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Evidence for Evolution

What is the Evidence for Evolution?

There are many different pieces of evidence for evolution; paleontology, biogeography, developmental biology, morphology, and genetics. I will be discussing what each piece of evidence means. 

Paleontology is the study of prehistoric life and shows that organisms have changed little by little over time. The most clear example of evidence are fossils, because they prove that many early fossils are identical or similar to organisms living now.

Biogeography shows that new species only create and arise near other similar species. This is evidence because species that are similar share a common time and space.

Developmental biology show how organisms can develop into adults from single cells. They all pass through many stages of life which are all very similar in each organism, this shows evidence of evolution. 

Morphology is an organisms shape and structure and how they adapt previous generations features to new uses. The evidence here is that organisms inherit traits from their ancestors and over time change.

Genetics is evidence of evolution of different organisms because it shows that we can group them by similarity of genes. If organisms have similar genes it proves that they evolved from similar species.

Plant Divisions

4 Plant Divisions:

Bryophytes are the most common plant division and are made up mosses, liverworts and hornworts. They are found in almost every habitat, including deserts but are most adaptable to moist environments. This is thought to be the first plant division dominate the environment. Two characteristics that distinguish them are that they lack specialized vascular tissue (xylem and phloem), and they are nutritionally dependent on the gametophyte. 

Pteridophytes are vascular plants such as ferns, horsetails, and lycophytes. This division reproduce using spores instead of seeds, which is why they are often referred to as 'seedless plants'. Two features that make them stand out are their large pinnate leaves and their ability of circinate vernation; meaning the young ferns have a protective spiral coiling.

Gymnosperms are plants that have 'naked' seeds, meaning they are not enclosed in fruit or pods. They include conifers, ginkgo, cycads, and gnetae. Features of this division are plants containing cones or strobili, with visible seeds.

Angiosperms are plants that have seeds enclosed in something such as a fruit. They also reproduce and bear  flowers, this means that the division includes all flowering plants; roses, sunflowers, fruit trees, etc. It is the most diverse and large group of plants because they can be anything from shrubs to trees.

Mutualism, Parasitism, Commensalism

What are Mutualism, Parasitism and Commensalism?

Mutualism is a relationship between organisms of different species in which both benefit from the relationship.   For example, bees and flowers. The bees help pollinate the flowers for reproduction which benefits the flower, while the bees get nectar from the flower which benefits the bees. It is a win-win kind of association.

Parasitism is a relationship when one organism (parasite) benefits at the expense of another organism of a different species (called the host). For example, a flea and a dog. The flea is benefiting by feeding off of the dogs blood, while the dog is being hurt and harmed by the flea. Only one organism is getting any benefit out of the relationship.

Commensalism a relationship between two different species in which one of them benefits from the relationship and the other is not harmed or benefiting from the association. For example, birds and trees. The bird benefits from the tree by using it as shelter and a place to find food, where as the tree is neither harmed or getting any benefit from the bird.  

Organic Compounds

The Four Organic Compounds 

1. Carbohydrates are the compound that provide energy to living cells. They are the main energy source because they activate instant cellular energy. The carbohydrates we use as food comes from photosynthesis of plants. The compounds monomers are monosaccharides or a single simple sugar (glucose, fructose) and disaccharides or two simple sugars bonded together. 



2. Lipids function as energy storage, structural components of cell membranes, and as signaling molecules. This compound is made up of naturally occurring molecules such as fat, waxes, sterols, etc. Fats are the biggest group of lipids. The monomers of this compound are fatty acids and glycerol. 


3. Proteins are involved in nearly all cell functions, each having their own specific function within the body. Proteins are used for structural support, bodily movement, and defense against germs. Antibodies, enzymes, hormonal proteins, and storage proteins are all types of protein with different functions. They not only vary in function but structure as well, each one is a distinct three dimensional shape. The monomers of this compound are are amino acids. 

