Bio 183 - Exam 2
List the 3 major steps in cellular respiration
The three major steps of cellular respiration are 1. Glycolysis 2. Kreb's Cycle (the citric acid cycle) 3. Electron transport chain
Describe the interior of flagella and cilia
There are 9 pairs of microtubules near the periphery, and 2 individual microtubules in the center.
Draw a chloroplast and label its parts
Thylakoid: A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy. Granum: (plural, grana) A stacked portion of the thylakoid membrane in the chloroplast. Grana function in the light reactions of photosynthesis. Stroma: The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. Lamella: A sheet like membrane found within a chloroplast of an autotrophic cell. They act as a type of wall at which chloroplasts can be fixed within, achieving the maximum light possible.
Describe 2 types of junctions that help hold animal cells together.
Tight Junction: A type of intercellular junction in animal cells that prevents the leakage of material between cells. It seals the space between the cells so that molecules outside the cell cannot pass between them. Adhering junction: A type of junction between cells forming tissues that are subjected to stretching and pulling, such as the skin. This type of junction provides very tight contact between adjacent cells and allows the cells to function as a unit and prevents the cells from being pulled apart
Distinguish between the terms transcription and translation
Transcription: The synthesis of mRNA from a DNA template. Translation: The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids.
Explain how microtubules and motor proteins interact to generate motion
Using ATP, motor proteins grip the adjacent pair of microtubules, pull, release, then bind again. The action of the motor proteins cause the microtubules to ben and the cilia/flagellum to move
Explain the relationship between color, wave-length of light, and the term "visible light".
Visible light is a small part of the electromagnetic spectrum, the part that our eyes can perceive. Blue and purple have the shortest wavelength and thus the highest energy of visible light.
Explain why one strand of DNA is synthesized in fragments during the replication process.
When a DNA molecule begins to replicate, the two strands separate at a place called the replication fork. As the synthesis of new DNA occurs, the original molecule continues to unwind so that replication can progress from one end of the molecule to the other. The new strands of DNA are growing in the overall direction of right to left. This works fine for the strand on the bottom, which is growing in the 5' to 3' direction. But remember that the two strands of a DNA molecule are oriented opposite to one another. This means that the strand being synthesized along the upper half of the original DNA must grow from left to right. To accomplish this while maintaining a net movement to the left, DNA is synthesized in short segments called Okazaki fragments. Although each small segment grows from left to right (in the 5' to 3' direction) the order of segment synthesis is from right to left
Is DNA the only way in which prokaryotic and eukaryotic cells can pass nuclear information to their descendents? Explain your answer.
Yes, they used a virus to infect bacteria and showed that the genetic material of the bacteria was DNA.
Give one example of a protist that is animal-like and one example of a protist that is plant-like.
Amoeba and paramecium: animal-like Algae and Dinoflagellate: plant-like Euglena: animal-and-plant-like
Distinguish between the terms heterotrophic and autotrophic.
Autotrophs are organisms that can produce their own food from the substances available in their surroundings using light (photosynthesis) or chemical energy (chemosynthesis). Heterotrophs cannot synthesize their own food and rely on other organisms — both plants and animals — for nutrition.
Indicate which wavelengths (colors) of light are most effective in energizing photosynthesis.
Blue/Purple
Explain the purpose of cellular respiration and write a general equation for it (you may use either words or chemical symbols).
Cellular respiration is the most efficient way for cell sto harvest energy stored in food or in other terms, the most efficient way to produce ATP Glucose + Oxygen -> Carbon Dioxide + Water + Energy/ATP
Describe two unusual features of slime molds.
Cellular slime mold - 1. Slime molds change shape to form a new structure capable of reproducing 2. If there is a food shortage, slime molds move toward one-another and unite to form a multi-celled organism that crawls where food is plentiful Plasmodial slime mold 1. It resemble hyphae because there a no partitions between nuclei 2. It moves via cytoplasmic streaming
Distinguish between the terms centrosome, centriole, and basal body.
