Genetics

During the second month of our biobiography project, we learned that a person’s genotype is all of their genetic information and a person’s phenotype has to do with the traits that are expressed, such as blond hair. In this unit, we spent a lot of time learning about genes, found on DNA, which is wound up into chromosomes, that are found in the nucleus of a cell. Genes are located on the 23 pairs of chromosomes in each human cell, and there are many genes, not all of which are expressed. As genes are passed down from parents to offspring, they usually share many visual traits. During the topic of genetics, we spent a lot of time reading and tajing notes from a website called, http://dnaftb.org/. For our Genetics Project, we got into groups of two, and with our partner, had casual conversations about a chromosome that we had picked, and how the genes found on it relate to our lives.

Mendelian Genetics

From learning about Gregor Mendel’s experiments with pea plants and fruit flies, I learned that genes come in pairs, don’t blend, can be either dominant or recessive, follow rules, and are real things.  From DNAFTB:

“Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits. He recognized the mathematical patterns of inheritance from one generation to the next. Mendel’s Laws of Heredity are usually stated as: The Law of Segregation: Each inherited trait is defined by a gene pair. Parental genes are randomly separated to the sex cells so that sex cells contain only one gene of the pair. Offspring therefore inherit one genetic allele from each parent when sex cells unite in fertilization. The Law of Independent Assortment: Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another. The Law of Dominance: An organism with alternate forms of a gene will express the form that is dominant.”

Molecular Genetics

After learning about the history behind genetics, we learned that genes are found on strands of DNA ( deoxyribonucleic acid) and RNA (ribonucleic acid), DNA is stored in chromosomes which are found in the nucleus of each cell, the differences between those two, and the Central Dogma of Genetics.  For chromosomes we wrote a genetics book with different chapters for each chromosome.  We also learned that the structure of DNA is in the shape of a double helix, or twisted ladder, shown in the diagram below.

DNA

DNA (Deoxyribonucleic acid) is a macromolecule in the form of a polymer, which is a string of repeated units called monomers. The monomer of a nucleic acid (such as DNA) is a nucleotide. The nucleotides are made up of a sugar, a phosphate group, and a base. There are four types of DNA bases (and nucleotides): Adenine, Guanine, Cytosine, and Thymine. The sugar and the phosphate are constant from nucleotide to nucleotide, and form the backbone of the nucleotide, or the sides of the ladder. A strand of DNA is a polymer of nucleotides.

The double helix, or twisted ladder shape is formed when: two strands of DNA line up next to one another, the bases bond to each other forming the rungs of the ladder, the sugar-phosphate portions form the sides of the ladder, and finally the ladder twists into a spiral to form a double helix. The double-helix structure of DNA molecule was discovered by James Watson, Francis Crick and Maurice Wilkins.

Each strand of DNA may be different because of the order in which nucleotides are bonded together

The bases of the nucleotides: Adenine, Cytosine, Guanine, and Thymine.

Bond to each other very specifically: Adenine will only bond with Thymine and Cytosine will only bond with Guanine. Two strands of DNA are complementary if they can form base pairs with each other. The base pairs are held together by hydrogen bonds. The A-T base pairs are held together by two hydrogen bonds, while the G-C base pairs are held together by three hydrogen bonds.

RNA

RNA is a polymer of nucleotides, similar to DNA. However, RNA is a single-stranded molecule while DNA is double-stranded. RNA forms base pairs by folding onto itself, enabling it to form many three-dimensional shapes, allowing it to play a major role in protein synthesis. Unlike DNA, RNA doesn’t use the nucleotide base, thymine; instead it uses a base called uracil. In RNA, uracil can form a base pair with adenine, just like thymine does in DNA.

Genetics

Genes correspond to sections within DNA, as one strand of DNA contains many genes. The sequence of DNA nucleotides in an organism, is an organism’s genetic information that is inherited, or passed down from parents. Genes contain instructions for building proteins, which are involved in many bodily functions such as producing eye color, or even expressing a disease, such as sickle cell anemia. DNA is packaged into compact units called chromosomes, located in the nucleus of a cell. Each human cell has 46 chromosomes, however, not all living things have 46 chromosomes, Mosquitoes have 6, Onions have 16, and Carp have 104. The full set of hereditary material in an organism is called its genome.

Genotype

The Genotype is the version of a DNA sequence that an individual has. A large amount of DNA, we all have in common, which is why we’re all humans, but there’s a large amount of variation in sequence among individuals. Those specific differences in sequence, when usually applied to an individual gene, are called a genotype. The genotype is expressed when the information encoded in the genes’ DNA is used to make protein and RNA molecules. A change in DNA sequence leads to an observable change in a trait in a person.

Phenotype

A phenotype is an individual’s observable traits, such as height, eye color, and blood type. Phenotypes are equally, or sometimes more so, influenced by environmental effects than genetic effects. A phenotype can be directly related to a genotype, but not all of the time. There are always environmental influences, such as what one eats, how much one exercises, how much one smokes, etc. All of these are environmental influences, which will affect the phenotype

Genetics TXT Book Chapter

For this project, we had to create a text book chapter, through texting.  Each pair chose a chromosome number, then looked through genes that are linked to that chromosome and found which ones related to us.  We also had to have a cover sheet which portrayed a strand of DNA and also portray one of the genes we chose. My partner and I ended up with chromosome 4, so we started researching and then had a conversation. It was hard to have a conversation that didn’t sound staged because we rarely talk about biology in texts, or instant messages, and this sort of made everything feel awkward. In addition to having the conversation, my partner Vidal, was in charge of our chapter’s title page, or illustration (on the right), and I was in charge of writing the introduction to our chromosome, found at the top of our conversation (shown below).

