BIO 183 Exam 2

Describe, in general terms, how "nano shells" might be used in a new treatment for cancer.

"nanoshells" to deliver just a little heat to breast tumor cells already treated with radiation boosts the killing potential of the treatment

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.

*** Collects solar energy and uses it to energize electrons

Define the terms "karyotype" and explain how a human karyotype is prepared.

- A display of chromosomes within the diploid cells is called a karyotype -Biologists photograph cells in mitosis, then cut out the chromosomes from the photograph and group them together in pairs

Describe the central vacuoles of plant cells, including their size, location within the cell, functions, and substances that might be stored within them.

- Plant cells use their vacuoles for transport and storing 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. - Vacuoles can store many types of molecules (opium, rubber, Na+)

Define the terms "proto-oncogene" and "tumor suppressor gene"; explain (in general terms) why mutations in each of these genes can lead to cancer.

- The many genes that code for proteins that regulate the cell cycle are called proto-oncogenes; they become oncogenes when mutated - many cancers are caused by mutations of tumor suppressor genes. These genes code for proteins which normally prevent cancer

Explain what happens and why when plant cells are surrounded by a concentrated solution of salt or sugar.

- The salts add to the osmotic activity of the vacuole therefore contributing to the turgor pressure - When plant cells are placed in concentrated sugar/salt solutions they lose water by osmosis and they become flaccid, that is the exact opposite of turgid

Indicate the overall process by which meiosis reduces the diploid chromosome number to haploid.

-As in mitosis, each chromosome replicates to form a pair of sister chromatids -then there is a cell division (meiosis I) in which the homologous chromosomes separate - Each daughter cell receives one replicated chromosome, which still consists of a pair of chromatids -finally, each cell divides again (meiosis II)

Describe the major cause and symptoms of melanoma.

-Exposure to ultraviolet rays from natural or artificial sources, such as sunlight and indoor tanning beds ->a change in an existing mole ->the development of a new pigmented or unusual looking growth on your skin

List the three check points within the cell cycle, then indicate one function of checkpoint proteins at each point.

-G1 checkpoint: (restriction point) determines if conditions are favorable for cell division and if the DNA is damaged. G1 cyclin is made in response to sufficient nutrients and growth factors -G2 checkpoint: checks for DNA damage, determines if all of the DNA is replicated, and monitors the levels of proteins that are needed for M phase -Metaphase checkpoint: determines if all chromosomes are attached to the spindle apparatus

Explain why one strand of DNA is synthesized in fragments during the replication process.

-the two strands of a DNA molecule are orientated opposite to one another -This means that strands 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

Indicate several environmental factors that regulate cell division in single-celled organisms.

-this process is regulated by environmental factors, primarily nutrient availability-other environmental factors that influence the rate of cell division are temperature and pH

List 3 ways in which eukaryotic chromosomes differ from prokaryotic chromosomes.

1) Prokaryotic cells have one small, circular chromosome. Eukaryotic cells have many linear chromosomes. 2) Eukaryotic cells have a greater number of genes and longer chromosomes than prokaryotic cells because they must make a larger number of different proteins. 3) Most eukaryotes are multi-celled organisms with each cell type requiring a different set of proteins, whereas prokaryotes are single celled.

Indicate why two different photosystems are needed during the light reactions of photosynthesis.

1. A photosystem absorbs a photon of light. This energizes an electron within the reaction center. Used to make ATP as the electron is moved to the second photosystem. 2. Now the electron has lost most of its energy, but it is energized again to an even higher level as the second reaction center absorbs a photon.

List 10 organelles (or membranes) found within animal cells and indicate the general function of each.