Centrosome: Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center; rich tubulin proteins. Centrioles: A structure in a animal cell composed of cylinders of microtubule triplets arranged in a 9 + 0 pattern. An animal cell usually has a pair of centrioles involved in cell division.The centrosome region contains two small structures called centrioles that apparently assist in organizing microtubule origin and growth. The centrioles are hollow structures. They somewhat resemble an axoneme. The two centrioles are typically oriented at right angles Basal Bodies: A eukaryotic cell organelle consisting of a 9 + 0 arrangement of microtubule triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole. Cilia and flagella protrude through the cell's plasma membrane to make contact with a basal body at the cell periphery. Every cilium and flagellum has a basal body at its base.
Explain why chloroplasts are green
Chloroplasts contain pigments that absorb certain wavelengths of light, but the one color/wavelength they can't absorb is green therefore green wavelengths are reflected.
Explain why chromosomes are only visible (by light microscopy) when cells are dividing
Chromosomes are highly compacted and when the cell is getting ready to divide, it must compact the chromosomes as tightly as possible to assure that complete chromosomes are distributed to the new cells.
Indicate how you would distinguish between a colonial protist and a multicellular protist.
Colonial Protist: All of the cells in the colony look alike and have the same function (exception - reproduction) Multicellular Protists: These are usually larger than colonial forms and have several types of specialized cells.
Give one example of a prokaryotic cell that has increased internal complexity
Cyanobacterium contains internal membranes on which photosynthetic reactions occur
Indicate the role of enzymes in DNA replication.
DNA Helicase: Protein that unwinds/separates the double-stranded DNA by breaking hydrogen bonds. DNA Polymerase: An enzyme that synthesizes DNA by adding complementary nucleotides to each strand of the original DNA. DNA Ligase: Enzyme that catalyzes the formation of a phosphodiester bond between adjacent 3' hydroxyl and 5' phosphoryl groups in a DNA molecule; it is used to join Okazaki fragments together in an unbroken nucleotide direction, only needed for one strand
Distinguish between the terms DNA, chromatin, and chromosome.
DNA: Deoxyribonucleic acid, a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life. It is usually found in the form of a double helix. Chromatin: Material found in the eukaryotic nucleus; consists of DNA and proteins. Chromosome: A structure of compact, intertwined molecules of DNA found in the nucleus of cells which carry the cell's genetic information. Humans have 23 pairs of chromosomes, 46 in all.
Distinguish between the terms chromatin, chromosome, and DNA
DNA: deoxyribonucleic acid, a self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information. Chromatin: The complex of DNA and proteins that make up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope Chromosome: A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins. ***Note that the term chromosome can be used for any of the above structures--even uncoiled DNA. On the other hand, the term chromatin is reserved for DNA bound to proteins.
Give one example of a cell in which very large size is not accompanied by greater complexity
Egg yolk - it's so large that it should violate cell size limits except most of the space is used purely to store food and living matter is limited to a thin disk region.
Describe the function of electron transport in cellular respiration
Electron Transport is a sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP. The energy released as electrons travel down the electron transport chain is used to pump hydrogen ions into the space between the inner and outer membranes. The energy released as hydrogen ions flow down their concentration gradient is used by the enzyme to make ATP.
Describe the plant cell wall, and indicate how the primary and secondary cell walls differ in function
The primary cell wall is the thinnest layer of the wall. It is formed first and it's flexible enough to allow the growing cell to expand. Fibrils are thin and not parallel making it weak. The secondary cell wall forms beneath the primary cell wall, after the cell stops growing. It is stronger and more rigid than the primary cell wall with thicker fibrils and more parallel configuration.
Regarding the mitotic phase of the cell cycle, how does its length compare to the S phase of the cycle?
S - 6 hours M - 30 minutes
Explain how each strand of DNA serves as a template for DNA replication.
Semi-conservative means that each new DNA molecule forming has one template strand from the original DNA/ parent and one newly synthesized strand When DNA is preparing to replicate the DNA strands separate and each parent strand acts as the template to determine the synthesis of a new strand.
