(L3) DNA Replication, Transcription, & Translation Flashcards
The genetic material is stored in the form of ______
DNA
Human genome consists of 3 x 10^9 base pairs of DNA distributed over ____ pairs of chromosomes.
23
_____ hold the information to build and maintain an organism’s cells and pass genetic traits to offspring
Genes
DNA is copied to RNA process
Transcription
RNA is used to produce proteins process
Translation
___ is a double-stranded helix with antiparallel
strands
DNA
Bases on opposite strands are linked by ________: A with T and G with C
Hydrogen bonding
The parent molecule unwinds, and two new daughter strands are built based on base-pairing molecules
DNA Replication
3 Models of DNA Replication
- Conservative
- Semi-Conservative
- Dispersive
What model does DNA replication portray?
Semi-Conservative
The replication of a DNA molecule begins at
special sites called ____________ where 2 strands are separated
Origins of Replication
DNA replication is catalyzed by ________ which needs an _________.
DNA polymerase; RNA primer
RNA primase synthesizes _______ on DNA strand
primer
DNA synthesis on the ________ is continuous
leading strand
DNA synthesis on the ___________ is discontinuous
lagging strand
DNA is added as short fragments _________ that are subsequently ligated together
Okazaki Fragments
This enzyme unwinds parental double helix.
Helicase
This enzyme stabilize separate strands
Binding proteins
This enzyme adds short primer to template strand
primase
This enzyme binds nucleotides to form new strands
DNA Polymerase III
This enzyme removes RNA primer and inserts the correct bases.
DNA polymerase I (exonuclease)
This enzyme joins the Okazaki fragments and seals other nicks in sugar-phosphate backbone
Ligase
This enzyme prevent single strands from rewinding
Binding proteins
Leading strand synthesis continues in a ______ direction.
5’ to 3’ direction
Discontinuous synthesis produces 5’ to 3’ DNA segments called _______.
Okazaki fragments
__________ enzyme adds DNA nucleotides to the RNA primer
DNA polymerase
REPLICATION FORK OVERVIEW
- Helicase
- Binding Proteins
- DNA polymerase
- RNA polymerase
- RNA primer
- Ligase
Chances of a mutation occurring at any one gene is over ________
1 in 100,000
A mismatching of base pairs can occur at a rate of _______.
1 per 10,000 bases
____________ proofread newly made DNA,
replacing any incorrect nucleotides
DNA polymerases
The process by which DNA directs protein synthesis, __________, includes two stages called transcription and translation
gene expression
Cells are governed by a cellular chain of command:
DNA → RNA → Protein
Is the synthesis of RNA under the direction of DNA
Transcription
Process of producing messenger RNA (mRNA)
Transcription
- Is the actual synthesis of a polypeptide which occurs under the direction of mRNA
- Occurs on ribosomes
Translation
Extensive RNA processing occurs in the _____
nucleus
___________ is the DNA directed synthesis of RNA
Transcription
- Single Stranded
- short, 1 gene
- Uses sugar ribose
- Uses the base Uracil instead of Thymine (AU)
CHARACTERISTICS OF RNA
Carries info specifying amino acid sequences of proteins from DNA to ribosomes
mRNA
Serves as adapter molecule in protein synthesis; translates mRNA codons into amino acids
tRNA
plays catalytic roles and structural roles in ribosomes
rRNA
serves as a precursor to mRNA, rRNA, or tRNA, before bein processed by splicing or cleavage.
Primary transcript
Plays structural and catalytic roles in spliceosomes , the complexes of protein and RNA that splice pre-mRNA
small nuclear RNA (snRNA)
The stages of transcription are:
Initiation
Elongation
Termination
After RNA polymerase binds to the promoter, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template strand.
Initiation
The polymerase moves downstream, unwinding the DNA and elongating the RNA transcript. In the wake of transcription, the DNA strands re-form a double helix.
elongation
Eventually, the RNA transcript is released, and the polymerase detaches from the DNA
Termination
Promoters signal the initiation of RNA synthesis
Initiation
RNA polymerase synthesizes a single strand
of RNA against the DNA template strand
(anti-sense strand), adding nucleotides to
the 3’ end of the RNA chain
elongation
When one of these is encountered by the polymerase, the RNA transcript is released from the DNA and the double helix can zip up again
Termination
Transcription of RNA processing occurs in the ____. After this, the messenger RNA moves to the ________ for translation
nucleus; cytoplasm
genome consists of non-coding regions called ____
introns
________ also allow for alternative RNA splicing
Introns
The original transcript from the DNA is called ____
pre-mRNA
The introns are removed by a process called _____ to produce messenger RNA (mRNA)
splicing
Proteins often have a modular architecture consisting of discrete structural and functional regions called _______
DOMAINS
______ is the RNA-directed synthesis of a
polypeptide
Translation
Translation involves:
mRNA
Ribosomes – ribosomal RNA
Transfer RNA
Genetic coding – codons
3 base codes for the production of a specific amino acid, sequence of three of the four different nucleotides
Codons
3 of the 64 codons are used as STOP signals; they are found at the ____ of every gene and mark the end of the protein
end
___ brings the amino acids to the ribosomes
tRNA
The AUG start codon is recognized by _______
methionyl-tRNA
_______, amino acids are added one by one to the preceding
amino acid
elongation stage
