Bio/Biochem Flashcards
Explain the shapes of the different types of bacteria (bacilli, spirilla, cocci)
Bacilli appear rod-shaped under a microscope.
Spirilla appear spiral or curved shaped.
Cocci appear round shaped, or nearly round.
How do you transfer genetic information between bacteria without altering phenotype?
Conjugation is a natural method for the exchange of genetic information between prokaryotic cells; a method that can also be induced in a laboratory setting without altering the phenotype.
Fusing two cells would be one way to transfer plasmids carrying altered genetic information. However, the phenotype of the fused cell would no longer be the same, but a hybrid of the two fused bacteria.
Explain the difference between gram-negative and gram-positive bacteria.
The Gram stain recognizes peptidoglycans coating the cell wall and Gram-positive bacteria have a cell wall containing high concentration of peptidoglycans. Bacteria that are Gram-negative contain relatively little peptidoglycan and will appear unstained next to Gram-positive bacteria.
All bacteria, whether they are stain positive or negative with the Gram stain have a cell wall, polysaccharides on the extracellular surface, and an inner plasma membrane.
Which region of the antibody will the antigen be bound to?
Antigens bind to the variable region (Fab region) specifically because of its unique random variability. The constant region could not fulfill this role. The purpose of the constant region is to remain recognizable to the host’s own tissues.
What is the difference between a positive and a negative control?
A positive control confirms that an effect that is expected has occurred.
A negative control confirms that an effect that was not expected did not occur.
If a fetus had 3 copies of a chromosome what chromosomal abnormality would best explain this?
- Deletion
- Aneuploidy
- Inversions
- Tetraploidy
Aneuploidy because it is the existence of an abnormal number of chromosomes in a cell. A fetus that has three copies instead of the expected two copies (one from each parent) would be an example of aneuploidy. Trisomy 21 (Down syndrome) is a common example of this.
Chromosomal deletions would result in fewer chromosomes, not an extra copy.
Inversions are regions of chromosomes that are rearranged, but inversions do not alter the chromosome number.
Tetraploidy is the existence of two complete sets of chromosomes (four total).
What is the most likely impact of a point mutation to the terminal guanine on a 5’ exon?
The intron will not be spliced from the mRNA transcript.
The first step in intron splicing is the nucleophilic attack of a 2’ hydroxyl at the phosphate of the guanine located at the end of the 5’ exon. This step forms the lariat structure. The proposed mutation would disrupt this process, preventing the excision of the intron from the transcript. That would mean the RNA is longer than intended because introns have not been removed
What phase of the cell cycle are growth factors important?
Growth factors (ex: TGFβ) stimulate cell division in healthy cells of sufficient size and in the presence of ample nutrients, by promoting the G1 transition and entry into S-phase.
The only place in the cell cycle that growth factors influence cell cycle progression is within the G1 checkpoint.
Acclimation
Acclimation occurs when an individual adapts to changes in their environment WITHOUT a change in genotype.