Draw a DNA double helix and indicate what constitutes the "sides" and "rungs" of the DNA ladder.
Sides: the sugars and the and the phosphate group Rungs: the nitrogenous bases connected together
Indicate where carbon fixation occurs within the Calvin cycle.
Takes place within the stoma, a light independent reaction. Carbon dioxide is incorporated into an organic molecule as the first step in the calvin cycle
Briefly, indicate the general functions of DNA, mRNA, tRNA, and ribosomes.
-DNA is the genetic codes of the cell contains the template to make mRNA -mRNA copies the genetic code and leaves the nucleus and goes through the cytosol to attach to a ribosome -tRNA brings the appropriate amino acids to the ribosomes as specified by the mRNA -On the ribosome, a polypeptide chain is formed
Draw a mitochondrion and indicate where within it (or outside of it) each of the three steps occurs.
-Glycolysis takes in the cytoplasm of the cell -Krebs cycle takes place in the mitochondrial matrix -The Electron Transport Chain Takes place in the mitochondrial inner membrane
Describe the central vacuoles of plant cells, including their size, location within the cell, functions, and substances that might be stored within them (see reading assignment).
-Plant cell suse their vacuole for transport and storing of nutrients, metabolites, and waste products. The mechanical stability provided by the combination of a cell wall and turgor pressure allows plant cells to grow to a relatively large size. if the cell loses water it will shrivel and die, become flaccid. -The vacuole typically resided near teh center of the cell and fills most of the interior space
Indicate several ways in which yeast differs from other types of fungi.
-Single-celled organism -Reproduces by budding -Yeast can generate ATP aerobic and anaerobically (glycolysis)
Give 3 examples that illustrate the role of microfilaments in cell motility.
-They form a contractile ring around the cell during cell division - They alter cell shape to generate cell movement over a cell surface -They interact with myosin to bring about muscle contractions
Explain what is meant by "membrane recycling" within a cell.
1. As the trans-face sacs are lost by forming vesicles, the medial sacs move forward and the last medial sac becomes the new trans sac. The incoming vesicles become the new cis-face sac. 2. During the processing and sorting, vesicles may move in both direction between golgi sacs ***Part of the membrane of one organelle in the endomembrane system buds off as a vesicle, then that vesicle fuses with another organelle and becomes part of that membrane.
List the 3 major structures that are found in plant cells, but not animal cells, and indicate the general function(s) of each.
1. Cell Wall - surrounds the plasma membrane and acts as an external support structure for plant cells; it's comprised of cellulose 2. Central Vacuole - a large, membrane-bound structure that occupies much of the space within the cell and stores water and various kinds of macromolecules; water pressure inside increases the rigidity of most plant cells 3. Chloroplast - contains chlorophyll and performs photosynthetic functions; where light is converted to chemical energy
When DNA synthesis is complete, the chromatin of eukaryotic cells undergoes supercoiling. Describe the steps in DNA compaction and supercoiling and explain why this is necessary.
1. DNA wraps around proteins to restore the basic chromatin structure of beads-on-a-string 2. During the G2 phase of the cell cycle, the chromatin coils and folds making it more compact 3. As the cell enters the mitotic phase, the compacted chromatin undergoes supercoiling to make the DNA more compact and easier to transport to ensure that each cell gets all the genetic material they need during reproduction Supercoiling: Coiled tertiary structure that forms when strain is placed on a DNA helix by overwinding or underwinding of the helix.
List 3 ways in which they differ from prokaryotic chromosomes
1. Eukaryotic cells have much more DNA than prokaryotic cells 2. Eukaryotes have many linear chromosomes and prokaryotes have one small, circular chromosome 3. Eukaryotes must make a larger number of different proteins than prokaryotes, therefore, eukaryotes have a greater number of genes and longer chromosomes ***most eukaryotes are multi-celled organisms with each cell type requiring a different set of proteins.
Name the starting molecule(s) and end product(s) for each step
1. Light dependant reactions start with water and light and end up with the waste product oxygen, ATP, and NADPH 2. Dark reactions start with Carbon dioxide and result in Glucose
List 3 ways in which plants use the sugar that they make by photosynthesis.