4. Nucleic Acids transfer genetic information from one generation to the next in living organisms. There are 2 types of nucleic acid; deoxyribonucleic acid (DNA), and ribonucleic acid (RNA). Each have their own role in transferring genetic information. The monomers of it are nucleotides, which have three parts; a nitrogenous base, a five carbon sugar, and a phosphate group. 

Natural Selection

What is Natural Selection?

Natural Selection was a evolution theory introduced by Darwin in 1859. His theory was that the organisms that were best adapted and equipped to compete in their environment would survive and pass on their strong genetic traits to offspring, and over time that would lead to evolution. It also goes the other way, organism that are less adapted to their environment will reproduce much slower and soon be eliminated leaving only the most evolved organisms to live and continue multiplying.  

Confused? Here are a couple examples.

• The peppered moth: Up until the industrial revolution the peppered moths were generally white in color with black spots. The air in London became full of soot and began turning the white trees that they camouflaged in, to a dark black. The birds began to eat the lighter colored moths because they were easily spotted. Over a few months dark moths started appearing and lighter moths became scarce. 
• The peacock:  The more impressive the tail of a male peacock, the higher its chances of finding a mate. Female peacocks choose mates based on the color of the feathers. According to experts, the brightness of the colors might signal to females that the animal has high-quality genes. This would make him ideal for reproduction and to ensure the survival of the offspring, so they're chosen first when it's time to mate.

Evolution

Evolution: Darwin vs. Lamarck

Darwin's theory is called descent with modification. This means that he believed that each generation of an organisms offspring is in someway different than the previous generation. Which in conclusion would mean that over time and many generations the organism would be evolving. 

Lamarck's ideas of evolution were not the same. He believed in inheritance of acquired traits, the idea was if an organism were to work on improving something over its entire life, it would be passed on to its offspring and they would inherit that improvement. For example, if a man were to work out every day and became very muscular than his children would also become muscular. His other idea of evolution in known as use and disuse, this is the thought that organisms will lose characteristics they do not use or need and they will develop characteristics that will be useful. An example is giraffes, they need long necks to be able to reach leaves on trees so over time they strengthen and stretch, their offspring then have slightly longer necks.

They both have different theories and ideas, but they seem to have one certain point in common and that is that evolution is a slow process and it takes time and process for organisms to evolve.

Phloem & Xylem

Are Phloem and Xylem Similar? What are the Differences?

Similarities: Phloem and xylem are tissues in a plant that transport food and water. Both are vascular tissues and when they work together to effectively transport food, water and minerals they form a vascular bundle. They each have a tubular shape and are in the roots, stems and leaves of the plant. 

Differences: 

phloem

 

• transports nutrition to storage and growing parts of plant
• has soft wall cells
• bidirectional, meaning moves up OR down plants stem
• elements; companion cells, bast fibers, intermediary cells, sieve tubes
• living tissue

xylem

• transports nutrition to aerial parts of plant
• has hard walled cells 
• unidirectional, moves only up the stem
• elements; tracheids, vessels, xylem parenchyma
• NON living tissue 
• gives mechanical strength to plant because of lignified cells

Human Body Systems

Human Body Systems!

Integumentary System: Your body is very prone to damage, and that's why we have this system! This is an organ system that helps protect the body. It has many functions such as to cushion, excrete wastes, regulate temperatures and is the site for sensory receptors to detect pain and sensation. This is the largest of the body's organ systems and it can include of skin, hair, and nails.

Muscular System: Ever wonder how your able to move so freely? This is the system to thank! It is an organ system made up of skeletal, smooth and cardiac muscles. Not only does it move your body, it also helps to keep posture and circulate blood throughout the body. Some muscles in this system include your heart or cardiac muscle and there are muscles in every area of your body; legs, arms, chest, etc. Your nervous system controls the movement in each muscle you move. 

Skeletal System: This is made up of all the bones, tendons, ligaments, and cartilage in the body. The skeletons main job is to provide support for your body, without it your body would collapse. It also helps protect all of your internal organs and body tissues; the skull protects your brain and eyes, the ribs protect your heart and lungs, and the vertebrae protects your spinal cord.

