The Evolutionary

Wednesday, April 8, 2009

Tree

Life Science. How could they be related? Did you know that a tree is made up of lots of tiny cells? Read on below.

Glossary

The Alphabet Glossary

Alleles: The different forms of a gene

Branching tree: A diagram that shows how scientists think that groups of organisms are related

Cell: Basic building block of life

DNA: Deoxyribonucleic acid

Evolution: The gradual change in a species over time

Fossil: Preserved remains of a species

Genetics: The study of heredity

Heredity: The passing of traits from parent to offspring

Interphase: Stage of the cell cycle before cell division

Karyotype: Picture of all the chromosomes in a cell

Lipid: Energy rich fat

Mitosis: Stage of the cell cycle in which cells divide

Natural Selection: The process by which individuals that are better adapted survive

Osmosis: Diffusion of water molecules through a cell

Phenotype: An organisms physical appearance

RNA: Ribonucleic acid

Species: A group of similar organisms tat can mate and produce fertile offspring

Trait: A physical characteristic

Variation: A difference in a species

Meiosis is the process by which the number of chromosomes is reduced by half to form sex cells. Meiosis is has four stages, Before Meiosis, Meiosis I, Meiosis II, and End of Meiosis. Before meiosis happens every chromosome in the cell is copied. Centromeres then hold the two chromatids together. In meiosis I the chromosomes line up in the middle of the cell and then separate and move to the opposite sides of the cells. The cell then splits and forms two cells. Each chromosome still has two chromatids. In Meiosis II the chromosome and their chromatids move to the center of the cell. The centromeres split and the chromatids separate. Single chromosomes move to opposite ends of the cell. After meiosis is finished four sex cells have been produced. Each cell only has half the number of chromosomes that the parent cell had.

DNA

DNA (deoxyribonucleic acid) is a nucleic acid that contains the genetic code for life. It also governs what traits you get and what you don't. DNA is made out of a series of four nitrogen bases: Thymine, Guanine, Cytosine, and Adenine. These nitrogen bases only pair with specific other bases, Adenine always pairs with Thymine while Guanine always pairs with Cytosine. the sides of a DNA ladder are made out of a sugar called deoxyribose and which lternated with another molecule known as phosphates.

Respiration

Respiration is the process by which cells obtain energy from glucose. During respiration cells break down simple food molecules such as sugar and release the energy they contain. Respiration can also mean breathing so as to avoid any confusion the respiration process that takes places inside cells is called cellular respiration. The respiration equation is below this line.

C6H12O6 + 6 O2 ----> 6 CO2 + 6 H20 + Energy

sugar + oxygen ------> carbon dioxide+ water+ energy

The equation above (the respiration equation) is also the exact opposite of the photosynthesis equation.

Photosynthesis

Photosynthesis is the process by which a cell captures sunlight and turns it into food. There are two stages of photosyntheis. The first stage of photosynthesis is the part where the sunlight is captured. The sunlight is captured by tiny organelles in a plants leaf called Chlorophyll which act very much like miniature solar panels.
The second stage is the part where the cell uses the captures sunlight and turns it into energy. The cell requires two raw materials to to complete this stage: water and carbon dioxide. The water for photosyntheis is captures through the roots of a plant. Carbon dioxide is captured through small holes in the underside of a leaf called the stomata. On the the materials get into the plant they move to the chloroplasts. Inside the chloroplasts the go through a series of processes which end up producing sugars and oxygen. The photosynthesis equation is below.
light energy
6 CO2 + 6 H2O ------------> C6H12O6 + 6 O2
carbon dioxide + water--------> sugar + oxygen

The photosynthesis equation is the exact opposite of the respiration equation.

The Cell Cycle

In order for a cell to divide, it has to go through the process called the cell cycle. The cell cycle consists of the following stages:
Interphase: The cell grows to its mature size and makes a copy of its DNA. The centrioles are copied as well.

Mitosis: Prophase- The nuclear envelope breaks down and spindle fibers form between the two centrioles.

Mitosis: Metaphase- The chromosomes align at the equator of the cell while each chromosome attaches to a spindle fiber at its centromere.

Mitosis: Anaphase- The duplicated chromosomes (called chromatids) are separated.

Mitosis: Telophase- The chromosomes reach the mitotic poles and the cell begins to pinch in.

Cytokinesis: The Cell splits in half. For plant cells a cell plate forms in the middle of the cell. The cell plate eventually turns into a cell membrane.

The Cell

The cell is the basic unit of life. Every living thing is composed of cells. Cells are miniscule and composed of many different parts. These parts are labeled for you on the left. The cell with the purple on the outside is an animal cell and the cell with the green on the outside is a plant cell. Notice how to animal cell is more round is shape than the plant cell. This is because the plant cell has a rigid cell wall while the animal cell has a more flexible cell membrane.

Gregor Mendel: Father of Genetics

Gregor Mendel was a Augustinian priest born on July 20, 1822. Mendel was born to a german family and worked as a beekeeper and gardner which explains his studies with plants. Mendel first started experimenting and studying plants after some of colleagues asked him to study some of the variations between two plants. After a while Mendel started to notice traits and similarities that kept popping up. He wrote down these variations which later became known as Mendel's Laws of Inheritance. After finishing his work with pea plants he later tried to conduct the same experiments with honey bees but ended up producing a very mean and nasty breed of them and decided to stop. Mendel died at on January 6, 1884 at the young age of 61.