Catégories : Tous - membrane - dna - action - growth

par Nicole Mille Anne Domingo Il y a 6 années

395

Final Exam

Cellular processes are regulated through various signaling mechanisms and checkpoints, ensuring proper cell growth and development. Key checkpoints such as G1/S, G2/M, and M are controlled by cyclin-dependent kinases (

Final Exam

Functional Groups

Methyl

affects gene expression when on DNA or on proteins bound to DNA

Phosphate

contributes positive charge

Sulfhydryl

two -sh groups can react forming a "cross-link that help stabilize protein structure

Amino Group

acts as a base

Carboxyl

covalent bond between O-H is very polar
acts as an acid

Carbonyl

sugars w/ aldehydes (aldoses)
sugars w/ ketone groups (ketoses)

Hydroxyl

usually ends with -ol
forms H bonds with H2O
polar because of electronegative oxygen

Organic Compounds

Opposite Charges can form Salts

Ex: NaCl

How Salts dissolve in water

hydration shell

Phospholipid Bilayer

Enantionmers
Mirror Images
Geometric
Different Spacial Arrangements
Stutural
Different Covalent Arrangements

Hydrocarbons

Hydrogen Bonding

Water Molecules

Properties
Solvent of Life
Denser as solid than

Contract when cooled

Expand when Heated

High Heat of Vaporization

High Humidity prevents Evaporation

High Specific Heat

Unit 1

Isomers

compounds with same # of atoms of same elements but different structures and different properties
Enantiomers

R isomer

L isomer

Cis-trans

cabons that have covalent bonds to the same atoms but differ in spatial arrangements due to the inflexibility of double bonds

trans isomer

2 x's on opposite sides

cis isomer

2 x's on same side

Structural

Carbon skeletons

Presence of Rings
Double bond position
Branching
Branched
Unbranched
Length

Genomics and Proteomics

The more closely two species are related evolutionarily, the more similar their DNA sequences are
DNA sequence data confirm models of evolution based on fossils and anatomical evidence
Recent technological advances in DNA sequencing have given rise to:
Proteomics

A similar approach for large sets of proteins

Genomics

An approach that analyzes large sets of genes or whole genomes

Biofinformatics

The use of computational tools and computer software to analyze these large data sets

Genomes and proteomics have transformed biological inquiry and applications

Macromolecules

Nucleic acids
Examples

RNA

Various functions in gene expression, including carrying instructions from DNA to ribosomes

Usually single stranded

Nitrogenous bases = C, G, A, U

Sugar = ribose

Stores hereditary information

Consists of:

Phosphate group

Usually double-stranded

Sugar = deoxyribose

Nitrogenous bases = C, G, A, T

Consists of a phosphate group, sugar, and nitrogenous base
Nucleic acids store, transmit, and help express hereditary information
Proteins
Proteins include a diversity of structures, resulting in a wide range of functions

Examples of proteins

Structural proteins

Provide structural support

Motor proteins

Function in cell movement

Receptor proteins

Receive signals from outside cell

Coordinate organismal responses

Transport proteins

Transport substances

Storage proteins

Store amino acids

Defensive proteins

Protect against disease

Enzymes

Catalyze chemical reactions

Consist of R groups (a type of amino acid monomer)

There are 20 types

Lipids
Components of lipids

Steroids

Signaling molecules that travel through the body (hormones)

Component of cell membranes (cholesterol)

Consist of a steroid backbone

Four fused rings with attached chemical groups

Phospholipids

Are lipid bilayers of membranes

Glycerol + phosphate group + two fatty acids

Consist of a phosphate head and 2 fatty acids

Glycerol

Examples of glycerol

Triacylglycerols

(Fats or oils) -> glycerol + three fatty acids

Important sources of energy

Consists of 3 fatty acids

Lipids are a diverse group of hydrophobic molecules
Carbohydrates
Examples of carbohydrates

Polysaccharides

Chitin (animals and fungi)

Strengthens exoskeletons and fungal cell walls

Glycogen (animals)

Starch (plants)

Stores glucose for energy

Cellulose (plants)

Strengthens plant cell walls

Disaccharides

Serve as fuel and are carbon sources that can be converted to other molecules or combined into polymers

Sucrose

Lactose

Monosaccharides

Fructose

Glucose

Carbohydrates serve as fuel and building material
Macromolecules are polymers, built from monomers
no anchorage dependance

each 3 carbon has a phosphate attached to it

Large carbohydrates (polysaccharides), proteins, and nucleic acids are polymers, which are chains of monomers