1. Cytosol: Contains the cytoskeleton; gives the cell its shape and helps in the movement of the cell 2. Nucleolus: found only in eukaryotes. It is a compact region of DNA where ribosomal RNA is made 3. Nucleus: This is the brain of the cell; only eukaryotic cells have a true nucleus 4. Ribosomes; "workbenches" for protein synthesis 5. Mitochondria: Power house of the cell; oxidizes nutrients to produce ATP(cellular respiration) 6. Lysosome: Contain hydrolytic enzymes. They are the "cleanup crew" of the cell 7. Golgi Apparatus: act as a distribution center to assure that each protein is carried to the correct place within the cell 8. Rough Endoplasmic Reticulum: Responsible for the assembly of proteins 9. Smooth endoplasmic reticulum: involved in the synthesis of cell products such as lipids 10. Vesicles: Many are involved in the transport of proteins, some carrying proteins to be secreted from the cell or bring substances in

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

Name 3 types of plastids and give the function of each.

1. Leucoplast: stores starch and some water 2. Chloroplast: contains chlorophyll, where photosynthesis occurs 3. Chromoplast: contains carotene and xanthophyll and create orange color

List two major steps in photosynthesis, the starting and end products for each step, where within a chloroplast each step occurs, and whether or not light is required.

1. Light dependent: started with water and end with waste of oxygen then product oxygen (requires light) 2. Calvin cycle: started with CO2 and end with glucose then product is a phosphate group and NADP+ (does not require light)

Describe the function of the following in cellular respiration: NAD/NADH electron transport ATP synthase oxygen

1. Produced by citric acid cycle and used to create ATP in electron transport.NAD+ is contained within a cell along with hydrogen atoms. NAD+ is reduced to NAD by an electron from a hydrogen atom. It then picks up a hydrogen atom to become NADH. NADH carries the electrons to a later stage of respiration and drops them off, becoming oxidized to its original form, NAD+. 2. Electron transport is the step where most of the energy is generated. NADH carries electrons to the mitochondrial inner membrane and releases them to an electron carrier protein within the membrane. At each step, the electron loses some of its energy until it arrives at the end of the chain and is taken up by oxygen. 3. ATP Synthase is an enzyme complex which creates ATP. As hydrogen ions flow down their concentration gradient through the ATP Synthase, it creates a rotational movement that aids in the generation of ATP. It basically acts as a molecular motor to make ATP from ADP and P 4. As hydrogen ions pass through the electron transport chain, oxygen combines with the hydrogen to form water, or it "phosphorylates." If oxygen is not available, the entire electron transport process comes to a halt.

Give 3 examples that illustrate the role of microfilaments in cell motility.

1. They form a contractile ring around the cell in cell division 2. They alter cell shape to generate cell movement over a surface 3. They interact with myosin for muscle contraction

Regarding the causes of cancer: Indicate the relationship between cancer and the cell cycle Describe how cancer spreads through the body. Define the term "carcinogen" and name several carcinogens.

1. cancer is a disease in which cells divide in an uncontrolled fashion; as cancer progresses, it may spread to other parts of the organisms body 2. spread of cancer: 1. Benign growth 2. malignant growth 3. metastasis occurs when cells enter the bloodstream or surrounding body fluids 3. At least 80% of human cancers are caused by agents, called carcinogens -Tobacco smoke -chemicals

List the three major structures that are found in plant cells, but not animal cells, and indicate the general functions of each.

1. cell wall: surrounds the plasma membrane; acts as an external support for plant cells 2. central vacuole: contains water and stores various kinds of macromolecules ; water pressure inside increases the ridgity of most plant cells 3. chloroplasts: contain chlorophyll and perform photosynthetic functions; have sites where light is converted into chemical energy

Explain the purpose of ATP within cells and the significance of its 3rd phosphate bond.

ATP is the storage form of energy most useful to cells. With the 3rd phosphate, the products of energy released from ATP can be recycled to make more ATP.

Indicate which type is composed of actin and which type is composed of tubulin proteins.

Actin: microfilaments Tulbin protein: microtubules

What "choices" does a cell have at the end of the mitotic phase?

After dividing, the cells can either continue and divide again or leave the cycle temporarily or permanently.

Indicate how you would distinguish between a colonial protist and a multicellular protist.

All of the cells within the colonial protist look alike and have the same function. Multi-cellular protists are usually larger than colonial forms and have several different types of specialized cells.

Give one example of a protist that is animal-like and one example of a protist that is plant-like.

