Biology Study Guide & 

Notes Genetics





DNA, Genetics, and Protein Synthesis Review Questions


  1. What are the three parts of a DNA nucleotide?

Deoxyribose , phosphate group , base


  1. Briefly describe DNA replication. Double helix unwinds and unzips with the help of helicase. Each single strand serves as a template. Complementary strand made from free-floating nucleotides. Because parent DNA has two strands to new identical DNA molecules are formed.


  1. What are the three differences between DNA and RNA? Number of strands DNA to RNA one, sugars deoxyribose and ribose, bases DNA a CTG and RNA ACUG



4. What is the mRNA transcript if the DNA is­ TACTCG? AUGAGC

5. What enzyme replicates DNA? Ameno acids    What enzyme creates pre­mRNA?





1 What is another term for haploid sex cells?  Gametes            haploid sex cell  or gamete is a cell which contains one complete set of chromosomes. The male gamete is a haploid cell and is used in sexual reproduction.


2 What is crossing­over?  When does it occur and what is its significance? It is when genes are swapped it incurs in meiosis one. It adds to the genetic variety of the gamete 

3 What is random assortment?  When does it occur and what is its significance? Random assortment is meiosis distributes a random mixture of mother and father chromosomes to each gamete it adds to the genetic variety. It occurs in meiosis.


4 How many cells are created by the end of Meiosis II? Cells divide twice during meiosis 1-2n cell turns into 4n cells.


5. What is a homologous pair? When 2 homologous chromosomes partnered together



Genetic Terms

1. Give an example of a genotype and a phenotype. A genotype is the actual genetic makeup of the organism example Bb  and a phenotype is the form or trait that is observed example Brown eyes


2. What is another name for a hybrid? heterozygous


3. What is the term to describe a trait that shows in a hybrid? Dominate


4. Briefly describe a gene. Located on chromosomes controls the traits of an organism


  1. How do incomplete and codominance differ?

 Incomplete neither allele is dominant example red white flowers pink offspring.

Co-dominance both alleles are dominant example red and white flowers red and white striped offspring.


Genetics Problems

1. Aa x Aa‡ ?

2. BbCc x BBCC‡ ?

3. What must be true about the parents of a color­blind female? That one of her parents carry the colorblind gene

4. If a baby has type O blood, can the baby’s father have type AB blood?yes

5. What must be true about the genotypes of two healthy parents that have a sickle­cell baby? They carry the sickle-cell gene

Gel Electrophoresis

1. What causes DNA to move through the gel? It uses electricity to separate molecules and a poor spongelike matrix to move to the job


2. What are the enzymes called that cut DNA at a specific site? The restriction map is the map of restriction enzyme sites that can be generated by cutting pieces of DNA with different combinations of restriction enzymes.


3. Do smaller or larger fragments move faster through the gel? Smaller fragments move faster and further


4. Briefly describe how a dyed gel is read. The purpose of the gel makes it easier to read the samples to visually track the DNA migration and alliance.


5. What is a DNA standard? the DNA ladder used in gel electrophoresis. The ladder is a collection of DNA fragments of known size (e.g. 100, 500, 1000, 2000, 5000, 10000 base pairs) so that if it is loaded beside the samples, it can offer a 'ruler' that can be used to determine the size of the fragments in the samples.

Protein Synthesis


1. What are the two steps of protein synthesis and where does each occur? The two main steps in protein syntheis are transcription and translation. In transcription, the enzyme RNA Polymerase uses a DNA strand as a template to make a transcript of messenger RNA. This transcript is then translated into protein by the ribosome.


2. Describe the role of the ribosome in protein synthesis. Ribosomes are the place where Protein Synthesis takes place.  In the Ribosome, the mRNA, tRNA, and Amino Acids meet to form a Protein. 


3. How do a codon and an anticodon differ? A codon is a sequence of three nucleotides which combined form a unit of genetic code in a RNA or DNA molecule. An anticodon is a sequence of three nucleotides which form a unit of genetic code in a transfer RNA molecule, equivalent to a complementary codon in messenger RNA.


4. How do mRNA and tRNA differ in structure and function? tRNA is transfer RNA. mRNA is messenger RNA. Both are made up of nucleotides, but I believe while mRNA is made from those containing the bases adenine, cytosine, guanine & uracil, tRNA has an additional one by the name of 'inosine'. So it looks like I've answered (b) first... As for location within the cell...well, your mRNA is transcribed from your DNA, so obviously it would have been in the nucleus. Then it would be transported out into the cytoplasm and sit around for ribosomes to come or be degraded by enzymes. On the other hand, tRNA function in transferring amino acids to ribosomes, so they'd be found in the cytoplasm.


5. In RNA processing, what is added to each end of the mRNA and what purposes do they serve? Each nucleotide is composed of three parts: (1) a nitrogenous base known as ... Themessenger RNA (mRNA) serves as an intermediate between DNA and protein. ...needs to be processed before they can serve as a blueprint for a protein. ... the removal of introns, a poly-A sequence is added to the 3' end of the transcript.



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