Z-DNA

Believe it or not there is more than one possible structure for DNA! There are three: A-DNA, B-DNA, and Z-DNA.

Source: http://www.tulane.edu/~biochem/nolan/lectures/rna/bzcomp2.htm

Z-DNA is a left handed double helix structure, which is the opposite of the most common form, B-DNA. There are also many other differences than the common form, such as base pairs per turn. The Z form has 12 bases per turn while the B form only has 10.5. The biological significance is still largely unknown but research is going on to determine it. Right now they think that it has something to do with supercoiling during DNA transcription. This will allow the DNA to open up and allow transcription factors to bind, allowing mRNA to be made and proteins to be created.

All in all, there isn't much known about Z-DNA. Scientists are working on it though!

So this is the last post for the A to Z Challenge. I can't believe that it's already over! May 7th is the date to write a reflections post on the challenge, to talk about pros and cons, what you liked most, what you didn't like, if you met anyone cool, stuff like that. Visit the A to Z Challenge site to learn more!

Y Chromosome

I figured I talked about the X chromosome when I wrote about X linked traits, why not talk about the Y chromosome? Only males have a Y chromosome and it is considerably smaller than the X chromosome. This means that it contains much less genetic information (which is why females have Barr Body formation).

Source: http://en.wikipedia.org/wiki/Y_chromosome

Scientists believe that the Y chromosome is one of the fastest evolving pieces of genetic material in humans with a 30% difference in humans and primates. It contains somewhere between 70 and 200 genes, which they are actively working on identifying. While the Y chromosome does contain genes that are only found on this one chromosome, there are areas that have pseudoautosomal genes (an autosomal chromosome is a non sex determining chromosome), which means they are found on both the X and Y chromosome.

There are diseases that can be associated with the Y chromosome, such as 46,XX where a male will have two X chromosomes and one Y, 48,XXYY where he will have double of both sex chromosomes, and 47,XYY where he will have two copies of the Y chromosome. These can have symptoms anywhere from a tall stature to infertility.

I can't believe this is the second to last post for the A to Z Challenge. I hope everyone has learned at least one thing from my posts!

X-Linked Traits

X-linked traits are carried on the X chromosome. Since males have one X chromosome and one Y chromosome, they are more susceptible to X-linked diseases, such as hemophilia. There are other traits found on the X chromosome that are not diseases, such as pattern baldness. Since males only have one X chromosome they only need one copy of the gene to start early balding, females need two. Since this ratio is so skewed, there are much fewer females with X-linked diseases than males.

Source: http://en.wikipedia.org/wiki/X-linked_recessive_inheritance

The picture above shows the inheritance of X-linked recessive traits in families. A father cannot pass on an X-linked disease to a son, only a daughter. A daughter will only show the trait if she receives both affected alleles from both parents. A only has to receive the affected allele from the mother to get the disease.

Some X-linked traits are hemophilia, color blindness, and pattern baldness. Do you know of any others?

Watson and Crick

James Watson and Francis Crick are credited with elucidating the double helix structure of DNA. With the help of other scientists they were able to understand how adenine pairs with thymine and how guanine pairs with cytosine. The other scientists that provided information for understanding the structure are Erwin Chargaff, Rosalind Franklin and Maurice Wilkins, and Linus Pauling.

Source: http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/biomolecules/dna/watson-crick-wilkins-franklin.aspx

At first, the men believed that the bases were on the outside of the double helix and the sugars and phosphate groups covalently bonded on the inside. After building the model, they discovered that it was not at all stable. They then built a model with the bases inside and sugars and phosphates outside, which created the stable double helix! Because of their great discovery Watson, Crick, and Wilkins were awarded the Nobel Prize in 1962. Unfortunately Rosalind Franklin could not receive the award because she had passed away in 1958.

Without the great minds of both Watson and Crick, I believe we would have never discovered as much as we have to this day.

Thank you everyone for your advice on studying yesterday!! I will use it all wisely.

