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Definition
| is a sequence of nucleotides in DNA that controls the expression of a trait. |
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| There are thousands of different kinds of genes in an organism's GENOME. A genome is the sum total of the genes in the haploid number of chromosomes. |
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Definition
| sequences of nucleotides in genes is transcribed and translated to produce the primary amino acid sequence of the thousands of proteins that lead to an organism's phenotype. |
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| DNA molecule consist of what... |
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Definition
| A DNA molecule consist of two polynucleotide strands running in opposite directions (antiparallel) and held together by hydrogen bonding between complementary bases. |
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Term
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Definition
| Nucleotide,pentose sugar, adn a phosphate. They are link to one another by covalent bonds between the phosphate group and the pentose sugar. |
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*The nitrogenous bases in DNA are...
*how doese Base pairing |
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Definition
(A) adenine, (G) guanine, (C) cytosine, (T) thyymine
The pentose sugar is deoxyribose
Base pairing:
A-G, C-T |
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Term
| Where (in DNA and RNA) on the carbons does the pentose sugar connect the adjacent pentose sugars? |
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Definition
| carbon 3' of one pentose sugar to an adjacent sugar on carbon 5' |
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Term
| Polynucleotides run in anti direction, what is the direction? |
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Definition
5'->3'
5'phosphate group-->3'hydroxyl group
3'hydroxyl group-->5'phosphate group
they run in opposite directions. |
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Term
| who discovered that DNA is 3D? |
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Definition
| in 1953 James Watson and Frances Crick using Chargaff rules and X-ray data of Rosalind Franklin to build a molecular model to deduce the antiparallel and double helix structure. |
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| What affect gene expression? |
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Definition
| Major and minor grooves in the three-dimensional helical structure are key for DNA-protien interactions that affect the changes in the gene expression. |
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Term
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Definition
*is a semi-conservative process
Transciption occurs:
Parent molecule consist of two DNA molecule that splits in to two template DNA and new nucleotides come in and do complementary base pairing with the two templates creating two new strands. The 2 daughter DNAs contain one parental strand and one new strand. |
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Term
| What is the molecular mechanism for DNA replication? |
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Definition
*DNA replication can occur at many spots, but it has to be at an origin of replication.
*this process involves many protiens and enzymes, replication complex
*DNA strand must be unwounded into two DNA template.
*DNA polymerase enzyme adds complementary bases to the 3' of the new strand
*The new strand 5' to 3', Parental strand is 3' to 5'
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Term
| What direction is DNA synthesis? |
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Definition
| DNa synthesis prceeds in a 5' to 3' fashion, but DNA polymerase reads the parental tempalte from a 3' to 5' fashion |
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Term
| What happens to the phosphate groups? |
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Definition
| Phosphate groups are releases when new bases are being added onto the new strand. The phosphate group is then hydrolyzed and reused later to make more nucleotides or other phosphate contianing compound. |
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Term
| What does DNA polymerase require in order to begin synthesis of the complementary DNA strand? |
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Definition
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Term
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Definition
| Primer is made of RNA and is synthesized by an enzyme called primase. |
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Term
| What is the purpose of a primer? |
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Definition
| Primer/primase addes nucleotides on to the 3' end as well. The primase gives a jump start, meaning it only synthezies the dna template a little bit then it falls off and DNA polymerase finishes the rest of the sythnesis |
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Term
| What happens becuase DNA polymerase can only synthesize in one direction? |
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Definition
| Since DNA polymerase can only synthesize 5 to 3', it causes a leading strand and a lagging strand. The lagging strand is the other DNA template that runs 5'-3' |
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Term
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Definition
| The leading strand runs from 3' to 5' and is synthesize continously by DNA polumerase in a 5' to 3' fashion. |
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Term
| What is a lagging strand? |
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Definition
| The lagging strand is hte the other DNa template taht runs fro ma 5' to 3' direction and DNA polymerase cannont synthezie it. So it is syntheize in a discontinous fashion, that DNA polymerase has to wait until the DNA strand is unqound enough so that the DNA polymerase cna gain access to synthesize. |
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Term
| What are okazaki fragments? |
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Definition
| The lagging strand is synthesize in a discontinouss fashion, these bits of strands are called okazaki fragments. |
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| Where does replication occur? and what is require? |
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Definition
| at the many origins of replications. Replication comp;ex of many proteins is required fro replication to happen. |
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Term
| What is a replication fork?? |
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Definition
| When the helicase starts to unwinds |
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Term
| What is needed in order for DNA polymerase to start synthesizing the DNA strands? |
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Definition
| Primase. Primase adds a short stretch of complementary bases in a 5' to 3' fashion before DNA polymerase takes over. |
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Term
| Because DNA polymerase adds in one direction what happens? |
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Definition
| Since DNA polymerase synthesizes only in 5' to 3' direction, leading and lagging strands occur. |
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Term
| laggin and leading strands |
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Definition
*Lagging strand is synthesize in a discontinous fashion causing it to make bits and pieces of new strands, okazaki fragments.
*leading strand is synthesize continously. |
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Term
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Definition
| Fragments made by the lagging strand. Eventally they are all connected by DNA ligase |
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Term
| what happens after the removal of the complementary RNA primer from teh 3' end of the parent DNA strand? |
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Definition
| Everytime the primer falls off the new duaghter strand becomes shorter and shorter, allowing it to replicate less adn less, because replication is producing shorter and shorter DNA molecules. |
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Term
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Definition
they are special nucleotides sequences (TTAGGG) that are located in eukaryotic chromosomes that prevent damage to the genes located near the end of the DNA molecule.
* telomeres have no genes adn consist of multiple repeats of the same sequence at the end of a chromosome. (2500 times in humans0
*In constantly dividing cells, telomerase retores the lost telomeric sequences. |
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Term
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Definition
Errors in replication leads to mutations, DNA polymerase error rate is 1/1,000,000 bases which equls 1000 mutations everytime a cell divide.
*Proof Reading by DNA polymerase during replication reduces these errors dramatically. there are also other protiens taht are invovled in fixing damaged DNA. Editing and repair of DNA is a continuous process that is essentail for survival of an organism. |
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