DNA and RNA Structure and Function
Primer sequence
provides a starting point and is added with complementary RNA nucleotides
Termination signals
repeated nucleotide sequences in the DNA template which results in the freeeing of the mRNA transcript
Leading Strand
the DNA strand that is continuously made up to the replication fork
Replication Forks
the areas where the double helix separates
tRNA charging
the attachment of a tRNA to its appropriate amino acid is called ___________
4 types of nitrogenous bases in DNA
(A) Adenine (C) Cytosine (G) Guanine (T) Thymine
how is gene expression expressed in prokaryotic cells
- Is is accomplished via regulation of DNA transcription into RNA - Is mostly done at the transcription level
Step 3 of prokaryotic protein synthesis
- Termination - Stop codon (UAA, UAG, UGA)
RNA polymerase
- an enzyme that adds nucleotides by temporarily pairing with DNA. - DNA unwinds prior to and rewinds after.
Step 2 of prokaryotic protein synthesis
- elongation - the basics are the same as the elongation step of eukaryotes - "A" site binds incoming tRNAs - "P" site binds tRNAs whose polypeptide chain yet has not been dissociated from their corresponding tRNA - "E" site releases dissociated tRNA
Step 1 of Prokaryotic Protein synthesis
- initiation - tRNA interacts with the start codon and links ot a special form of methionine (usaually removed from the polypeptide once translation is complete)
introns
- intervening sequences - Noncoding segments of nucleic acid that lie between coding sequences. - removed while pre-mRNA is still in the nucleous
Step 1 of eukaryotic mRNA processing
- it gets coated with stablizing proteins to prevent degredation - occurs while it is still made
E.Coli (representative or prokaryotes) initiation stage of protein synthesis consists of
- small subunit of ribosome - mRNA template - three initiation factors - a special inititator tRNA
There is/are ____ start codon(s) labeled _____, whose purpose is to ____ and resides ______
1 AUG Initiate translation and specifying the amino acid methionine Resides at the 5' end of the mRNA
DNA Replication Process
1. DNA unwinds at origin of replication 2. New bases are added to the parental strand of DNA and the new strand is pieced together 3. Primers are replace with DNA nucleotides and the backbone sealed by DNA ligase
There is/are _____ stop codons and they are ______, ______, and ________. Whose purpose is to _____.
3 UAG, UGA, UAA Terminate protein synthesis
Much like mRNA synthesis, protein synthesis consist of ___ stages which are____
3 stages (similar to mRNA) Initiation, elongation, and termination
DNA composition
3' up and 5' up are the outsides and the pairings are what connects them
Escherichia Coli base pairs
4.6 million base pairs ~1000 nucleotides are added per second
Escherichia coli within Prokaryotes
4.6 million base pairs that would extend 1.6mm and must be supercoiled
What direction is DNA synthesized
5' to 3' (5-carbon sugar)
Poly-A tail
50 - 250 Adenine nucleotides added to the 3' end of a pre-mRNA.
How many combinations are there using the three-nucleotide code
64 (4x4x4)
AT and CG bondage
AT 2 hydrogen bonds CG 3 hydrogen bonds
of the 4 nitrogen bases of DNA which are double-ringed purines and which are single-ringed
Adenine and Guanine (the ones eding in NINE) are double Cytosine and Thymine (ending only in INE) are single
what are the complementary base pairs of DNA
Adenine-Thymine (AT) Guanine-Cytosine (CG)
Helicase
An enzyme that unwinds DNA
what is the difference between DNA and RNA 5-carbon sugar
DNA - deoxyribose has a hydrogen atom at the 2' RNA - ribose which has a hydroxyl group at 2'
Two types of nucleic acids
DNA and RNA
In prokaryotic organisms, why does translation and transcription occur simultaneously
Because prokaryotic organisms lack cell nuclei
Central Dogma
DNA encodes RNA which encodes proteins
Explain the protein synthesis process in Eukaryotes
DNA is inside cell's nucleous and is transcribed into mRNA there and then transported out of the nucleous into the cytoplasm via tRNA
Initiation Stage or DNA replication
DNA is made available to the proteins and enzymes
DNA packing in Eukaryotes
DNA is wrapped around histones and become nucleosomes. Nucleosomesare linke to the next via a short piece of DNA without the histones. The nucleosomes are stacked on each other to form a 30nm wide chromatin fiber. This fiber is coiled to form a thicker more compact structure 700nm wide
What replaces the RNA primer
DNA nucleotides
Elongation Stage of DNA Replication
DNA nucleotides are added to the 3' end of the DNA template (DNA polymerase)
Transcription Bubble
DNA region of unwinding during initation
What is a Nucleotide comprised of
Deoxyribose (5-carbon sugar) Phosphate group Nitrogen Base
Where are ribosomes located
P - cytoplasm E - cytoplasm and endoplasmic reticulum
Nucleotide Excision Repair
Enzymes cut out incorrect bases and fill in correct bases
In Eukaryotes when does gene expression occur
Epigenetic level Transcription level Post-transcription level Transitional level Post-transitional level
Lac Operon
In E coli, consists of the three lactase digesting genes and their associated promoter and operator.
