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66 Cards in this Set
- Front
- Back
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Which kinds of organisms have circular chromosomes? Which kinds have linear chromosomes?
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circular: Bacteria, Archaea (also, in Eukaryotes: mtDNA and cpDNA)
linear: Plants, Animals and Fungi |
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How many double-helices (i.e., how many strands) of DNA does it take to make one chromosome?
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one
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How many pieces of double-stranded DNA do you have in each of your nuclei (assume the cell is not dividing)?
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46
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DNA is a polymer made up of what kind of units?
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nucleotides
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Name the three main components of a nucleotide.
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deoxyribose sugar, phosphate group, and nitrogenous base
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What is a phosphate group? What kind of charge does it have?
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part of the backbone, negative charge
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What sugar is found in DNA? How many carbons are in it?
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deoxyribose, 5
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Be able to draw the general shape of deoxyribose and label each carbon by number. Which are the three important attachment points and what do they attach to?
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5- PO4
3-nucleotide attaches 1- nitrogenous base |
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Where does the phosphate group attach to a deoxyribose?
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5
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On which carbon of deoxyribose does the base attach?
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1
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If a new nucleotide were to be added to a chain of nucleotides, on to which carbon would the new nucleotide be added?
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3
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Which two parts of a nucleotide form the "backbone" of a strand of DNA?
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sugar and PO4
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Of the four bases (adenine, guanine, cytosine, and thymine) found in DNA, which two are purines? What is the general shape of a purine?
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GA, double ring
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Which two are pyrimidines? What is the general shape of a pyrimidine?
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CT,single
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Look at Figure 16.5 in your book. Pick out a single nucleotide (sugar + phosphate + base) to examine. How many rings do you count in the structure of a pyrimidine nucleotide? a purine nucleotide?
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1, 2
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In dsDNA, which bases form pairs? How many hydrogen bonds are found between each? Which type of base pair takes the most heat to denature it?
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AT and GC, double(AT) triple (GC)
triple bond |
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What does "DNA sequence" refer to?
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A nucleotide sequence that gives order of bases and orientation of 5' and 3' ends.
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What does "nucleotide sequence" refer to?
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A nucleotide sequence that gives order of bases and orientation of 5' and 3' ends.
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What does "complementary" mean when it comes to DNA?
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the base pair will be across from it and the opposite ends
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In which way are the two strands of DNA oriented in dsDNA?
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antiparallel
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If I give you a DNA sequence, please be able to tell me what would be the "complementary" DNA sequence to it. In other words, what bases would pair with it and what would be their 5' and 3' orientation.
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...
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Given base-pairing rules, if DNA contains 20% A, can you figure out the G, C, and T content?
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t= 20
G=30 C=30 |
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What is found at the 5' end of a strand of DNA? What is found at the 3' end? What does it mean if two strands of DNA are "anti-parallel"?
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5= PO4
3=next nucleotide anti= "complementary" or opposite in a way |
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How can DNA be easily denatured in the lab? Which is easier to denature, GC rich DNA or AT rich DNA?
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with heat, AT
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Why does Ethidium bromide work as a stain for DNA?
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allows under UV, intercalates btw base pairs that are flat, planar molecules
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Explain the difference in bases used in ribonucleotides and deoxyribonucleotides.
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ribo uses U instead of T
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What is different about deoxyribose and ribose? Does the difference occur at one of the important attachment sites (i.e., 1', 3', or 5' C?)
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ribose has 2 OH groups, the difference occurs at 2'
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On which carbon does the phosphate group attach to ribose? Is this the same as for DNA?
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5', yes
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We often think of RNA as a single-stranded molecule. Can RNA exist as a double-stranded molecule? Explain
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yes, the RNA loops back around
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Why does DNA replication happen? When does DNA replication happen in the life of a cell (what part of the cell cycle)?
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to continue life, mitosis
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Will mitosis happen if DNA replication does not happen?
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no
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What are the purposes of mitosis?
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to divide the cells
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Know the cell cycle. Diagram it and label it.
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...
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Do all cells progress through the cycle at the same rate? Explain two factors that impact the rate of progression of a normal cell through the cell cycle.
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depends on age (developemental stage)
and depends on tissue type |
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Where do the instructions for moving a cell through the cell cycle ultimately come from?
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DNA
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For a cancer cell, what is going on with the cell cycle? Can inhibiting DNA replication help someone with cancer?
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too much mitosis, yes
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What does DNA replication have to do with sister chromatids? What is a centromere?
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it creates sister chromatids. a centromere are DNA and proteins that hold sis chromatids together from the time they are synthesized.
