Exam 4 Content Flashcards
What does GPCR stand for?
G-protein coupled receptor
Where are GPCR’s located?
They are located on a cell’s surface
What do GPCR’s do?
They bind to energy rich GTP to send the message from the signaling molecule to the enzyme along the surface membrane of the cell.
What does RTK stand for?
It stands for Receptor Tryosine Kinase
Where are RTK’s located?
They are located along the entirety of the cell membrane along with being outside and inside the cell itself
What do RTK’s do?
They are protein kinases which means that they transfer a phosphate from ATP to another protein
What is one big difference between GPCR’s and RTK’s?
RTK’s can activate multiple pathways meanwhile GPCR’s only activate one pathway
What does it mean if a RTK starts working abnormally?
It is associated with many different types of cancers
Where is the ligand gated ion channel located?
It is located along the membrane
What does a ligand gated ion channel do?
When the signal molecule binds to the receptor it allows specific ions though a channel that is located in the receptor
How many kinds of receptors are there?
3 on the cellular membrane and intercellular receptors too
How many types of cell communication are there?
There are 3:
-direct
-local
-long distance
What does direct cell communication mean?
It is when the signal passes though junctions that connect two cells
How does direct cell communication work?
The substance is dissolved in the cytosol so it can move between the cells
How do cells communicate in local cell communication?
Signal molecules are released from a cell and travel until they reach the target cells
What is local cell communication useful for?
It is useful for embryotic development, immune response and maintaining adult stem cell populations
What are the 3 types of local cell communication?
-Autocrine (self signaling)
-Paracrine (adjacent cells)
-Synaptic (neurons)
What is autocrine signaling?
The signal is released and accepted by the same cell
What is paracrine signaling?
It is when a signal is released by a cell and it travels to a nearby cell
What is synaptic signaling?
It happens in the nervous system when an electric signal in the neuron releases neurotransmitters and as they diffuse across the synapse, they activate a response in the target cell
What is long distance signaling?
It is a type of signaling that is related to hormones and it travels long distances
How does long distance signaling work?
What happens is when a hormone is released from a cell it travels through the bloodstream to until it finds the cell that responds to its signal
What are the 3 steps to cell signaling?
1) Cell reception
2) Cell transduction (downstream/cascade effect)
3) Cellular response
What happens in cellular reception?
The signaling molecule binds to the receptor protein that is located on the cell surface
What happens in cellular transduction?
The binding of the receptor causes the shape of the receptor protein to change. Which causes the signal to get transformed into something that can bring a cellular response. While that response sometimes occurs in one step, most of the time it requires a series of steps that is known as the signal transduction pathway.
What happens in cellular response?
The transduced signal produces a specific response from the cell itself. ex enzyme creation, cell growth, and movement
What are intercellular receptors?
They are cellular receptors that recieve responses from inside the cell itself
What kind of messengers are recieved in intercellular reception?
Small and hydrophobic messengers like steroids such as cholesterol, estrogen, testosterone, and cortisol
What happens after the message is recieved in the cell?
transcription sometimes occurs in the nucleus of the cell
What is the role of protein kinases?
They transfer phosphates from ATP and give them to proteins
What happens in phosphorylation?
Protein kinases pull a robin hood and take phosphates from ATP and give them to proteins
What happens when many protein kinases are activated in signal transduction pathways?
A phosphorylation cascade occurs
How often are second messengers activated in signaling pathways?
Quite frequently
What are characteristics of second messengers?
They are non-protein, hydrophilic molecules or ions that move though a cell via diffusion
What are some common second messengers?
Cyclic AMP, calcium ions, and IP3
What is Cyclic AMP or cAMP?
It is a small molecule that is produces from ATP
What is adenylyl cyclase?
It is an enzyme in the plasma membrane that converts ATP to cAMP when it recieves the extracellular signal to do so.
What kind of receptors involve cAMP?
GPCRs and cAMP is used to activate protein synthase A
How are calcium ions used as second messengers?
Because its concentration is much lower in the cytoplasm of the cell than in the extracellular space and messengers can change the concentration which triggers a response to occur again
What are the 2 types of cellular response?
Nuclear and cytoplasmic
What happens in nuclear responses?
The response typically results in genes getting turned on or off in the nucleus
What happens in cytoplasmic responses?
These responses result in the opening of an ion channel, or a change in the activity in a metabolic enzyme
What are the four aspects of signal regulation?
-Amplification of the signal (and the response)
-Specifity of the response
- efficiency of the response that is enhanced by scaffolding proteins
- termination of the signal
Why is the specifity of a cell response necessary?
Because the same signal can have different responses based on the proteins and pathways ex ACh can have stimulatory or inhibitory effects
What do saffolding proteins do?
They are large relay proteins that other relay proteins attach to
How can scaffolding proteins increase signaling effiency?
They can increase signaling efficiency grouping together similar proteins that are a part of the same pathway
How is epinephrine used as a flight or fight response in cell signaling?
It is used as long distance cell signaling by getting released from glands in the endocrine system and continue through the bloodstream
What is the role of calcium in cell signaling?
The role of calcium in cell signaling is that it is a second messenger
What are the 3 mechanisms of regulation in cell signaling?
-inactivation of the signal
-changes in the concentration of signaling molecules
-Unbound receptors become inactive
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What is mitosis?
The is the division of a cell into two identical daughter cells
What is meiosis?
It is the division of 4 genetically unique daughter cells
What is a somatic cell?
A non reproductive cell that produces 2 identical daughter cells
What is a gamete cell?