Circulatory System: An organ system that passes nutrients (amino acids, gases, hormones, blood cells, etc.) to and from cells in the body using the heart, arteries, and veins. This system is needed to help fight diseases, stabilize pH and body temperature, and maintain homeostasis.

Digestive System: We all love food, but how does our body break it down? This system uses a digestive tract, hollow organs joined in a long tube from the mouth to the anus, to break down and absorb it. It enters through the mouth and down the esophagus, then to the stomach where tiny glands help digest the food. It then goes through the small intestine to the large intestine (colon), where it then exits the body through the anus. Along the way your muscular system contracts and helps it move through. The pancreas and liver are two more very important organs that work together with the nervous system to help break down food in your body.

Nervous System: A network of neurons (cells) that coordinate actions by sending signals throughout the body. There are two parts of this system, the central which contains the brain, spinal cord and retna; and the peripheral which is made of ganglia and nerves. The peripheral is sensory, it connects to the central nervous system telling it what the body feels; pain, temperature, etc. 

Endocrine System: This system contains glands that create different types of hormones (chemicals) that are sent into the blood. These hormones are what regulates the body. They spread through the blood stream using tiny glands throughout the body. Metabolism, growth and development, and mood are some of the things that hormones control.

Reproductive System: Without this system there would be no reproduction. It is made up of organs that work together, including the external genitalia and the gamete producing gonads. Both male and female reproductive systems are not the same. A females reproductive system is used to produce egg cells and to protect the offspring until birth. The female reproductive system relies on hormones created by the endocrine system. The males system is used to produce and deposit sperm. This meaning it requires both a female and male reproductive system to create an offspring. 

Respiratory System: This is the system that allows you to breath. It uses airways(nose,mouth), lungs and the muscular system to take in respiratory gases in your body and perform a gas exchange. Oxygen is exchanged to carbon dioxide by diffusion with external gases and the blood. This action removes the carbon dioxide and other toxins from your blood circulation, acting as a cleanser. 

Excretory (urinary) System: It is a biological system that removes excess and unnecessary materials from the body. It gets rid of wastes of the metabolism, gases and liquids (urine,sweat). The bladder, skin, lungs and kidneys are all major organs in the excretory system. It works along with the respiratory and circulatory systems by getting rid of gaseous waste from the lungs, and waste from the bloodstream through urination. Without this you could not maintain homeostasis in your body and the excess materials would cause much damage.

Immune/Lymphatic System: It is a variety of structures and processes that protects the body against diseases, viruses, toxins and parasites. This system is made up of special cells, tissues, proteins, and organs that are able to protect the body from anything not suppose to be in it. It monitors the body by using white blood cells called leukocytes. There are two types of leukocytes; phagocytes which chew up invading organisms and, lymphocytes which allow the body to recognize intruders and help it destroy them. This system helps keep you alive every day.

*underlined systems are systems that interact with system being discussed

Autosomes & Sex Chromosomes

All About Autosomes and Sex Chromosomes:

Let me start off by explaining that Autosomes and Sex Chromosomes are from the same chromosome, which contains 46 chromosomes total.

In each chromosome there are TWO Sex Chromosomes out of the total 46 chromosomes. Sex chromosomes are an X or Y chromosome that determines the sex of an organism. 

Autosomes complete the rest of the 44 of 46 remaining chromosomes. They are chromosomes that do not determine the sex of an organism.

*This picture shows the 44 Autosomes and the 2 Sex Chromosomes making one complete chromosome.

Domains of Life

The Three Domains of Life

Eukarya: This is the most familiar domain to us because it is made up of the kingdoms animalia (animals), plantae (plants), fungi, and protista. They have a huge diversity when it comes to form but they all share fundamental characteristics such as cellular organization and biochemistry. 

Bacteria: This domain is made up of the eubacteria. It is most commonly known for the causes of disease in humans and animals, but it plays many other roles in life. Bacteria can produce certain antibiotics (streptomycin), help break down dead organic matter, make up the base of the food web in many environments, and much more. This domain is very important because of its unique characteristics of being extremely flexible, rapid growth, and extreme age.