Polymers can disassemble by the reverse process, which is hydrolysis

Monomers form larger molecules by dehydration reactions, in which water molecules are released

The components of lipids vary

Chemical bonding

Ionic
Transfer of Electrons

cation

Positive Charge

anion

Negative Charge

Metallic
Covalent
Nonpolar

Similar Electronegativies

Van Der Waals Interactions

Separation of charges

Hydrophobic Interactions

Cage Away from Water

Hydrophobic Tails

Polar

Hydrophillic

Hydrophilic Heads

Different Electronegativities

Dipole Dipole Interactions

Partial positive

Paritial negative

Unit 4: Photosynthesis

Begins with Glucose

fermentation occurs without oxygen

enzyme hexokinase phosphorylates glucose phosphoglucoisomerase converts glucose 6-phosphate into isomer
Fermentation occurs when no oxygen is present
Glycolysis

2 molecules of pyruvate per glucose and 4 ATP, Net 2 ATP are produced

2 NAD+ are reduced to NADH with the addition of hydrogen

each 3 carbon has a phosphate atachted to it

Uses 2 ATP to break up glucose into 2- 3 carbon chains

hit by photon of light that energy is transferred and funneled to the reaction center

Signal sequence is recognized by signal recognition protein (SRP)

phosphorlation occurs initating chain of events promoting transcrption

Regulators include CDKs

Checkpoints include G1/S, G2/M, and M

1st stage of Cellular Respiration with oxygen

Store energy (Calvin cycle) Part 2

Use energy (respiration)

Oxidative phosphorylation

Citric acid cycle

glycolysis

Act 3:
and glucoses will quickly be assembled into starch
TWO g3ps are needed to make 1 glucose(which was released in act 2)
another carbon from carbon dioxide attaches again, attaches to the carbon ribulose bisphosphate to make unstable 6 carbon intermediate and so on and so forth
basically be rearranged with the help of ATP to form a 5 carbon sugar and becomes a starting point ones again
5 g3p CONTINUES IN THE CYCLE
ADP and NADP will return to the light reactions and get recharged
NADPH has been oxidized to form NADP (lost electrons)
ATP becomes ADP
End of act 2, we have 6 G3P, one will be released to make glucose ultimately and FIVE will continue
need 3 more atp
G3P is half a glucose, so far we have spent 6 atp and 6 nadph
end of 2nd act makes the product
ATP is used to phosphorylate the other side of the 3 carbon molecule, and 3 carbon molecule is reduced by NADPH to form one molecule of G3P
Act 1:
co2 enters the cycle diffused into the leaf through the stomata and into the chloroplast, and its carbon is snapped onto a pre-existing 5 carbon carboyhdate by the enzyme rubisco

this makes a highly unstable 6 carbon molecule and breaks down immediately due to its 2 phosphate groups

CO2 fixation
carbon fixing reactions are light independent
we need a source of carbon, so we use co2
products of the light reactions except of o2 are reactants in calvin cycle
energy in ATP and NADPH is transferred into sugar, a more stable storage form

Starts on photosystem II in the process: Light Reactions: Part I

Chemiosmosis
Mitochondria and Chloroplast Differences in Chemiosmosis

where electrons are coming from that moved down from ETC and established the proton gradient

Respiration

the high energy electrons are coming from food as we break down like glucose that has a high PE which we use to make ATP

Photosynthesis

source of the electrons - the excited energy, higher energy state, is coming from chlorophyll molecules as photon hits a cholorphyll molecule that excites a electron and that energy is what is driving the generation of ATP

proton movement in both organelles.

Chloroplasts

protons pumped in the thylakoid space, (stacks)

pump protons pump in the inner membrane gradient

Mitochondria and Chloroplast similarities in Chemiosmosis

ATP is generated in the compartment where its needed

ATP synthase uses proton motive force to phosphorylate ADP to make ATP

both respiration and photosynthesis, rely on a proton gradient that is generated by the ETC as electrons move down their electron transport chain

both cases, there is inherent energy and electron transport chain pumping protons across the membrane

