cb3 - genetics

• what is meiosis, where does it occur?

  Cell division, occurs in reproductive cells.
• define a haploid

  half of chromosomes of a normal body cell
• define a diploid

  has 23 pairs of/ 46 chromosomes
• what is the backbone of a dna structure made from?

  Sugar and phosphate.
• the two strands of dna twist to form a double helix shape. because the bases always pair up in the same way, we call them complementary base pairs. hydrogen bonding occurs between the bases.
• what is mutation and how might a mutation affect the phenotype of a person?

  Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease.
• mutations may occur when: a cell is exposed to radiation, chemicals or viruses.
• a genome is

  the entire set of genetic material in an organism, including all the genes and the DNA that controls them
• genotype


  the alleles that an organism has
• homozygous


  both alleles for one gene are the same
• heterozygous

  the alleles for one gene are different
• recessive


  both alleles need to be expressed in the phenotype.
• phenotype


  what the organism looks like
• dominant

  if the allele is present it will always be expressed in the phenotype
• what is an allele?

  the different forms of a gene
• what does it mean if a person is a carrier for a disease?

  they might not necessarily know that they have the disease but they can pass it down to their offspring
• one advantage to pea plants of using sexual reproduction to produce offspring?

  is that it produces a large number of offspring/ Sexual reproduction creates offspring that are genetically unique from their parents, which may contribute to better survival for the species.
• genetic code


  sequence of bases
• a gene is a particular sequence of bases

  codes for a protein
• a triplet - each group of three bases 


  code for a specific amino acid
• a string of amino acids make a protein in a certain sequence.

  all proteins have a different sequence of amino acids - a unique shape and carry out a particular function.
• main uses of proteins:

  enzymes - biological catalysts

  hormones - messages around body

  structural proteins. - strengthen cells/tissues