Blog 3.E

Blog 3.E

All organisms must communicate with one another in order to survive and reproduce.

Bacteria and other microorganisms communicate so they don’t multiply too much and overcrowd a space, so they know when to reproduce, and more.

Multi cellular organisms communicate to know the whereabouts of other organisms, whether they be potential mates, prey or otherwise. They use a variety of methods to convey their methods. Wolves use chemicals (urine) and sound (howling) to let other animals know where they and their territory are.

They use sight, sun placement and weather patters to migrate and navigate so they don’t get lost or can move to an area with a preferable climate and recources.

Animals such as bears use scents to identify their young, find food and even to navigate.

The nervous system consists of the Central Nervous System and the Peripheral Nervous System. The CNS is the brain and spinal chord and the PNS are all the nerves branching off of them.

A neuron is a nerve cell that receives and transfers a neural signal. The signal enters the dendrites, which are around the cell body, transfer through the cell body, goes through the axon and out the axon terminal and over the synapse and into another cell’s dendrites.

Citations:

http://askabiologist.asu.edu/sites/default/files/resources/articles/neuron_anatomy.jpg

http://hkcdn.alltop.com/wp-content/uploads/2010/03/7695776-media_httpfarm5static_gFJyC.jpg?b715c1

https://herbsandanimals.files.wordpress.com/2010/02/polar-bear-with-baby.jpg

http://img.ehowcdn.com/615x200/ehow/images/a07/tg/m0/tips-communication-spanish-speaking-people-800x800.jpg

Blog 3.D

3. D. 1

1. Explain what factors are involved in cell communication.

Signal transduction: reception, transduction, response.

2. Explain why signal transduction process are generally under strong selective pressures. They need to tell the cell to do something and if the cell doesn’t or of the ligand signals the wrong cell to do the wrong thing then it could cause maaajor complications.

3. Explain how signal transduction pathways influence how the cell responds to the environment using Quorum Sensing as an example.

Cells send out signals via ligands which bind to receptors on the outside of the destined cell. These signals tell the cell what to do. Quorum sensing is used to sense how many bacteria are in the cell’s environment. Based on this, the cell will replicate, not replicate, or to or not to perform certain cell processes like attack a host or glow. One bacteria by itself or in a small group will hardly affect an organism but a significant number of bacteria could have a huge effect on it.

4. Why is signal transduction important? It is important because cells need to be able to communicate and respond to either their own or extracellular signals to keep themselves alive, their organism alive and more.

3.D.2

1. Explain cell to cell contact communication and give an example.
Contact-dependent signaling- an example is killer T cells destroying infected cells.

2. Explain cell communication over short distances and give an example.
This is called paracrine signaling and an example is neural signals, which leave the axon, hop a gap and enter the next dendrite through receptors on that dendrite. 

3. Explain cell communication when signals travel over a long distance and give an example.
This is called endocrine signaling and an example would be the adrenal glands sending adrenaline to the legs in preparation for a flight reaction.

3.D.3

1. How does signaling begin in a signal transduction pathway? It begins by a ligand attaching to a receptor.

2. Explain the ligand receptor relationship. What does it initiate?
The ligand-receptor relationship is the receptor on the cell’s exterior which binds to certain ligands, which are protein signals. It releases GDP which goes on to a few more processes and ultimately amplifies the ligand’s signal. It causes the cell to respond, also.

3. Explain a G protein linked receptor. It is linked to the receptor and when a ligand binds to it the G protein (GDP) turns into GTP and goes on to trigger other things like cAMP and amplifies the signal. 

4. Explain a ligand gated ion channel.
These need proteins (like sodium) to hook on and open the channel so ligands can pass through.

5. Explain receptor tyrosine kinases.

RTK: growth factor – binds and activates receptor/dimer – fills with phosphates- tyrosine- sends out signals to muscles etc

6. Signal transduction is the process by which a signal is converted to a cell response. Explain the entire process of signal transduction. Use the following terms (ligand, receptor, protein kinase, secondary messenger, phosphorylation, transduction, cell response)

The ligand- einepherine, for example, binds to a receptor which changes its shape and releases G protein, changing it to GTP. It goes to Adenolate cyclase makes cAMP – phosphorylation cascade amplifies the signal, which is to have the cells turn glycogen to glucose

3.D.4

1. Conditions where signal transduction is blocked or defective can alter cell response. Give an example of when this occurs. What happens?
Well, if the signal transduction pathway is blocked the effects are usually harmful to the cell. AN example would be how cholera secretes toxins that tell the cells to send water to the intestines, which causes excessive diarrhea and dehydrates the body/cells. It modifies the G protein so it can’t go back to GDP and the cells can’t stop signaling the water to quit going to the intestines.

Citations:

http://upload.wikimedia.org/wikipedia/commons/a/a4/1Signal_Transduction_Pathways_Model.jpg

http://www.scq.ubc.ca/conversing-at-the-cellular-level-an-introduction-to-signal-transduction/
http://www.ebi.ac.uk/interpro/potm/2005_9/Page2_files/image004.jpg

Blog 3A

3.C.1

1. Explain how alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the phenotype.

They can cause changes in the nucleotide sequences which can change the amino acids. This could possibly change the phenotype which would kill the organism or cause a simple change in the organism that could be an advantage or a disadvantage.

2. How can errors in DNA replication or DNA repair mechanisms, and external factors cause random changes.

The repair sequence could possibly change the original strand of DNA, making it a copy of the new strand. Radiation and carcinogens could also cause the DNA to mutate.

3. Explain how errors in mitosis or meiosis can result in changes in phenotype.

They can change the number of chromosomes and affect fertility and the phenotype. In plants, they could make a new type of plants, i.e one with thorns or without.

4. Explain how changes in genotype may affect phenotypes that are subject to natural selection.  Use the example antibiotic resistance mutations.

Mutations such as this cause the cell to produce enzymes that break down the antibiotics, therefore making the cell immune.

5. Genetic changes can enhance survival and reproduction. Explain how selection results in evolutionary changes.

3.C.2

1. What increases genetic variation? Eukaryotes: random mutation, random assortment, crossing over, random fertilization. Prokaryotes: random mutation. Bacterial conjugation, transformation, transduction.

2. Explain how the following increase variation: transformation, transduction, conjugation, and horizontal gene transfer.

3. How does sexual reproduction increase genetic variation? It causes the offspring to inherit its parents genetic information and also to combine and mix those chromosomes. It is a combination and mixture of the parents.

3.C.3

1. Explain how viruses replicate.

Viruses attach to bacterial and eukaryotic calls. They insert their genetic information and depending on what kind it is, the genetic information goes to the ribosomes or nucleus to be replicated. When the genetic information is replicated it uses the cell’s protein making mechanisms to make a new virus, over and over until the cell is full of viruses and lyses. The process repeats.

2. Explain the process of the lytic cycle.

Bacteria inserts its DNA into the host, the bacteria merges with the cell’s DNA, the DNA is replicated and through transcription in the host cell the ribosomes make copies of the virus until the virus load lyses the cell. The

3. Where do mutations occur during viral replication?

In the RNA.

4. Why do viruses have a higher rate of mutation? Because mistakes are easily made in transcription and the cell cannot check it for errors. And they replicate via RNA.

5. Explain HIV

HIV is an RNA virus that uses ribosomes in cells to replicate itself. It has a very high mutation rate so it is extremely difficult to cure.

6. How do viruses infect a host cell?

They latch onto the cell membrane and insert their genetic information which enters the nucleus an

7. What is a lysogenic(latent) infection? What can this result in?

It occurs when the viruses integrate their DNA into the host cell and the DNA is latent.