 

Chromosome 4. The fourth chromosome pair, out of 23 lined up from largest to smallest. Chromosome 4 is tightly packed with long strands of deoxyribonucleic acid, holding around 6 percent to 6.5 percent of the total DNA in cells. Scientists believe that chromosome 4 includes more than 186 million base pairs of the material that make up DNA, and encodes between 700 and 1,100 genes that make us who we are, or affect us in some way. Chromosome 4 is home to many diseases and disorders such as Parkinsons disease, Huntington’s disease, bladder cancer, Wolfram syndrome, and non syndromic deafness, Hemophilia C, achondroplasia, and even Chronic Lymphocytic Leukemia.  Chromosome 4 does not only hold the genes for diseases. It also holds the genes that a person may not even pay attention to, such as whether they think the odor of cinnamon is pleasant, or genes that affect a person’s phenotype, such as red hair. Not all of these genes may be expressed but, they can be passed down from generation to generation.

 

vantonio: Hey…

What you doing???

aarcaro: Eh.. nothing really how bout u?

vantonio: Well same.. I am bored that is why I decided to chat you. Haha

aarcaro: Oh I see..

vantonio: Yeah… OMG!!!!

guess what?

aarcaro: What?

vantonio: My mom made me this gnarly coffee with milk and cinnamon and marshmallows… its so damn good!!!!!

aarcaro: Ew coffee… I don’t like coffee…

vantonio: UGH!!!!

aarcaro: Cinnamon’s ok though

vantonio: how dare you to say that… What does a cinnamon have that coffee doesn’t?

I mean I do like the smell of cinnamon but I don’t like the way it tastes

😉

aarcaro: Then why do you put it on your coffee? Haha

I’m not sure if I like the smell of cinnamon…

vantonio: Umm..

How are you not sure if you like something or not.

aarcaro: I don’t know I guess I’ve just never payed much attention to it..

vantonio: I mean I know right away what I like…

aarcaro: I wonder what makes someone like or dislike the smell of cinnamon…

vantonio: Yea…

aarcaro: Well, I just found out that there is this gene called “CINN” on chromosome 4 that plays a role in if someone thinks that the odor of cinnamon is pleasant

Our likes when it comes to things like odors must be determined by the expression of specific genes

vantonio: Really?!?!?

Well… DUDE!!! don’t genes come from parents?

Meaning your mom passes her genes to you… and you pass them to your kids

aarcaro: Yea they determine things like someones hair color..

vantonio: What do you mean by hair color???

is it like pink or red or blue or WHAT???

aarcaro: Pink or blue hair? I’m pretty sure people don’t have that.. but people do have red hair… although I think its more orange than red.. unless they dye it red red

vantonio: So what… How do genes relate to people who have red hair?

aarcaro: Well…. the gene for red hair is also on chromosome 4 and is called HCL2 (or hair color 2 red) and if that gene is passed on from your parents you could get red hair

vantonio: Dude… How do you know all of this??

aarcaro: Well.. we are taking biology class.

And the Internet knows all…

vantonio: anything else that will amaze me and my stone brains about this chromosome?

aarcaro: Well……. did you know that another gene on chromosome 4 has to do with one’s susceptibility to obesity..

Meaning that if that gene is active, a person is more likely to become overweight

vantonio: Dude… it will be so sick if there was a way to turn that thing off.

heh heh

But that is good to know

aarcaro: Yea.. its kinda weird how a small chromosome in our cells can affect our life so drastically…

vantonio: AHH!!!! OUCH!!!

aarcaro: ?

what?

vantonio: way to go..  I got a paper cut on my pinky.

😥

aarcaro: That sucks..

vantonio: Meany..

Make it better

it was your fault

Now.. tell me what genes have to do with cuts.

NOW!!!!

aarcaro: haha really?

vantonio: Yes…

It’s to make me feel better

aarcaro: Yea right…

Well there is one gene…

vantonio: Then say… it to me

aarcaro: Its called PF4 (platelet factor 4) and its a protein that plays a part in wound repair and blood coagulation…

vantonio: So do all this genes really affect peoples DNA??

aarcaro: Well the genes are found in peoples DNA yea.. and that affects people’s lives…

There is a gene that affects DNA though…

vantonio: Ugh… what kind of friend are you… if you just tell me that there is a gene.. But don’t tell me what the gene is?

Which gene is it?

aarcaro: Huh? Well this gene called HMGB2 which stands for high-mobility group box 2 encodes a protein that can bend DNA and form it into DNA circles

vantonio: Wow…

Ha ha its so cool how I went from been bored to learning things about genes

heh heh..

well I am getting yelled at to go eat..

aarcaro: Hahah well ok.. just be careful you don’t wanna get obese!

vantonio: Me Mama doesn’t understand how important it is for my brains to learn new things

aarcaro: Ok so I’ll see you later..

Adios..

vantonio: Peace Out..

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