DNA & RNA

• Heredity - passing features from parents to offspring by means of genes
• Characteristics - arise from the interaction of genes and their environmeny
• Gene - section of DNA that controls the production of a protein ( 3% of DNA in human cells are expressed, the rest id non-coding)
• Chromosomes - made of DNA & Protein
• Gene expression - the way in which a gene works to produce protein
• DNA (Deoxyribose Nucleic Acid) - long, double stranded molecule
• Bases of DNA - Adenine (A), Thymine (T), Cytosine(C) and Guanine(G)
• Genetic code- the sequence of bases in DNA (or RNA) that cause the production of protein
• Each group of three bases is the code for an amino acid
• Gene - Sequence of bases that produces a protein
• DNA replication - the process of making two identical copies of DNA in a cell
• DNA replication consists of each new strand being half new DNA and half original DNA. Each new strand is identical to its partner and to the original DNA strand
• DNA profile - unique pattern from a person's cells.
• DNA bands can distinguish a person's DNA from another's
• DNA profiles are obtained by: Relesing DNA from cells; Cutting DNA from cells using restriction enzymes; Separating fragments according to their size
• DNA profiles uses: determine wether a person is the parent of a child; crime scene investigations to determine suspect.
• Gnetic (DNA) screening - person's DNA can be tested to show presence of abnormalitites
• DNA - has deoxyribose; contains the base Thymine (T); double stranded (double helix); found in nucleus
• RNA - has the sugar ribose; has the base uracil (U); fiund in nucleus and cytoplasm, single stranded
• DNA makes a protein - DNA strands separate; bases of DNA link up with complementary bases to form mRNA ( the code is transcribed); mRNA enters the ribosome; correct sequence of amino acids are linked together in the ribosome to format protein (code is translated); protein folds in correct shape.
• Detailed structure of DNA - nucleotides, which contain phosphate, deoxyribose sugar and a base. Purines are Adennine (A) and Guanine (G) and Pyridimines are Thymine (T) and Cytosine(C); Nucleotide pairs join together due to hydrogen bonding e.g A=T and A=C; A double helix is formed in which the phosphates and sugars form the sides of the molecule, and the base pairs are like rugs inside the double helix
• Protein synthesis - the process of making proteins from amino acids.
• To isolate DNA from onion cells: chop onion tissue into salt/detergent mix ( clumps DNA and breaks down cell membranes ); Heat the mix in a water bath (to stop enzymes damaging the DNA); Place in ice-cold water bath (prevents damage to DNA); Filter the mix to remove cell parts; Add protease enzyme to the filtrate to break down protein; Add ice cold ethanol; DNA is visible