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Cell Bio > EXAM #3 Review > Flashcards

EXAM #3 Review Flashcards

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Biology 101 flashcards
1
Q

A signal molecule that binds to a plasma-membrane protein is a:

A

Ligand

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2
Q

The three stages of cell signaling are:

A

Reception, transduction, and response

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3
Q

True/False
The addition and removal of phosphate groups on proteins are mediated by two different enzymes, phosphatases, which bind ATP and transfer a phosphate group to the target protein, and kinases, which remove phosphate groups from proteins.

A

False

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4
Q

What determines if a signaling molecule binds to a receptor on the surface or enters the cell?

A

size, hydrophobicity, and ability to cross the plasma membrane

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5
Q 
Adenylyl cyclase is used in a GPCR signal transduction pathway to
A. Form ATP from cAMP
B. Remove a phosphate from cAMP
C. Hydrolyze GTP to GDP
D.  Bind a ligand
E. None of the above
A

E. None of the above

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6
Q

Identify the description of signal amplification
A. One receptor protein binds to many different primary messenger molecules
B. One messenger molecule activates many second messengers
C. One intracellular enzyme modifies one protein within the cell
D. A primary messenger activates transcription by binding to many different promoters

A

B. One messenger molecule activates many second messengers

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7
Q

Which of the following mutations would NOT result in constitutive activation of the associated signaling protein?

A. A mutation in Ras that prevents its hydrolysis of bound GTP to GDP

B. A mutation in MAP kinase that prevents its association with MAPKK

C. A mutation in MAPKKK that prevents its translocation to the nucleus

D. A and B

E. A and C

A

A. A mutation in Ras that prevents its hydrolysis of bound GTP to GDP

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8
Q

True/False
While a GPCR pathway controls the synthesis and degradation of glycogen, insulin signaling is controlled by a receptor tyrosine kinase pathway.

A

True

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9
Q

Name the four essential structural components of a receptor tyrosine kinase molecule

A
  1. Extracellular ligand binding domain
  2. Single membrane spanning alpha helix
  3. Cytosolic region with weak protein tyrosine kinase activity
  4. C-terminal domain containin tyrosine residues
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10
Q 
Which of the following a NOT a characteristic of microfilaments 
A. Composed of tubulin subunits
B.  Function in muscle contraction
C. Dynamically grow and shrink
D.  Have a cable-like structure
A

A. Composed of tubulin subunits

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11
Q

What cellular filament is found in the flagella of eukaryotic cells?

A

Microtubules

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12
Q 
What cytoskeletal component is comprised of G-actin subunits organized into polymers
A. F-actin
B. Microtubules
C. Microfilaments
D. Myosin
A

C. Microfilaments

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13
Q

True/False

Cilia and flagella are composed of microtubules arranged in a 9+4 formation

A

False

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14
Q

Name the cytoskeletal structure essential for mitosis.

A

Centrosomes (microtubules)

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15
Q 
During what stage do condensed chromosomes consisting of two sister chromatids begin to appear?
A. Anaphase
B. Telophase
C. Prophase
D. Interphase
A

C. Prophase

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16
Q

What types of motor proteins are associated with movement of chromosomes during mitosis?

A

Kinesin and dynein motors

17
Q

What is the function of centrioles in the transmission of genetic information

A

Formation of the mitotic spindle

18
Q

kangaroo has 16 total chromosomes in a diploid cell. How many kinetochores are present in a kangaroo cell at mitosis?

A

32

19
Q

Interphase is the longest stage of the cell cycle. What three sub-phases occur during interphase?

A

G1, S, G2

20
Q

What cyclin molecule interacts with two different cyclin dependent kinase molecules to mediate the cell cycle?

A

Cyclin A

21
Q

If DNA damage is detected after DNA replication has been completed, protein kinases phosphorylate ________, which prevents dephosphorylation of _________, inhibiting activation of the mitosis promoting factor (MPF).

