dna and inheritance

• definition of gene

  a section of DNA found on a chromosome that codes for a particular characteristic or protein
• definition of an allele

  different versions of the same gene
• dominant allele


  the allele most frequently found, a gene always expressed when present
• recessive allele

  the weakest/weaker allele, a gene only expressed in a homozygous pair
• what is protein?

  polymers made from long chains of amino acids joined together
• DNA

  deoxyribonucleic acid, the material inside the nucleus of cells, carrying the genetic information of a living being, the raw material of genes
• genotype 


  The collection of genes an organism has, a genetic code
• phenotype 


  The physical characteristic of an organism determined by the genotype
• homozygous

  alleles that are both identical for the same characteristic
• heterozygous

  alleles that are both different for the same characteristic
• f1

  The first generation genetic cross
• f2

  The second generation genetic cross
• selfing

  The pollen of one flower transferred to the stigma (part of the female reproductive system) of the same flower, can be seen as self-pollinating
• structure of DNA

  it is made of two polynucleotide chains it is twisted to form a double helix, 1 nucleotide consists of three substances = pentose sugar, phosphate group, and a base
• 4 bases of DNA

  • adenine complimentary with thymine

  • guanine complimentary with cytosine
• cause of twist in the DNA

  The unevenness of hydrogen bonds between the complementary bases, cause the DNA to twist and form the double helix
• process of manufacture of protein


  bases from a code determining which amino acids are used to make a given protein, 3 bases = triplet code
• triplet code/ codon

  sequence of amino acid produces a specific protein, the sequence is determined by the triplet code coding for 1 amino acid
• process of protein development

  DNA untwists in order for the RNA to take the code and transfer to the ribose to become amino acids, a sequence of amino acid = protein
• Monohybrid inheritance

  The inheritance of one gene
• dna construction

  too long chains of alternating sugar and phosphate
• how is an amino acid coded

  The triplet of bases codes for amino acid
• genetic crosses

  gene code for characteristic, genes can have different versions called alleles that are inherited through sexual reproduction one from each parent, so they occur in pairs
• use of punnet Square

  to estimate the outcome of genetic crosses and possible offspring combinations
• use of genetic profiling

  to compare similarities between DNA samples
• what can genetic profiling techniques be used for?

  criminal cases, paternity cases, compare species for classification purposes, identifying genes associated with disease
• genetic modification

  allows genetic material from one organism to be transferred into the DNA of another organism
• advantages of genetic modification

  genes for disease resistance can be transferred to crop plants to increase yield, herbicide resistant genes can also increase yield as herbicides can be used to kill competing plants.
• disadvantages of genetic modification

  Creation of super weeds, if the herbicide resistance genes are taken up by weeds species, unknown, long-term effects of modifying genomes, unknown, health, effective, modified organisms
• male and female chromosomes

  male - two different XY

  female - two the same XX
• how to produce a DNA fingerprint step 1 and 2

  Isolation - separate the DNA from other tissues, fragmentation - using an enzyme to break the DNA into short lengths
• how to produce a DNA fingerprint, step 3

  Separation - pass an electric current across a layer of gel which has the DNA fragments at one end, the fragments will move different distances across the gel. This is called gel electrophoresis
• how to produce a DNA fingerprint step 4

  comparison - match the pattern of fragments on the gel with other samples of DNA
• advantages V disadvantages

  genetic profiling

  
• genetic engineering

  to take genes from one organism and placing them into the genome of another
• gender determination

  There is a 50% chance of a woman having a boy because sperm and egg cells combine is random, and roughly half of the sperm cells will be carrying an X chromosome and half a Y
• genetic cross Aa : Aa

  gives a 3:1 ratio of dominant: recessive phenotypes among the offspring
• genetic cross Aa: aa

  gives a 1:1 ratio of dominant: recessive phenotypes among the offspring
• sexual reproduction

  sex chromosomes separate in the gametes and combine randomly at fertilisation
• definition of a genome 


  all the genetic material of an organism