RESULT: HIGH PROTON CONCENTRATION BUILDING UP IN THE THYLAKOID SPACE
pumping of protons from the stroms to the thylakoid space using the energy inherent in the ETC
protons are released from the thylakoid space
atp synthases allows protons to move down their concentration gradient to produce ATP from ADP
can be used to do work
using proton motive force to generate atp
Light reactions:
this is called NON- CYCLIC FLOW
olar energy is used to make ATP and NADP not for cellular work but for calvin cycle
Act3:
this electron goes to a shorter ETC, then electron carrier NADP grabs the electron and becomes NADPH
electron in that reaction center bounces to a higher state
Photosystem transfers electrons, reduces NADP+ to NADPH
Act 2:
proton gradient is used to make ATP
primary e acceptor passes it to ETC, uses energy to move protons against concentration gradient to move it into the thylakoid space
Energy is transferred through Electron Transport Chain to Photosystem I
Act 1 :
protons (from water) are released to thylakoid space (lowering pH) , used to drive the synthesis of ATP
O2 IS RELEASED AS A BY-PRODUCT
Chlorophylls lost electron is REPLACED BY TAKING AN ELECTRON FROM WATER “splitting water”
H2O split into oxygen and hydrogen
Energy is captured by Photosystem II

Photosystem

Reaction center is where the electron will be excited and ultimately lost from the chrolophyll, primary electron acceptor grabs it chlorophyll loses it
Photon hits the photosystem and hits the cholorphyll molecules and ultimately funneled by the reaction center (special chlorophyll molecules)
a ray of satellite dishes that tries to gather light
collection of proteins and pigment molecules

Retrieve energy (light reactions)

-not make sugars directly
NADPH & ATP is used to drive calvin cycle
light reactions gather energy and transfer it to electron carriers (NADPH is an electron carrier) or use energy to make ATP
harvest energy

UNIT 2: DNA Replication, Transcription, Translation

Translocation

The vesicle is sent to lysosomes, extracellular matrix, plasma membrane
The golgi further modifies the protein and packages it
The protein is transported to golgi
The protein is modified to glycoprotein by chaperones
The protein is now in the lumen of ER
Signal sequence is reached for signal peptidase to make a cut
Translation is done
Free ribosome bound
Endomembrane system
ER- GOLGI- PLASMA MEMBRANE OR GOES BACK TO THE ER
2 Membranes
Chloroplast

Mutations

Nonsense
Early stop codon that stops translation
Missense
Change in Amino Acid
1 or 2 Nucleotides
silent
- no change in amino acid
1 nucleotide change
happens in nucleotides of DNA

DNA Translation

Steps:
-translation is finished
-hydrolysis reaction breaks the ribosomal complex
-release factor attaches to stop codon on A site
-the mRNA shifts in codon to P site then E
-tRNA comes into A site

release factor comes into this site

- this happens in P site
- large ribosomal unit attaches to the complex
- tRNA attaches to the codon
- scans for AUG codon
small ribosomal subunit attaches
Amino acid

synthases

connects the tRNA to the correct amino acid, reads it first inorder to use the enzyme

another trna comes in and puts another anticodon at the a site
Initation
Small subunit ribosome

Large subunit ribosome attaches to the TRNA

Trna comes with anticodon, happens at P site

scans where it starts

DNA transcription

Splicesosomes
RNA splicing occurs before the cap is added
cuts out the introns
Poly A polymerase
brings a bunch of As to stabilize
Ribonuclease
cuts the sequence at the poly A
Poly A
signals the nuclease to make a cut at the mRNA strand
Promoter
TATA box

+1 sequence -

RNA pol II binds because it needs transcription factor to bind

contains transcription factor which contains protein

found in promoter

located upstream
happens downstream
uses the template strand

DNA Replication

DNA III - extends and proofreads
In pro - 1 ORI
In euk- 2 ORI
e use both strands

B cells

carries golgi bodies

secrete antibodies

PCR

Elongation
dnTP

energy used in PCR TO KEEP ELONGATION MOVING

Tag polymerase (from archea) elongate synthetic DNA primers
Temp is slightly increased
Annealing
DNA primers are added to parent strands through hydrogen bonds
Temperature is reduced
Both strands separate
Hydrogen bond is broken
Temp is increased so that hydrogen bonds can break and strands can separate
Denaturation
artificial
Makes a lot of dna
polymerase chain reaction, all happens in the test tube!