Have you ever wondered what the world would be like today if we hadn't discovered what we know? What kind of world do you think we would live in if major discoveries weren't made, like Watson and Crick and the elucidation of the DNA double helix?

V is for Vesicle

A vesicle is something that is used to carry molecules through the body. Since the body consists of mostly water, these vesicles need to be hydrophilic on the outside, but most molecules in need of transport are hydrophobic, so the inside of the vesicle must be hydrophobic. This means that they can be made from phospholipids. Phospholipids have a hydrophobic tail and a hydrophilic body (and they look like sperm).

Source: http://en.wikipedia.org/wiki/Vesicle_(biology_and_chemistry)

This is a picture of a liposome. It has a phospholipid bilayer to accommodate hydrophilic molecules.

Since there are so many molecules that need to be transported in the body there are many, many vesicles. The ones that I am most familiar with are those that carry neurotransmitters because that is what I am currently learning about in my psychopharmacology class. In our neurons we have vesicles that take our neurotransmitters to the presynaptic part of the nerve. Once the vesicles reach the destination they push the molecules through their membrane and out into the cytoplasm or cell body (wherever they are, really).

Side note: I have six finals and five quizzes, one lab report, one essay, and one project all this week. The problem is that I can think of about a hundred things more thrilling than studying. How do you study? Any tips or suggestions that make for good studying habits?

U is for...Uracil? No...

Urey-Miller Experiment!

This is one of my favorite experiments, quite possibly because it's one of the few that I can remember easily. The purpose of this experiment was to figure out how the macromolecules came to be on this earth. There are four macromolecules that life needs: carbohydrates, lipids, proteins, and nucleic acids. From research scientists found that before life, none of these existed in the environment. So the Urey-Miller experiment simulated hypothetical conditions that were thought to be in existence during the time of early earth (before life): water (H2O), methane (CH4), ammonia (NH3), and hydrogen (H2). Using an electric shock as a catalyst (which represented lightening), they were able to synthesize carbohydrates, lipids, and proteins from inorganic materials. After Miller's death the experiment was reexamined and found to contain the 20 amino acids needed for life (precursors to nucleic acids!).

Source: http://en.wikipedia.org/wiki/Miller–Urey_experiment

There are some scientists that believe earth's atmosphere had a much different composition than what was used in this experiment. Much evidence shows that there were many volcanic eruptions during early earth times. This means that hydrogen sulfide and sulfur dioxide would also be in the atmosphere, which results in many different molecules becoming synthesized.

Do you think that live was formed from the composition of the early earth atmosphere?

T is for Telomeres

Telomeres are the ends of chromosomes. They are particularly important because they keep the ends of chromosomes from deteriorating. During replication a special enzyme, named telomerase, is used to replication the ends of chromosomes. This process is very important on the lagging strand because it works backwards (works 3' to 5' instead of 5' to 3'). To do this, multiple primers must be placed on the DNA (replication can ONLY work 5' to 3', so even though the lagging strand is working 3' to 5', it skips ahead and works backwards). This creates a huge problem when the end of the chromosome is reached because there is no more DNA strand to place a primer on! Instead of just forgetting about those nucleotides and shortening the chromosome each time replication occurs, telomerase comes in to save the day. This is the only example of a reverse transcriptase in our body (viruses use these very often, it's how some are so deadly, like HIV). The telomerase will ad a 3' overhang that is about 12 to 16 nucleotides long. It is made up of several guanine and thymine bases.

Source: http://en.wikibooks.org/wiki/Medical_Physiology/Cellular_Physiology/DNA_and_Reproduction

Without telomeres and telomerase, our chromosomes would be shorter after every round of replication. This would eventually lead to loss of genes, meaning loss of proteins, and eventually our body wouldn't be able to function. Loss of telomeric ends is a theory of why we age and why some people age faster than others. I haven't looked into it personally but that's what I've heard.