Animal-like: Amoeba Plant-like: Algae

Indicate how communication between neighboring cells differs in plant vs. animal tissues.

Animal: gap junctions Plant: pores

Compare the general life cycles of animals, plants, and multicellular fungi.

Animals: diploid multicellular organism. Gametes are the only haploid cells. Undergo no further division prior to fertilization. After fertilization diploid zygote undergoes meiosis Plants: alteration of generations, multicellular in both diploid and haploid states Fungi: Haploid unicellular or multicellular organism, gametes fuse and form diploid zygote, organism carries out mitosis and produces gametes

Explain what is meant by "membrane recycling" within a cell.

As trans membranes are lost by forming vesicles, the medial sacs move forward. Incoming vesicles fuse to form new cis sacs in the rear. During processing and sorting, vesicles may move forward or backwards between membranes. Membranes moving proteins are constantly moving and being reused by each organelle.

Distinguish between asexual and sexual reproduction and give an example of each.

Asexual reproduction does not involve the fusion of gametes haploid cells which does occur in sexual reproduction. Offspring of asexual reproduction are identical to their parents, whereas there is variability in the offspring from sexual reproduction. Asexual reproduction occurs within a single individual, whereas sexual reproduction requires two individuals. Most prokaryotes reproduce asexually as do many single celled protists such as the amoeba. Almost all animals reproduce sexually.

Describe the endosymbiotic theory and give evidence that supports this theory.

Bacteria enters eukaryotic cells and forms symbiotic relationships. Evidence: Mitochondria have their own cell membranes Mitochondria have their own DNA genome Mitochondria reproduction is the same as bacteria Chloroplasts led to plants!

Explain why animals evolved so much later than photoautotrophic organisms during earth's history.

Because oxygen was a byproduct of photosynthesis.

Give several examples of cells that continuously divide in mature animals and plants.

Bone marrow and stem cells Animals: skin and liver cells Plant: root tips

Describe the interior of flagella and cilia (include a labeled diagram).

Both flagella and cilia contain microtubules. They have an identical 9 + 2 arrangement of microtubules. Motor proteins are attached to them and help create movement.

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.

Both mitochondria and chloroplast produce ATP. ATP is produced not only in cellular respiration, but also as an intermediate in sugar production in photosynthesis. Inter-membrane space = thylakoid space Inner membrane = thylakoid membrane Matrix = stroma

Explain the purpose of cellular respiration and write a general equation for it (you may use either words or chemical symbols).

C6H12O6 + 6O2 --> 6CO2 +6H2O + Energy Glucose is concerted into carbon dioxide and water with the release of energy.

Indicate location and function of: Centromere Kinetochore Centrosome Mitotic spindle (an microtubules within the spindle)

Centromeres: the sister chromatids are attached along most of their length, but the point of tightest attachment is called the centromere Kinetochores: each chromatid bears a kinetochore that contains motor proteins. Microtubules of the spindle attach to both kinetochores Centrosome: -the two centrosomes within the cell serve as organizing centers for these new microtubules -many of the newly formed microtubules stretch across the cell and connect the two centrosomes Mitotic spindle: either ends of the cell; they are involved in the movement of chromosomes during mitosis

Distinguish between the terms chromatin, chromosome, and DNA.

Chromatin is DNA combined with protein. A chromosome is DNA in any form, whether tightly packed in loops or coils or completely uncoiled.

Indicate the function of each of the following in control of the cell cycle in multi-celled organisms: cytokins growth factors such as EGF gene expression

Cytokins: cytokinins are used to stimulate cell division within the tissue resulting in a mass of new cells called a callus growth factors: the EGF protein binds to a receptor on the plasma membrane and initiates a signal within the cell that leads to proteins entering the nucleus and activating a specific set of genes gene expression: the process by which information from a gene(DNA) is made into a functional gene product(protein) using mRNA

Describe how DNA is compacted in order to fit within the nucleus.

DNA coils around histone proteins (called histomes) to for chromatin. Then the chromatin coils tightly. Some coiled chromatin pack even more by forming loops. These loops can form larger loops and coil again.

