Genetics Review Sheet
Name: ANSWER KEY
VOCABULARY
Chromosome
Gene
Trait
Allele
Dominant
Recessive
Phenotype
Genotype
Purebred
Homozygous
Hybrid
Heterozygous
Mendel
Probability
Punnett square
Haploid
Diploid
Mitosis
Meiosis
Replication
Cytokinesis
Mutation
Tumor
Pedigree
DNA
RNA
Amino acid
If you have questions about any of the vocabulary words listed above- ask Ms. Gray during class time,
OR email her a question at lgray@psdschools.org
DNA STRUCTURE AND FUNCTION
Resources: DNA worksheet, DNA extraction lab, DNA quiz
What is a gene? A segment of DNA, that codes for a specific trait. Remember: since a gene is a
segment of DNA, it could also be a section of a chromosome…
Where are chromosomes located? In the nucleus of a cell!
2 main scientists that established the structure of DNA? James Watson and Francis Crick, 1953
Female scientist who paved the way for them? Rosalin Franklin
Shape of DNA? The double helix….looks like a twisted ladder.
Sugar of DNA? Deoxyribose
4 bases of DNA? Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)
What pairs with what? A-T, C-G
MITOSIS
Resources: Mitosis Poster
During what stage of mitosis does DNA replicate? Interphase
How many cells are made from mitosis? 2 identical “daughter cells”
How many chromosomes are found in each human cell after mitosis? Haploid or diploid? 46
chromosomes = diploid!
What type of cells are made? Body cells!!
Whet happens during cytokinesis? The cytoplasm “pinches” and they become 2 distinct,
separate cells.
CANCER
Resources: Cancer- Cell Division Gone Wrong Worksheet, Cancer reading.
What is cancer? A class of diseases characterized by cells growing and dividing uncontrollably.
How do you treat cancer? Surgery- remove abnormal cells or tumor; Chemotherapy- very strong
medicines that kill cancerous cells (and other cells); Radiation- beams of high energy that kill cells.
There is NO CURE for cancer- but these are the 3 available forms of treatment.
How do you get cancer? Cancer is NOT contagious- meaning you can’t get it by contact or
sharing a drink with someone. Cancer is caused by a mutation that causes the cell to grow and divide
too quickly. Cancer can occur because of environmental effects on the body (like cigarettes, or sun
damage, etc). Some cancers are inherited (the mutation is passed from parent to child). Other forms of
cancer occur spontaneously (at random).
PUNNETT SQUARES
Resources: SpongeBob Worksheet, Challenge worksheet(s), Punnett Square/Mitosis
and Meiosis Quiz If you would like more Punnett practice- see Ms. Gray (I have a lot more
worksheets!!)
Be able to set up and execute a Punnett square problem.
Be able to describe the outcome of a Punnett square problem:
- What are the possible genotypes? Remember- the 2 letter code!
- What are the possible phenotypes? The physical characteristic the results from the
genotype.
Figure out the probability or percentage of inheritance.
SEX CHROMOSOMES and SEX-LINKED TRAITS
Resources: Notes in Journal
Sex chromosomes (the chromosomes that make us male or female) are which numbered pair of
chromosomes? The 23rd
What sex chromosomes does a male have? Female? Male = XY female=XX
Can you do a Punnett square that shows the probability of having a boy or girl? Check your
notes- we did this in class!
Disorders on the X chromosome affect which sex more? Why? Disorders on the X chromosome
(sex linked traits) affect males more. Males only have one X chromosome. If the trait is a recessive trait
found only on the x-chromosome, males only need one recessive allele to display the trait. Females
have two x’s. If they get the recessive allele on one, there is still a good chance they will receive a gene
that masks the recessive trait (a dominant allele) on their 2nd X.
MITOSIS VS MEIOSIS
Resources: Class notes, T-Chart, Venn Diagram, Mitosis vs. Meiosis Worksheet,
Punnett Square/Mitosis and Meiosis Quiz.
How many cells are made from meiosis? 4
How many chromosomes are found in each human cell after meiosis? Haploid or diploid? 23
chromosomes are found in each resulting cell- they are haploid! (have ½ the genetic material that a
diploid cell does).
What type of cells are made? Reproductive cells
How are mitosis and meiosis similar? They are both processes of cell division; Both start with
one diploid cell; both undergo very similar phases, or sequence of events.
How are mitosis and meiosis different? Mitosis results in 2 diploid cells while meiosis results in
4 haploid. Meiosis undergoes 2 cell divisions, mitosis only has 1. Meiosis makes reproductive cells,
mitosis makes body cells.
PROTIEN SYNTHESIS
Resources: Class notes, Flow Chart, practice notes from sentence activity.
Outline the process of protein synthesis- what are the steps that occur?
1. DNA “unzips” in the nucleus.
2. mRNA copies the DNA code into its own unique language (U’s instead of T’s). It then takes
that “message” out of the nucleus, and into the cytoplasm where it meets up with the
ribosome!
3. tRNA (Transfer RNA) attaches to mRNA (messenger RNA). The tRNA molecules carry
specific amino acids to the ribosome. There they “read” the message in mRNA by matching
up with 3-letter codes (“codons”).
4. The protein chain grows as each amino acid (the building blocks of protein) is attached.
5. The protein chain grows until the ribosome reaches the “stop codon” which tells the
ribosome that the protein chain is complete. The process continues and another protein is
started.
Where does protein synthesis start in the cell? Where is the protein actually made? Starts in the
nucleus. The protein is actually made at the ribosome, which is outside the nucleus and in the cytoplasm
of the cell.
What does mRNA stand for? What does tRNA stand for? mRNA= messenger RNA tRNA=
transfer RNA.
Translate DNA into RNA: model the process of protein synthesis. Use worksheet and in class
notes. Don’t forget- no T’s in RNA, U’s instead.
Proteins are made of what building blocks? Amino acids
MUTATIONS
Resources: Class notes, journal entry
In what ways do mutations occur in a cell? There are many ways. Some examples are during
DNA Replication, when DNA is copying itself. Maybe it skips a pair of nitrogen base pairs, or one
mismatches, maybe a group of base pairs is added out of no where (wasn’t in original DNA). A
mutation is a change in the genetic information of the cell.
How do mutations lead to genetic diversity? Mutations lead to changes in phenotype- or
physical characteristics. Think about animals and how some look very similar, with different featureslike dog breeds. Every time DNA mutates, it changes the phenotype. Not there is potential that
organism passes the change onto it’s offspring.
Be able to explain how whether or not a mutation is harmful in part depends on an organism’s
environment. Think about the monkey example we talked about in class. Pretend a
mutation causes a change in the fur color of a monkey in the wild. The hair was brown, now it is white
as a result of a drastic mutation. A monkey at the zoo is ok! But in the wile they stand out in the forest.
They are no longer camouflaged like when they were brown. This is an example of how environment
can determine whether or not a mutation is dangerous.
PEDIGREES
Resources: Family puzzle, pedigree worksheet.
What information do pedigrees tell us? The inheritance of a particular trait throughout a family.
What would a geneticist use a pedigree for? To map or follow the inheritance of a particular trait
within a family. Pretend a family is wanting to have a child but a certain disease runs in both of their
families. A geneticist could track their family’s inheritance of the disease and better determine the
likelihood their baby would have the disease.
Using the information on a pedigree, can you figure out a person’s genotype? Look at the
“Family Puzzle” in class activity.
Be comfortable analyzing and drawing conclusions by looking at a pedigree. See Ms. Gray if
you are confused about this 