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BIOE Exam 3
DNA
78
Biology
Undergraduate 1
04/01/2013

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Term
What do the nucleic acids in DNA and RNA form?
Definition
polynucleotide chains
Term
What is the structure of a nucleotide?
Definition
has a pentose sugar ring core with a phosphate group off the left side and a base (AGTC) with a nitrogen ring on the right
Term
What are the two types of bases in a nucleotide?
Definition
pyrimidine and purine
Term
Pyrimidine
Definition
is a hexagonal ring. forms cytosine, thymine, and uracil
Term
Purine
Definition
looks like a figure eight. forms adenine and guanine.
Term
What are the two types of pentose in a nucleotide?
Definition
ribose and 2-deoxyribose
Term
Ribose
Definition
has a hydroxide group off the 2' carbon. found in RNA.
Term
2-Deoxyribose
Definition
only has a H off the 2' carbon. found in DNA.
Term
What is RNA built with?
Definition
ribonucleotides
Term
What is a ribonucleotide composed of?
Definition
a phosphate group, a ribose sugar, and one of the four bases (adenine, guanine, uracil, and cytosine)
Term
What is DNA built with?
Definition
deoxyribonucleotides
Term
What is a deoxyribonucleotide composed of?
Definition
a phophate group, a 2-deoxyribose sugar, and one of four bases (adenine, guanine, thymine, cytosine)
Term
What are nucleotides made of?
Definition
nucleic acids
Term
What is the bond that holds nucleotides together?
Definition
phosphodeister link
Term
Phosphodiester bond
Definition
between the 5' -OH of one pentose and the 3' -OH of the next
Term
What orients a polynucleotide?
Definition
the 5' end and 3' ends give it a chemical polarity
Term
What's the difference between the 5' end and the 3' end of a polynucleotide?
Definition
the 5' end is a phosphate group and the 3' end is a hydroxyl group
Term
What bonds two strands of DNA together?
Definition
the hydrogen bonds between the bases. can only form between a purine and a pyrimidine base.
Term
DNA paired strands
Definition
held together with H bonds, A and T bond and G and C bond, the chains must be in opposite orientations (one with the 5' end on top and one with the 5' end on bottom)
Term
What is on the inside part of the DNA molecule?
Definition
the complementary base pairs
Term
What is on the outside part of the DNA molecule?
Definition
the sugar phosphate backbones
Term
What is the shape of a DNA molecule?
Definition
a right handed double helix
Term
Who discovered the structure of DNA and when?
Definition
Watson and Crick, 1953
Term
What exactly does the nucleotide sequence do?
Definition
provides the instructions to build certain proteins
Term
How many feet of DNA are in a nucleus?
Definition
6.5 ft
Term
How is so much DNA fit in to the nucleus?
Definition
the DNA is packed into chromosomes
Term
How many chromosomes do humans have?
Definition
24, but we have 2 copies in each cell
Term
Histone
Definition
the positively charged protein core of a nucleosome
Term
Nucleosome
Definition
a protein core with DNA tightly wrapped around it
Term
Chromatin
Definition
DNA combined with protein complexes
Term
DNA packing
Definition
DNA forms into a double helix, which wrap around protein to form a nucleosome, which connect together with protein to form chromatin. long lines of chromatin pack together to form a chromosome. ultimately, the DNA is packed 10,000 times shorter
Term
Semiconservative replication
Definition
each daughter DNA helix is composed of one conserved and one newly synthesized strand. the original strands remain intact for many generations
Term
What does A pair with in DNA?
Definition
T
Term
What does T pair with in DNA?
Definition
A
Term
What does G pair with?
Definition
C
Term
What does C pair with?
Definition
G
Term
DNA polymerase
Definition
this enzyme adds nucleotides to the 3' end. they nucleotides enter as triphosphates which provide energy for new bond formation. always moves from 5'-->3'.
Term
How does DNA synthesis start?
Definition
the two strands are locked firmly together from H bonds. to be peeled apart for synthesis, would need a temperature close to boiling water, which doesnt happen in a cell. instead, an initiator protein binds and pries the 2 strands apart at the middle
Term
Bidirectional replication
Definition
two active regions called replication forks for at the origin (where the initiator protein split the strand.) they move in opposite directions, unzipping the protein as they go.
Term
Leading and Lagging strands
Definition
the strand with the original strand beginning with 5' is the lagging strand, because synthesis occurs in short fragments (Okazaki). they will later be joined by a ligase. the original strand beginning with 3' is the leading strand.