Have you heard anything about telomeres and aging? If there is in fact a correlation and we are able to fix degeneration of telomeres, eliminating aging, do you think we should?

S is for Sister Chromatids

Sister chromatids are two identical chromosomes attached to each other at the centromere. Since they are identical, they carry exactly the same genes. So what's the point of having two identical chromosomes attached to each other? This is the body's way of making more cells. When it undergoes mitosis the DNA needs to replicate itself so the new daughter cell will have the same amount of genetic material.

Source: http://www.thestudentroom.co.uk/showthread.php?t=1605268

Sorry for such a short post today, it's currently student appreciation weekend and I'm focusing all of my energy on feeling appreciated. Out of everything that USP does incorrectly, they always nail SAW. Tons of free food, live music, and bouncy castles. What more could a college student ask for? A free shirt? Got one of those too.

R is for RNA (and Resonance)

RNA, or ribonucleic acid, is one of the ways that the genetic code gets implemented. There are many forms of RNA: mRNA, tRNA, rRNA, snRNA, miRNA, and a ton more. I don't know too much about any of them except mRNA and tRNA and enough about rRNA to get me through translation. Shall we start with the difference between RNA and DNA? The main difference, which is actually how each got their names, comes from the substituents on the 2' carbon of the sugars. RNA has a hydroxyl (-OH) group on it's 2' carbon. DNA (deoxyribonucleic acid) has just a hydrogen (H), hence deoxy. The sugar on each molecule is still ribose, just missing a hydroxyl group in DNA at the 2' carbon.

Another difference is that RNA is single stranded while DNA forms a double helix with another strand. The last main difference that I would like to point out is in RNA the base thymine is replaced by uracil. To be honest, I have no idea why, but there is no thymine in RNA.

Source: http://www.accessexcellence.org/RC/VL/GG/rna.php

mRNA, which stands for messenger RNA, is how the genes from our DNA get passed outside of the cell and made into proteins. Since ribosomes, which are made up of rRNA and provide the docking station for tRNA to synthesize a protein, cannot get into the nucleus of the cell and DNA cannot leave the nucleus of the cell, mRNA fixes this problem. The mRNA will bind to the ribosome, and as the ribosome "reads" the mRNA, tRNA's carrying the proper amino acid will dock to it and synthesize the growing polypeptide chain.

Do you think that the amino acid attached to the top of the tRNA can read the mRNA to make sure that it's the correct amino acid or do you think the tRNA is responsible for the correct amino acid?

Also for all you organic chemistry people out there: when in doubt, resonance.

Questions

Scientists are taught to ask lots and lots of questions. One of the first things we learned in freshman biology was the scientific method. The scientific method is constructed around asking questions, it's actually the first step. Without a question, how will a person be driven to do an experiment?

Source: http://www.sciencebuddies.org/mentoring/project_scientific_method.shtml

Part of understanding the goals of science is to realize that the questions we ask may never be answered, maybe because there is no answer. In one of my current classes we had a discussion about whether or not science can answer everything and the truth is that it cannot. At least not in today's world. Nothing can be proven 100% because we cannot test every single object on this earth to see if it fits our hypothesis. For many of our categories there are exceptions, for instance the Platypus is considered a mammal even though it lays eggs. There will almost always be an exception.

Answer to yesterday's question: It turns out that some amino acids in a protein's primary structure do not matter. As long as what it is changed to is either around the same size and/or polarity, the protein will not be effected. Other amino acids will greatly effect the protein: if it is necessary for a small amino acid to be at a certain spot on the chain and it gets switched out for a larger one, the protein will not be able to work correctly. It all depends on the location, size, and/or polarity.

Today's question is more of a though provoking one. There is no right or wrong answer. Do you think that one day science will have the ability to answer everything?

