Review for Grade 12 U Bio

So instructions for homework were to write down ten words from the list and to define them.  Obviously, the obvious choice would be the words that we don't know or understand.  Or have completely forgotten.

RNA:  one of three major macromolecules essential for lifeforms.  called the ribonucleic acid.  RNA is single stranded whereas DNA is double stranded.  also, RNA substitutes uracil in place of thymine.  RNA contains ribose sugar rather than deoxyribose.  found both in the nucleus and the cytoplasm.

Uracil:  is a base which can replace thymine.  found in RNA only.  replaces thymine when DNA transcription takes places (creating complementary copy of RNA for DNA sequence).

mRNA:  called the messenger RNA, it is one of three major classes of RNA molecules.  the mRNA acts as the intermediary between DNA and ribosomes.  translated into protein by ribosomes.  it is the end product of transcription of a gene.

Telomere:  long sequences of repetitive, noncoding DNA on end of chromosomes.  protects chromosomes from deterioration.

histones:  positively charged proteins that bind to negatively charged DNA in chromosomes.  found in the nucleus.  packages chromosomes into order.  key protein component of chromatin.  acts as spools around which DNA winds so that it has some sort of structure.

London Forces:  type of force acting between atoms and molecules. part of Van der Waals Force.  also known as dispersion forces.

Van der Waals Force:  intermolecular forces of attraction including London forces, dipole-dipole forces, and hydrogen bonds.

Cleavage Furrow:  indentation where cytokinesis starts.  only happens in animal cells, because plant cells have cell plates instead.  starts on outside of cell and moves inwards towards the middle. cell plates start in the middle and work outwards.

Genome:  The complete set of chromosomes of an organism containing all its genes and associated DNA

G1 and G2 are growth cycles.  S phase is when DNA gets replicated.

Cell Cycle:  the cycle that a cell goes through in life.

Intermolecular Bonds:  chemical bonds between molecules.

Intramolecular Bonds:  Covalent bond that holds atoms of a molecule together, and ionic  bond that holds ions together in a salt.

Germ cells:  opposite of somatic cells; cells that give rise to gametes of organisms that produce sexually.  undergo mitosis and meiosis to develop into gametes.