Biol 102 Unit 4

Cell Signaling, Cytoskeleton, Cell Division

Describe the makeup of microtubules

Rigid, cylindrical tube made of Alpha and beta tubulin subunits.

Describe the make up of Actin

Solid, thinner structures, organized into a branching network, is recycled

The cytoskeleton has 4 main functions

1) Provide structural support and cell shape

2)Position organelles

3) Provided tracks from mRNA and organelles to move within cells

4) move cells

Actin binds and hydrolyzes___

ATP

Alpha and beta tubulin bind a molecule of GTP

GTP

How does muscle contraction work

Myosin is a motor protein that moves along actin filaments, causing muscle contraction by sliding the actin and myosin filaments past each other

Provides energy for skeletal muscle

ATP

Centrosomes in animals are ____ organizing centers

Microtubule

Spindle pole

The centrosome that microtubules stretch from during mitosis

Cofilin

Severs actin filamets

Arp2/3 complex

Catalyzes the nucleation phase for actin

Cyclin - Cyclin dependent Kinase complex (CDK)

Molecular switch that regulate cell cycle check points

Dynamic instability

The rapid shrinking of microtubule

When a microtubule stops growing and starts to rapidly shrink

Catastophe

Kinesin

Microtubule motor protein related to myosin

What is the longest part of cell cycle

G1

The restriction points of the cell cycle can be passed even if the environmental conditions are not favorable

Yes, in the case of mutated check proteins

centriole

In side the centrosome, along with gamma tubulin ring complex made of microtubles and can be mother and daughter

Centromere

Middle of the x in a chromosome

Kinetochore

complex that forms on the centromere to allow the microtubules to attach to the chromosome

What is the order of mitosis 1-5

PPMAT

When is the spindle assembly checkpoint silenced

when All kinetochores are attached to microtubles

Meiosis in oocytes generates eggs with a reduced genome size because

DNA is not replicated between Meiosis 1 and II

What do Phosphatases do

Remove phosphate groups from molecules not GTP

What does a Kinase do

Add phosphate groups

What is a molecular switch

a biological molecule that switched between active and inactive

Nucleation

The longest stage of actin assembly unless a template is added

___- ___ is at the minus end of actin while ___ -____ is at the plus end

Actin ADP, Actin ATP

Intermediate Filaments

Fibrous protein that is not polarized apart of the cytoskeleton

What do Microtubules do durring cell division

Control chromosome separation

filamentous action role during cell migration

Pseudopod formation

Effector protiens

amplify signaling pathways in the cytoplasm

Describe calcium signaling

1) calcium is released as the result of some signal

2) it binds to a receptor (Like calmodulin)

3) the receptor actives down stream pathways

Trimeric G protien

a protein complex composed of three subunits (α, β, and γ) that transmits signals from cell surface receptors to intracellular signaling pathways in response to external stimuli

G alpha

Binds to GTP when interacting directly with the Receptor

Arestin

Binds to receptors to turn them off

GTPase

hydrolyzes GTP (guanosine triphosphate) to GDP (guanosine diphosphate)

Ras

Binds to GTPase that is an effector for tyrosine kinases

List the order of events with a G protein coupled receptor

1) Ligand binds to receptor

2) a GDP molecule is exchanged for a GTP molecule

3) G alpha is activated and activates an effector

4) a second Messager is produced

5) G alpha is deactivated

Endocrine signaling

Long distance signaling

Autocrine signaling

Same cell signaling

Paracrine signaling

Neighbor cell signaling

membrane signaling

Connected cell signaling

GAP

GTPase Activating Protein, accelerates the hydrolysis of GTP to GDP and inactivating them

GEF

Guanine nucleotide exchange factor, Premotes the exchanf of GDP from GTP on GTPases

A signaling molecule can have _______ purposes

Many Different

What are the steps of Receptor tyrosine kinase

1) Ligand Bonds

2) dimerization of the two complexes

3) Autophosphorylation

4)Adaptor protein recruitment

5)Activation of GEF

6) Ras activation

7) downstream signalling

Put the Cytoskeleton Filaments in order of size

Actin < Intermedial < Microtubules

apical layer

Faces lumen of the cell exposed to the enviorment

Basal

attached to connective tissue in the ECM

Formin

Shifts actin to allow easy edition of actin monomers

Profilin

Binds to the monomer and aids in the exchange in ADT for ATP

Cappin

A cap to stop elongation

The plus end of microtuble is ____ and the minus end is ____

GTP, GDP

Alpha and beta tublins come together to make ___

Protofiliments

Kinesins are ____ that walk toward ____ and hydrolyse ____

Microtubule Motors plus end ATP

Dynein

Massive Microtubule motor

G1 takes____ Hours and its purpose is to _____

10, Grow and duplicate organelles and proteins and RNA

S phase is ______ hours and _______

7.5 Hours , Duplicates DNA, Histones, and Centrosomes duplicate

G2 Phase

Cell continues to grow for division

Name the check points in the cell cycle

1) G1 (restriction point ) ensures favorable enviroment

2)G2 ensures no DNA dammage

3) Metaphase ensures chromosomes are attached to miotic spindle

p53

will stop a damaged cell from continuing to replacte by binding to p21 and lettign p21 inactive cdk

Prophase

• Chromatin condenses into visible chromosomes (each with two sister chromatids).

• The nuclear envelope begins to break down.

• The nucleolus disappears.

• The mitotic spindle begins to form from the centrosomes.

• Centrosomes move toward opposite poles of the cell.

Prometaphase

• The nuclear envelope fully disintegrates.

• Spindle fibers extend from the centrosomes and attach to the kinetochores of the chromosomes.

• Chromosomes begin moving toward the cell's center.

Metaphase

• Chromosomes align at the metaphase plate (center of the cell).

• Spindle fibers ensure that each chromosome is attached to spindle fibers from both poles.

Anaphase

• Sister chromatids are pulled apart toward opposite poles of the cell.

• The centromere splits, and the chromatids are now considered individual chromosomes.

Telophase

• Chromosomes begin to de-condense back into chromatin.

• Two new nuclear envelopes form around the separated sets of chromosomes.

• The nucleolus reappears in each nucleus.

Cytokinesis

• A cleavage furrow forms at the center of the cell, where the actin filaments contract to pinch the cell membrane inward.

• This process continues until the cell is pinched in two, forming two distinct daughter cells.