Archaea: Archaebacteria is what makes up this domain. It was not scientifically recognized as a domain of life until very recently. They look similar to those or the bacteria domain, but the harsh and extreme conditions in which they live make them very different. Archaeans have been found living in hot springs, deep sea rift vents and even the digest systems of cows. Because of this it makes them one of the hardest domains to study.

Incomplete Dominance

What Is Incomplete Dominance?

This is a form of inheritance in a cell where one allele (form of gene) for a specific trait is not dominant over the other allele, which in conclusion makes a combined phenotype (physical trait).  

Confused? Above is an example. When you cross pollinate between a red and a white snapdragon plant, the offspring will be pink. This is because the red allele is not completely dominant over the white allele, so because of that the two allele's are combined to make the outcome of a pink flower. 

Genotype and Phenotype

What are Genotypes and Phenotypes? How do they relate to each other?

A Genotype is the genetic make up or "internally coded, inheritable information" of a cell, organism or beings trait or set of traits. It is the complete amount of genes transmitted from the parent to the offspring. It can be looked at as a blue print or set of instructions for each living creature. It determines eye color, height, size, hair, etc. Genotypes control everything and are involved with all aspects of life of a cell or organism. 

A Phenotype is the physical outcome of the organism, the sum of all atoms, molecules and macromolecules. They are anything that is part of the observable structure, function or behavior of a living organism. They are the outcome of an organisms genotypes. 

They relate because the Genotype codes for the Phenotype. This meaning that without the genotype to be the code or instructions, the cell would not be able to interpret and produce the phenotype or outward appearance of the organism. So, without genotypes there would be no differences in the way every organism looked or functioned. 

Allele vs. Gene

How are alleles and genes different? And how do they correspond with each other?

Alleles are pairs of genes and help code for an organism. Genes come from the parent organisms in order to help with the make up of an organism. 

There are always two genes in an allele, if the genes are the same then the allele they make are considered to be homozygous, if the genes are different then the allele is heterozygous. An example of a homozygous allele would be if both parent organisms have blue eyes. They would then pass the blue eyed genes down to their offspring and their offspring would have blue eyes.

A heterozygous allele is a bit more complicated then homozygous allele. A heterozygous allele receives two genes just like the other but depending on what gene is domiment is the trait that the organism gets, although there are some exceptions where there can be a mix of the traits. A normal example of a heterozygous allele would be where one of the parent organisms has blue eyes and the other has brown. Brown eyes is a dominate trait so most likely the organism will have brown eyes. In some rare occasions an organism could have brown eyes but with a small amount of blue in them.  

Translation

What is Translation?

Once transcription occurs translation has to then do its job in the ribosomes by taking the base code of a mRNA molecule and translating a peptide into a chain of amino acids.

This is how it works: Molecules of mRNA come out of the nucleus then go to the ribosomes where codons are translated by tRNA molecules into amino acids. this is done by the RNA's specific code where three nucleotides, called a codon, are arranged to with the directions for the amino acid that matches them. The ribosome then surrounds the mRNA and uses it to make a chain of amino acids in the same order that they will be in in the finished protein. 

Since this is not the finished product it is more like a blue print for the finished product. The reason it is not the finished product is because amino acid synthesis happens during digestion there for this is when it needs to be reviewed. 

Eukaryote Transcription vs. Prokaryote Transcription

Different Types of Transcription?

Eukaryotes and Prokaryotes are different in so many ways but also the same. I explained a lot of the same and different ways in the "Eukaryotic and Prokaryotic Cells" post. One thing I did not describe was the transcription process of each. 

When you begin discussing the process it can become a little grey when you are trying to define an eukaryote from a prokaryote simply because the processes of both are so similar. They do the exact same job but it must be done in different areas and one is a bit more complicated than the other. 

