Midterm

All 64 possible codons ha e corresponding anticodons in tRNA True or False

False

All B sheets are comprised of protein strands running anti parallel to each other True or false

False

Mitochondria snd chloroplasts are integral parts of the endowment and system and are specifically connected to the endoplasmic reticulum. True or false

False

Most proteins retain metabolic activity when denatured True or false

False

Purified phospholipids mixed in water will only form membranes if the appropriate enzyme is present. True or False

False

The codons in mRNA specify the amino acids that are used to make a protein. Is this statement true or false? Some amino acids are specified by just one codon, whereas others are specified by multiple codons.

False

Enzymes present in the linen of the Golgi apparatus are responsible for modifying proteins and lipids. Where may these proteins have been before they entered the Golgi apparatus. A. In the nucleus B. Floating in the cytosol C. In the rough endoplasmic reticulum D. Translated in free ribosomes

In the rough endoplasmic reticulum

How many different mRA sequences could encode the amino acid sequence Met- Leu-Val-His? A. 48 B. 24 C. 12 D. 84

A. 48

A proton pump is needed in the lysosomal membrane because A. All of these choices are correct B. The interiors of the lysosome needs to be acidic C. Protons cannot move across a membrane on their own D. Protons are being moved from low to high concentration

A. All of these choices are correct

In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain the proper degree of fluidity. Which change in fatty acids of phospholipds would be msot effective in mainting membrane fluidity in a colder environment? A. decrease in phospholipid fatty acid side chain length and a decrease in side chain saturation B. An increase in phospholipid fatty acid chain length and an increase in side chain saturaton C. a decrease in phospholipid fatty acid side chain length and an increase in side chain saturation D. an increase in phospholipid fatty acid side chain length and a decrease in side chain saturation

A. decrease in phospholipid fatty acid side chain length and a decrease in side chain saturation

Referring to the following mRNA sequence, 5'-AUGAGACUUACCGSS-3', what would the anticodon look like if the second nucleotide if the fourth codon was mutated to U? A. 3'-AUG-5' B. 3'- UAG-5' C. 3'- TAG- 5' D. 3'- AAC-5'

B. 3'- UAG-5'

Which factors are used during translation? A. Elongation factors B. All of these choices are correct C. Release factors D. Initiation factors

B. All of these choices are correct

Where are lysosome enzymes synthesized? A. In the cytosol B. On the rough endoplasmic reticulum C. On the Golgi apparatus D. In a vesicle

B. On the rough endoplasmic reticulum

Which is more likely to form a Michelle rather than a liposome if mixed in aqueous environment? A. Phospholipids with two fatty acid tails B. Phospholipids with a single fatty acid tail C. Phospholipids with one or two fatty acid tails are equally likely to form a Michelle rather than a liposome. D. Neither type of phospholipid could form a Michelle.

B. Phospholipids with a single fatty acid tail

A protein with an internal signal sequence is most likely to be located in: A. The extra cellular space B. The nucleus C. A mitochondria D. The cytoplasm E. A chloroplast

B. The nucleus

What would be synthesized on the rough endoplasmic reticulum? A. Cytoskeletal proteins B. Transmembrane protein receptors C. mRNAs D. Nuclear proteins

B. Transmembrane protein receptors

During the translation of mRNA molecules, the new polypeptides are often directed to specific parts of the cell by the presence or absence of short sequences of amino acids called signal peptides. What would you expect to find in the polypeptide that will eventually fold to become a histone protein? A. An amino-terminal signal peptide B. No signal peptide C. A nuclear localization signal D. A signal anchor peptide

C. A nuclear localization signal

Which of the environmental factors affect the interactions between amino acids that in turn determine the shape of a protein? A. pH B. Ion concentration C. All of these choices are correct E. Hydrophilic if hydrophobic propertied of the environment F. Temperature and ion concentration

C. All of these choices are correct

If a mutation blocked the function of the signal recognition particle, making it unable to bind signal sequence, what would result? A. All proteins would end up in the nucleus. B. All proteins would be secreted from the cell. C. All proteins would be translated on free ribosomes. D. All proteins would end up in the mitochondria or chloroplast.