1. Much of the glucose is broken down again by the process of cellular respiration to produce the ATP needed for work within the call. 2. In growing cells ,the glucose monomers are joined together to make cellulose for the cell wall 3. Glucose also serves as the carbon skeleton from which other molecules are synthesized
Name 3 types of plastids and give the function of each
1. Proplastid - can develop into any other type of plastid 2. Chromoplastid - contain the pigment granules and amyloplastid which contain stored starch 3. Chloroplastid - most complex plastid which contains the pigment chlorophyll as well as stacks of precisely arranged internal membranes called thylakoids
Describe how DNA is compacted in order to fit within the nucleus
1. The DNA coils around the histone proteins (A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA) to form chromatin; a bead-on-a-string configuration 2. Next, much of the chromatin coils tightly 3. Some of the coiled chromatin packs even more tightly ny forming loops along a supporting protein scaffold 4. This looped structure can form larger loops and coil again
List the two major steps in photosynthesis
1. The light reactions - water is split, O2 is given off, light energy is stored as ATP and NADPH 2. The dark reactions - utilizes ATP and NADPH to "fix" carbon dioxide into sugar, does not require light
Describe 2 ways in which the cells of a multicellular fungus differ from those of a plant or animal
1. They have cell walls that are composed of chitin rather than cellulose 2. hyphae are divided into cells by internal cell walls that serve as partitions. However, each internal cell wall contains a large pore, so the adjacent cells are in close contact with one another and cell contents can move freely throughout the hypha. 3. Reproduce via spores that land in a new spot and reproduce if conditions are favorable
List 10 organelles (or membranes) found within animal cells and indicate the general function of each
1. cytosol - The medium that holds all the organelles. It gives the cell its shape and can assist in the movement of the cell. 2. DNA - provides instructions for the cell 3. Nucleolus - a compact region of DNA where ribosomal RNA is made 4. Nuclear Membrane - the membrane surrounding DNA with pores that allow large molecules to pass between the nucleus and cytosol. 5. Free Ribosomes - "work benches" for protein synthesis 6. Mitochondria - Power Plant of the cell that oxidizes nutrients to produce ATP (cellular respiration) 7. Lysosomes - cleaning crew of the cell containing hydrolytic enzymes that digest worn-out organelles and particulate matter 8. Golgi Apparatus - assists in protein synthesis and acts as a distribution center for proteins to ensure that each protein is carried to the right place within the cell. 9. Rough Endoplasmic Reticulum - facilitates protein synthesis and is used for proteins for other membranes 10. Smooth Endoplasmic Reticulum - involved in the synthesis of cell products like lipids ***11. Vesicles - Involved in the transport of proteins, some carrying proteins to be secreted from the cell and comes bringing substances in.
List the 3 types of filamentous structures that form the cytoskeleton and one role that it plays in cell structure.
1. microfilaments - their main function is to maintain the cell's shape by strengthening the periphery of the cell. They are responsible for contraction and cell shape change in many cell types. Ex: They form a contractile ring around the cell during cell division 2. intermediate filaments - prevent the cell from stretching and hold some of the organelles in place 3. microtubules - act as girdle in the cell by resisting compression. They move vesicles to their destination within a cell and play an important role in cell shape changes and organelle motility (ex: cilla and flagella)
Explain why increased size is associated with greater internal complexity in the eukaryotes
A large cell is like a factory- large cells require complex internal structures with compartmentalized functions to increase efficiency.
Indicate why two different photosystems are needed during the light reactions of photosynthesis.
A photosystem absorbs a photon of light. This energizes an electron within the reaction center. The electron travels from photosystem 1 to photosystem 2 via an electron transport chain. Now, the electron has lost most of its energy by the time it reaches the 2nd photosystem, but it is energized again to an even higher level as the second reaction center absorbs a photon.