Eukaryotes have membrane bound organelles. Because of this, eukaryotes have a mitochondria and a nucleus where the DNA is held. This is extremely important since RNA is created using DNA. Prokaryotes on the other hand have transcription happen right out in the cytoplasm since there are not any membrane bound organelles and instead everything is floating within the cytoplasm. 

Because of fact that one type of cell has organelles and one does not the one with organelles must also move RNA after transcription out of either the mitochondria or nucleus and into the cytoplasm in order for translation to occur, while a prokaryote does not need to move the RNA anywhere for translation because it is already in the correct place. 

Transcription in Eukaryotic Cells

Transcription in Eukaryotic Cells

What is transcription? Transcription is the process that creates RNA inside a cell. It is used to develop proteins inside the cytoplasm of a cell although the actual transcription happens in the nucleus and mitochondria. Since transcription does not happen in the cytoplasm, translation has to occur right after transcription takes place.

What happens during Transcription? During transcription messenger RNA (what carries information from DNA to the organelles that synthesize proteins) is transcribed from the original strand of a gene. RNA polymerase separates the two strands of DNA and puts together the RNA nucleotide pairs with the DNA. The moment the DNA has been transcribed the two DNA strands coil back together as the RNA is pushed out from the polymerase. When it has finally realized that it is finished the polymerase transcribes a 'terminator sequence' and the transcription ends, the RNA is released, and the polymerase releases from the DNA.

DNA Replication

DNA Replication?

DNA can copy its self over and over again in order to keep creating for the organism it is working for. This action is called DNA replication and takes place in the cell nucleus. 

How does DNA replication work? The molecules of DNA are made up of two strands of DNA that are connected together by hydrogen bonds. Hydrogen bonds always form between pairs that complement each other such as adenine compliments thymine and cytosine always pairs with guanine. When a molecule of DNA is trying to split fee of each other, an enzyme, called DNA gyrases, relaxes the strands so that they can split into two separate strands. Then the nucleotides in the nucleus bond with the unpaired bases with the help of DNA polymerase to the split strands and form two new DNA molecules. Once the strands are paired you have two new sets of DNA. Because there is one strand for the original and one new strand the replication process is considered semi-conservative, where one half is conserved from the original pair.

Why are there so many things to do for DNA replication? There are many things that have to happen in order for DNA to be replicated. This is because it carries genetic information and codes for everything in order for the cells to do their jobs. If the code is not replicated correctly then the information passed can cause extreme harm to the cell and the organism to the point where they could both die. 

DNA Vs. RNA

What exactly is DNA and RNA? We hear about DNA starting when we are little kids but do we really know what they are other then three little letters?

What is DNA made of?  DNA is made up of chains of nucleotides, molecules made up from purine, pentose sugar, and a phosphate group, put onto a sugar and phosphate backbone and wrapped around each other; this is called a double helix. There are four bases in DNA; guanine, cytosine, adenine, and thymine. Guanine and cytosine are always together on the helix and adenine always pairs with thymine as well. The reason this DNA is like this is so that it can duplicate itself by dividing and copying itself since it can match the other half. 

What does DNA do?  DNA stands for Deoxyribonucleic Acid. It is an acid that is in the cells of all living organisms. It is the code for all of the genetic material in an organism that determines what that organism will turn into by combining the genes from the parent organisms and passes a combination of traits down to the offspring. It also does some other things that are critical to life of the organism. DNA also holds the code that a cell needs to make RNA. When DNA is altered in anyway by something called a mutagen, it can cause health problems to the organism. 

What is RNA and what is it made up of? RNA stands for Ribonucleic Acid. It is a chain of nucleotides that is also in the cells of every organism such as DNA. It is made in long strands that have a backbone, just as DNA does, made up of groups of phosphates and riboes. Since it only has one backbone, it cannot form a double helix, instead it folds onto itself to help it fit into tight places. There are four bases that make up RNA just as DNA has. RNA's four bases consist of adenine, cytosine, guanine, and uracil. RNA is also what a mutagen looks for. If a mutagen takes over RNA it is able to change the DNA and make the cell do what the mutagen wants it to do rather then what it is supposed to do. 

