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Bio 5.5 and 16
The Molecular Basis of Inheritence
71
Biology
Undergraduate 1
10/03/2012

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Term
DNA
Definition
Deoxyribonucleic Acid that contains the instructions for building proteins, including enzymes.
Term
Gene
Definition
A segment of DNA coding for a single polypeptide
Term
Polypeptide
Definition
Sequence of amino acids
Term
Genome
Definition
Complete set of an organism' genetic information.
Term
Proteins are made up of how many polypeptides?
Definition
At least one polypeptide.
Term
How many genes does a human have?
Definition
More than 25,000 genes.
Term
Which cells have a full copy of the genome?
Definition
Almost every cell.
Term
Nucleic Acids
Definition
The class of compounds that DNA belongs to.
Term
Nucleotides
Definition
The monomers that make up Nucleic Acids, comprised of a nitrogenous base, a five carbon sugar and a phosphate group.
Term
Polynucleotides
Definition
The name for the polymers of Nucleic Acids.
Term
Each chromosome contains...
Definition
one long DNA strand.
Term
DNA and RNA are both...
Definition
nucleic acids
Term
C
Definition
Cytosine
Term
T
Definition
Thymine
Term
U
Definition
Uracil (in RNA), that trades for Thymine.
Term
A
Definition
Adenine
Term
G
Definition
Guanine
Term
Nucleoside
Definition
The portion of a nucleotide without any phosphate groups.
Term
The two families of nitrogenous bases are
Definition
Pyrimidines and Purines.
Term
Pyramidines
Definition
C,T,U, with only one carbon ring.
Term
Purines
Definition
G,A, with two rings.
Term
Differences between RNA and DNA
Definition
- Single versus double strand
- DNA has one less oxygen in the five carbon sugar.
- T bases in DNA become U bases in RNA
Term
What comprises the double helix?
Definition
- Two polynucleotides with sugar phosphate alternating the backbone.
- Nitrogenous bases making the "rungs."
Term
Bonds between the nitrogenous bases are...
Definition
Hydrogen bonds.
Term
Bonds between the nucleotides are...
Definition
covalent bonds.
Term
Anti-parallel
Definition
How the two sugar phosphate backbones of DNA run in opposite 5'-3' directions from one another.
Term
What is the directionality of the polynucleotides based on?
Definition
The kind of carbon the last phosphate is attached to.
Term
If one polynucleotide runs 5'-AGGTCCG-3'then the compliment runs
Definition
3'-TCCAGGC-5'
Term
5-carbon sugar attachments in DNA
Definition
1' to nitrogenous base
5' to phosphate
3' to next nucleotide
Term
Two nucleotides (DNA rungs)
Definition
[image]
Term
Semiconservative replication
Definition
Each daughter strand has half of the parent strand.
Term
The error rate of replication is
Definition
One in every 100,000 nucletides are paried incorrectly (humans have ~6 billion base pairs), but DNA polymerase, involved in proofreading and correcting, reduces it to one error per 10 billion nucleotides.
Term
Chromosomes
Definition
Tightly coiled DNA around histone proteins.
Term
Sister chromatids
Definition
Two identical DNA strands (to be seperated during cell division)
Term
Why does DNA coil?
Definition
To take up less room than it would stretched out.
Term
Chromatin
Definition
Coiled DNA around histone proteins. LESS dense than chromosomes.
Term
The two organelles that can make their own protein.
Definition
Chloroplasts and mitochondria
Term
Why must each cell have DNA?
Definition
So it can make protein.
Term
Chromatin is less densely coiled so that...
Definition
the DNA does not tangle and break.
Term
Mutation
Definition
A permanent change in a DNA sequence.
Term
Inheritance of mutation
Definition
In somatic cells, the mutation stays in the individual. In germ-line cells, the mutations are passed on.
Term
What can cause mutations?
Definition
Radiation, chemicals, chance error in cells.
Term
What could be the effects of mutations?
Definition
It could be fatal, have no effect, or be beneficial and lead to evolution.
Term
Point mutation
Definition
Change at one point in the sequence, which can still lead to different or non-functional proteins.
Term
"Shrinking chromosomes" occur because...
Definition
DNA polymerase can only add nucleotides to the 3' end, so when the 5' lagging strand loses its RNA primer, the DNA is not replaced.
Term
Through "shrinking chromosomes" each replication results in...
Definition
shorter chromosomes.
Term
What prevents genes from being eroded away during successive rounds of DNA replication from the shrinking chromosome" phenomenon?
Definition
Telomeres
Term
Telomeres
Definition
Special repeated nucleotoide sequence at the ends of DNA that protect genes.
Term
Telomere pattern
Definition
TTAGGG repeated 100-1,000 times.
Term
Telomerase
Definition
An enzyme in germ cells that catalyzes the lengthening of telomeres.
Term
The genes of germ cells...
Definition
must persist virtually unchanged from an organism to its offspring, so that the"shrinking chromosomes" phenomenon would eventually delete essential genes.
Term
How do germ cells compensate for "shrinking chromosome" phenomenon when they must pass on unchanged genes?
Definition
They have telomerase that catalyzes the lengthening of telomeres, thus restoring their original length
Term
Why can't enzymes initiate the building of a complimentary chain.
Definition
They can only ADD nucleotides to the end of an already existing chain that is base paired with the template stand. The initial nucleotide chain is actually an RNA primer.
Term
How many nucleotides is an RN primer?
Definition
5-10 nucleotides
Term
How fast does polymerase III add nucleotides?
Definition
500/second in bacteria and 50/second in humans
Term
What does polymerase III enter as?
Definition
As nucleoside triphosphate (high energy)
Term
What are the differences between prokaryote and eukaryotic DNA?
Definition
Term
Primase
Definition
The enzyme that synthesizes RNA primer.
Term
RNA Primer
Definition
The short sequence of complementing nucleotides added to the template strand. It is the
Term
In what direction are complementary nucleotides added to the template strand?
Definition
Always from 5' -> 3'.
(New chains can only grow 3'-wards.)
Term
What is the difference between the way leading and lagging strands are synthesized?
Definition
The nucleotides are added continuously to the leading strand, but discontinuously, in Okazaki fragments, to the lagging strand.
Term
Helicase
Definition
Enzyme that untwists and breaks the DNA.
Term
Topoisomerase
Definition
Enzyme that breaks, swings and rejoins DNA to relieve tension from untwisting.
Term
Single-strand Binding Protein
Definition
Protein that prevents split polynucleotides from re-pairing.
Term
RNA Primer
Definition
Short sequence of complimentary nucleotides (5-10) attached by Primase.
Term
Primase
Definition
Enzyme that synthesizes RNA primer.
Term
DNA Polymerase III
Definition
Enzyme that catalyzes the synthesizes of new DNA.
Term
DNA Polymerase I
Definition
Enzyme that catalyzes the replacement of RNA Primer with new DNA.
Term
DNA Ligase
Definition
The enzyme that joins the sugar-phosphate backbones of all the Okazaki fragments into a continuous DNA strand.
Term
Leading Strand
Definition
The strand that runs from the origin of replication to the replication fork from in the 5' to 3' direction.
Term
Lagging Strand
Definition
The strand that runs from the origin of replication to the replication fork from the 3' to 5' direction.
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