MCAT-Biology

• Conjugation is the exchange of genetic information between prokaryotes, typically in the form of plasmid DNA. 


  It does not occur in eukaryotes.
• Alternative splicing produces multiple protein products by producing distinct mRNA molecules from the same gene.


  from the same gene
• Transformation occurs when prokaryotes pick up foreign genetic material from their surroundings


  Eukaryotes do NOT undergo transformation to acquire genetic material
• Duplicated genes can undergo mutations, causing them to have similar but NOT identical sequences. 


  Differences allow genes to carry out distinct roles
• Frameshift mutations; result from the insertion or deletion of a number of nucleotide base pairs NOT divisible by three.


  Reading frame of the mRNA transcript changes, leading to multiple a.a. changes downstream, interferes with protein function.
• Nonsense mutations, occur when a base pair substitutions causes a premature stop codon to be inserted into a gene. 


  Premature stop codon leads to early termination of translation and the production of a short protein.
• Missense mutations, occur when a base pair substitution results in a codon that encodes a different amino acid.


  Mutant amino acid formed that can potentially interfere with protein function.
• Silent mutations, mutation alters the sequence of the gene and mRNA transcript but NOT the sequence of a.a in the encoded protein.


  Protein retains its wild-type function and is NOT affected by silent mutations
• Osteocytes


  release signaling molecules to travel to other bone cells via canaliculi.
• Chondrocytes


  Cartilage producing cells, that produce collagen so calcium phosphate attaches and hardens bones
• DNA -> cDNA


  reverse transcriptase
• DNA -> cDNA


  Same sequence but thymine changes to Uracil
• Kinesin


  Anterograde transport (away from cell body)
• Dynein


  Retrograde transport (towards cell body)
• Microtubular motor proteins


  Kinesin and Dynein
• Confounding variable


  Can have an unforeseen effect on independent or dependent variables
• Mediating variables


  Explains how two other variables are related
• p+q=1


  Hardy-Weinberg equation
• Where transcription and translation occur

  In the nucleus
• Prokaryotes pass genetic info to other individuals via

  Conjugation
• Eukaryotic cells 


  Have membrane-bound organelles as well as a mechanism for intron splicing by spliceosome.
• Heterochromatin


  Closed conformation of DNA=histone complex
• Euchromatin


  Open conformation of DNA-histone complex
• Northern Blots


  detect target RNA in a sample
• Processing occurs in the nucleus


  Includes splicing
• Synthesize

  To put together different entities to make a new whole (building blocks)
• Transcription 


  Process of synthesizing RNA from template DNA
• Posterior pituitary releases oxytocin


  Oxytocin promotes breast milk ejection
• Anterior pituitary releases TSH
• DNA winds tightly around histones to form


  nucleosome
• DNA is predominantly negatively charged


  because of phosphate groups on the backbone
• Histones form salt bridges between positively charged a.a and negatively charged phosphate groups
• Acetylcholine binds to receptors on the motor end plate to trigger muscle contraction
• Glutamate

  Excitatory neurotransmitter
• GABA

  Inhibitory neurotransmitter
• Norepinephrine and Epinephrine 


  Hormones part of your fight-or-flight
• Action potential (depolarizing current) travels down the T tubules in skeletal muscle tissue