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Use what you know about cohesins to decide: When in the cell cycle do sister chromatids become joined together: G1, S, G2, or mitosis?
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s phase
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Remember, one chromosome = one double helix of DNA. In a human cell (chromosome number = 46), within the nucleus of a non-dividing cell, how many DNA double-helices are there? (1, 2, 46, 92, hundreds?) After DNA replication, how many DNA double helices are there? (1, 2, 46, 92, hundreds)
What does it mean that DNA replication is "semiconservative"? |
92, 184, it is .5 new and .5 old sis chrom.
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When you look at a mitotic chromosome (X shaped), where are the original template DNA strands located (a) both in the same chromatid or (b) one in each chromatid?
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b
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What are dNTP's? When in the cell cycle are they used? Based on what you know about the cell cycle, what would happen to the cell cycle if dNTP synthesis is prevented somehow?
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triphosphate nucleotides= building blocks, ?
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What is the name of the enzyme that builds the new strand of DNA during DNA replication? Which "direction" does it work? Will it add a new nucleotide onto the 5' end or the 3' end of the growing strand of DNA?
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DNA polymerase, 5-3, 3
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You can watch the steps of DNA replication in the Chapter 16 BioFlix Animations. I will show this in class on Friday to sum up the steps we have talked about.
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...
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In natural DNA replication, what enzyme unwinds the DNA?
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helicase
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On a prokaryotic chromosome, will there be one or many origins of replication?
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one
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On a eukaryotic chromosome, will there be one or many origins of replication?
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many
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What seems to be characteristic of the nucleotide sequence of origins of replication?
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they are all the same
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What bad thing can happen to DNA during the unwinding process?
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stress can break the SP backbone (chromosomes break and lose parts)
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What enzymes deal with the stress induced by unwinding the double helix?
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topoisomerase
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What proteins keep the DNA unwound for DNA replication?
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single-stranded binding proteins
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During natural DNA replication, what are primers made of? What enzyme synthesizes the primers? Why are primers necessary?
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RNA primase, RNA, they prime the reaction for DNA polymerase
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What enzyme builds new DNA?
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DNA polymerase
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In which "direction" is DNA polymerase able to synthesize new DNA? What other "rule" does DNA polymerase have to follow (i.e., what does it need to get started)?
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5-3, it needs to start from a ds
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How is it determined which nucleotide (dATP, dGTP, dCTP, or dTTP) is added next in a growing chain of DNA?
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in an antiparallel fashion
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What happens to RNA primers during DNA replication?
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a nucleotide gets added to the end of a primer
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What is the role of DNA ligase in DNA replication?
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seals SP backbone btw pieces of DNA synthesized at diff times
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What do cohesins do in DNA replication and when do they begin this job?
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hold new sis chromatids together
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In which "direction" is DNA polymerase able to synthesize new DNA? What other "rule" does DNA polymerase have to follow (i.e., what does it need to get started)?
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5-3, it needs to start from a ds
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Be able to identify on a diagram which direction new DNA is being built relative to the template strand of DNA (add in the 5' and 3' notations and use an arrow to show which way the new DNA is growing).
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...
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What are telomeres? What happens to our telomeres as we age?
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tips of chromosomes, they get shorter
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What happens to the chromosomes if telomeres become shortened? What does this have to do with mitosis?
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they stick together, it stops mitosis
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What is it about DNA polymerase that makes it unable to finish the job of DNA replication at the telomeres? Which end of the newly synthesized DNA has a problem?
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it can't fill in the gap and leaves it SS, 3 prime
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What does telomerase do? Where do the instructions for making telomerase come from? Does every body cell have the instructions (the gene) for making telomerase? What kinds of cells have high levels of the telomerase protein? What does this have to do with immortality in cancer cells?
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it lengthens the telomere, in stem cells. yes, cancer cells, they do not shorten
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Define mitosis. What is mitosis used for?
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a form of cell division in which chromosome number is maintained. it is used to make more chromosomes
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Be able to diagram and/or explain the steps describing what happens to chromosomes during the cell cycle to maintain constant chromosome number during mitosis.
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1.prior to mitosis, DNA replication (s phase), each chromosome gets a sister chromatid
2.chromosomes condense, nuclear membrane breaks down 3.spindle fibers attach to centromeres of chromosomes, chromosomes line up along the middle of the cell 4. spindle fibers pull the chromatids apard, end up on opposite sides of the cell 5. cell divides trapping chromatids in diff. cells |
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Start with a cell that is in G1 phase and diagram it with 6 chromosomes. Now follow this same cell through S-phase and mitosis to show the genetic composition of the two daughter cells that are produced at the end of the cell cycle
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..
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