Unit 485 : cell Communication Cycle Heredity ,

1. Cell Communication
Hard topics

kynase
-

Complex /
(as 9- sg RNA
to
activate
↳ used
genes
dea**✓ problematic
t
:
STP ?
this process ?
CRISPR
MCQ # 1

interruption of M to a
single cell

→
stop inhibition → cell continue cell division

protein 3 can still attach even cells connent .

⑥
MCQ #2
-08¥ → response
disrupted .
→ glucose to

normal cell

glucose ⇐
""

Irk>

÷÷÷E"÷i⇒
→ Enix
receptor

"°"
IRS -1
→ am Emi

# 48 -
IA ) → intern

# 49 -

(C)
MCQ #3

more ATP → thicker .

C X DX

r*ɱ④
*÷÷
#4
⑤ second messenger

FRQ # 1
molecule binds
Step 1- is when the signaling to

the it allow
receptor .

By doing so
,

the
the
signal molecule to enter
cell .

Step 2 to change shape to enter nucleus

.

change gene
Step 3 express nn .

MCQ #5

#6
①
#"
⑤ no cycle regulation .
Unit 4 : cell Communications :

cellular must be able to communicate with

organisms
other cells to relay information

Prokaryotic cells = send & receive signals that regulate growth

ex)
quorum sensing
-

Eukaryotic cells = coordinate efforts as a whole

organism
ex)
fight off infections
,
respond to stimuli,

growth spurts ,
maintain homeostasis, - . .

Example : Quorum
sensing
1) bacteria can secrete chemical

signals to the
neighboring environment

2) neighboring bacteria that sense these

signals can respond in various ways

:

for specialized functions

→ stop dividing ,
express genes

Example : Yeast Mating Signals

-

2 types of yeast : a
,
✗

a -
send a signals
L receive a signals

✗ send ✗ signals
[ receive a signals

bound to receptor
-
Once signal is a

+ yeast begin growing towards that direction

→ fusion of 2 cells
→
exchange DNA

→
diversify genes
→ meiosis into a or a types
 Communication Methods
1. Direct contact cells communicate through direct contact
=
neighboring
① ②

l l l l
0=1711 '¥¥E¥± 7¥ -0¥

① Example : cardiac muscle cells =

ions transfer through gap junction

② Example : cytotoxic T cells = direct

binding of
antigens & TCR proteins

2. Paracrine signaling = secrete signals a short distance

through ECF or blood . → short distant

ex) growth factors ( SHH protein)

-
once signal is created & secreted outward
→
neighboring cells receive the signals
& begin dividing
short distance
p
secrete
3. Synaptic signaling = neurons chemical signals
a short distance towards target cells

ex) dopa min , acetylcholine

-
neurotransmitter molecules are secreted
into synapses
↳
gaps btw axon terminals

& target cells

4. Endocrine signaling =
chemical signals are secreted into 10h9
the blood stream & distance
y
can travel throughout the entire organism
ex) insulin ,
glucagon
-

peptide hormones secreted in the pancreas

travels through blood &

affects liver & muscle cells

Intro to signal Transduction

of cell
3 stages signaling
Regardless of type ,

basic principle :
all cell
signaling follows the same

stage 1) Reception = receive signal

stage 2) Transduction =
relay signal
Response to cell
stage 3) =
changes
 Ligands = molecules that bind to receptors & act as
signals
-

ligands can be large polar or small nonpolar molecules

small nonpolar ligands can pass through cell membrane easily

f) large polar ligands cannot .

" "
Receptors =
proteins that can catch ligand signals
-
receptor proteins can exist in the membrane or

within the cytoplasm / nucleus depending ,

on
type of ligand

Membrane Bound Receptors

-
receptor proteins embedded in the plasma membrane

can be divided into 3 regions :

Reception met outside the cell

by membrane receptor proteins
✓
-
membrane receptors → polar ( hydrophilic ) ligands

↳ eh coupled receptor, kinase

G protein -

Tyr ,
ion channel

-
intracellular receptors →
nonpolar ( hydrophobic) ligands
↳ \
ex) lipid -
based hormone receptors are received
within the cell
 6 Protein -

Coupled Receptors
1) transmembrane receptor protein

2) Crosses the membrane 7 times

3) widespread & diverse functions ( vision , embryo dev .

,
- - .

)
4) malfunctions linked with diseases, infections ( cholera , - . .