Distinguish between DNA, chromatin, and chromosome.

DNA is the double helix structure Chromatin is the unraveled condensed structure of DNA Chromosome is the highest condensed structure of the DNA double helix

Briefly, indicate the general functions of DNA, mRNA, tRNA, and ribosomes.

DNA: the genetic material within the nucleus controls cellular activities by specifying the proteins the cell makes RNA: copies genetic information from one strand of the double stranded DNA to begin protein synthesis mRNA: messenger RNA that transfers genetic instructions from the nucleus to the cytoplasm tRNA: transfer RNA that brings the appropriate amino acid as specified by the nRNA's code Ribosomes: the workbenches for protein synthesis in all cells

Give one example of a prokaryotic cell that has increased internal complexity.

Epulopisium, baterium that lives in gut of fish, is so large that it needs two nucleoid regions to serve its large volume of cytoplasm. It also has tubules and vesicles that form an internal transport system.

Compare the relative size of prokaryote, animal, and plant cells.

Eukaryotic cells are much larger than prokaryotes. The smallest eukaryotic cell is larger than all but a few prokaryotes, and plant cells are generally larger than animal cells.

Indicate when and how glucose is finally made in the Calvin cycle.

Final product of photosystems. Glucose is broken down by the process of cellular respiration to produce ATP needed for work within.

Distinguish between flagella and cilia based on their length and beating pattern.

Flagella are usually longer than cilia. They beat in an undulating pattern and generate a force somewhat like a propeller. Cilia are usually shorter than flagella. They beat by moving straight backward to generate force, then bend and move forward in a recovery stoke.

Describe 2 ways in which the cells of a multicellular fungus differ from those of a plant or animal.

Fungal cells lack chloroplasts All fungi are heterotrophic

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: All DNA copied to later divide at the end of G2; rapid growth S phase: DNA replication G2: cell prepares to divide Mitosis: exact duplication and division of chromosomes

Indicate the starting molecule and end product for each of the three steps.

Glycolysis starts with a glucose molecule and produces 2 pyruvates and energy in the form of ATP NADH The Krebs Cycles starts with AcetlyCoA (that formed from pyruvate) and produces 6 NADH, 2 FADH2, and 2 ATP. (aka Citric Acid Cycle) The Electron Transport Chain starts with O2, NADH, and FADH2, and produces H2O and 32 ATP

List the three major steps in cellular respiration

Glycolysis, the Krebs cycle (Citric acid cycle), and the Electron Transport chain.

Indicate where within or outside of the mitochondrion each of the three steps occurs.

Glycolysis: in the cytoplasm Krebs cycle: mitochondrial matrix Electron transport chain: mitochondrial inner membrane

Indicate the role of enzymes in DNA replication.

Helicase: unzipping the DNA helix Primase: synthesizing the RNA primer DNA polymerase III: adding bases to the new DNA chain; proofreading the chain for mistakes DNA polymerase I: removing primer, closing gaps, repairing mismatches Ligase: final binding of nicks in DNA during synthesis and repair Gyrase: supercoiling

Distinguish between the terms heterotrophic and autotrophic.

Heterotrophic organisms depend on other organisms for food (animals, fungi, single celled protista) Autotrophic organisms can make their own food (plants, algae, some protists)

Compare the process of cytokinesis in animal vs. plant cells.

In animal cells, a central ring of microfilaments constricts the cells, dividing the cytoplasm into two cells. In plant cells, vesicles along the cell midline fuse to form a new cell wall, thus dividing the cytoplasm into two cells.

Distinguish between the terms transcription and translation.

Transcription is the transfer of genetic information from DNA to RNA in protein synthesis. Translation is when mRNA is translated by tRNA into a string of amino acids.

Draw a DNA double helix and indicate what constitutes the "sides" and "rungs" of the DNA ladder.

In this DNA ladder, the phosphate group and 5-carbon sugar act as two sides of the ladder and the middle of the ladder is the nitrogen pair bases

Explain the relationship between the nucleolus and protein synthesis.

