Bio Exam #3

How do bacteria reproduce?

binary fusion

During telophase, chromosomes uncoil to allow for gene (blank).

expression

MPF was first discovered in studies of (Blank)

frog oocytes

Passage through which checkpoint is a commitment to cell division?

g2/M checkpoint

One complete set of chromosomes necessary to define an organism is also known as the (blank) number of chromosomes.

haploid

The haploid and diploid number of chromosomes in an organism are usually represented as (Blank).

n for the haploid number, and 2n for the diploid number

The bacterial genome consist of a single loop of DNA located in which of the following regions of the cell?

nuceloid

During telophase, the nuclear envelope re-forms to produce two separate (Blank).

nuclei

The region in a bacterial cell where DNA is located is called the

nucleoid

In bacterial cells, the replication of DNA begins at a specific site called the origin (Blank) , of replication, and proceeds in both directions around the circular DNA until a specific (Blank)site is reached.

origin, termination

In bacterial cells, the (blank) replication of DNA begins at a specific site called the of replication, and proceeds in both directions around the circular DNA until a specific (blank) site is reached.

origin, terminus

MPF is activated by a (blank) enzyme which removes inhibitory phosphates from its (blank) component.

phosphatase, Cdc2

Cdks are enzymes which regulate proteins within the cell cycle via (Blank)

phosphorylation

Cytokinesis in (blank)cells does not involve a cleavage furrow, but rather a cell plate.

plant

Cytokinesis in plant cells involves the formation of a cell (blank) which starts at a right angle to the spindle apparatus in the interior of the cell and extends out to the plasma (blank).

plate, membrane

Which is the first stage of mitosis?

prophase

The enzymatic activity of MPF involves the phosphorylation of which types of molecules?

proteins

Bacterial cells divide to produce new cells for which of the following?

reproduction, population growth

After DNA replication each condensed chromosome is made of two identical halves called

sister chromatids

During the (Blank) phase of the cell cycle, the chromosomes are replicated.

synthesis

(blank) is the final phase of mitosis.

telophase

During the stage of mitosis known as (blank) chromosomes uncoil into extended forms that will permit gene expression.

telophase

When is the spindle apparatus broken down?

telophase

Order the steps of signaling via a GPCR as they occur in the cell (start at the top). cellular response, Activation of effector protein, Binding of ligand to the receptor, & Activation of G protein

1. Binding of ligand to the receptor 2. Activation of G protein 3. Activation of effector protein 4. cellular response

In liver cells, glucagon and epinephrine bind to two different GPCRs but initiate the same signaling pathway. Place the proteins that are activated in this pathway in the correct order of activation, starting at the top.Protein kinase A, Phosphorylase kinase, adenylyl cyclase, & Glycogen Phosphorylase

1. adenylyl cyclase 2. Protein kinase A 3. Phosphorylase kinase 4. Glycogen Phosphorylase

Click and drag on elements in order Order the steps in binary fission from first to last, starting at the top.

1. bacterial DNA molecule begins replication 2. cell elongates and the replicating DNA is partitions such that the origins are at the 1/4 and 3/4 positions in the cell 3. separation begins 4. the cell pinched in two, forming two daughter cells

What is the haploid number of chromosomes in humans?

23

Typically, a dividing mammalian cell completes its cell cycle in about how many hours?

24hrs

Cells control the cell cycle by integrating internal information and external signals and delaying (or even halting) the cell cycle at (blank) (number) checkpoints.

3

Identify the diploid number of chromosomes in humans.

46

G-protein-coupled receptors contain (Blank) transmembrane segments.

7

Which of the following cells never leave the G0 phase of the cell cycle?

Human muscle cells Human neurons

How are the two second messengers IP3 and Ca2+ related inside the cell?

IP3 activates receptors on the ER which act as Ca2+ channels.

Which statement accurately compares cell division in bacterial and eukaryotic cells?

In both types of cells, cell division produces two new cells with the same genetic information as the original cell.

In a cell's life, cell growth occurs primarily during what phase?

G1

In yeast cells the Cdc2 enzymes works with different cyclins to control which checkpoints in the cell cycle?

G1/S G2/M

Which of the following checkpoints is the primary checkpoint at which external signals can influence the cell cycle?

G1/S checkpoint

Which of the following is the start or restriction point for cell division?

G1/S checkpoint

Where were cyclins first discovered?

In the embryos of sea urchins

Condensation of chromosomes is initiated in the (Blank) phase of interphase and continues until the end of prophase.

G2

In the eukaryotic cell cycle, what is the name of the phase that occurs after the replication of DNA and before the start of mitosis?

G2

Which of the following phases occurs after the replication of DNA and before the start of mitosis?

G2

Damage to DNA can halt division of the cell at which stage of the cell cycle?

G2/M checkpoint G1/S checkpoint

What are the three checkpoints at which the cell cycle can be delayed, or even halted, depending on the cell's internal state and any external signals it may have received?

G2/M checkpoint G1/S checkpoint Metaphase checkpoint

What is the role of a G protein in the cAMP signaling pathway?

It activates adenylyl cyclase.

The pathogenic bacterium V. cholerae produces a toxin that binds to a GPCR in the epithelium of the gut. What happens to the affected GPCR?

