genetics

• Cell continuity is the ability of cells to divide and survive from one generation to the next
• a gene is a section of DNA that contains the instructions for the formation of a protein
• somatic cells are any cells in the body that are not involved in reproduction
• The first 22 pairs in each cell are called autosomes - they carry genes for everyday functioning of the cell
• Each pair of chromosomes are called a homologous pair
• a haploid cell has one set of chromosomes
• a diploid cell has 2 sets of chromosomes
• interphase is the time when the cell is not dividing - 90% of the time
• mitosis is when the cell is dividing
• mitosis is a form of nuclear division in which one nuclear divided to form 2 nuclei, each with the same number of chromosomes as the parent nuclei
• cancer is a group of disorders where normal cells lose their ability to control the rate of mitosis
• meiosis is a form of division where the daughter cell contains half the number of chromosomes of the parent cell
• in single celled organisms the function of mitosis is to asexually reproduce
• in multi celled organisms the purpose of mitosis is for growth and repair
• the function of meiosis is to prodce gametes which allows variation
• a species is a group of organisms that are capable of interbreeding with each other to produce fertile offspring
• acquired variation are not controlled by genes eg. the ability to speak
• inherited variations are controlled by genes eg. producing hair
• gene expression is the precise way in which the genetic information in a gene is decoded in the cell and used to make protein
• chromosomes are highly coiled structures made up of 40% DNA and 60% protein
• DNA - deocyribonucleic acid
• DNA was discovered by watson and crick
• DNA is double stranded, the strands held together by bases - forming a double helix
• DNA is made up of nucleotides that join together to form long chains called polynucleotides
• characteristics = heredity + environment
• nucleotieds are made up of three parts - a phosphate group, a sugar (called deoxyribose) and one of four nitrogen-containing bases
• the four nitrogen-containing bases are adenine, guanine, cytosine and thymine
• adenine always joins to thymine
• cytosine always joins to guanine
• adenine and guanine belong to a group of molecules called purienes
• thymine and cytosine belong to a group of molecules called pyrimidines
• the genetic code - the sequence of DNA bases that determines the sequence of amino acids which determines the protein made
• DNA profiling is a method of making a unique pattern of bands from the DNA of a person, which can then be distinguish that DNA from other DNA
• Genetic screening is DNA analysis for medical purposes to show the presence or absence of certain genes
• RNA is single stranded, contains uracil instead of thymine
• RNA is found in the nucleus and cytoplasm
• RNA contains the sugar ribose
• MRM - messenger RNA - carries the code from DNA to the ribosome
• rRNA - ribosome RNA - forms the ribosome
• tRNA - transfer RNA- carries an anticodon and an amine acid. Codons complementary to codons on MRNA