It is the specific region of DNA that codes for ribosomal RNA. Some cells have multiple nucleoluses.

Describe the structure and function of the Golgi apparatus; what is the relationship between the Golgi and the ER?

It produces many non-protein products, such as lipids and steroid hormones. it also stores calcium ions and plays a major role in detoxifying harmful substances. It can also metabolize carbohydrates. (Function) The interconnected sacs of the Golgi serve as the final processing and sorting center for proteins. Sorting also occurs here. (Relationship) As protein filled vesicles depart the rough ER and head towards the golgi apparatus for transport, the vesicles merge and form new sacs on the golgi. The membranes fuse and are now part of the golgi.

Explain why photoautotrophs are so important to life on earth; name at least 3 categories of photoautotrophic organisms.

Life on earth is solar powered by photoautotrophs. They are autotrophs that use energy from sunlight; these organisms range from prokaryotes to single celled eukaryotes to multicellular algae and the similar land plants (algae, protists, and bacteria)

Explain when and how oxygen is released during photosynthesis.

Light energy from the sun is absorbed by photosystem II and it is used to split a molecule of water

List 3 specific functions that lysosomes perform for the cell.

Lysosomes function as digestive compartments for the cell. they digest cell debris and invading microorganisms. They also assist in disposing of worn-out organelles.

Explain the significance of meiosis and fertilization in sexual life cycles.

Meiosis maintains the normal diploid number to make the gametes and then allowing the diploid number to be restored through fertilization.

List two ways that meiosis differs from mitosis.

Meiosis- sexual, 23 chromosomes, offspring doesn't look like parents mitosis- asexual, 46 chromosomes, offspring looks like parent

List the 3 types of filamentous structures that form the cytoskeleton, and one role it plays in cell structure.

Microfilaments, (The main function of microfilaments is to maintain the cell's shape) intermediate filaments, (Intermediate filament holds organelles in place and prevents the cell from stretching.) and microtubules (Microtubules act as a support structure and help resist compression.)

Describe how vesicles are moved through the cytoplasm, including the roles of microtubules and motor proteins.

Microtubules serve as tracks that guide vesicles to their destination within the cell. They are carried along a microtubule by motor proteins. These motor proteins are not myosin. The two most common motor proteins that associate with microtubules are dynein and kinesin.

What are the two major events that occur during the mitotic phase?

Mitosis and Cytokinesis

How does the length of the mitotic phase compare to the S phase of the cycle?

Mitotic phase: 24 hours S phase: 8 hours

Distinguish between the terms centrosome, centriole, and basal body.

Most microtubules originate near the center of the cell and grow outward toward the periphery. The center that organizes microtubules is rich tubulin proteins and is called a centrosome. The centrosome region contains two small structures called centrioles that assist in organizing microtubule origin and growth. The centrioles are hollow structures. They somewhat resemble an axoneme, but are very short and have 9 triplets of microtubules around the periphery (instead of doublets) and no central tubules. 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. This structure is identical to a centriole and plays a role in organizing the microtubules within the cilium.

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. The cytoplasmic animal cells do not usually move in such a direct way; an exception is the amoeboid motion of some motile cells, such as white blood cells.

Explain how microtubules and motor proteins interact to generate motion.

Motor proteins attached to peripheral microtubules use ATP, dynein arms cause microtubules to bend.

Name 3 different types of fungi

Mushrooms, molds, and yeasts

Indicate the general structure and function of peroxisomes.

Peroxisomes are small membrane-bound compartments that contain peroxidase. They perform several different functions involving oxidation. For example, they break down fatty acids into smaller molecules that can enter the Krebs cycle. They also detoxify alcohol and other poisons. They produce their own membranes, and sometimes replicate by splitting.

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?

Plant swells, but does not burst (turgid); animal cells burst (lysed) Hyper: wilted Hypo: turgid Iso: no net movement

Describe two unusual features of slime molds.

Plasmodial slime mold is a single cell with multiple nuclei. The cellular slime molds live most of their life as individual cells that move by ameboid motion. If a food shortage occurs, they migrate toward one another and unite to form a multi-celled single organism that crawls to a new area where food is more plentiful.