Term
In which direction does replication occur?
Definition
5'-->3'
Term
DNA helicase
Definition
opens up the double helix ahead of the replication fork
Term
single strand binding protein (SSB protein)
Definition
binds tightly to the singel strand DNA to stabilize it
Term
Sliding clamp
Definition
keeps the polymerase on while it's moving
Term
Primase
Definition
creates a 10 nucleotide primer that allows the polymerase to start a new DNA chain on the lagging strand.these are later removed and replaced by repair polymerase forming one long strand of DNA
Term
Polymerase
Definition
adds the new nucleotides, forming the new daughter strand
Term
ligase
Definition
binds the okazaki fragments together
Term
How often do replication errors occur?
Definition
1 in 10^7 nucleotides
Term
Mutations
Definition
heritable changes in the nucleotide sequences. i.e. sickle cell anemia.
Term
Multiple replication origins
Definition
occurs in eukaryotic cells. DNA replication origins occur in many places in the DNA strand, in humans around 10,000 places.
Term
DNA and Proteins
Definition
each protein is a unique sequence of aminoacids. each sequence of nucleotides calls different amino acids. therefore, DNA directs the syntheses of all proteins
Term
Gene
Definition
a segment of DNA that contains the information required for the synthesis of one type of protein
Term
Genome
Definition
the total genetic information carried by DNA in a cell. contains the information necessary for the synthesis of proteins in the body.
Term
Central Dogma of Molecular Biology
Definition
DNA-->RNA-->Protein. the genetic information encoded in DNA is copied first into an RNA molecule and then into a protein molecule.
Term
DNA-->RNA
Definition
transcription.
Term
RNA-->Protein
Definition
translation
Term
RNA transcription
Definition
RNA polymerase unwinds a short section of DNA. it uses the 3'-5' DNA strand for a template. the RNA polymerase then adds ribonucleotides to create the new RNA transcript complementary to the DNA strand.
Term
What does A pair with in RNA?
Definition
U
Term
What does U pair with in RNA?
Definition
A
Term
RNA polymerase
Definition
moves along the DNA, unwinding it and adding 1 nucleotide at a time in the 5'-3' direction
Term
Exons
Definition
coding nucleotide sequences within a eukaryotic gene
Term
Introns
Definition
non-coding nucleotide sequences within a eukaryotic gene
Term
RNA splicing
Definition
in RNA transcription both exons and introns are copied, but later introns are cut out and exons are joined together.
Term
RNA processing
Definition
occurs before the RNA leaves the nucleus. capping and polyadenylation occur, producing messenger RNA (mRNA) which leaves the cell.
Term
Capping
Definition
adds a methylated guanine to the 5' end of RNA
Term
Polyadenylation
Definition
addition of a series of repeated adenine nucleotides to the 3' end of RNA
Term
RNA leaving the nucleus
Definition
specific signal proteins bind to the 5' cap and the poly-A tail, which signal the nuclear pores that the RNA is export ready
Term
Replication
Definition
occurs in the nucleus, when DNA replicates itself
Term
Transcription
Definition
occurs in the nucleus, when RNA is formed form DNA
Term
Translation
Definition
occurs in the cytoplasm, where the information in RNA copied from on gene directs the synthesizing of one protein. mRNA is read in groups of three, and these 64 options are read to specify one of 20 different amino acids. mRNA is read from 5'-3' in this process
Term
Codon
Definition
one group of three consecutive nucleotides in mRNA
Term
tRNA
Definition
transfer RNA. a small RNA molecule that contains a set of 3 nucleotides that binds the codon in an mRNA molecule through complimentary base pairing. this folds the proteins and reveals two regions crucial for protein synthesis
Term
Anticodon
Definition
a set of 3 nucleotides that binds the complementary codon in an mRNA molecule
Term
Where does the amino acid attach?
Definition
the short single stranded region at the 3' end where the amino acid that matches the codon will attach
Term
Ribosomes
Definition
moves the mRNA along, captures the tRNAs and holds them in position, and links the amino acids to form a protein chain, all in a accurate and rapid manner.
Term
Ribosome Structure
Definition
contains two subunits both containing ribosomal RNA and proteins
Term
What is the first step of initiation?
Definition
the tRNA brings the amino acid to the correct site by binding the codon of mRNA
Term
What is the second step of translation?
Definition
the ribosome covalently links the amino acids together
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