Messelson and Stahl

semi-conservative
Discovered that DNA was a double helix
Made 3D replica of the dna

Chargraff’s Rule

Watson and Crick
Always have to be 50% 50%. A& C= 50%... G&T= 50%
15% A, 15% T….. 35% G, 35% C
Number of purines = number of pyramidines
Pyramidines - C and T
PURE AS GOLD

Hershey and Chase

RNA is not genetic material because it is unstable
this is due to the OH group in the ribosugar
Used radioactive phosphorus and sulfur

Mckay & Mcleoud (M&M)

didn’t prove anything
test tube
reinforced the transforming principle
redid griffith’s 4th trial

Griffith

Four trials
There was a transforming principle!
Heat S & R- dead rat
Heat S - alive
R- alive rat
S- dead rat
Streptococcus pneumonia
Looking for a vaccine for pnemonia
Bacteriologist

3 domains of life:

Eukarya
ECM

collagen

-peripheral proteins - sodium, potassium ion channels

plasma membrane

Junctions

Desmosomes

Signaling

Intermediate filaments found in here

Selected passage

Gap/ Plasmodesmata

Allows everything to pass through

Tight

Rat = poison by opening the gap junctions

Intestines and skin

No passage of the free nucleus

Cytoskeleton

Intermediate filaments

Progeria

fibers

Structure and maintenance, stability

Nuclear lamina, keratin

Microtubules

Found in flagella

Motor protein

kinesin

cell division

structure

monomer: tubulin

Beta

Alpha

Microfilaments

Actin Monomer

movement

muscle contraction

Amoeba

Transport/motor protein

myosin

Ribosomes

Translation

rRNA and proteins

Two components

Free bound

Golgi

Chaperones

helps in modification and folding

2nd tag of protein

Modification

Synthesis

Sends them out

Helps package proteins

Smooth ER

Detoxification

Iipid synthesis

Rough ER

Glycoproteins

sugars in the rough ER

Protein modifications

Nucleus

Double membrane

Mitochondria

Cristae

where atp and cellular respiration happens

Has a double membrane

DNA and protein

Cellular respiration

Produces ATP

Vacuoles

Central vacuole

found in plants, rigid

food vacuole (vesicle)

carries things for transportation

contractile vacuoles

prevents lysine when cell self-destructs

rigid, moving excess water out of the cell

Peroxisomes

Form water

Produce Hydrogen Peroxide to form water! H2O2 to H2O

pH acidic
Lysosomes

has hydrolase

phagocytosis

autophagy

recycles organelles or any cell material

engulfs outside materials

lysozyme

break down macromolecules

which helps engulfs and digest bacteria

DNA
Nuclelous
Chromatid in nucleus
Has lamina

helps with stability and structure of the nucleus

intermediate filament,

Has envelope
Has nucleus- double membrane
Bacteria
Has UNBRANCHED lipids, its saturated, because its rigid
Coupled DNA rep and transcription
No introns
Flagellum
Cilia - hairlike projections of the exterior of the bacteria, for movement
Pili- attachment for reproduction
chromatin/somes
Plasmid
No nucleus
Petidoglycan - sugar coated cell wall
Capsule
Archaea
Has introns
thermophiles
methanophiles
halophiles

Miller Urey

Hydrocarbons, hydrogen cyanide, amino acids
Ribozyme oldest organelle
contains RNA and protein
Tried to recreate the environment
redid experiment of Oparin Harding

Oparin Harding theory

Volcanic eruption was the source of molecules

Cell Cycle (Division)

Somatic cells

Normally in G0 phase
2N diploid cells (one from dad one from mom)
Body cells
have autosome (NON SEX) chromosome -

Regulators of Cell Division

Tumor Suppressor Genes
P-53

If p-53 is mutated, there will be continuous cell division

When there is a thymine dimer, p-53 is needed

Makes a protein that hurts gene expression

Transcription factor

Pauses cell cycle

Suppresses cell division/ cycle
Proto Oncogenes
When mutated or muted can cause cancer - become oncogenes
Are normal cancer genes
Cancer cells
Oncogenes

Cancer causing genes

A disease of signaling cycle
Forms tumor on top of each layer
They establish their anchor in different plane
They propagate mutations
Doesnt exhibit any growth inhibitions
Density dependent inhibitor
Forms single layer
Would not grown when mixed cut in environment
Cyclins
They form CDK-cyclin complex
cyclin dependent kinases ___ to phosphorlyze

Germ Cells

Produce haploid cells (1N)
Produce gametes

Karyotypes

can be used to diagnose diseases
Down syndrome

Chromosomes 21 has 3 chromosomes instead of 2

Cell Cycle (Mitosis)

checkpoints G1/G2/M

Failure of CDKs cause cancer
If Ras is hyperactive a signal will continually be expressed, never turning off
Tumor suppressor P.53 is mutated it can not do its job
oncogenes cause cancer
no density dependent inhibitioln
accumulation of mutants
disrupt and inavde issues

