Term
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Definition
| A molecule composed of deoxyribose nucleotides; contains the genetic information of all living things. |
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Term
| What do the molecular instructions in DNA do for the cell? |
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Definition
| Proteins are synthesized from the genetic materials in DNA. It also directs reproduction. |
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| Relationship between DNA, genes, and chromosomes |
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Definition
DNA - in chromosomes when wrapped up
Chromatin - DNA uncoiled (spaghetti)
Genes - nitrogen bases/actual sequences
DNA - sugar phosphate nitrogen bases |
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Term
| Significance of experiment by Fredrick Griffith in the 1920s. |
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Definition
| It marked a turning point in our understanding of genetics because other researchers suspected that the substance that causes transformation might be the long-sought molecule of heredity. (See Book) |
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Term
| What are the monomer units of DNA called? |
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Definition
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Term
| How many types of nucleotides are there? |
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Definition
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Term
| Three Parts of a Nucleotide |
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Definition
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Term
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Definition
Adenine
Guanine
Cytosine
Thymine |
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Term
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Definition
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Definition
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Definition
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Term
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Definition
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Term
| What did Chargaff discover? |
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Definition
| He discovered that the DNA of any species has equal amounts of adenine and thyme as well as equal amounts of guanine and cytosine. |
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Term
| What is Chagaff's discovery called? |
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Definition
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Term
| Structure of DNA molecule (number of strands, organization of nucleotides, orientation of strands, and types of bonds that hold the nucleotide subunits together) |
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Definition
2 Strands
Nucleotide bases oriented on the inside forming the "rungs" of the ladder. The nucleotides are attached to the sugar.
The strands run in opposite directions.
Three hydrogen bonds hold C and G together and only two hydrogen bonds hold A and T. |
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Term
| Why is DNA referred to as a double helix? |
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Definition
| Strands of DNA wind about each other in a double helix, like a twisted ladder with the sugar-phosphate backbone forming the uprights and the complementary base pairs forming the rungs. |
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Term
| Describe the base pairing arrangement in DNA. |
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Definition
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Term
| What type of bonds hold the base pairs together? How many? |
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Definition
| Hydrogen bonds hold the base pairs together. Two bonds hold A and T, and three bonds hold G and C. |
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Term
| What ensures the DNA molecule is the same width across at each rung on the DNA ladder? |
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Definition
| It is the same width because A and G consist of two fused rings and are larger, but only T bonds with A and only C with G. This keeps the size consistent. |
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Term
| Why did scientists have trouble believing that DNA was the carrier of genetic information? |
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Definition
| Some still thought that genes are made of protein. DNA is very simplistic and only has four subunits; many thought that it would be more complex. |
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Term
| How is genetic information encoded in the DNA molecule? |
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Definition
| The sequence of the bases is important, not the number. It is encoded by the sequence of the four bases. DNA also has billions of nucleotides. |
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Term
| What allows so much different genetic information to come from a molecule with only four subunits? |
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Definition
| The different sequences of genetic information and the different orders and combinations. |
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Term
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Definition
| A process that copies the double-stranded DNA molecule, producing two identical DNA double helices. |
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Term
| Why do cells replicate their DNA? |
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Definition
| The DNA must be replicated in order to replicate the actual cells. The daughter cells both need identical copies of DNA, too. |
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Term
| Why is the timing of DNA replication carefully controlled by the cell? |
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Definition
| So that it can be passed on and replicated with no mistakes. |
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Term
| Why are the base pairs considered the foundation of DNA replication? |
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Definition
| It is the foundation because only A can be paired with T and only G with C. So if one strand read A-T-G then the other would have to read T-A-C. |
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Term
| DNA helicases (in DNA replication) |
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Definition
| Enzymes that pull apart the parental DNA double helix so that the bases of the two DNA strands no longer form base pairs with one another. |
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Term
| DNA polymerase (in DNA replication) |
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Definition
| Enzymes that move along each separated DNA strand with complementary nucleotides. |
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Term
| DNA ligase (DNA replication) |
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Definition
| Joins the small DNA segments into a single daughter strand (lagging strand). See book** |
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Term
| Process of DNA replication |
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Definition
1) Enzymes called DNA helicases pull apart the parental DNA strand.
2) Other enzymes called DNA polymerases move along each separated DNA strand with complementary nucleotides.
3) Complementary nucleotides are paired up forming two new strands complementary to the parent ones.
4)DNA ligase joins the small DNA segments into a single daughter strand. (lagging)
5) One parent strand pairs with a daughter strand to form a double helix. |
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Term
| How is the synthesis of each new DNA strand different? |
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Definition
| The opposite bases are paired to the DNA. |
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Term
| Why can't both strands be synthesized continuously? |
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Definition
| The leading strand and lagging strand are in opposite directions and it would take too long. The strands run form 5' (phosphate) to 3' (glucose), so only one strand can be synthesized at a time because the DNA polymerase can only go one way. |
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Term
| Why is the process of DNA replication called semi-conservative? |
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Definition
| Because each new daughter strand is paired up with one of the original parent strands. |
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Term
| How do the newly synthesized DNA helics compare to the parent strand and to each other? |
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Definition
| If no mistakes were made, then the strands should be identical. |
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Term
| What happens to the new DNA helics during cell division? |
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Definition
| One set of DNA goes to one daughter cell, and the other goes to the other cell. They get passed on to the new cells. |
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Term
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Definition
| Changes in the base sequence of DNA in a gene, often used to refer to a genetic change that is significant enough to alter the appearance or function of an organism. |
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Term
| What ensures DNA replication is error-free? |
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Definition
| The specificity of hydrogen bonding between complementary base pairs makes DNA replication highly accurate. |
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Term
| What are some sources of genetic mutation? |
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Definition
| Environmental conditions such as chemicals and radiation can cause errors or even changes in DNA composition between replications. |
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Term
| How are most of these changes in DNA sequences fixed? |
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Definition
| Repair enzymes recognize the "mismatch," cut out the incorrect nucleotide, and replace it with a nucleotide that contains a complementary base. |
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Term
| Replication in leading strand |
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Definition
| DNA is replicated continuously from 5' to 3'. |
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Term
| Replication in the lagging strand |
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Definition
| Replication happens in fragments. Small strands called okazaki fragments are made and then connected by DNA ligase. This is because the DNA polymerase only runs from 5' to 3'. |
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