What does RNA do? RNA has many jobs that it is responsible for; some of them are the synthesis of proteins, gene expression, gene regulation, and also the duplication of the genes. RNA plays just as an important role as DNA does, even though it may not be as widely known. It is just as important because it helps create DNA.

Mitosis VS ...

Mitosis can be compared to a couple of different cell actions. But what makes it different?

Mitosis is the process of which a cell divides and creates copies of itself, the main purpose of this being to help the organism grow or to replace cells that are either worn out, damaged, or simply old.  Mitosis does not happen in certain types of cells because those cells do not create identical copies of themselves though different types of cell reproduction consists of prophase, metaphase, anaphase, and telophase. At the end of mitosis, there is an ending result of two cells that are exactly the same.

Binary fission is a form of asexual reproduction. It can duplicate whole organisms as well as single cells in eukaryotic organisms. In the process of a single cell, two daughter cells are made by a single parent cell by cloning itself. The cell starts by creating copies of DNA and makes two complete sets. The cell then grows and the DNA move to opposite ends of the cell staying there until the cell is big enough to where it splits into two, introducing two daughter cells with identical DNA.

What makes mitosis and binary fission different from each other? They both sound like they are the same since they both make exact copies. Mitosis is more complicated then binary fission since it only takes about two to three steps to complete. Mitosis and binary fission both have the same possible side effects if the cell does not copy correctly. What makes them different is that binary fission is a form of asexual reproduction. It can duplicate a whole organism while mitosis can only make duplicates of cells. 
                                                          
Meiosis is the process of which a cell divides and reproduces cells. Meiosis only happens in certain types of reproductive cells called gametes, in humans these are called eggs and sperm and in plants they are called spores. Unlike mitosis, DNA from each contributing cell mixes up and forms the X. At the end of meiosis, there is an ending result of four cells. 

Since meiosis and mitosis are very alike in that they both reproduce cells and use the same cycle, there are a few key differences between mitosis and meiosis. A big contributing factor to their differences is that mitosis ends with identical cells while meiosis ends with cells that are alike but not identical. Another difference is that meiosis only happens in certain types of cells and needs two cells in order to reproduce where mitosis only needs one single cell. One more difference would be that in mitosis the two parts of the X are identical where in meiosis the X is made up of different pieces of DNA from each cell.  

The Cell Cycle

What are all of the stages to the Cell Cycle?

The Cell Cycle starts with its first stage called Interphase. The cell will be in this stage the longest amount of time out of all of the stages of the cycle.

During the first part of Interphase is called the G1 phase. Before the cell goes into the G1 phase it starts out in a resting state and begins to get ready for division. The cell then begins the G1 phase and begins to grow and synthesize amino acids turning them into proteins and then into enzymes.

The next stage of Interphase is called the S phase. This stage begins by DNA synthesis and by the end of the stage there are two sister chromatids. 

The last stage of Interphase is called the G2 phase. Once again biosynthesis is happening in the cell making sure that everything is done and that the cell can then move onto Mitosis. Once Interphase is at its end the cell has doubled everything and has two times the amount of material that it needs and can now start Mitosis.

Mitosis is the next stage of the cell cycle. During Mitosis there are multiple stages in itself. 

-The first stage of Mitosis is called Prophase. During Prophase the chromatine in the cell condenses and the nuclear envelope dissolves and the spindle is made to move chromosomes.

-The second stage is called Metaphase. This is the stage of Mitosis where the chromosomes align going straight across the center of the cell.

-The third stage is Anaphase. This is where the sister chromatids separate into individual chromatids and move to opposite sides of the cell.  

-The final stage of Mitosis is called Telophase. During Telophase a nuclear envelope forms around each of the two sets of chromosomes. 

Finally the last part of the Cell Cycle is able to take place. This stage is called Cytokinesis. This is where the cytoplasm of the single cell splits and is then two cells that have the same genetic code.