Meiosis

Meiosis II: similar to mitosis (produces 4 cells)
Telophase II

Cytoplasm is divided into 2 haploid cells (gametes) -- cytokinesis

Nuclear membrane returns

Anaphase II

Microtubles shorten and ends of cells are aligned

Sister chromatids are pulled apart

Metaphase II

Random alignment

Chromosomes align at equator of cell

Prophase II

No synapses or recombination

Daughter cells have one copy of each hydrolysis chromosomes

Centrosomes appear and forms kinetochores

Chromosomes condense and nuclear envelope breaks down

Gametes are formed through meiosis
Meiosis 1 (produces 2 diploid cells)

Telophase 1

Nuclear membrane reappears

Cell divides into 2 daughter cells

Anaphase 1

Sister chromatids are attached at centromere

To 2 poles of the cell

Homolysis chromosomes separate and migrate

Metaphase 1

Different combinations

Align randomly

Synapse chromosomes align at the equator

Prophase 1

Two centrosomes are present with microtubules -- kinetochores

Nuclear membrane begins to break down

No two siblings aside from twin are genetically identical

Sister chromatids from each chromosomes are no longer identical

Chromosome material is exchanged by the 2 parts of sister chromatids

Each pair of homolysis chromosomes undergoes synapses to form a complex

Duplicated sister chromatids join together at the centromere

DNA condenses to form chromosomes

2 unique daughter cells that have the amount of DNA as parent germline cells

DNA in the germ cells are duplicated before meiosis begin
Cells are going through the interphase
Produces gametes

1 copy of each chromosome

Haploid cells

2 copies of each chromosome in diploid organelles
Germ line cells produce gametes

Mitosis

Cytokinesis
Organelles are replicated
Cleavage furrow is formed
Cell is divided in nearly equal cells
Cell is composed by a contractile ring form microfilament
telophase
Chromosomes uncoil and become uncondensed
Spindle fibers are broken up
Nuclear membrane reappear and 2 sets of chromosomes
anaphase
Sister chromatids separate and move to the ends of the cell
Chromosome separate
The cell becomes bigger
Metaphase
Chromosome align at the center of cell
Sister chromatids are ready to separate
Prometaphase
Kinetochore attaches to chromosomes in centromeres
Nuclear envelope is degraded
microtubules appear and attaches to kinetchore
prophase
Microtubules appears from centrosomes in animals
Chromosome structure appears
DNA condenses
Nucleolus disappear
Condensation of chromosome

G2

more growth

S

most of the life of the cell is spend here (interphase)

G1

cell finishes growing
DNA is replicated
Synthesis phase
Cell grows nearly to its full size

UNIT 3: Cell Membrane

Checkpoints include G1/S, G2/M, and M

Regulators include CDKs

phosphorlation occurs initiating chain of events promoting transcription


Cells

No anchorage dependence

No density-dependent inhibition


causes uncontrolled cell growth





Regulation of Gene Expression

Prokaryotic Gene Expression
Operons

Operon is turned off

Repressor protein binds to operon

Binds to repressor protein

Tryptophan functions as a corepressor

Operon is on when there is no tryp

Operon is off when there is tryp

Tryptophan is synthesized

When lactose is available

No presence of glucose

When there is high levels of camp

Contribute activator proetin (CAP) binds to operator

Repressor is suppressed with allolactose

The Lac Operon

Adds acetyl groups to lactose to make it easier for B GALACTIDASE to break down lactose

make transacetylase

Gene Y

The gene Y codes for permease

the lactose goes through the transmembrane

Gene Z

They breakdown lactose

Made by Gene Z

Uses Enzyme B Galactose

Glucose and galactose

Found in prokaryotes like Ecoli

Both + and - regulation

Negative Regulation

The trp operon

Repressor proteins inhibit transcription

Positive Regulation

The lac operon - both positive and negative

Activators help with transription

Activators, repressors [operator, promoter & terminator]

Terminator Sequence

The end sequence in which transcription ceases

Operators

Repressors does the opposite

On or off switch of transcription

Basal level expression

Activators binds to this sequence to start high level expression

Induced expression

Proteins help decrease expression

Help increase expression above basal level

Regulated expression

Basal low level expression

Continuous/ Constituted Expression

Expression ALWAYS ON

Incorporation activates and enhancers for gene expression
Distal Control Element
Specific transcription factors