Describe the function of ATP synthase in cellular respiration
ATP Synthase is an enzyme that allows protons to move through the mitochondrial membrane and trigger phosphorylation of ADP to ATP. ATP synthases provides a port through which hydrogen ions diffuse into the matrix of a mitochondrion.
Explain why ATP and NADPH are needed in the Calvin cycle
ATP and NADPH are used to fix carbon dioxide resulting in the production of sugar. 3-carbon sugar molecules are phosphorylated by ATP to increase their energy, and the electrons carried by NADPH are added
Explain the purpose of ATP within cells and the significance of its 3rd phosphate bond.
ATP is a storage form of energy most useful for cells, and the main function of the mitochondria is to produce ATP through cellular respiration. The energy of ATP is stored in the 3rd phosphate bond and when that bond is broken the energy released is used to perform a variety of cellular functions.
Compare the mechanism of ATP production during photosynthesis to that which occurs during cellular respiration, and indicate the exact region within organelles where each occurs.
ATP is made as the energy lost by the electron is used to pump hydrogen atoms from the stroma to the thylakoid internal membrane, forming a gradient which produces ATP with the help of ATP synthase.
Explain why photoautotrophs are so important to life on earth; name at least 3 categories of photoautotrophic organisms.
All life depends on photoautotrophs and other types of organisms that can "fix" carbon dioxide, for chemical energy. Without autotrophs, there would be no life on earth. Additionally, photoautotrophs are responsible for creating an oxygen-rich atmosphere.
Name the 4 types of nucleotides found in DNA and indicate (in general terms) how they differ from one another.
All the nucleotides have different nitrogenous bases Thymidine(T) and Cytosine(C) have one carbon ring as their main structure whereas Adenine(A) and Guanine(G) have a double ring structure T-A C-G
Describe the general purpose of the endomembrane system and explain why eukaryotic cells need it.
Endomembrane System: The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. The Endomembrane systems perform important metabolic functions and regulate protein traffic within the cell. It includes the RER, SER, Golgi Apparatus, lysosomes, and outer nuclear membrane ***It is associated with the plasma membrane
Compare the relative size of prokaryote, animal and plant cells
Eukaryotes are typically larger than prokaryotes, the smallest eukaryotic cell is larger than all but a few prokaryotes. The average animal cell is smaller than the average plant cell.
Compare the replication of DNA in prokaryotes and eukaryotes regarding the amount of DNA to be synthesized
Eukaryotes synthesize more DNA than Prokaryotes
Distinguish between flagella and cilia based on their length and beating pattern
Flagella are much longer than cilia, but fewer in number. Flagella beat in an undulating pattern and generate force somewhat like a propeller. Cilia, on the other hand, beat by moving straight backward to generate force, then bend to move forward in a recovery stroke. This propels the cell forward. Cili move in a wave-like pattern
Indicate which organism(s) can utilize alcoholic fermentation and how this process is used commercially.
Fungi are not the only organisms that can do this; so can some prokaryotes. When certain fungi (such as yeast) metabolize glucose in the absence of oxygen, ethanol (drinking alcohol) is produced as an end product. When prokaryotes use the fermentation process, lactate is produced. Yeast is used for alcohol fermentation, which is essential for baking and wine production
List, in order, the 4 main stages of the cell cycle and indicate what happens in each stage. Begin with the stage that immediately follows cell division.
G1-Phase: cell metabolizes and grow S-Phase: DNA is replicated G2-Phase: The cell prepared to divide M-Phase: Phase during which the chromosomes are condensed and the nucleus and cytoplasm divide. Mitosis and cytokinesis occur in this phase.
Indicate when (and how) glucose, is finally made in the calvin cycle.
Glucose is the final product of the Calvin cycle, made by combining two of the G3P phosphorylated sugars
Indicate the starting molecule and end product for each of the three steps
Glycolysis: start - glucose end - pyruvate, 2 ATP and NADH Krebs Cycle start - acetyl CoA end = 1 ATP, 3 NADH, 1 FADH2 Electron Transport Chain start = NADH (electron) end - 32 ATP
Draw your favorite multicellular fungus and label its two main parts
Hyphae: A thread-like multinucleate tube with a cell wall; the organ of vegetative growth in most fungi. Hyphae increase in length by growth at their tips and give rise to new hyphae by side-branching. Spore: A reproductive cell capable of developing into a new individual without fusing with another reproductive cell. Fungal spores serve a function similar to that of seeds in plants; they germinate and grow into new individuals under suitable conditions of moisture, temperature, and food availability.
