Punnet Square I
Punnet Square II
Making Babies
Traits Lab
Mapping Traits
Protein Synthesis
DNA Replication

Genetics Facts

Student Objectives
DNA Structure
Protein Syntheses & Bioengineering

Genetics Sites

Human Genome Project
DNA Learning Center


Henderson's Dictionary of Biological Terms. 10th Ed. John Wiley & Sons.

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Take a sniff. Can you smell that? No it's not my nasty morning breath. It's something almost as unpleasant as our unit test on genetics. Not to worry mate, as long as you understand the material discussed in this handy review sheet you should do just fine.

Key Vocabulary: (relax, you know most of it already!)

amino acids
base pairs
homozygous dominant
RNA polymerase
deoxyribonucleic acid
homozygous recessive
somatic cell
DNA polymerase
DNA replication
double helix

* Index Cards are beautiful things people (don't forget to include examples!)

How should I study

You need to study the vocabulary. It is not necessary to memorize definitions, but you need to know what each of the words means to answer questions like the ones below. We suggest index cards that include definitions, BUT ALSO INCLUDE EXAMPLES AND DRAWINGS.

Sample questions:

  • A snork is an animal found only in Hunter's Point. Some snorks can be as tall as ten feet and some as short as eight inches! All snorks have orange beards that they are constantly tripping over. Snorks survive on a diet consisting of skittles and mountain dew. Draw a picture of a snork and include the following: gene, trait, alleles, genotype, and phenotype.
  • The fruit fly, Drosophila melanogaster, has 4 pairs of chromosomes. a) Draw a fruit fly cell with four chromosome pairs. b) Draw this cell in the different stages of meiosis. c) How many total chromosomes would be in each of the gametes after meiosis?
  • Draw a fly's eye cells that went through mitosis. Show the total number of chromosomes that would be in each of the new eye cell?
  • Can you give an example of a somatic cell? Can you give an example of a gamete? Name two major differences between somatic cells and gametes.
  • In humans, after mitosis happens, two _______________ cells are formed that have __________ pairs of chromosomes in each. The total number of chromosomes in each cell is __________.
  • In humans, after meiosis happens, two _______________ cells are formed that have __________ pairs of chromosomes in each. The total number of chromosomes in each cell is __________.
  • When Anton's sperm carrying 23 chromosomes (including an X chromosome) fertilizes Judy's egg the result is a single cell called a . Will this grow and develop into a boy or a girl? How do you know?
  • The gene for petal color is found on chromosome #3 in roses. Red roses are dominant over yellow roses. A gardener mates a yellow rose plant with a heterozygous rose plant. Using drawings of the chromosome with the petal color gene, show meiosis for both roses, then show the fertilization of their gametes. Finally, using a punnett square, predict the genotype and phenotype probabilities of the offspring. SHOW YOUR WORK.
  • Sickle cell anemia is an inherited disease that causes red blood cells to be shaped like a crescent moon. It is dominant to have normal, round-shaped red blood cells. A woman who is heterozygous marries a man who is homozygous dominant for sickle cell. What are the chances that they will have a child with the disease? SHOW YOUR WORK.
  • In horses, brown hair is dominant over white hair. If a horse with white hair had parents who each had brown hair, what would the genotype of each parent horse have to be? EXPLAIN YOUR ANSWER.
  • In humans there are four main blood types: A, B, O, and AB, where types A and B are codominant. There are three different alleles for blood type, written this way:

IA = type A

IB=type B

1=type O

Possible Genotype Corresponding Phenotype

IA IA ¾ ¾ ¾ ¾ ® 10 Type A blood

IA IO ¾ ¾ ¾ ¾ ® Type A blood

IB IB ¾ ¾ ¾ ¾ ® Type B blood

IB IO ¾ ¾ ¾ ¾ ® Type B blood

IO IO ¾ ¾ ¾ ¾ ® Type O blood

IA IB ¾ ¾ ¾ ¾ ® Type AB blood

Use the information above to answer the question on the next page.

  1. On my favorite soap opera General Hospital, Monica just had a baby. Is the father Alan or Rick? Monica's blood type is A, Alan's is AB, and Rick's is O. Monica's baby has the blood type O. Who is the father? Explain your answer using a punnett square.
  2. I have blood type A. My sister has type O blood. My brother has type AB blood. If my dad's blood type was type A, what did my mom's blood type have to be? What did her genotype have to be?
  1. Sometimes a mistake is made during meiosis while making an egg in a woman. The result is an egg with 24 total chromosomes. This can cause serious problems for her baby. Can you explain why this is such a problem? You can use a picture to explain your answer.
  2. Draw a DNA molecule with 3 base pairs. Next, draw a rough sketch of a double helix. Label both drawings, showing the molecules that form the "backbone" and glue of the DNA molecule. HINT: Follow Chargaff's rule.
  3. If we "unzipped" a DNA molecule into two halves, could you figure out what the other half of the molecule looked like? Try it in the example below.


  5. How many base pairs does the DNA molecule you completed above have?
  6. In DNA replication, the enzyme _______________ unwinds and unzips the double stranded DNA and makes it _______________-stranded. Then, the enzyme _______________ finds the complementary base to match base on the single DNA strand. From one complete strand of DNA, we get _______________ complete strands of DNA.
  7. Where does DNA replication begin on a chromosome? In the middle? On the end?
  8. Where does transcription occur in the cell? What molecule is the product of transcription? HINT: Think about what the word "transcription" means to help you answer the question.
  9. Make a two-column chart like the following, and list three major differences between DNA and RNA (both mRNA and tRNA):
  10. DNA







  11. Look at the codon chart on page 186 of your book. Why do you think there are certain mRNA codons (UAA, UAG, and UGA) that code for "stop," instead of a normal amino acid? What do you think happens to the chain of amino acids (the protein) when the ribosome reads one of those codons?
  12. The codon chart is like a two-language dictionary, like a Chinese-English dictionary. Except, we are translating between the language of DNA (____________________ sequences) into the language of proteins (____________________ sequences). Every ____________________ bases translates into ____________________ amino acid.
  13. Codons are found on ____________________ RNA, while anti-codons are found on ____________________RNA. RNA has a ____________________ - shape and contains a single amino acid to add to the growing protein chain.
  14. After a ribosome has been used as the site of translation for one protein, can it be re-used?
  15. What's the difference between mRNA and tRNA in terms of SHAPE? LOCATION? JOB?
  16. List some examples and uses for proteins in your body.



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