Repressors

inhibits expression

Activators

Activators help to initiate high level transcription

increase expression

High level expression

lens cell in eye

May even be located in an intron
Example: enhancers
Far sequences in DNA to the gene
Proximal Control Element
General transcription factors bind to the site
Close sequences in DNA to the gene
gene are lowly expressed (basal)
Chromatin
Condensation silences gene expression
Euchromatin
Genes expressed
Less compacted
Heterochromatin
No genes expressed
Highly compacted
All cells have the same genes
About 20% genes are expressed

DNA Packaging

The loop domain then coils to form a metaphase chromosomes
The tight helical fiber is formed into loops, which are held together by a protein scaffolds at the bottom
Linker DNA is the strand of DNA not winded by histones
Beads on string
H1 is found outside nucleosome

Helps form tight helical fiber (the next level)

Brings nucleosomes together

Histone Core

Forms a histone octamer

2 molecules of each histone

H2A, H2B, H3, H4 [no H1]

Nucleosome- Histone + DNA
Histones are proteins, in which DNA wind around twice

Neuron Communication

Chemical Synapse
Communication occurs through a neurotransmitter

Neurotransmitter ligands

Does not enter post synaptic membrane

Taken up by pre synaptic membrane

Breaks down through hydrolytic reaction

Neurotransmitter binds to post synaptic membrane receptor (ligand gated)

Ions go through membrane depolarization

Ca2+ can go in

The spaces between the presynaptic membrane of axon and post synaptic membrane of dendrite of the synaptic cleft

Electrical Synapse
Electrical current flows from one cell to another through gap junctions

Stages of Signaling

Cell Response
cell responds to the signal
Transduction
relate molecules to a signal transduction pathway

Phosphorylate cascade

phosphatase hydrolyzes the phosphate group to turn off kinase

Amplifies message until it reaches its target

the other kinase does same to another

Adds a phosphate group from ATP to another protein kinase

CAMP becomes inactive to AMP

Phosphodiesterase removes the cyclic component of CAMP through hydrolytic reactions

CAMP starts transduction and then inactivate

Active Adenyl cyclase make cyclic AMP (second messenger) from ATP

G protein binds to adenyl cyclase going back to GDP

Inactive G protein is activated carrying GTP

Reception
ligand binds to receptor protein

G protein uses the enzyme, Phosphatase to remove the phosphate group from GTP to GDP

Once enzyme is activated, G protein goes back to GDP

Alpha G protein diffuses from the receptor and finds an enzyme

receptor activates and GDP is converted to GTP

G protein Coupled Receptor

Alpha, Beta, Gamma Subunits

Binds GDP to GTP

Signal molecule

Hydrophilic
Helps initiate proteins to be made for male sexual traits
Testosterone Signal

Goes through phospholipid bilayer

The factor binds to promoter to start transcription

Binds to receptor to make transcription factor

Channel Receptors
Tyrosine Kinase Receptors

receptor is outside along membrane, receptor is polar

Relay proteins attach to the phosphate groups of the tyrosine to begin transduction

Kinase is activated and phosphorylation behinds

Signal molecule binds together to form dimer

Adds phosphate groups to tyrosine

Phosphorlyzes from ATP

Hydrophobic
receptor is inside cell

Cell Signaling and Transduction

Combinatorial Gene expression
Cell signaling helps to bring activators
Eukaryotes
Long distance signaling
Local signaling

short distance, have the receptor, target cell is close by

Yeast

signals for cells to combine to one

Physical contact
Desmosomes Junctions

signal receptors

Gap Junctions

plasmodesmata in plant

Subtopic

Action Potential

Hyperpolarization
Na+ and K+ is used to reach threshold
More K+ in cell
Inside is more negative
Depolarization
Happens until threshold reaches (+62 mv)
Cell gets less -
Na+ comes into cell

Growth Factor

Development
Survival factors
Death Factors
Hormones
Cytokines
Inhibit proliferation
Apoptosis (kill itself)
Metabolic activation
Proliferation (mitosis)
Differentiation
Cell moves (chemotaxis)
Gene is turned on or off
Cell starts growing and dividing

Ion channels

Gated channels
Charge of electrical voltage in cell
Voltage gated
stretch gated - mechanical stimulus

Hydrogen Pump

Sucrose H+ cotransporter
Energy us coming from proton gradient
Comes in with H+ when enters cell
No energy needed to bring it back
Sucrose moves against concentration gradient
Facilitated diffusion
Helps H+ come back into the cell
direction of the pathway depends on placement of protons
protons pumped against concentration gradient

Electrogenic pump