Explain what happens (and why) when plant cells are surrounded by a concentrated solution of salt or sugar.
In a hypertonic solution, in which the cells are surrounded by a concentrated solution of salt or water, water will move out of the cell. The cell will then become shrunken or flaccid, and the plasma membrane may detach from the cell wall.
Compare the consequences of a hypotonic environment for animal cells vs. plant cells; how does the plant, as a whole, respond to a hypertonic, isotonic, and hypotonic environment?
In a hypotonic solution the environment has a low concentration. In a hypertonic solution the environment has a high concentration. Animal cells prefer isotonic, normal, conditions so in hypotonic solutions they burst and in hypertonic solutions they shrink. Plant cells are usually in hypotonic solution so the won't burst because of it and instead become turgid which is good. In hypertonic solutions plant cells become shrunken/flaccid. The plasma membrane can begin to detach from the wall.
Compare the extracellular matrix of plant vs. animal tissues
In animal cells the ECM typically consists of long, glycoproteins extending from the membrane and attracts water, giving it a gel-like consistency. Collagen: A glycoprotein in the extracellular matrix that forms strong fibers found extensively in connective tissue and bone. In plants the ECM is rather obvious and consists of the cell wall and the middle lamella which acts like a sort of glue.
Explain the difference between aerobic respiration, alcohol fermentation, and lactate fermentation regarding oxygen requirement, end products, and amount of ATP produced:
Lactate fermentation - requires no oxygen, produces 2 ATP as well as Lactic Acid and Carbon dioxide Alcohol fermentation - little or no oxygen required, produces 2 ATP as well as ethanol and carbon dioxide aerobic respiration Aerobic respiration - requires oxygen, produces 36 ATP as well as carbon dioxide and water
List 3 specific functions that they perform for the cell
Lysosomes are the "clean-up crew" of the cell. They... 1. contain hydrolytic enzymes that can degrade a variety of macromolecules 2. Digest cellular debris and invading microorganisms 3. Degrade old organelles
Describe how vesicles are moved through the cytoplasm, including the roles of microtubules and motor proteins.
MIcrotubules serve as track that guide vesicles to their destination within the cell. Motor proteins act as foot-like structures that attach to the microtubule and enable the motor to progress along the tubule in an upside-down "walking motion" while always remaining attached by on "foot"
Draw each type, indicating their basic shape and size, relative to one another and indicate where each type of filamentous structure is located.
Microfilaments - 7 nm in cell periphery Intermediate filaments - 10 nm throughout cell Microtubules - 25 nm throughout cell
Indicate which type is composed of actin and which type is composed of tubulin proteins.
Microfilaments and intermediate filaments are made of actin. Microtubules are composed of tubulin proteins
Explain why microfilaments and microtubules are said to have a dynamic structure
Microfilaments and microtubules are constantly dissociating, reforming, and changing in length. The proteins are constantly turning over.
Regarding the mitotic phase of the cell cycle, what are the two major events that occur during the mitotic phase?
Mitosis: where the nucleus divides Cytokinesis: Where the entire cell divides
Compare the mechanism of rapid cytoplasmic movement in plant vs. animal cells.
Most plant cells are large, and rapid cytoplasmic movements are sometimes utilized to distribute molecules throughout the cell. Thy cytoplasm of animal cells does not usually move in such a direct way; an exception is amoeboid movement of some motile cells such as white blood cells.
Name 3 different types of fungi
Mushrooms Yeast Mold
Describe the function of NAD/NADH in cellular respiration
NAD+ is a positively charged molecule that picks up two negatively charged electrons, transforming it into NADH. NADH is used to transport electrons to the electron transport chain and becomes oxidized back to it's original form NAD+.