Receptor Tyrosine kinase

1) membrane protein with 3 prominent regions of tyrosine

to dimer formation
2) ligand binding leads

3) Dimers phosphorylate each others tyrosine

4) malfunctions linked with abnormal cell growth
 Ion Channel Receptors
"
1) membrane receptor gate
"
acts as for ion flow

ligand binding
"
2) results in protein shape change open
"

3) important role in neuron

signaling

lipid -
based Hormone Receptor

-
Aldosterone ( steroid hormones passes through membrane

receptor located in cytoplasm

-

Process :

1) activated complex enters nucleus & binds to specific gene

2) Activated complex functions as transcription factor,

stimulating transcription of gene

3) mRNA transcription leads to translation

4) response protein formed

t
< effects >
① Changes to target cell

② increased secretion of protein cell division - - -

, ,
 series of enzymatic rxns
Phosphorylation Cascade
→ that greatly amplifies the initial signal .

Activated receptors can cause chain rxns of

changes inside the cell .

Transduction Roles

1) original ligand might not be actual signal

that causes final response of the cell

2) more steps in a sequence adds more points of control & regulation

3) Chain reactions can amplify signal response

second first messenger ligand

Messengers
:

= small ,
non -

polar , water-soluble molecules / ions

signal transduction
that participates in

→ act as signals within the cytoplasm

( replacing the original signal that cannot pass through plasma membrane)
"
ex) CAMP, Ca ( IB )
Cyclic AMP C CAMP)
CAMP activates
next step of Protein

ATP > CAMP > kinase A

transduction
enzyme
(Adenylyl cyclase)

"
ca and IB

Ligand →
Gptn activate → Phospholipase C activate

→ PIP , cleavage → IB formation

→
binding to IP } -

gated calcium channel

→ release of Cations in cytoplasm → cellular response

 Cellular Responses

cellular response can be varied in results :

gene transcription leading to protein synthesis

-

-
release of calcium ions into cytoplasm
-
membrane growth in a particular direction

same ligands result in different

can responses depending on type of cell :

Epinephrine ( liver) : break down glycogen

-

Epinephrine C heart) : contraction of muscle tissue

ex)
apoptosis , cytokines , quorum sensing ,
insulin , - . .

Apoptosis = death of cell

1) When cytochrome c is leaked from mitochondria to cytoplasm

→ it
triggers apoptosis response

* mitochondria that plays

cytochrome c = protein in a role

in oxidative phosphorylation

2) Death signals is also picked up from outside of cell

→ resulting in a cascade of pathways that activates

Ced -3 Ced -4, proteins

,

→
apoptosis reaction
Cytokines = various polar proteins that play a role in cell
signaling

1) Interferons released
:
protein signals by

(
virus -
infected cells

prevents protein synthesis & cell division from occurring

Mitosis
2)
Promoting Factor : protein signals created within the cell

to promote cell division ( mitosis)

Quorum Sensing CQS)

 Mitosis =
reproduction of the nucleus

= the splitting of duplicated chromosomes into 2 separate sets

-
Consist of 4 stages

1 .
Prophase

1) Chromatin begins to coil into chromosome form

2) nuclear envelope ( membrane) disappears

3) mitotic spindle begins to form

1- Chromosome
→ 1 double stranded
-

chromosome
2. Metaphase
1) Chromosomes line up at the middle of the cell
C metaphase plate

2) microtubules attach to the centromere

region of chromosomes

1 double stranded
chromosome
3. Anaphase

1) shortest stage ( → 5min )

2) Chromatids separate to opposite ends

[ now referred as individual chromosomes)

2 chromosomes

4. Telophase

1) daughter nuclei form

2) chromosomes become less condensed

( return to chromatid forms)
3)
remaining microtubules de polymerized
1 chromosome for each nucleus
Cytokinesis =
splitting of cell into 2 daughter cells
1211012021 Notes :

Cancer disease from accumulation of genetic (mutations)

resulting
=
a

common Terms

Proto-oncogene =
a normal cellular gene that regulates
cell
growth that can be activated

to
generate an
oncogene .

Oncogene mutant form of

gene that favors
-

=
a a

-
On co protein

Angiogenesis
-

-
Papillomavirus

p53 prohibited by E 7 &E6

ur

↳ otzotok DEKE : -
def .

-
What happens when prohibited .

-
What it does
Meiosis :

diff .
btw Meiosis & Mitosis you need to know .
,

chromatids → anaphase ( mitosis

1) splitting .

& chromosome →
anaphase I Cme
ios Dj
splitting

2)
crossing over

Mendel & Heredity

*
-

phenylketonuria
-
sickle cell anemia

purine the square no

↳ chromosome
Only work when having unaffected
( no mutation

ratio isn't exact → Kc mutations can happen .

¥¥•ncen¥
÷
ADP ATP synthase

) ↳
µ,
ATP

tow Ht concentration ( pH 8)