P is for Protein

And also purchased ice cream from the ice cream man for the FIRST TIME EVER :)

But back to proteins. They are what structural genes code for. Everything that your body does is a result of proteins. That ice cream that I just ate is currently being emulsified in my belly by three proteins: bile salts, pancreatic lipase, and lipoprotein lipase. Proteins are probably one of the most important molecules in the body. Enzymes are probably the best known category of proteins. Most end with the suffix -ase, such as carboxylase, lipase, dehydrogenase. There are seven major categories of proteins, I believe. To be honest though I do not remember what they are. They all have some function in the body though, all proteins are actively doing something in your body.

Source: http://en.wikipedia.org/wiki/Protein

The above picture is myoglobin, which is a major part of blood (second only to hemoglobin). Proteins have four structures:

1. Primary
2. Secondary
3. Tertiary
4. Quaternary

The primary structure of a protein is it's amino acid sequence. The secondary structure is made up of hydrogen bonding between the amino groups in the primary structure. They can either bond to form an alpha-helix or a beta-pleated-sheet. A protein's tertiary structure is the way it folds. I like to think that this is the most important structure because if it incorrectly folds the protein will most likely not be able to do it's job, or even worse, do the wrong job. It's final structure involves interactions with other proteins. Quaternary structure is how the protein bonds with other proteins. Hemoglobin, for example, is made up of two alpha subunits and two beta subunits.

There is so much more I could say! I love proteins. They are so so so important to how our body works, it's really amazing.

Answer to Tuesday's question: A famous experiment demonstrating osmosis is the dialysis tubing experiment! You put starch and a colored substance on one side of a semipermeable dialysis tube and submerge it into water. The color will seep out of the tube but turn to a different color.

If you were to change one amino acid in the primary structure of a protein, do you think it would change the entire protein or render it useless?

Osmosis!

As in Osmosis Jones :) No, no. Osmosis is the net movement of a solvent through a partially permeable membrane from an area of high concentration to an area of low concentration. Not to be confused with diffusion, which is just a net movement of molecules from a high concentration to a low concentration. The overall goal with both osmosis and diffusion is to equalize the concentration both inside and outside, say, a cell.

There are three states that a solution can be in:
1. Isotonic - Equal concentrations both inside and outside of the cell
2. Hypertonic - More solute in the cell than solvent (more water outside the cell, more molecule inside)
3. Hypotonic - More solvent in the cell than solute (the opposite of above)

I think that's right? Sorry, it's been a really long time since I've had to look at this stuff.

My favorite example of osmosis is explaining why, if you are stranded at sea, you should not drink the salt water. Sure it tastes good and temptation is hard to resist when you are baking in the sun, but you will kill yourself much, much quicker. This is because of the high concentration of salt in the sea water compared to the water in your body. Once you have a high concentration of salt water in your body (creating a hypotonic environment), the fresh water will rush out of your cell in hopes to equalize the concentration! Which will not happen because there is not enough fresh water in your body at that point. You will die.

But at least now you know WHY.

Source: http://www.movieposterdb.com/poster/b59084de

Answer to yesterday's question: A nucleotide is a base (either A, T, G, or C), a sugar (either deoxyribose or ribose), and a phosphate group. A nucleoside is just a base and a sugar.

What famous experiments can you find demonstrating osmosis? I'm sure all of you performed this in your high school biology class!

Nucleotides

Nucleotides are the building blocks of DNA. There are four in DNA: adenine, guanine, thymine, and cytosine. In RNA thymine is substituted out for uracil. Nucleotides are split up into two categories based on their ring structure. There are the purines, which are two aromatic rings, and they are adenine and guanine. The pyrimidines only are made up of one aromatic ring and they are thymine, cytosine, and uracil. The way I like to remember which is which is that purines are the larger molecule even though they have the shorter name!

Source: http://www.dna-sequencing-service.com/dna-sequencing/dna-nucleotides/

Unfortunately all of the pictures that I found including uracil weren't very good and I could hardly read the names. So how do nucleotides "build" DNA? Research done by Chargaff proved that there are equal amounts of adenine and thymine and equal amounts of cytosine and guanine. Watson and Crick later elucidated that adenine hydrogen bonds with thymine and guanine hydrogen bonds with cytosine to create a double helix structure. There are three hydrogen bonds formed between G and C, but only two hydrogen bonds between A and T, making them the weaker pair.