They are reproductive cells (egg and sperm) that produces cells that are genetically unique and have half as many chromosomes as somatic cells
What is a zygote and what type of divisions do zygotes undergo?
A zygote is a fertilized egg cell and it goes through mitosis
What is a stem cell?
It is a type of cell that can either differentiate into a specific cell or undergo mitosis and replicate itself
What happens in interphase?
It is divided into 3 phases:
G1- cell duplicates most organelles
S- the DNA in the cell is doubled and sister chromatids are connected by a centromere
G2- chemical componets are prepared
What is M phase?
It includes the the phases such as prophase, prometaphase, metaphase, anaphase, and telophase
What happens in prophase?
3 things happen:
-chromosomes shorten
-the centrosomes move to the poles
-nucleoli disappear
What happens in prometaphase?
The nuclear envelope dissolves and miotic spindle grows
How does the release of epinephrine for a flight or fight response break down glucose?
It causes the breakdown of glucose once the liver releases epinephrine as a response. When it reaches the cell it attaches to a GPCR which sets off a cascade effect of protein kinases until it activates the glucose enzyme that breaks down glucose and releases the sugars into the cytoplasm into the cell.
What happens in metaphase?
Sister chromatids align on in the middle of the cell on the metaphase plate to ensure equal division
What happens in anaphase?
The centromeres holding the sister chromatids apart and the mirotubeules pull the chromosomes apart
What happens in telophase?
-The chromosomes reach their opposite poles
-spindles fall apart
-chromosomes unwind
-nucleolus and nuclear membrane reforms around each pole
What happens in Cytokinesis?
The poles are divided by a clevage furrow and are separated
How many autosomes are in a human cell? What about sex chromosomes?
44 autosomes
2 sex chromasomes
What happens in prophase of of meiosis that does not happen in mitosis?
The pairing of homologous chromosomes which is called synapsis
What are homologous chromosomes?
They are chromosomes that are found in meiosis that get paired up together but are not genetically identical
At what phase of meiosis is genetic material shared to create variation?
Prophase 1
What type of chromatids is the genetic material shared between in meiosis?
Non-sister chromatids share homologous portions
What kind of cell can undergoes meiosis?
Diploid cells
What is order in size from smallest to largest? Gene, genome, and chromosome
Gene-chromosome-genome
How many types of cells in the body undergo meiosis?
1 the reproductive cells
What is G0?
it is a phase in interphase a cell goes into if it does not pass the first checkpoint in at the end of G1 in interphase
In what phase of cell division does DNA replication occur?
DNA replication occurs in S phase of interphase
What is DNA replication? And what is the result?
It is when a chromosomes are copied or duplicated resulting in sister chromatids
What is the relationship between chromatin and chromosomes?
The relationship is that chromatin is just the uncoiled version of DNA and it gets formed into chromosomes during prophase
What does RNA polymerase do?
It is the protein that transcribes DNA into mRNA
What does mRNA do?
It takes the information from DNA and is used to build amino acids that form proteins
What is the difference between a DNA template stand and a coding strand?
The template strand is the strand across from the mRNA strand and is code for the mRNA is built off of. Meanwhile the coding strand is the other strand
What does the promoter do in transcription?
It is a nucleotide sequence in DNA that binds to RNA polymerase and creates a space for mRNA to be transcribed from DNA
What is the start site on DNA for transcription?
the TATA box
What is the ‘flag’ for the mRNA to know where to start?
The transcription factor on the DNA
What is the transcription initiation complex made up of?
Transcription factors + RNA polymerase= initiation factors
What is the polyadenlation signal?
It is AAUAA on the DNA strand and that is signal for the mRNA to be done
What order are the prime numbers on the mRNA strand?
5’ to 3’
What is the transcription direction on the mRNA strand?
RNA polymerase reads the template strand in the 3’ to 5’ direction which produces the mRNA strand to go from 5’ to 3’
What makes a strand the template strand?
which ever one goes from 3’ to 5’ and which one has the code that determines where the transcription factors go which ultimately determines where the RNA polymerase goes
What is a spliceosome and what is its function?
The spliceosomes cut out the introns which are not necessary of the mRNA
What happens to a mRNA after it is made?
It gets a 5’ cap and a poly a tail which helps get shipped out of the nucleus, protects from enzymes that would degrade it, and helps ribosomes bind to it to build proteins
Exons vs introns
Exons are the extroverts that want out of the nucleus meanwhile introns don’t want to leave because they are introverts and so they don’t do work
Why is good that some different codon combinations code for the same amino acid?
Because the rendundacy of the code allows the some of the proteins to still remain fuctional based on what the change was
What is the code for the start codon?
Aug
What are the codes for the stop codons?
UAA, UAG, and UGA
What is an anticodon?
It is the opposite code attached to tRNA that helps it pair up with the right mRNA
Where does translation occur?
In the cytoplasm but more specifically in a ribosome
How is translation terminated?
It is terminated when the tRNA recognizes the stop codon in the a site of the ribosome
What happens in a silent mutation?
There is a swap of the codons but it still codes for the same amino acid
What happens in a frameshift mutation?
An extra codon is added shifting the reading code
What is a missense?
It is when the change/swap of a codon causes the amino acid to change
What happens when a codon is deleted?
It would be a framshift mutation and cause excessive missense downstream from it
What causes nonsense to occur in a mutation?
When a stop codon is added too close to the start to codon to acutually code a protein
What kinds of mutations has the smallest impact on a protein?
Silent mutations but missense mutations have a minimal effect as well
The type of mutation that would have the greatest impact on the protein?
Nonsense and frameshift because both render the protein nonfunctional
