Cell Bio Exam 3 Study Guide

Functions of the nuclear envelope

1. a selective barrier that separates nuclear and cytoplasmic elements 2. localizes chromosomes within the cell 3. sequesters many of the mRNA processing activities from the cytosol.

3 steps of cytokinesis in a plant cell

1. phragmoplast align Golgi-derived vesicles in the center of the dividing cell 2. Golgi-derived vesicles fuse to form the cell plate 3. vesicles with non-cellulose components assemble to form the primary cell wall

what type of protein is Ras?

A monomeric G-protein

What type of proetin is expected to be secreted from the cell.

A protein that is N-linked glycosylated

The low pH of lysosomes is established by

ATP-dependent proton pumps

the reception of a signal released by the same cell

Autocrine

What establishes the low level of cytosolic calcium ions in inactivated cells

Calcium ATPases

Intracellular messangers (4)

Calcium ions, IP3, DAG, cAMP

What cells would have a more rough ER?

Cells synthesizing secretory proteins

What is a sign that a cell has entered prophase?

Chromosome condensation

second messengers (4)

Cyclic adenosine monophosphate (cAMP), inositol trisphosphate (IP3), diacylglycerol (DAG), and calcium ions (CA2+)

3 examples of small or lipophilic primary messages that cross the plasma membrane and interact with steroid receptors

Estrogen, testosterone, and cortisol

Cellular response downstream of the GPCR-G protein will be long or prolonged if...

If G-protein binds a nonhydrolyzable analogue of GTP

signal that requires physical contact between cells. It is contact dependent.

Juxtacrine signaling

enzymes that add phosphate groups

Kinase

What activates MAPK (ERK)?

MEK (MAPKK or MAP2K)

Which proteins being to cross the membrane while being synthesized (aka cotranslational import)

Most proteins destined to enter the ER and the endomembrane system

What does the core oligosaccharide side chain in the ER contain?

N-acetyl glucosamine, mannose and glucose.

For a scientist to make a protein that will accumulate in the nucleus, he/she must add a(n) __________________ to the DNA that encodes for that protein

Nuclear Localization sequence

Where does clathrin organize a coat and form vesicles?

On the trans-golgi network (TGN) and the plasma membrane

What does the activation of the serine/threonine protein kinase Akt require?

PI 3-kinase to create phosphorylated lipids that serve as docking sites that localize Akt (protein kinase B) to the plasma membrane

enzymes that remove phosphate groups

Phosphatases

What transfers the terminal phosphate from ATP onto a protein?

Protein kinases

What activates MEK (MAPKK or MAP2K)?

Raf (MAPKKK or MAP3K)

What phase is Genomic, nuclear DNA is replicated in?

Synthesis phase (S-phase) of interphase of the cell cycle

What is site for N-linked glycosylation of polypeptides?

The endoplasmic reticulum (ER)

What involves the formation of large portein aggregates

The sorting of secretory proteins into regulated secretory vesicles in the trans-Golgi network.

What does a GTP-binding protein do to become activated?

a GTP-binding protein exchanges its bound GDP for GTP

What is Ras activated by?

a guanine nucleotide exchange factor, Sos

The centrosome contains

a pair of centrioles.

What is a hormone?

a signal that is used when a signal is sent to most cells throughout a multicellular organism

what does not occur in plant cells?

abscission

shortest stage of mitosis

anaphase

The Nuclear localization signal (NLS) in a nuclear protein

bound by importins or nuclear import receptors that direct the nuclear protein to the nuclear pore

What happens in interphase? (3 things)

cells grow in size the DNA is replicated the centrosomes are duplicated

What cells would have more smooth ER?

cells synthesizing steroid hormones

The continuous release of mucus by the epithelial cells lining the respiratory tract is an example of

constitutive secretion

importins/nuclear import receptors are

cytoplasmic proteins

When does clathrin form the coat?

during receptor-mediated endocytosis-coated pit formation

During anaphase A,

each chromosome is pulled to its respective spindle pole as its kinetochore microtubules shorten.

The DNA that encodes for a protein that is to accumulate in the ER will need to

encode for a signal sequence in order to be imported into the ER.

mitogens

extracellular signals that encourage cell division

Extracellular signals that regulate cell growth or proliferation

growth factors

What does hydrolysis of GTP to GDP in the Ras protein do?

helps to inactivate the RTK pathway

In receptor tyrosine kinase (RTK) pathways, GTPase activating proteins (GAP) stimulate _______________

hydrolysis of GTP to GDP in the Ras protein

When does nuclear envelope breakdown/fragmentation occur?

in prometaphase

Where will a protein destined to be secreted from a cell be found first?

in the ER

Where does N-Glycosylation of proteins start

in the Endoplasmic Reticulum

What is the nuclear envelope made up of?

inner membrane, intermambrane space, and the outer membrane

The ER is the major site for:

new membrane synthesis in the cell

Cells in Gap zero (G0 ) are

non-proliferative and do not divide

What organelles receive proteins by posttranslational import of proteins synthesized on cytoplasmic ribosomes?

nucleus, mitochondria, chloroplasts and peroxisomes

Where does clathrin form the coat?

on/at the plasma membrane

function of PI-3 kinase

phosphorylates a lipid in the plasma membrane.

The sequential order of the stages/phases of mitosis

prophase prometaphase metaphase anaphase telophase.

What is synthesized on the rough ER?

proteins to be delivered to the ER lumen

Role of Rho proteins

regulating the assembly and activation of the contractile ring during cytokinesis in animal cells

Most common types of protein kinase?

serine/threonine kinases

All members of the nuclear receptor family interact with

signaling molecules that diffuse through the plasma membrane

What is synthesized on the smooth ER?

steroid hormones

The mitotic spindle and sister chromatids appear to be ____________________ during metaphase, but in reality, _____________________

still and inactive each sister chromatid is being pulled toward its respective pole

The length of time that a G protein will signal is determined by

the GTPase activity of Gα.

Cells grow mostly in what phase?

the Gap one phase (G1 phase) of interphase of the cell cycle

N-linked oligosaccharides on secreted glycoproteins are attached to

the asparagine in the sequence AsnX-Ser/Thr.

Anaphase B may coincide with or follow anaphase A, depending on what?

the cell type

cytosolic proteins are completely translated in the ___________ and are transported to a target organelle by __________________.

the cytosol posttranslational import

The centrosome is

the microtubule organizing center (MTOC) in animal cells.

Genes that encode for nuclear proteins have DNA that encodes for what?

the nuclear localization sequence.

The ER membrane is contiguous with

the outer nuclear membrane

What would a protein need in order to accumulate in the ER?

the protein would have to have a KDEL sequence near its C-terminus (ER retrieval sequence) or a R-X-R sequence (ER retention).

During anaphase B,

the spindle poles are pushed further apart as interpolar or polar microtubules lengthen

What does a eukaryotic cell G2-M checkpoint evaluate?

the status of DNA replication

generation time

the time it takes a cell to progress through a complete cell cycle

what is cotranslational import

the transfer of polypeptides into the ER

What happens when a G-protein-coupled receptor (GPCR) activates a G protein?

the α subunit exchanges its bound GDP for GTP