CB3 – Genetics (p26-31) B b b b Meiosis Inheritance DNA Structure Key Words Meiosis 1) How many daughter cells are produced? 2) What type of cells are produced during meiosis? 3) How many times does cell division occur? 4) Are the daughter cells identical or genetically different? 5) In humans, how many chromosomes does each daughter cell contain? 6) How do the number of chromosomes in the daughter cells compare with the number of chromosomes in the parent cell? Inheritance 1) Complete the Punnett square 2) What is the % chance that the offspring will have blue eyes? 3) What is the % chance that the offspring will be homozygous? 4) What is the phenotype of the offspring if their genotype is Bb? 5) Which allele is the dominant allele? 6) Do the two parents have the same genotype? Explain. 7) If both parents were homozygous dominant, what would be the % chance of the offspring having blue eyes? B b DNA Structure A is ___________ T is ___________ C is ___________ G is ____________ 1 2 3 b b Term Number Bases Hydrogen bond Phosphate Sugar KEY B = brown eyes b = blue eyes Genetic Mutation Mutations are ____________ to the DNA ____________ sequence. Mutations occur spontaneously, but can also be caused by chemicals or ________________ radiation. Most mutations are harmless and have no effect on the ________________. However, sometimes a ________________ can have a big effect on the phenotype. For example, it might result in the production of a ________________ which is so different that it can’t carry out its ___________________. 4 Variation Fill in the table to give examples of how variation can be caused. ionising changes mutation phenotype base protein function

CB3 – Genetics (p26-31) B b b b Meiosis Inheritance DNA Structure Key Words Meiosis 1) How many daughter cells are produced? 4 2) What type of cells are produced during meiosis? Gametes (sex cells) 3) How many times does cell division occur? 2 times 4) Are the daughter cells identical or genetically different? Genetically different 5) In humans, how many chromosomes does each daughter cell contain? 23 6) How do the number of chromosomes in the daughter cells compare with the number of chromosomes in the parent cell? Half the number in the daughter cells (haploid) Inheritance 1) Complete the Punnett square 2) What is the % chance that the offspring will have blue eyes? 50% 3) What is the % chance that the offspring will be homozygous? 4) What is the phenotype of the offspring if their genotype is Bb? Brown eyes 5) Which allele is the dominant allele? B = brown eyes 6) Do the two parents have the same genotype? Explain. No – one is Bb and the other is bb 7) If both parents were homozygous dominant, what would be the % chance of the offspring having blue eyes? 0% B b DNA Structure A is adenine T is thymine C is cytosine G is guanine 1 2 3 b Bb bb b Bb bb Term Number Bases 4 Hydrogen bond 2 Phosphate 1 Sugar 3 KEY B = brown eyes b = blue eyes Genetic Mutation Mutations are changes to the DNA base sequence. Mutations occur spontaneously, but can also be caused by chemicals or ionising radiation. Most mutations are harmless and have no effect on the phenotype. However, sometimes a mutation can have a big effect on the phenotype. For example, it might result in the production of a protein which is so different that it can’t carry out its function. 4 Variation Fill in the table to give examples of how variation can be caused. Eye colour Scars Height Nose shape Language Weight ionising changes mutation phenotype base protein function