Describe the function of oxygen in cellular respiration
Oxygen serves as the final electron acceptor in the electron transport system. At this point, the oxygen combines with hydrogen to form water. If oxygen is not available, the entire electron transport process comes to a halt.
Indicate the general structure and function of peroxisomes
Peroxisomes are small membrane- bound compartments that contain peroxidase. They perform several different functions involving oxidation (ex: detox of alcohol and other poisons). They produce their own membrane and sometimes replicate by splitting.
Explain when (and how) oxygen is released during photosynthesis.
Photosystem 1 absorbs a photon which energizes an electron, that electron moves through the system gradually losing energy until it reaches the second photosystem which again absorbs a photon and energizes the electron. When the first photosystem electron is energized it takes i a new one from water, splitting it into protons and oxygen.
Explain (in general terms) what a photosystem does, and indicate how absorption of light by chlorophyll in a beaker differs from absorption of light by a chloroplast.
Photosystems collect solar energy and use it to energize electrons
Indicate how communication between neighboring cells differs in plant vs. animal tissues.
Plant cells have pores/channels which allow the cytoplasm of adjacent cells to pass through the cell wall. This provides an intimate connection between plant cells that animal cells do not have. Plasmodesmata: Adjacent cells within a plant are connected to one another by strands of cytoplasm called plasmodesmata. Small openings with the cell walls provide spaces for "bridges" between the cells. The plasma membranes, as well as cytoplasm of the cells, pass through these openings. Most cells within a plant are attached in this way, allowing molecules to pass freely from one cell to another. Even macromolecules such as proteins and RNA have been seen to pass through the plasmodesmata.
Compare the replication of DNA in prokaryotes and eukaryotes regarding the number of replication points during DNA synthesis
Prokaryotes have a single "origin of replication" and replication moves in both directions along the DNA molecule. Eukaryotes have multiple replication points present alond each uncoiled DNA molecule, and replication also occurs in multiple directions away from the origin points.
Visualize a protein that is being synthesized on a ribosome and is destined to be exported from the cell. Now describe (or draw) the path of the protein through the endomembrane system to its final destination and indicate what happens to the protein at each step along the way.
Protein synthesized on ribosome in the ER. If a glycoprotein needs to be formed, it is added by enzymes in the RER. A vesicle then buds of the RER and fuses with the cis-face of the golgi apparatus. As the protein travels through the medial sacs of the Golgi, it is modified, and once it reaches the Trans-face, another vesicle buds off. This vesicle travels to the plasma membrane and fuses with it. The protein is then secreted.
Describe the structure and function of the Golgi apparatus; what is the relationship between the Golgi and endoplasmic reticulum?
The Golgi Apparatus is a series of interconnected sacs that serve a the distribution center for proteins. It packages proteins and lipids destined for export, packages enzymes into lysosomes for cellular use, and modifies proteins that fuse with the membrane of other organelles or fuse with the plasma membrane where they are usually secreted. Golgi Cis-Face: The face of the Golgi apparatus where vesicles from the Rough Endoplasmic Reticulum enter and proceed to further compartments known as the medial sacs. Golgi Medial Sacs: The series of sacs in between the cis and trans face of the Golgi apparatus where contents undergo further processing. Golgi Trans-Face: The face of the Golgi apparatus from which coated transport vesicles are sent off to their final destinations.
Indicate which step produces the most NADH and which produces the most ATP
The Krebs cycle produces the most NADH (3 per turn) The Electron Transport Chain produces the most ATP (32 ATP)
Indicate the type of organism(s) that comprise the Protista "Kingdoms".
The Protista are a group of kingdoms that have not been fully classified. This group is extremely diverse, containing primarily single-celled organisms, but also some colonial and multicellular forms. Some of the protista are more animal-like, some are plant-like, and others a bit like the fungi. Thus, Protista is actually a "miscellaneous" category, containing all eukaryotes that are not true animals, plants or fungi.