Nucleotides also serve another very important function: when translating RNA into a protein a set of three nucleotides will code for an amino acid. This is called the genetic code. It is said to be mostly universal and degenerate. What is degenerate? When I first heard it I thought it sounded like something terrible, but all it actually means is that one amino acid has many codons (a triplet of nucleotides that codes for an amino acid).

Answer to Saturday's question: Gregor Mendel was actually thought to be crazy back in his time. Nobody believed his results and he was considered a fraud. The leading theory of inheritance in Mendel's day was a blending theory. Scientists thought that both parent's traits mixed together and their offspring was a blend of them all.

Do you know what the difference is between a nucleotide and a nucleoside?

Mendel, Gregor Mendel

Gregor Mendel can often be heard of as the father of modern genetics. He is most famous for his work with the pean plants in his garden. Mendel came up with the idea of individual assortment - genes will cause a specific phenotype and these genes would each assort themselves individually from one another. He chose seven characteristics of his pea plants to work with: seed color, seed shape, position of flower, color of flower, stem length, pod shape, and pod color. Each of these characteristics had two options:

• Seed color was either green or yellow
• Seed shape was either round or wrinkled
• Position of flower was either axial or terminal
• Color of flower was either white or purple
• Stem length was either long or short
• Pod shape was either inflated or constricted
• Pod color was either green or yellow

Source: http://beautifulcoolwallpapers.wordpress.com/2011/07/20/gregor-mendel-2/

Through many experiments (termed dihybrid crosses) Mendel concluded that each trait assorted itself independently of the others. A Punnett square can be used to determine Mendelian Inheritance. With all the different patterns of inheritance that multicellular organisms have, it's amazing that Mendel had chosen seven different traits at random that represented independent assortment. I started to think one time what if he chose different traits? What would have happened to our knowledge about genetics had Mendel not done the work that he did?

Source: http://en.wikipedia.org/wiki/Gregor_Mendel

Do you know if Gregor Mendel was as popular back in his day as he is now? What was the leading theory of genetic inheritance in Mendel's time?

Lipoprotiens

Time to switch to biochemistry. A lipoprotein is a molecule that contains both proteins and lipids. This combination allows fats to move through water. Originally fats cannot move though water because they are hydrophobic (afraid of water). Why do we need movement of lipids throughout our body? So they can be metabolized, of course! Dietary fats are emulsified in the gut by bile salts secreted from the pancreas, and whatever else is not needed diffuses through to the epithelial cells, re-esterified, and packaged into chylomicrons. These chylomicrons are then used to deliver the lipids, these specific type known as triglycerides, into skeletal muscle and adipose cells.

Source: http://www.answers.com/topic/lipoprotein

Answers to yesterdays question: The extra chromosome ends up in the cell of a Klinefelter's Syndrome individual due to a mix up during meiosis. During either Stage I or Stage II the sister chromatids don't separate from each other correctly, ending up with an extra chromosome in one gamete! Another disorder with an extra chromosome is Down Syndrome, which is an extra of chromosome 21 (often called Trisomy 21).

Klinefelter's Syndrome

This symptom is characterized by three sex chromosomes instead of two. The chromosomal makeup will be XXY, and the Klinefelter's Syndrome is also known as XXY Syndrome. Since there is still a Y chromosome the person will be a male, just with an extra X. There aren't many physical signs of this disease, and if there are any they don't normally occur until puberty. Some symptoms are a less muscular body, less facial hair, less body hair, broader hips, larger breasts, and weaker bones. Another physical symptom is most will be taller than the average male. I think the worst symptom of this symptom is infertility. Most of the symptoms of Klinefelter's results from a smaller amount of testosterone being produced by the body. Here is a karyotype of a person with Klinefelter's Syndrome:

Source: http://en.wikipedia.org/wiki/Klinefelter's_syndrome

This syndrome happens to about 1 in 500 to 1 in 1000 male births. While it is irreversible, treatment options are testosterone treatments. Some men also have cosmetic surgery to reduce their breast size.

