Cell Biology Exam 1

3. Sample EXAM 1 question: 11. Rank the following items in order of size from the smallest to the largest A. Hemoglobin (a protein) B. Hydrogen atom C. Disaccharide D. Tetrahymena cell E. E. coli cell F. Water molecule

(Smallest) Hydrogen atom, water molecule, disaccharide, hemoglobin, E. coli, Tetrahymena (Largest)

13. A solution at pH = 5 is acidic / basic (choose one) and has an OH- concentration of ______ (2 pts)

13. A solution at pH = 5 is acidic / basic (choose one) and has an OH- concentration of __10-9_ (2 pts)

14. Rank carbon, hydrogen, nitrogen and oxygen in terms of the number of bonds each typically forms: (Least) __________ -> ___________ -> _____________ ->___________ (most) (4 pts)

14. Rank carbon, hydrogen, nitrogen and oxygen in terms of the number of bonds each typically forms: (Least) _____H_____->______O_____ -> _____N______ -> ____C_______ (most) (4 pts)

2. Which of the following organelles is surrounded by two layers of membrane? A.Endoplasmic reticulum B. Nucleus C. Lysosome D. Peroxisome E. Vesicle F. Golgi apparatus

B. Nucleus Why is the answer nucleus: Because the nucleus is bound by 2 membrane (called the Nuclear Envelope)

9. Which of the following are in common between starch and cellulose? A. Their main function in plants B. The size of their monosaccharide subunits C. The type of glycosidic linkage used D. The amount of hydrogen bonding that occurs between parallel strands E. All of these are in common between starch and cellulose

B. The size of their monosaccharide subunits

1. How many electrons are involved in a single covalent bond? A. one B. two C. three D. four

B. two Why is the answer B: because the bond is formed by the sharing of 1 electrons pair between 2 atoms in which each atom contributes 1 electrons.

2. Alternative question: Define mitochondria

Mitochondria: Free living at some point and had their own DNA The mitochondria is bund by 2 membranes Is the powerhouse of the cell=> where ATP is made

12. Which of the following statements is true? A. As you move from the 4X to 10X objective, the field of view increases B. If you view an object with the 40X objective, the total magnification is 4X C. As you move from a 40X to 10X objective, the depth of field increases D. If you view an item with a 40X objective, the total magnification is 40X

C. As you move from a 40X to 10X objective, the depth of field increases

3. Which of the following is smallest? A. ribosome B. lipid droplet C. protein D. mitochondrion E. prokaryotic cell

C. protein

2. define Vacuoles

Vacuoles: membrane-bound organelle found in both plant and animal cells, in animal cells vacuoles are smaller and help sequester waste products

2. define Vesicles

Vesicles: Move materials

4. What unit of length would you generally use to give the measurements of a typical human cell? A. Micrometers B. Millimeters C. Centimeters D. Nanometers E. Picometers

Why is A the correct Answer: A typical human red blood cell is ~ 8 micrometers in diameter, which is a size that requires a light microscope. And plant and animal cells range( ~10 to 100 micrometers)

3. Which of the following is smallest? A. ribosome B. lipid droplet C. protein D. mitochondrion E. prokaryotic cell

Why is C correct: Because proteins are significantly smaller than organelles or cells. They are composed of amino acids and are not typically visible to the naked eye

2. Alternative question: Define Nucleus

contains genetic information(DNA) RNA goes to the cytosol for transcription The nucleus is bounded by 2 membranes called (nuclear envelope) Nuclear envelope contains Nuclear pores, which is how RNA goes out of the Nucleus

1. Alternative question: how many electrons are involved in a double or triple covalent bond?

double covalent (4 electrons or 2 pairs of electrons) and triple (6 electrons or 3 pairs of electrons)

19. If you see the same window as above, but you are holding a P-1000 pipettor, how many milliliters will be pipetted? (2 pts)

0.76 ml

17. Consider the dipeptide, shown. (14 pts)A. Which bond (A, B, C, D, E) is the peptide bond? B. Which bond (A, B, C, D, E) is closest to the C- terminus? C. At cellular pH, is the N terminus charged? If yes, what is the charge? D. Circle the dipeptide's backbone E. Place boxes around "R" groups F. What type of tertiary interactions will the first (left) amino acid participate in? G. What type of tertiary interaction will the second (right) amino acid participate in?