Compare the replication of DNA in prokaryotes and eukaryotes regarding: number and length of chromosomes amount of DNA to be synthesized number or replication points during DNA synthesis

Prokaryote: single and short Eukaryote: Multiple and long; Less in prokaryotes than eukaryotes; Prokaryotes have a single origin and eukaryotes have multiple origins

Compare the functions of the rough vs. smooth endoplasmic reticulum, giving at least two functions for each.

R.E.R. assists in the processing of proteins and sends these proteins on to the golgi apparatus. it also serves as a membrane factory for the cell. That is, it provides most of the membranes in the endomembrane system. S.E.R. produces many non-protein products, such as lipids and steroid hormones. it also stores calcium ions and plays a major role in detoxifying harmful substances. It can also metabolize carbohydrates.

Compare the structure of the rough vs. smooth endoplasmic reticulum.

RER consists of a series of thin channels formed by endomembranes. Ribosomes are binded to the outer surface of the membranes. Smooth ER structure is basically identical to that of the rough endoplasmic reticulum, except it does not bind ribosomes. The two structures are even connected.

Indicate which wave-lengths (colors) of light are most effective in energizing photosynthesis.

Red and Blue

Explain why ATP and NADPH are needed in the Calvin cycle.

Regenerates its starting material after molecules enter and leave the cycle. - Builds sugar from smaller molecules by using ATP and reducing power of electroms carried by NADPH

List 3 ways in which plants use the sugar that they make by photosynthesis.

Respiration, making fruits, making cell walls.

Explain how each strand of DNA serves as a template for DNA replication.

Semi-conservative means that each new DNA molecule that is forming has one template strand from the original DNA and one newly synthesized strand-When replication is complete, each new DNA molecule has one strand from the parent DNA and one strand that is new

Indicate the type of organisms that comprise the Protista "Kingdoms".

Single celled protists, colonial protists, and multicellular protists.

Give one example of a cell in which very large size is not accompanied by greater complexity.

Some giant Prokaryotes, specifically the giant bacteria shown to us under "few prokaryotes." Also, the yolk of a bird egg technically is a giant single eukaryotic cell with minimum complexity.

Indicate where carbon fixation occurs within the Calvin cycle.

Storm of the chloroplasts. Light independent reactions

Indicate which step produces the most NADH and which produces the most ATP.

The Krebs cycle produces the most NADH The Electron Transport Chain produces the most ATP

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.

The RER processes the protein then sends it to the Golgi apparatus via a vesicle. The protein is inside the Golgi and the vesicle membrane becomes part of the Golgi membrane system. The protein passes through the Golgi sacs until it gets to the other side called the "trans face. Then it it packaged inside vesicles and transported to the final destination, outside of the cell.

Describe the plant cell wall, and indicate how the primary and secondary walls differ in function.

The cell wall is the supporting structure that surrounds plant cells 1. primary: thinnest, it was formed first when the cells were still growing. Flexible and allows growing cell walls to expand. Fibrils are thin and not parallel making them weak. 2. secondary: added beneath the primary after the cells had stopped growing. It is stronger and more rigid. Fibrils are thick and more parallel, stronger.

How does the nature of chromatin change at the end of the mitotic phase (extent of packing)?

The chromatin of the chromosomes spreads out.

Explain the function of hydrogen bonds within the DNA double helix.

The hydrogen bonds connect the pairs of nitrogenous bases.

Explain why the increased size is associated with greater internal complexity in the eukaryotes.

The larger size of eukaryotic cells requires a complex network of membranes and other structures to perform the necessary life functions.

Compare the extrtacellular matrix or plant vs. animal tissues.

The major structural protein of the extracellular matrix in animal cells is collagen, which is the single most abundant protein in animal tissues. The collagens are a large family of proteins. In plants, the ECM is primarily composed of cellulose. It is the major structural material of which plants are made. The result is a series of stiff, elongated fibrils - the perfect material for building the cell walls of plants.

Describe the structure of the nuclear membrane; why are nuclear pores so large?