How do you think an extra chromosome ends up in the cell? Can you think of any other diseases where there is an extra chromosome?

J is for Jen!

Because I could not come up with a damn thing science related. There was always jugular, but I don't know much about that. So I guess I will just say a little about myself.

I am a bioinformatics major and psychology minor at University of the Sciences. Currently I am a third year student which means I graduate next year! Hopefully I will get into a genetic counseling program, but there's only 25 accredited schools in the country. We shall see!

My stress levels at the moment are through the freakin roof. There isn't one week during April that I don't have at least one exam and starting the week of the 22nd I have 7 finals in one week. But I only have one final during finals week! That makes up for it, I guess. My anxiety has been very high lately, so if there are no posts past the week of the 22nd I didn't survive.

How do you deal with anxiety? What calms you down when you feel extremely stressed?

Answers to yesterdays question: some side effects for X chromosome condensation are certain genes won't be expressed. Some women experience sweating on one side of the body but not on the other. Researchers were able to determine that only one X chromosome condenses by looking at different diseases where a person has an abnormal number of sex chromosomes, such as with Triple X Syndrome. When looking at this person's chromosomes, it was noticed that two of the X chromosomes were condensed, not just one! The body can actually count how many need to be condensed. It's simply amazing :)

I is for Inheritance Patterns

There can be many forms of inheritance (maternal inheritance is the only one I can think of at the moment) but I am going to stick to single chromosome inheritance. A lot of popular knowledge on this subject has to do with different diseases that a person can inherit, such as X-linked and autosomal. The inheritance pattern that I would like to go over is epigenetic inheritance. This is a pattern in which a modification occurs to a gene or chromosome that alters gene expression. There are two types that I studied, which are dosage compensation and genomic imprinting. Dosage compensation is my favorite :)

The purpose of dosage compensation is to even out the sex chromosomes. Females have two X's and males have an X and a Y. The Y chromosome is considerably smaller, which means there are much less genes on it. To make everything even, one of the females X chromosomes is condensed. This turns off that X chromosome, and under a microscope it appears as a small black spot in the cell's nucleus (called a Barr Body).

Source: http://glencoe.mcgraw-hill.com/sites/dl/free/0078664276/281029/ccq_ch13_q3.gif

What do you think some of the side effects are for females when one X chromosome is "turned off"? How do you think scientists were able to prove this?

Heterozygote and Homozygote

This sort of goes back to my post having to deal with Alleles. A homozygote is an individual with a dominant allele and a recessive allele for the same gene (humans have two alleles for each gene). A heterozygote means that a person either has two dominant alleles or two recessive alleles. An easy way (or at least I think easy) to understand this is to look at diseases: say you have a recessive disease, which means you will need to have both recessive alleles for the disease to affect you. An example of this is sickle cell anemia. If a person only has one copy of the recessive allele (a heterozygote), then they will not have the disease but will be considered a carrier. They can pass the disease on to a child if the other parent is a carrier as well. A person with both dominant alleles will neither have the disease nor be a carrier and cannot have a child with the disease.

Here's a good picture to explain it:

Source: http://genome.wellcome.ac.uk/doc_WTD020850.html

Now here's to hoping that I remember everything for my upcoming genetics exam as well as I did with this!

Gametes

Gametes are the reproductive cells in organisms. I can't remember if I mentioned this before but humans have 46 chromosomes, two copies of each one. Our last pair of chromosomes are our sex chromosomes, XX for females and XY for males. Gametes will contain one set of chromosomes. This is how we can pass down X-linked traits (which I will not elaborate on, in this post at least).