It becomes locked in the "ON" state.

How does calmodulin initiate a cellular response?

It binds to and activates other proteins.

In the cAMP signaling pathway, cAMP activates the enzyme PKA. What does this enzyme do?

It phosphorylates different target proteins depending on the cell.

What is the action of activated PKA in the kidney's tubule cells?

It stimulates the production of water channels.

Choose all true statements about the activity of MPF.

MPF activity varies during the cell cycle. MPF acts as a protein kinase.

What event must occur before a G protein can return to its inactive state?

The GTP must be hydrolyzed to GDP.

Regarding GPCRs, what is the fate of the three subunits in the activated G protein?

The activated G protein dissociates into Gα and Gβγ either of which could activate effector molecules.

Which of the following describes the response of skeletal muscle cells to an outflow of Ca2+ from the ER?

The cells respond by contracting.

Protein kinase A is activated by the second messenge

cAMP

The symptoms of cholera are due to a large increase in the intracellular levels of the second messenger (blank) in gut cells.

cAMP

Adenylyl cyclase is an effector protein that produces the second messenger (Blank)

cAMP or cyclic-AMP

What is a sequence of growth, replication, and division that produces new eukaryotic cells called?

cell cycle

What usually occurs during the G1 phase?

cells are growing

If necessary (e.g., if DNA is damaged), the cell cycle can be arrested at specific points called (Blank).

checkpoints

Cytokinesis in animal cells involves the formation of a (blank) furrow around the cell.

cleavage

When DNA replicates, the sister chromatids are held together at their centromeres by which of the following complex of proteins?

cohesins

In multicellular eukaryotic organisms, the production of new cells follows a highly regulated sequence of growth, DNA replication, and division. This sequence is referred to as the cell (blank) , which consists of the G1, S, G2, and M phases

cycle

The cell (black) of multicellular eukaryotes is regulated by multiple Cdks and external signals.

cycle

Full activation of the Cdc2 kinase requires complexing with a (blank) and the correct pattern of. (blank).

cyclin, phosphorylation

Protein kinases that regulate the cell cycle and are only active when complexed with the protein cyclin are called (Blank)

cyclin-dependent kinases

The (blank) is another name for the anaphase-promoting complex (APC/C).

cyclostome

Which of the following will typically have lower calcium levels?

cytoplasm

How is the activity of MPF controlled in the cell?

The kinase component of MPF is inhibited by phosphorylation.

(Blank) proteins link GPCRs with effector proteins.

G

Phosphorylation within the cell cycle is performed by enzymes called

Cdk

The (Blank) enzymes control progression through the checkpoints in the cell cycle.

Cdk

In humans, light-sensing receptors and odorant receptors (responsible for our sense of smell) are (Blank)

G protein-coupled receptors

Select the two components of an active Cdk.

Cyclin A protein kinase

Two irreversible points in the cell cycle are replication of (blank) material and (blank) of sister chromatids.

DNA, separation

What does the second messenger DAG activate?

Protein Kinase C

Which enzyme is activated by cAMP?

Protein kinase A

What is the order in which molecules are activated in a signal transduction pathway involving a GPCR?

Receptor, G protein, effector protein

Once a GPCR is activated, it causes the G protein to do which of the following?

Release GDP and bind GTP

Which of the following is the key event in anaphase?

Removal of cohesin proteins from the centromeres of sister chromatids

Which of the following does not occur during the mitosis phase of the cell cycle?

Replication of chromosomes

During which phase of the cell cycle are the chromosomes replicated?

S phase

The genome of most bacteria is composed of (Blank).

a single, circular DNA molecule

In a typical, mature, dividing mammalian cell, what proportion of the cell cycles is taken by mitosis?

a very small fraction (about 5%)

During the five phases of (blank) , the replicated genetic material is partitioned into (blank) new nuclei.

mitosis, 2

The cleavage furrow of animal cells is formed with the help of a constricting belt made of the protein (blank).

actin

The enzyme that produces cAMP from ATP is called

adenylyl cyclase

At the beginning of which phase do the centromeres of sister chromatids split apart allowing sister chromatids to separate from each other?

anaphase

During the (blank) of mitosis, the centromeres of sister chromatids split apart allowing sister chromatids to move away from each other.

anaphase

The shortest stage of mitosis is

anaphase

Which of the following is the shortest stage of mitosis?

anaphase

Because they are composed of three different subunits, G proteins associated with GPCRs are also known as (Blank) G protein

heterotrimeric

Cell division in both bacterial and eukaryotic cells produces genetically (blank) cells.

identical

During (blank) which includes the G1, S and G2 phases of the cell cycle, the cell grows and chromosomes replicate in preparation for cell division.

interphase

While preparing to divide, the cell grows and copies its chromosomes during which stage?

interphase

Diacylglycerol (DAG) activates protein (blank) (blank)

kinase C

During prometaphase, which protein complex on each sister chromatid attaches to the spindle?

kinetochore

MPF is an acronym for

maturation promoting factor

During (blank) the chromosomes are aligned midway between the spindle poles.

metaphase

The part of the cell cycle that is subdivided into five phases, during which the spindle apparatus assembles, binds to chromosomes, and moves sister chromatids apart, is

mitosis