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In DNA, which basepairs take less energy to pull apart? AT or CG?
- AT.
- AT are held together by only 2 h-bonds, whereas CG are held together by 3 h-bonds, thus AT bonds are easier to break.
- Mnemonic: Automatic Transmissions (AT) are easier to break!
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What is each letter in the genetic code (U, C, A, G, T) called?
Nucleotide
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What is the common name of a group of three nucleotides joined together?
codon
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how many nucleotides are required to code for a single nucleic acid?
three.
- Each codon codes for one nucleic acid
- a codon is made up of three nucleotides (three letters)
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What is a basepair?
- a pair of a nucleotide with its respective nucleotide in the other strand of DNA or RNA
- basepairs:
- AT
- CG
- AU (U instead of T in RNA)
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type of mutations that cause an aminoacid to be replaced by another aminoacid?
What type of mutation is this?
missense mutations
these are a type of point mutations
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what type of mutations cuase a stop codon?
what type are they?
nonsense mutations
these are a type of point mutations
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what type of mutations don't cause make no difference because they code for the same aminoacid?
silent mutations
these are a type of point mutations
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What are the three different types of point mutations?
- missense
- nonsense
- silent
- .... mutations
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What are the most deleterious type of mutations? and why?
because they are "frameshift mutations". they cause a shift in reading frame
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what does an insertion mutation do? what significance does this have?
insertion mutation causes inserts a new nucleotide to the DNA sequence
bigger impact? - this causes a shift in the reading frame.
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what type of mutation results in the removal of nucleotides from the DNA seqence? What is their impact?
deletion mutations.
Superbad because they cause a shift in reading frame
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Grab a piece of paper and draw the cell cycle.
Clearly draw Interphase and mitotsis regions.
What are the subphases of Interphase?
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What is the G0 subphase of interphase?
What cells are in G0?
- G0 is a subphase of interphase used by cells that are stuck in interphase and never come out of it.
- The more specialized a celld become, the less likely they are to divide: neurons, RBC, outter skin cells
- Since they dont form by mitosis, their precursors: stem cells
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In what phase of the cell cycle is G1 located?
What happens in it? Describe it
- G1 is a subphase of Interphase
- high rates of protein synthesis (new organelles made)
- enzymes made (specially those needed for DNA replication)
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In what phase of the cell cycle is S subphase located?
What happens in it? Describe it
- S stands for Synthesis of new DNA so DNA Replication occurs
- by the end of S subphase, cell contains two identical copies of the genome
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What are the subphases of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
- mnemonic: "P-MAT"
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What is the first sign of prophase?
- the genome becomes visible after condensing into tightly packed chromosomes, instead of diffuse chromatin.
- Chromosomes appear joined with their sisters (Ms. Chromatids) by their centromeres.
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what are chromatids?
- Ms. Chromatids, are the sisters of Mr. Chromosomes.
- chromatids, are the names of the sisters of the crhomosomes., thus in prophase is where they first appear, and they appear holing hands, ( joined by their centromeres)
- (just coming up with some type of story so I remember this, as I keep forgeting it. not any more thanks to this analogy)
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what is the name when Mr. Crhomosome is seen holding hands (joined at centromere) with his sister, Ms. Chromatid, what is this group called?
homologous pair
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What happens in prophase?
- DNA becomes visible as homologous pairs of sister chromatids
- nucleolus dissapers
- Spindle & kinetochore fibers appear
- asters form: centriole pairs move to oppocite ends of cell
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What happens in Metaphase and Anaphase?
- Metaphase: homologous pairs line up in center of cell
- Anaphase (A-shape): spindle fibers shorten pulling sister chromatids apart and this looks like two A's
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What happens in Telophase
- nuclear membrane reforms in each half of the cell
- nucleolus reappears
- genome decondenses
- cytokinesis (cells split)
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What is kinetochore?
protein structure where spindle fibers attach to each sisster chromatid during metaphase and anaphase
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