Biology Resources and Helpful Information

Cells are the smallest unit of life and are in all living organisms. The main characteristics that determine if an organism is living: composed of cells (cellular),  metabolism, growth, environmental stimuli, and reproduction or able to pass genes to offspring (heredity). 

Prokaryotes are single cell living organisms and they do not have organelles or nuclei surrounded by membranes. Eukaryotes DO have a membrane that surrounds organelles and nuclei. 

An atom is the smallest unit of matter. It has a nucleus containing protons (positively charged) and neutrons (neutral charge) surrounded by electrons (negatively charged). Atoms combine to form molecules that contain at least one or two elements, such as, carbon and oxygen. 

Covalent bonds happen when two atoms or more share their electrons. Ionic bonds happen when one or more electrons are donated between two atoms. 

There are three distinctions that can determine if a molecule loves water (hydrophilic) hates water (hydrophobic) or both (amphipathic). Molecules that are hydrophilic interact with hydrogen bonds making them "gravitate" towards water. Molecules that are hydrophobic do not interact with water, meaning they are "water-feating." Molecules can be both hydrophobic and hydrophilic. Think about laundry detergent, it interacts with water as well as oil or grease stains. 

Polar means that there is an unequal sharing of electrons between atoms. Nonpolar means that there is an equal sharing of electrons. 

Interphase is when the cell grows and then replicates it's DNA. Mitotic phase happens when the DNA is replicated and cytoplasmic contents are separated and cell finally divides.  

Yes, there are three stages of interphase. When the cell is grown and ready to divide, it moves to something called G 1 phase. 

Little noticeable changes happen during G 1, but the cell is growing and functioning as it normally would. The cell is accumulating chromosomal DNA and other proteins and making sure the cell has enough energy to replicate the nucleus and each chromosome. 

During this phase, visually, the cell will look thinner. The cell is copying two identical copies of each chromosome or sister chromatids. These will attach firmly to the centromere region. Think of an " X " and where the lines connect in the middle, this is where they are attaching, but at a microscopic-level. 

During the G 2 phase, the cell will replenish its energy and have proteins necessary for chromosome manipulation. Cell may continue to grow during this phase. Some organelles are duplicated and cytoskeleton detaches to provide resources for the first mitotic phase. 

The original purpose of mitosis is to create two identical daughter cells. The nucleus and cytoplasm must  divide. The mitotic phase has four stages, prophase, metaphase, anaphase, and telepathy- just kidding- telophase! 

Three really big things happen during prophase. 

1. chromosomes condense and are visible. 

2. Microtubules form and radiate from the centrosomes at the opposite end of the cell. 

3. The nuclear envelope begins to break down so that the microtubules can have access to the chromosomes. 

Two big things happen during metaphase. 

1. Chromosomes line up in the equator (or middle) of cell.

2. Microtubules attach to each of the chromosomes at their centromeres. (Remember that " X " ? They are attaching at this point) 

One big thing happens during anaphase. 

1. Sister chromatids separate and move towards the opposite end of the cell. 

Four big things happen during telophase. 

1. Chromosomes are no longer visible or are "uncondensed."

2. The network of microtubules breaks down. 

3. Nuclear envelope reforms around the DNA. 

4. In animal cells, cytokinesis, causes the original cell to split into two daughter cells. In plant cells, a cell plate forms meaning this will eventually become the cell wall. The daughter cells will ultimately become separated because of the cell wall.