzymes are reusable catalysts that speed up metabolic reactions. Without enzymes, metabolic reactions would take so long that an organism would not receive the needed substances fast enough. There would be a build up of reactions waiting to occur because the amount of time and energy needed to reach the activation point wouldn't be available. Imagine having to wait hours for painkillers to kick in when you have a raging headache. Sounds fun! Enzymes speed up chemical reactions by lowering the activation energy needed for products to form. This allows molecules involved in the reaction to absorb more energy in lower temperatures, causing the reaction to again enough energy to form products more quickly. Take a look at the figure below: it shows how substrates and enzymes work to lower the activation energy.

Mastering Biology | Pearson; Campbell Biology

Enzyme Environmental Conditions

Analyze data showing how changes in enzyme structure, substrate concentration, and environmental conditions (pH, temperature, salinity, etc.) affect enzymatic activity - ie. include a graph of each example and predict the effects when one of the parameters is further changed.

Justify and explain your predictions.

Enzymes have ideal states of pH and temperature in which they have optimal enzymatic activity. If an enzyme is placed in an environment in which the pH or temperature is not ideal, the rate at which it functions will be altered. Take a look at the graphs below. If a typical human enzyme was placed in a thermophilic bacteria, the human enzyme would be inactive and possible become denatured. Why? Because the optimal temperature for the enzyme to activate is around 37 degrees, anything past 50 degrees is too high and the enzyme can become damaged because it is not in an environment in which it can survive. Same goes for pH with pepsin and trypsin. They cannot exchange locations and be expected to function because they are only stable and functioning in their own environment.

Mastering Biology | Pearson; Campbell Biology