A

CDC25, CDK1

22
Q

True/False
Crossing over and the exchange of genetic information between homologous chromosomes occurs during prophase II of meiosis

A

False,

occurs during Prophase I of meiosis

23
Q

True or False
Due to both their extreme size and hydrophilicity, steroid hormones cannot be transported through the plasma membrane and must instead rely on signal transduction pathways to impact cellular function

A

False

24
Q 
What of the following is NOT an example of a secondary messenger
A. Calcium
B. cAMP
C. Phosphokinase A
D. cGMP
A

C. Phosphokinase A

25
Q

Glycogen synthesis is controlled using a GPCR signal transduction pathway in response to glucogon or epinephrine. Which statement regarding this pathway is NOT correct

A. Phosphorylation of glycogen synthase by activated phosphokinase A leads to glycogen degradation to glucose

B. High cAMP levels inactivate phosphokinase A, allowing for phosphorylation of both glycogen synthase and glycogen phosphorylase

C. Activated phosphokinase A inactivates glycogen synthase via phosphorylation, preventing synthesis of glycogen molecules

D. A and B

E. A and C

F. B and D

A

D: A and B

26
Q

Which of the following is NOT a step in rod phototransduction by rhodopsin?
A. Activation of rhodopsin by photons
B. Conversion of cGMP to GMP by phosphodiesterase
C. Opening of cGMP-dependent ion channels and hyperpolarization of the membrane
D. Activation of phosphodiesterase by light-activated rhodopsin through Gαt

A

C. Opening of cGMP-dependent ion channels and hyperpolarization of the membrane

27
Q

True or False
Receptor tyrosine kinases (RTKs) are another type of signal transduction receptor molecule. Instead of using a heterotrimeric G protein complex to transduce the signal, RTKs are able to activate Ras GTPase, which then activates an effector molecule.

A

True

28
Q

Which of the following statements about myofibrils is correct?
A. Myofibrils are composed of filaments of actin and keratin
B. Myofibrils are cylindrical bundles of actin and myosin found in the cytoplasm of muscle fibers
C. Myofibrils are organized into chains called sarcomeres that are involved in muscle contraction
D. A and B
E. A and C
F. B and C

A

F: B and C

29
Q

What is the answer to the extra credit question on the exam?

A

Happy Holidays!

30
Q

True/False

Free energy from the hydrolysis of GTP drives the polymerization of actin monomers

A

False (actin polymerization utilizes ATP)

31
Q

Unlike microfilaments and microtubules, intermediate filaments are a diverse group of proteins that share structural features and cellular roles. Which of the following statements regarding intermediate filaments is NOT correct?

A. All intermediate filaments consist of a central α-helical rod domain with variable amino and carboxy terminal regions

B. Are not found in yeast of plant cells

C. Formed by protofilaments of antiparallel tetramers

D. Are highly dynamic and show (+)/(-) polarity based on the sequence of their amino termini

A

D. Are highly dynamic and show (+)/(-) polarity based on the sequence of their amino termini

32
Q

Which of the following in the sliding filament model of muscle contraction does not occur
A. Ca+ is released from the sarcoplasmic reticulum and bind to troponin
B. Myosin releases actin
C. Power stroke
D. ATP binds to actin

A

D. ATP binds to actin

33
Q 
The G1 checkpoint in budding yeast is called what?
A. The point of no return
B. The turning point
C. The START point
D. The restriction point
A

C. The START point

34
Q 
You discover a mutant kidney cell that continues to undergo mitosis even though it has not reached adequate size. A protein analysis of the cell shows high levels of cyclin E throughout the cell cycle; however, sequencing of the cyclin E gene reveals no mutations. What other genes would you then analyze to explain this phenotype?
A. Cyclin A
B. Wee1
C. Rb
D. CDC25
A

C. Rb

35
Q 
Mitosis promoting factor or maturation promoting factor (MPF) is a dimer that controls entry and exit from mitosis. It is composed of what cyclin/CDK pair
A. Cyclin A/CDK1
B. Cyclin B/CDK1
C. Cyclin D/CDK4/6
D. Cyclin B/CDK2
A

B. Cyclin B/CDK1

36
Q 
What two protein kinases recognize DNA damage in the form of double or single-stranded breaks to halt progression through the cell cycle
A. CDC25; Wee1
B. PKA; PKC
C. Rb; E2F
D. ATR; ATM
A

D. ATR; ATM

37
Q

A pre-replication complex consisting of origin recognition proteins and an inactive helicase complex associates with origins of replication prior to the initiation of S phase. What processes are responsible for activation of the pre-replication complex

A. Phosphorylation of helicase by cyclin E/CDK2 and DDK

B. Dephosphorylation of helicase by cyclin E/CDK2 and DDK

C. Upregulation of DNA polymerase production by phosphorylation of Rb

D. Activation of helicase after DNA cleavage by topoisomerases+

A

A. Phosphorylation of helicase by cyclin E/CDK2 and DDK

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