Mutations & Codon (mRNA)
In the 1960s the molecular biologist George Streisinger developed the strand-slippage hypothesis. Streisinger noticed that mutations occurred in areas of DNA that contained many repeated sequences. When a strand-slippage error occurs, an insertion mutation can result. How does the insertion mutation affect the DNA?
Nitrogenous bases are added.
MCQ QUESTION!
Which of these is the direct result of an error in the transcription of a DNA nucleotide?
A. The nuclear membrane is ruptured.
B. Amino acids do not bond to tRNA.
C. A codon sequence is incorrect.
D. Transportation of mRNA does not occur.
C. A codon sequence is incorrect.
Organisms can be classified based on homology, which is shared characteristics inherited from a common ancestor. In the past, homologies were based on studies of anatomical structures and patterns of embryonic development. In more recent years, the use of molecular biology techniques has allowed homologies to be compared at the level of nucleotide sequences. Nucleotide sequence comparisons are possible because all organisms share which of the following?
DNA Bases
Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has how many chromosomes?
23 chromosomes
What is the correct order for the 2 steps of protein synthesis occur?
1. Transcription
2. Translation
In the early 1900s a scientist hypothesized a link between DNA and the production of proteins in the cytoplasm. However, the fact that DNA could not be found outside the nucleus led scientists to believe that another substance was also involved in the synthesis of protein in the cytoplasm. In the 1940s scientists performed an experiment that ultimately identified the site of protein synthesis. They also identified the molecule responsible for transporting information from the nucleus to the site of protein synthesis. What was this newly identified molecule?
mRNA
What is the function of tRNA (Transfer RNA)
Transport amino acids to mRNA
How is information for a specific protein carried on the DNA molecule?
(Hint: Think about the part of DNA which chooses a humans characteristics)
Through the sequence of Nitrogenous Bases
If a sperm cell has 6 chromosomes, it comes from an animal whose somatic cells have ___ chromosomes.
12 chromosomes
People who have leukemia, a cancer that affects white blood cells, are often given Cytarabine. This drug inhibits the synthesis of DNA. Which phase of the cell cycle is most affected by Cytarabine?
S-Phase
A segment of DNA produces methionine, threonine, histidine, aspartate, and glycine when translated. A substitution mutation occurs and causes the synthesis of the segment as shown.
New DNA strand: 3’-TACAGGGTGCTACCCACT-5’
(Please use codon chart)
Which is the new peptide chain when the new DNA segment is translated?
Methionine, serine, histidine, aspartate, glycine
What is the purpose of tRNA and mRNA meeting at the ribosome?
(This is very general question, so you will have a good chance at recieving the points if you answer somewhat correctly)
To translate the genetic code into a specific sequence of amino acids
What is complementary to the DNA sequence below?
CAGCCATC
GTCGGTAG
During meiosis, homologous chromosomes exchange genetic material. This exchange of genetic material increases what?
Genetic Variation
Nitrogenous bases are located on both strands of the DNA double helix. What is the significance of the nitrogenous bases?
The order of nitrogenous bases determines the order of amino acids in the proteins synthesized.
The survival of a species depends on its ability to adapt to changes in the environment. A species must be capable of surviving and reproducing despite changes to food sources, climate, or threats from predators. Which statement correctly describes a way that mutations increase the likelihood that a species will survive in a changing environment?
Mutations are a source of variation in the species.
Complete the following chart of the attachment of nitrogenous bases:
Guanine - ?
Adinine - ?
Guanine - Cytosine
Adinine - Thymine
In the early 1980s scientists were able to produce two biomolecules by splicing a human gene into the bacterium E. coli to make recombinant human insulin and growth hormone. Which statement best explains why this experiment was successful?
The genes for all organisms are composed of the same building blocks.
Scientists can bioengineer skin in a laboratory to treat severe burns and other types of skin injuries. This bioengineered tissue is grown from living cells. The cellular process that enables the cells to grow and develop into tissue is —
Mitosis
Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does the presence of an oncogene lead to the formation of a tumor?
Cell division is unregulated.
How many codons is presented in the following text?
CGACGTTAT
3 codons
For the given phase, choose the type of molecule that is most closely associated with the phase.
May contain the nitrogenous base uracil.
(The answer might be more than one, and you need to get them all correct!)
mRNA and tRNA
When cells leave the cell cycle, they exit during G1 phase and then enter G0 phase, a resting period. Most normal cells can leave G0 phase and reenter the cell cycle at G1 phase before entering S phase. Cancer cells are different because they cannot enter G0 phase and are likely to do which of the following?
(Hint: Think more about cancer)Repeat the cell cycle continuously
THIS IS A VERY HARD QUESTION!!!
At which stage of meiosis is each chromosome composed of a single chromatid?
Anaphase
As a fertilized egg divides, the cells differentiate because they —
have specific genes activated