3 stages of Eukaryote DNA replication
Initiation Elongation Termination
The area between the Promoter and the three genes
Is where the operator is resides
Building Blocks of DNA
Nucleotides
exons
Protein-coding sequences signifies that they are expressed
Origins of Replication
Sites where the replication of a DNA molecule begins.
Step 3 of eukaryotic mRNA processing
Termination
Mismatch Repair
The cellular process that uses special enzymes to fix incorrectly paired nucleotides.
Telomeres
The ends of chromosomes
Gene Expression
The process of turning on a gene to produce RNA and protein
Template strand
The strand of DNA used in transcription to produce mRNA
Lagging Strand
The strand with the Okazaki Fragments
How does eukaryote protein synthesis differ from prokaryotes
Transcription and Translation occur at the same time in Prokaryotes in the same place where as Eukaryotes Transcription and Translation occur in two different place (separated by nuc mem)
Promoter
a region of DNA that initiates transcription of a particular gene
DNA for Prokaryotes
a single, circular chromosome found in the nueloid which is located within the cytoplasm
DNA polymerase
adds DNA nucleotides to the DNA's backbone
Step 2 of eukaryotic mRNA processing
after elongation occurs, 200 adenine residues are added to the 3' end - the poly-A-tail
telomerase
an enzyme that helps elongate the lagging strand so the Nucleotides can be added Not present in Adult Somatic cells associated with aging as the telomeres are continue to shortened
Okazaki Fragments
are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA
Large subunit of a ribosome
binds tRNAs together sequentually
Lac Operon repressor protein
binds to the operator to prevent RNA polymerase
mRNA template
converts nucleotide-based genetic information into a protein product
mRNA
messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
Translation requires . . .
input for mRNA ribosomes tRNAs various enzymatic factors
semiconservative replication
each new DNA molecule consists of one new strand and one old strand
DNA ligase
enzyme that links DNA fragments together
What does translation involve
it involves the decoding of the mRNA message into a polypeptide product (proteins)
Which of the 5-carbon sugar is the phosphate group attached
it is attached to the 5' carbon of one nucleotide and the 3' carbon of the next nucleotide
Which nitrogen base is missing from RNA that is present in DNA
it is missing Thymine however it contains uracil (U)
Small subunit of a ribosome
it is responsible for binding the mRNA template
what do tRNAs need to function
it needs to have specific amino acids bonded to it
Non-template strand
mRNA similarily identical except RNA uses Uracil (U) instead of Thymine (T)
Eukaryotic RNA Processing
mRNA's must undergo several steps which make it last longer than prokaryotic mRNA (5sec)
Which RNA molecule are involved in producing proteins of the DNA code
mRNA/tRNA/rRNA
What is a ribosome
macromolecule made of structural and catalytic rRNAs and many polypeptides
Differences between Prokaryotes and Eukaryotes
point of origin (P single/ E many) Rate of replication (P 1000ps / E 50-100) chromosome structure (P circular / E linear) Telomerase (P none / E present)
splicing
process of removing introns and rejoining exons of pre-mRNA's
Genetic Code
the relationship between a nucleotide codon and its amino acid
What is the "backbone" of DNA
the sugar-phosphate group
Prokaryotes termination signal
the transcription would have been used to make copies of the protein which DNA demands because it happens concurrently
Number of tRNAs w/n a cytoplasm
there are 40 - 60 w/n a cytoplasm
What is the bond for which the phosphate and sugar group connected
they are connected via a covalent bond
where are replication forks formed
they are formed at the origin of replication
Triplet Codon
three nucleotide sequence on mRNA that codes for specific amino acids
tRNA
type of RNA that carries each amino acid to a ribosome during protein synthesis