17. Consider the dipeptide, shown. (14 pts)A. Which bond (A, B, C, D, E) is the peptide bond? B. Which bond (A, B, C, D, E) is closest to the C- terminus? C. At cellular pH, is the N terminus charged? If yes, what is the charge? Yes, positive D. Circle the dipeptide's backbone E. Place boxes around "R" groups F. What type of tertiary interactions will the first (left) amino acid participate in? Hydrophobic interactions G. What type of tertiary interaction will the second (right) amino acid participate in? Hydrogen bonding

19. If you see this in the window of a P-20 pipettor, how many microliters will be pipetted? (2 pts) 0 7 6

7.6 microliters

4. What unit of length would you generally use to give the measurements of a typical human cell? A. Micrometers B. Millimeters C. Centimeters D. Nanometers E. Picometers

A. Micrometers

6. If you change one amino acid or another in a protein, what level of protein structure have you definitely altered? A. Primary B. Secondary C. Tertiary D. Quaternary E. Depends on the amino acid

A. Primary

11. The cell theory states all of the following except: A. All organisms consist of 1 or more cells B. All cells are enclosed in a phospholipid bilayer C. The cell is the basic unit of all living things D. All cells arise only from pre-existing cells

B. All cells are enclosed in a phospholipid bilayer

4. Alternative Question: Which of the following would NOT be suitable to use to give the measurement of a typical human cell and why did they not work?

B. Millimeters C. Centimeters D. Nanometers E. Picometers Millimeters and centimeters: Are too large to accurately represent the dimensions of most cells. Nanometers: Would be suitable for objects for objects like atoms and viruses that are smaller than cells. Picometers: is used to measure atomic radii.

3.Alternative question: Which of the following is Largest and why? A. ribosome B. lipid droplet C. protein D. mitochondrion E. prokaryotic cell

Answer: (largest) Prokaryotic cell: This is a complete single-celled organism like bacteria. It's relatively larger compared to other structures listed here. Mitochondrion: These are organelles within cells, and while they vary in size, they are generally larger than most organelles but still much smaller than a whole cell. Ribosome: Ribosomes are tiny structures, even smaller than mitochondria. They're crucial in protein synthesis. Lipid droplet: These can vary in size, but they're typically smaller than organelles like mitochondria and much smaller than a cell. Protein: Proteins are molecular structures, significantly smaller than organelles or cells. They are composed of amino acids and are not typically visible to the naked eye. The prokaryotic cell is the largest, followed by the mitochondrion, lipid droplet, ribosome, and finally, individual proteins. (smallest)

2. Alternative Question: Other than the nucleus what organelles are surrounded by 2 layers of membrane?

Answer: The nucleus, chloroplast, and mitochondria are cellular organelles and all of them are enclosed in a double membrane.

2. Alternative question: Define Chloroplast

Chloroplast: Free living at some point and had their own DNA The chloroplast has 2 membranes and inner and outer membranes The chloroplast are green because they contain chlorophyll Is a pigment and helps the chlorophyll captures light energy

7. If you change the number of protons in an atom, you create _____. A. A cation B. An anion C. An isotope D. A different element

D. A different element

10. Some proteins have α helices, some have β sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements? A. Specific amino acid sequences B. Side-chain interactions C. The hydrophobic-core interactions D. Hydrogen bonds along the protein backbone

D. Hydrogen bonds along the protein backbone

8. You isolate an organic molecule that contains only C, H, O, N, and S. This molecule is probably a: A. Sugar B. Nucleic Acid C. Fatty acid D. Protein

D. Protein

5. A nonpolar covalent bond can form when A. one of the atoms has a greater affinity for electrons than the other atom of the same molecule B. one of the atoms has a greater affinity for neutrons than the other atom of the same molecule C. there is the gain of one or more electrons from one atom to another atom of the same molecule D. two atoms of a molecule attract the electrons equally E. there is the loss of one or more electrons from one atom to another atom of the same molecule

D. two atoms of a molecule attract the electrons equally

2. define the Endoplasmic reticulum

Endoplasmic Reticulum The ER is spread throughout the cell The outer membrane of the nucleus is con w/ the ER Rough ER: is studded with ribosomes to make proteins Some proteins are made on the ER Unbounded (free ribosome) also make proteins Smooth ER (ER w/out ribosome): smooth ER- makes lipids and new membrane material