Source: http://legacy.owensboro.kctcs.edu/gcaplan/bio/notes/gametogenesis.jpg

This is a really good picture that describes how gametes are produced. First the cell must go through mitosis, which creates sister chromatids. It then enters meiosis I, where they separate into different cells, very similar to how mitosis works. Meiosis II then starts, and separates the sister chromatids once again. The difference between mitosis and meiosis is that the cellular yield is four haploid (containing one set of chromosomes) cells instead of two diploid (containing two sets of chromosomes) cells.

Answer to yesterdays question: Frederick Griffith died from a bomb dropping down in his laboratory (located in the back of his house if I remember correctly). The S strain of the bacteria Griffith used was deadly because it secreted a capsule that stopped the body's defense mechanisms, while the R strain did not. This meant that the body could easily fight the R strain but the S strain was deadly with no antibiotics.

I must apologize for the lack of commenting I've been doing. This is an extremely stressful weekend, but I WILL catch up either Tuesday evening or Wednesday morning! My genetics test is this coming Tuesday and I feel so unprepared.

Frederick Griffith

Frederick Griffith was an Englishman who studied bacteriology. His experiment is famous for elucidating the "transforming factor" in genetics. He worked with two strands of Streptococcus pneumoniae, one a smooth strain (produced smooth colonies on growth media) and the other a rough strain (produced rough colonies on growth media).

Frederick Griffith

Source: http://en.wikipedia.org/wiki/Frederick_Griffith

In his experiment, Griffith infected mice with the S strain and with the R strain. The mouse with the S strain died, while the one that received the R strain survived. He then heat-killed the S strain and administered it to a mouse. The mouse survived. The next step in his experimental processed was to combine heat-killed S strain and live R strain, which he gave to the mouse. The mouse died! Through this he concluded that the dead S strain must have given the live R strain something, which he called a transforming factor. The experiment is summarized by this picture:

Source: http://en.wikipedia.org/wiki/Griffith%27s_experiment

Through other experiments scientists discovered this transforming factor was in fact DNA. Frederick Griffith is a very important person in the history of genetics!

Do you know how Frederick Griffith died? Do you know why the S strain was deadly and why the R strain was not? Also, does this post count as double, for F and G?! Just kidding. You're still getting a G :)

Extinction

What a sad topic this is. So what does extinction have to do with my theme? A lot of people blame (rightfully so if you ask me) humans for the possible extinctions of many species alive today and for those that have already disappeared from this earth. Apparently humans are not the only reason for some species going extinct, though. I recently wrote a paper on research done by Bruford, Goossens, Hu, Li, Wei, Zhang B, Zhang S, Zhang Z, and Zhu that explained what is going on with the giant panda population.

Source: http://www.traveladventures.org/continents/asia/images/giant-panda08.jpg

These researchers believe, along with many others, that the giant panda was destined to become extinct. Through population genetics they have found that giant pandas have extremely low genetic variability. This means that the panda isn't able to adapt well to environmental changes and mutations, if they occur. On the bright side researchers hope to find a way to increase the variation in the giant panda genome in hopes that its ever nearing extinction may either be pushed back or never happen. From what I understood of the article more scientists are looking at the giant panda demographics and hoping to find answers with different populations.

The answer to yesterdays question is your genome is .1% different than mine. All humans are about 99.9% similar.

What do you think about this reason for the possible extinction of giant pandas? Have you heard anything like this for other species?

DNA

DNA stands for deoxyribose nucleic acid. DNA is what makes an organism what it is. It is made up of a nucleotides that all bound together by a phosphodiester bond (a bond formed between two phosphate groups). So what is a nucleotide? I'm sure many of you know about the four different bases found in DNA - adenine, guanine, thymine, and cytosine. Those aren't the only components of a nucleotide, though. The other two components needed to make a nucleotide are a sugar (deoxyribose) and a phosphate group.