C. All proteins would be translated on free ribosomes.

A researcher has decided a technique that allows her to label all the integral membrane an proteins with a fluorescent tag. She uses a laser to bleach the fluorescent in a specific area of the cell membrane. After 24 hours, she notices that fluorescence has returned to the bleached area. What can she deduce from this experiment. A. Integral membrane proteins may not be permanently associated with the cell membrane. B. Integral membrane proteins are stationary in the membrane and cannot undergo lateral movement. C. Integral membrane proteins are able to move laterally within the cell membrane. D. Integral membrane proteins are not located within the cell membrane.

C. Integral membrane proteins are able to move laterally within the cell membrane

Individuals with a condition known as exercise intolerance lack sufficient ATP and suffer extreme fatigue from minimal exertion. Defects in which structures are most likely responsible for this condition? A. Golgi apparatus B. Ribosomes C. Mitochondria D. Lysosome E. Endoplasmic reticulum

C. Mitochondria

Disorders of which organelle are often associated with defects in transport from compartment to compartment, resulting in poor sorting of protein components within the cell? A. Nucleus B. Plasmids C. The Golgi apparatus D. Plasma membrane E. Endoplasmic reticulum

C. The Golgi apparatus

Where are the ribosomes that translate proteins to be secreted from the cell? A. in the nucleolus B. in the cytosol C. attacjed to the rough endoplasmic reticulum D. attached to the Golgi apparatus.

C. attacjed to the rough endoplasmic reticulum

Which part of a cholesterol molecule is polar? A. both the four interconnected planar rinds and the hydrocarbon tail. B. The four interconnected planar rings C. the OH group D. the hydrocarbon tail.

C. the OH group

During the translation of mRNA molecules, the new polypeptides are often directed to specific parts of the cell by the presence or absence of short sequences of amino acids called signal peptides. What would you expect to find in the polypeptide that will eventually fold to become RNA polymerase? A. No signal peptide B. An amino-terminal signal peptide C. A signal anchor peptide D. A nuclear localization signal

D. A nuclear localization signal

Some diseases result from defective transport across the membrane. For example, cystic fibrosis results when a chloride ion transporter does not function. What is affected when this transporter does not function? A. The electrical gradient of the cell B. Neither the chloride gradient nor the electrical gradient of the cell. C. The chloride concentration gradient. D. Both the chloride concentration gradint and the electrical gradient of the cell.

D. Both the chloride concentration gradint and the electrical gradient of the cell.

Which one is responsible for the addition of amino acids after translation initiation has begun? A. tRNA B. Small ribosomes subunits C. mRNA D. Elongation factors

D. Elongation factors

Which of the statements is true regarding glycine? A. Glycine is an asymmetric amino acid. B. Glycine is special because it contain a -SH group important in protein folding. C. Glycine is similar to tyrosine in terms of structure and chemical properties. D. Glycine increases the flexibility of the peptide backbone. E. Glycine is a large, polar amino acid.

D. Glycine increases the flexibility of the peptide backbone

In which of the ribosomal sites does the anticodon of a tRNA pair complete with the mRNA codon? A. The P site only B. The A site, the P site, and the E site C. The P site and the E site D. The A site and the P site E. The A site only

D. The A site and the P site

While many proteins move freely in the plane of the membrane, there are some proteins that are confined to specific places or regions of the membrane. If a membrane protein that is confined to a specific membrane region were labeled in a FRAP experiment, what result would you predict? A. the bleached spot will slowly recover fluorescence over time. B. The entire cell will become fluorescent over time C. the entire cell will become bleached over time D. the bleached spot will not recover fluorescence over time. E. it is impossible to predict the results of this experiment.

D. the bleached spot will not recover fluorescence over time.

All polypeptides have tertiary structure True or false

True

The sequence of amino acids in a protein is referred to as its primary structure True or false

True