# Cell Biology/Glossary
## Alpha Helix

    DNA forms a specific formation called a alpha helix.

## Amino Acid

    The basic subunit of proteins.

## Atom

    One unit of a given element.

## Carbon

    One of the common elements found in organic matter and living things.

## Cell Wall

    found in prokaryotic plants and it provides structural support and protection.

## Chloroplasts

    convert light/food into usable energy. (ATP production)

## Cholesterol

    Found in cell membranes, affects the rigidity of the membrane. Also a basic compound used to form man hormones.

## Chromosome

    A group of genes/DNA that are contiguous, a functional unit. Humans have 23 pairs chromosomes.

## Cilia

    Hair-like structures.

## Cisternae

    The flatten sacs of the Rough Endoplasmic Reticulum.

## Crossover

    Genetics term for chromosomes literally crossing over DNA from one chromosome to another.

## Cyanophytes

    One type of prokaryote (cell without a nucleus).

## Cytoplasm

    the protoplasm outside the nucleus

## Cytoskeleton

    Microtubules, actin and intermediate filaments. This produces the support structure/shape of cells. Of course plant cells have a much more rigid shape due to the cell wall.

## Cytosol

    The 'fluid' portion of the cell, it is made up of water and many free proteins and other elements - all except the organelles.

## DNA

    Deoxyribonucleic Acid, made up of 4 nucleotides: Adenine, Guanine, Thymine, and Cytosine (A,G,T,C).

## Element

    Element is one atom of a particular substance found on the periodic table. (Things such as Carbon, Hydrogen, Oxygen, etc.)

## Endoplasmic Reticulum (ER)

    Important for protein synthesis. It is a transport network for molecules destined for specific modifications and locations. There are two types: Rough ER - has ribosomes, and tends to be more in 'sheets'. Smooth ER - Does not have ribosomes and tends to be more of a tubular network.

## Eukaryote

    A Cell with a nucleus.

## Gene

    A section of DNA molecule that produces a functional RNA molecule

## Golgi Apparatus

    important for glycosylation, secretion.

## Hydrogen

    A common element in organic and living organisms.

## Hydrophilic

    'likes water' (hydro = water; philic = like). Meaning that a hydrophilic molecule or portion would be attracted to water. Much like the opposite poles of a magnet pulling each other together.

## Hydrophobic

    'fears water' (hydro = water; phobic = fear). Meaning that a hydrophobic molecule or portion would be repulsed/push-away a water molecule. This would be like trying to put together the same pole of two magnets. Examples: oils, fatty acids (i.e. the 'tails' of phospholipids), cholesterol.

## Lysosomes

    Digestive sacks - the main point of digestion, these are only found in animal cells.

## Meiosis

    is a type of cell division. See section on meiosis. This occurs for formation of egg/sperm cells, which in the end have 1/2 the normal number of chromosomes, only 1 copy of each chromosome.

## Micrometer

    A unit of measure in the metric system. 10^-6 meters.

## Microtubules

    made from tubulin, and make up centrioles,cilia, etc.

## Millimeter

    A unit of measure in the metric system. 10^-3 meters.

## Mitochondria

    convert foods into usable energy. (ATP production) A mitochondrion does this through aerobic respiration. They have 2 membranes, the inner membranes shapes differ between different types of cells, but they form projections called cristae. The mitochondrion is about the size of a bacteria, and it carries its own genetic material and ribosomes.

## Mitosis

    The cell division, that is found in most non-reproductive cells.

## Nanometer

    A unit of measure in the metric system. 10^-9 meters.

## Nitrogen

    A common element in organic and living organisms.

## Nucleic Acid

    Basic Building block for DNA.

## Nucleolus

    Or densely packed portion of the Nucleus.

## Nucleus

    (only in eukaryotes) - where genetic material (DNA) is located, RNA is transcribed.

## Organelles

    (which also have membranes) in 'higher' eukaryote organisms:

## Osmosis

    The diffusion of water through a semi-permeable membrane down the water potential gradient (from areas of high water potential to areas of low water potential)

## Oxygen

    A common element in organic and living organisms.

## Peptidoglycan

    This is the main component of prokaryotic cell walls, it is made from a large protein polymer and sugar.

## Peroxisomes

    Use oxygen to carry out catabolic reactions, in both plant and animals.

## Phospholipid

    See the section of the course on Cell Membranes and specifically phospholipids.

## Phosphorus

    A common element in organic and living organisms.

## Plasma membrane

    The surface around the cell made up of phospholipids, proteins, cholesterol, etc.. See the section on the Cell Membrane

## Prokaryote

    Cells without a nucleus.

## Protoplasm

    the living material in the cell

## Pseudopod

    literally means 'false foot'

## RNA

    Ribonucleic Acid

## Ribosomes

    half are on the endoplasmic reticulum, the other half are 'free' in the cytosol, which is where the RNA goes for translation into proteins.

## Sulphur

    A common element in organic and living organisms.

## tRNA

    Transfer RNA, a 3D structure. It works with the ribosome and mRNA to form proteins (called translation). It has an 'anti-codon' which will match codons of the mRNA, and also has a amino-acid. The tRNA is a key to the having the amino acid match a specific codon on the mRNA, See the Codon Table to see how these are matched in general. There are differences in how the matches take place in mitochondria and bacteria.