Biology 2.3

• what is the shape of dna

  Double helix
• What is the dna held by

  Bases
• What is the backbone made up from

  Alternating sugar and phosphate
• Rules of base pairing

  Adenine only pairs with thymine

  guanine only pairs with cytosine
• Amino acids are the units that make up a protein
• Every 3 based code for one amino acid
• A gene is a large section of DNA with many bases and codes for a protein
• Definition of dna profiling

  Cutting DNA into short pieces. The peices of dna are then put on a gel and seperated into bands
• what are the uses of dna profiling

  To investigate crimes

  patenting testing

  identifying victims

  comparing dna of different organisms for classification

  discoveing new genetic diseases
• Alleles are a version of a gene
• Two alleles controls a characteristic
• Some alleles can be dominant
• some alleles can be recessive (weak)
• An allele is a version of a gene (come In pairs)
• What is a dominant allele 


  Always expressed over other alleles
• What is a recessive allele


  only expressed if there is no dominant allele present
• What does homozygous mean 


  There are two of the same allele
• What does heterozygous 


  Means there is one dominant allele and one recessive allele
• What is a genotype

  what alleles someone possess
• What is a phenotype

  physical trait
• What is the f1 generation 


  Offspring’s produced when 2 organisms are bred togheyr
• What is the f2 generation 


  Offspring’s produced when the 2 offsprings were bred togheter
• What is selfing 


  When gametes from the same parents fuse
• How are dominant allele shown

  BB
• How are recessive alleles represented

  bb
• What is genetic engineering 


  Transfering a gene from one organism into another organism dna
• 4 advantages of genetic engineering

  Bigger yield of croos

  ressistant to diseases

  could grown in harsh condiations

  woukd need fewer chemical sprays
• 4 disadvantages of genetic engineering

  Could reduce biodiversity

  seeds are expensive

  new protins in GM crops could cause allergies
• What is a female copies

  Xx
• What is a males copies 


  Xy
• What is the percentage of a girl and boy

  50/50%