Compare the structure of the rough vs. smooth endoplasmic reticulum
The RER is continuous with the outer nuclear membrane and binds ribosomes. The RER and SER are similar and are, in fact, continuous with one another, but the smooth ER does not bind ribosomes.
Describe the endosymbiotic theory and give evidence that supports this theory (reading assignment)
The endosymbiotic theory states that an early eukaryotic cell engulfed a prokaryotic cell by endocytosis, much as one of our phagocytic white blood cells engulfs a bacterium. The two types of organelles that may have previously been prokaryotes are chloroplast and the mitochondria. The host cell profited from the chemical energy the produced, and the prokaryote benefited from the protected, nutrient-rich environment surrounding it. Evidence is that mitochondria has its own membrane, it's own DNA, and reproduces by pinching like bacteria.
Compare the functions of the rough vs. smooth endoplasmic reticulum, giving at least two functions for each.
The function of the RER is protein synthesis. After the protein is synthesized it is sent via vesicles to the Golgi Apparatus. The RER provides most of the membranes in the endomembrane system. The function of the SER is lipid synthesis, carbohydrate metabolism, and detoxification
Explain why leakage from a lysosome does not usually damage the cell.
The hydrolytic enzymes in the lysosomes only function at an acidic pH, so if leakage does occur, the neutral pH of the cytosol greatly reduced their activity.
Indicate whether or not light is required.
The light reactions require light and the dark reactions do not
Indicate where within a chloroplast each step occurs
The light reactions take place within the granum/ thylakoid membranes The dark reactions take place within the stroma
Can animal cells ever utilize fermentation to produce energy? If so, give an example.
The muscles of mammals can utilize both aerobic respiration and lactic acid fermentation to produce energy. During short bursts of strenuous activity, such as sprinting, fermentation is utilized. However, the lactic acid buildup soon causes muscle fatigue and pain. As muscle activity ceases, sufficient oxygen is again available and the cells return to aerobic respiration. While fermentation can produce ATP, it is far less efficient than aerobic respiration. Thus sprinters can hold their breath and run at full speed during the 100 yard dash, but long distance runners must rely on aerobic respiration and an efficient cardiovascular system to provide a continuous supply of oxygen to their muscle cells.
Describe the structure of the nuclear membrane; why are nuclear pores so large?
The nuclear membrane has a double membrane, each a lipid bilayer with associated proteins. The outer membrane is continuous with the ER. The nuclear pores are large protein complexes that cross the nuclear envelope. Nuclear pores are so large because they need to be able to let large molecules such as mRNA pass from the nucleus to the cytoplasm.
Explain the relationship between the nucleolus and protein synthesis
The nucleolus is a specific region of the DNA that codes for ribosomal RNA. The greater the cell's need for protein synthesis (and thus for more ribosomes), the more active the nucleolus will be. The rRNA and proteins are being assembled into two types of ribosome subunits. Once assembled, these subunits will exit the nucleus through the membrane pores and join together to form ribosomes.
Give several examples of cells that continuously divide in mature animals and plants.
animals: bone marrow and stem cell (produce blood cells), skin cells, intestinal tract cells plants: root tips
Explain the function of hydrogen bonds within the DNA double helix.
hydrogen bonds connect pairs of nitrogenous bases
Overall Calvin Cycle
in step 1, carbon dioxide molecules are incorporated into 5-carbon sugars. This is the all-important carbon fixation step. In the next step, 3-carbon sugar molecules are phosphorylated by ATP to increase their energy, and the electrons carried by NADPH are added. In step 3, the product G3P is released from the cycle. Finally, a fourth step is required to regenerate the original 5-carbon sugar so that carbon fixation can continue in a new cycle. Two of the G3P sugars combine to form the 6-carbon sugar glucose that is the main product of photosynthesis.
Name the 3 parts of a nucleotide.
phosphate group, 5 carbon sugar, nitrogenous base
Compare the replication of DNA in prokaryotes and eukaryotes regarding the number of and length of chromosomes
prokaryote: single and short eukaryote: multiple and long
