Unit 4 - Signal Transduction, Cell Communication & Cell Cycle

Question 1

Lipid Characteristics

Answer 1

• nonpolar
• cross the membrane
• receptors in nucleus

steroid hormones

Question 2

Protein Characteristics

Answer 2

• polar
• CANNOT cross the membrane
• membrane protein receptors

Question 3

Direct

Answer 3

• Plasmodesmata
• Gap Junctions

Question 4

Short Distance w/ signals

Answer 4

• nerve cells
• skin (white blood cells, same cell, local regulators—immune system)

Question 5

Long Distance w/ signals

Answer 5

• hormones in endocrine (travel through blood)
• different cells

Question 6

Endocrine

Answer 6

secrets ligand that travels through blood

Question 7

Paracrine

Answer 7

sends ligand and binds to nearby cell

Question 8

Autocrine

Answer 8

sends ligand which binds to its own membrane

Question 9

Synaptic signaling

Answer 9

Neurotransmitters are the ligand which go to the ion channel receptor which is a gate

Question 10

Endocrine example

Answer 10

Gland will release ligand (can be lipid or protein)

Lipid will go through blood stream and enter nucleus directly

Protein will have to bind to another receptor which will then go to a target cell

Question 11

Quorum Sensing

Answer 11

Restriction of activity until there is a high density

Then bacteria will sense that it is time to start and turn on gene expression

Question 12

Receptor mutation

Answer 12

chemicals can activate/inhibit the release of signals

Question 13

G-Protein signal transduction

Answer 13

Ligand attaches to the protein which starts a signaling pathway
The G-protein is inactive until the ligand binds and the GDP will turn to GTP and move the alpha sub unit to the Adenylyl Cyclase
This will convert a bunch of ATP into cAMP (secondary messenger) which will attach to kinase that will phosphorylate proteins as the response

Question 14

Signaling Cascade

Answer 14

Amplifies a signal

Question 15

Kinase

Answer 15

phosphorylate other molecules to enable them to do work

Question 16

Negative Feedback Loop

Answer 16

Body temp, maintaining homeostasis

Insulin and glucose in pancreas

Question 17

Positive Feedback Loop

Answer 17

Amplify response

fruit ripening, child birth contractions, blood clots

Question 18

G1

Answer 18

normal functions for life
- cellular content (minus the chromosomes) are doubled—cell grows

Question 19

G1 checkpoint

Answer 19

checks if there is any DNA damage, cell size/growth, nutrients

go = irreversibly commited

Question 20

S

Answer 20

copy the DNA

parent will split into 2 identical daughter cells

mutations can occure

Question 21

G2

Answer 21

finals checks of the doubled DNA

Question 22

G2 checkpoint

Answer 22

checks for the completion of replication and DNA damage

go = mitosis
stop = try to fix/apoptosis

Question 23

M checkpoint

Answer 23

check the microtubule attachment on chromosomes at metaphase

go = anaphase
stop = allow spindles to attach

Question 24

Chromatin

Answer 24

uncondensed DNA

Question 25

Kinetochore

Answer 25

where spindle fibers attach

Question 26

Prophase

Answer 26

1. duplicated chromosomes condense
2. nuclear encelope breaks down
3. centrosomes (each sister chromatid) move to opposite sides

Question 27

Metaphase

Answer 27

1. line chromosomes up int he middle
   - centrosomes send out spindle fibers to attach to kinetochore

Question 28

Anaphase

Answer 28

1. sister chromatids are pulled to opposite sides
   - once they are separated they are considered individual chromosomes

Question 29

Telophase

Answer 29

1. new nuclear envelope
2. DNA uncondenses

Question 30

Cytokinesis

Answer 30

Animals: cleavage burrow
Plants: new cell plate

back in G1

Question 31

Cyclin/CDK

Answer 31

There is always a constant amount of CDK in the body

Depending on checkpoints and whether to go or not, cyclin will activate CDK to start a response and then stop/break down to stop a response

Question 32

P53

Answer 32

Tumor suppressor cell
creates a CDK inhibitor – if it is not functioning, there is no inhibitor which will allow mutated DNA to pass through the checkpoint and uncontrolled cell growth

Question 33

RAS (Proto-oncogene)

Answer 33

active even without a ligand

leads to overexpression and overdividing

Question 34

Anchorage Dependence

Answer 34

rely on the attachment of other cells/the extracellular matrix to divide

Question 35

Chi < critical

Chi > critical

Answer 35

fail to reject the null

reject the null