The membrane bears many large pores. Nuclear membrane pores must be large enough to allow large muscles such as mRNA to pass from the nucleus to the cytoplasm.

Compare the role of motor proteins in moving a microfilament vs. moving a cargo.

The motor protein is attached to a stationary support and tries to walk along microfilament. It "walks" in place, and as a result the microfilament moves. The motor protein moves along the tubule like a train engine on a track, pulling the cargo with it.In some plant and fungal cells, microfilaments can serve as the tracks to move organelles. In animal cells, however, microtubules usually perform this function.​

Describe the general purpose of the endomembrane system and explain why eukaryotic cells need it.

The rough and smooth endoplasmic reticulum, the Golgi apparatus, lysosomes, and the outer nuclear membrane are all included in the endomembrane system. Generally, it assists in the synthesis of proteins and their transport throughout the cell, among other things. Eukaryotic cells need endomembrane systems to transport proteins into, out of, and around cells.

Explain why leakage from a lysosome does not usually damage the cell.

These enzymes only function well at an acidic pH, so if leakage does occur, the neutral pH of the cytosol greatly reduces their activity.

Explain why microfilaments and microtubules are said to have a dynamic structure.

They are constantly dissociating, reforming, and changing in length.

Indicate several ways in which yeast differs from other types of fungi.

They are single celled organisms. They reproduce through an unusual budding procedure.

Explain why chloroplasts are green.

They contain the pigment chlorophyll.

Indicate the role of cyclins in regulation of the cell cycle.

They regulate entry and progression of cells through the cell cycle

Name the 4 types of nucleotides found in DNA and indicate how they differ from one another.

Thymine and cytosine have one carbon ring as their main structure, whereas adenine and guanine have a double ring structure.

Describe 2 types of junctions that help hold animal cells together (regarding junctional complexes)

Tight junction: seal the space between cells so that molecules outside of the cells cannot pass between them Adhering junction: are very strong and prevent the cells from being pulled apart.

Explain the relationship between color, wave-length of light, and the term "visible light".

Visible light: a small part of the electromagnetic spectrum, the part that our eyes can perceive. Blue and purple light have the shortest wavelengths and thus the highest energy of visible light.

Explain why chromosomes are only visible (by light microscopy) when cells are dividing.

When cells are not divided, their cells are in the euchromatin (condensed chromosomes) or heterochromatin (uncondensed chromosomes) state. When cells divide, they pack their chromosomes tightly together. They are clearly visible by light microscopy in the condensed state.

Indicate which organisms can utilize alcoholic fermentation and how this process is used commercially.

Yeasts; used to make breads, wines, beers

Is DNA the only way in which prokaryotic and eukaryotic cells can pass nuclear information to their descendants? Explain your answer.

Yes, they used a virus that infects bacteria and showed that the genetic material of the bacteria was DNA

Can animal cells ever utilize fermentation to produce energy? If so, give an example.

Yes. During short bursts of strenuous activity, fermentation is utilized. Lactic acid build up creates muscle fatigue and pain. An example is a runner running the 100meter dash.

Explain the difference between aerobic respiration, alcohol fermentation, and lactate fermentation regarding oxygen requirement, end products, and amount of ATP produced.

aerobic respiration - O2: a lot required End: CO2, Water, 36 ATP Amt. ATP: 36 ATP alcohol fermentation - O2: Some End: CO2 and ethanol Amt. ATP: 2 ATP lactate fermentation - O2: none End: lactic acid Amt. ATP: -

Distinguish between diploid and haploid.

diploid: 2 copies of each chromosome haploid: single copy of each chromosome

Distinguish between homologous chromosomes and sister chromatids.

homologous chromosomes=pair of the same chromosome, but not identical (different alleles) sister chromatids= 2 replicas of a single chromosome held together by the centromere after DNA replication

Explain what occurs during anaphase of mitosis and the role of motor proteins in this process.

molecular motor proteins create repulsive forces that will push the centrosomes to opposite side of the nucleus

Name the 3 parts of a nucleotide

sugar, phosphate, nitrogenous base