Source: http://publications.nigms.nih.gov/thenewgenetics/images/ch1_nucleotide.jpg

One of the incredibly fascinating features of DNA is that the bases have extreme selectivity when bonding to one another. Adenine will only form a hydrogen bond with thymine and guanine will only form a hydrogen bond with cytosine, each forming a 1:1 ratio. It is partially because of this (known as Chargaff's rule) that Watson and Crick were able to elucidate the structure of DNA. Although there is much more that can be said on this topic, I won't try to explain anything else. Mainly because I don't fully understand it so there's no way I'm going to be able to explain it to others.

Answers to yesterdays questions: transcription is the processes of copying DNA into single stranded mRNA. Translation is the processing of that mRNA into a polypeptide. A polypeptide is a sequence of amino acids, but a protein is a polypeptide with function.

Do you know what percentage of your genome is different than everyone else's?

Central Dogma of Genetics Updated

The central dogma of genetics describes the way our genetic code creates our body. There's no better way to describe this than with a picture. Also knowing me I will over explain everything and confuse everyone.

Source: http://upload.wikimedia.org/wikipedia/en/thumb/d/dd/Extended_Central_Dogma_with_Enzymes.jpg/550px-Extended_Central_Dogma_with_Enzymes.jpg

Without this process our genes would almost be useless. DNA can replicate itself, which is how complex organisms are multicellular yet still the same individual organism. DNA can also be transcribed into RNA. When I first started my degree I thought all RNA was translated into proteins. Turns out it's not! While 90% of the RNA transcribed is made into proteins (or so my textbook tells me), the other 10% can be made into structural components of molecules (like ribosomes).

I really can't think of much more to say on this topic, I think the picture covers it all! Do you know the difference between transcription and translation? What about the difference between a polypeptide and a protein (I just learned this today)?

I forgot to answer yesterday's questions!! Good job Sky Luke Corbelli for answering both them correctly! It is estimated that humans have around 20,000 to 22,000 genes. This is a significant decrease from the estimated 30,000 to 32,000 they thought before the accomplishment of the human genome project (pre 2003). Plants are more genetically rich than humans because they have much more redundancy in their genome. They still haven't figured out the significance of redundant genes.

And this is for my sister: C is for Connor!!

B is for Bioinformatics!

For today's post I have chosen a subject that is very near and dear to my heart: Bioinformatics. Why is it especially important to me? Bioinformatics is what I am majoring in at University of the Sciences!

Source: http://www.dtrends.com/Figures/com_hum_mol.jpg

Bioinformatics can be described as the application of statistics and computer science to the field of molecular biology. This field of science has many objectives, but they all mainly focus on the discovery of genes and their corresponding proteins. Many believe that bioinformatics is the future of science because the world is moving towards the application of our knowledge on genetics: proteins.

With a degree in bioinformatics an individual can go into many fields such as robotics, biotechnology and pharmaceutical research. My goal is to become a genetic counselor.

Do you know how many genes a human has? Do you know why a plant has more genes than a human but a human is considered a more complex organism?

A is for Allele

An allele is defined as one form out of two of a gene that can either be inherited or achieved through a mutation. Each human has two alleles, one for each chromosome (humans have two of each chromosome). There are only two possible traits for an allele: positive or negative. Since everyone has two alleles, an individual with two positive alleles is termed homozygous dominant, an individual with one positive and one negative allele is termed heterozygous, and an individual with two negative alleles is termed homozygous recessive.

The way I was first taught to understand alleles was the blue eye/brown eye problem. Blue eyes are known to be recessive, brown eyes are known to be dominant. To have blue eyes, a person must be homozygous recessive or the trait will not be shown. Even one copy of the dominant allele gives rise to that trait. So that means if you have one recessive allele and one dominant allele, you will have brown eyes. If you have two copies of the dominant allele, you will still have brown eyes.

A lot of times this isn't the case with traits, multiple alleles are necessary for one single trait (like skin color).

PS: This is my first post for the A to Z Challenge, good luck to everyone who is participating!