2. define Golgi apparatus

Golgi apparatus: "sort machine" and modifies proteins Stacks of membrane and is really Dynamic => these little vesicles go to different parts of the cells EX: plasma membrane, where their material will be released Or exocytosis ( some vesicles will fuse with the lysosome- which carries digestive enzyme) Function: proteins are glycosylated (sugars are added) and sorted Putting finishing touches on proteins before sending them off

20. Briefly explain why the following statements are false. (18 pts) A. Nonpolar amino acids tend to be found on the outside of proteins B. Antibodies are "Y" shaped with three antigen binding sites C. Electrons are always shared equally between covalently bonded atoms. D. If you heat a protein, the first type of tertiary bond that breaks is the disulfide bonds E. The sequence of the atoms in the polypeptide backbone varies between different proteins. F. The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure.

Nonpolar amino acids tend to be found on the outside of proteins Nonpolar amino acids form hydrophobic interactions with each other and are usually found on the inside of proteins where they are shielded from the aqueous environment of the cell. The polar amino acids are usually on the outside of the protein where they can interact with the aqueous cytosol. Antibodies are "Y" shaped with three antigen binding sites Antibodies are Y shaped, but they only have two antigen binding sites, one at the tip of each "hand" of the Y. Electrons are always shared equally between covalently bonded atoms. Electrons are shared equally in nonpolar covalent bonds, but in polar covalent bonds, they are shared unequally with the electrons attracted to the more electronegative atom. If you heat a protein, the first type of tertiary bond that breaks is the disulfide bonds Disulfide bonds are the strongest of the tertiary bond types and these would be the last type of bonds to break when heating a protein. The first bonds to break would be hydrophobic, then hydrogen, then ionic and finally disulfide. The sequence of the atoms in the polypeptide backbone varies between different proteins. The sequence of the atoms in the polypeptide backbone is unchanging and is always N-C-C-N- C-C.... The R-groups, however do change from one amino to the next. The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure. Double bonds are found in unsaturated fatty acids. The double bond causes a "kink" in the hydrocarbon chain and this leads to greater fluidity (less packing) of unsaturated fatty acids compared to saturated fatty acids that are less fluid.

2. Alternative: What do vacuole, vesicles, lysosome, golgi apparatus, ER, and peroxisome have in common?

Organelles w/ 1 layer of membrane

23. List three distinct useful features of Tetrahymena that make them suitable for our cell biology labs, and very briefly explain why it is a useful feature (6 pts)

So many things you could say here -It's a really complex single celled organism that is non pathogenic (won't harm us)Has a rapid life cycle so it is easy to grow in the labIt is eukaryotic and things we learn in Tet might be applicable to other euks. And on the other hand it is far from humans on the euk evolulutionary tree. The things that are in common between us and Tet probably arose in the earliest euk organism, and the things that are different provide insight into novel mechanisms for carrying out cellular processesFor a single cell they are large and easy to see under the light microscopeEtc.

15. Draw three water molecules and show how they might be hydrogen bonded together. Indicate the hydrogen bonds with dashed lines and covalent bonds with solid lines. (3 pts)

pic

16. The graph at right is an energy diagram for the reaction of substrate S converted to product P. (8 pts) A. Is this reaction energetically favorable? YES or NO (circleone). Indicate the following on the graph: B. The activation energy for the reaction C. The free energy change for the reaction D. Draw a new curve on the graph to indicate how an enzyme that converts S to P will change the energetics of the reaction.

pic

21. Given this micrometer slide with vertical markings every 0.1 mm. Draw on the slide how a cell 200 micrometers in diameter would appear. (2 pts)

pic

22. Select all the cell types in which the listed structure or molecule can be found. Note that the structure or molecule can be found in more than one type of cell. In the blank column write in the function of the structure or molecule. (15 pts)

pic Structure or molecule Nucleus Plasma membrane chloroplast Cell wall Endoplasmic reticulum select all that apply Animal plant bacterial Animal plant bacterial Animal plant bacterial Animal plant bacterial Animal plant bacterial