Dna, Rna, And Protein Synthsis Flashcards
What are the essential roles for a substance to be the genetic instructions.
- store genetic instructions
- copy instructions (replication)
- transmit information (transcription)
Chemical Composition of DNA
- Deoxyribose Sugar
- Phosphate Group
- Nitrogenous Base
All three make up nucleotide
Two types of Nitrogenous bases
- Purines: adenine+guanine and possess 2 C+n rings
- Pyrimidines: thymine+cytosine and posses 1 C+n ring.
The building unit for nucleic acids are …… And are …..
Nucleotides and are covalently bonded together.
Scientist who discovered the complementary base pairs
Chargaff
A=
T
G=
C
Chargaff rule states that
A always pairs with T and G always pairs with C
Scientists who identified the shape of DNA
Wilkins and Franklin
Instruments used by Franklin and Wilkins
X-Ray images of DNA crystals
What is the shape of DNA
Helix (spirals)
2 strands of nucleotides exist which means
DNA is referred to as the double helix.
Scientists who developed the model of DNA
Watson and Crick.
The DNA structure consists of 2 strands of
nucleotides that run in opposite directions which are anti-parallel
The 2 strands create a backbone and are composed of
alternating sugar and phosphate.
Nucleotides in the backbone are held together by
covalent bonds
Stands in the middle are held together by
Hydrogen bonds.
Hydrogen bonds allow for the
separation for replication.
A= T because of
two hydrogen bonds.
G=C because of
three hydrogen bonds.
The genetic instructions are dependent on
the exact sequence of bases on each chain.
Copying process required for cell division
Replication
Why is replication essential?
Replication makes sure that each new cell has a complete set of genetic instructions.
Replications occurs in what phase?
The S phase of interphase.
Replication is regulated by
several enzymes in a series of steps.
What is the replication fork?
The point at which two chains separate.
What are the helicases?
The specific enzymes that do the separating of the chains.
How do helicases separate chains?
By breaking the hydrogen bonds between the base pairs.
What is DNA polymerase?
the enzyme that assists in matching base pairs during replication.
What are free nucleotides?
independent nucleotides not attached in a chain but are available to help with the constructing though of the new chain
Each original chain acts as a template
for a new chain.
What type of bond is between the chain of nucleotides?
A Covalent Bond
What type of bond is between the base pairs?
Hydrogen Bond
Replication occurs at
many points simultaneously
What is the benefit of replication occurring at many points?
Speed.
The replication process results in two new exact copies of the
exact copies of the original DNA molecule.
The human genome consists of
3 million base pairs that must be copied
Accuracy and Repair of Replication
- Essential that DNA is copied accurately
- High degree of accuracy is created at several points
- 1 error in 1 billion base pairs
- Certain parts of DNA are more prone to errors.
What is Mutation?
change in the genetic code by changing the nucleotide sequence.
The Segment of DNA determining a trait
Gene
DNA is in the
nucleus
Protein Synthesis takes place in the
Ribosomes which are located in the Cytoplasm.
RNA is responsible for
the movement of genetic instructions from the nucleus to the ribosomes.
Structure of RNA
nucleotides consisting of a phosphate, sugar, and a base.
What are the differences between DNA and RNA?
- DNA is double stranded while RNA is single stranded
- DNA has deoxiribose sugar while RNA as Ribose sugar
- RNA has the base uracil instead of thymene
Messenger RNA is responsible for
acquiring genetic instructions for a protein from DNA and carries it to the ribosomes.
Ribosomal RNA is
globular form and makes up ribosomes
Transfer RNA is responsible for
transfering specific amino acids from the cytoplasm to the ribosomes.
Transcription is
changing the DNA sequence into mRNA
Promoters are
segment of nucleotides that mark the beginning of a gene for transcription.
RNA polymerase is the
primary transcription enzyme that synthesizes or creates mRNA.
Steps in RNA polymerase
- Binds to promoter
- Region of DNA separates
- Only one of the DNA chains acts as a template.
A template is the
pattern for the protein
Second stage in Transcription
RNA polymerase attaches to the DNA template and adds complementary RNA nucleotides.
Transcription continues until RNA polymerase reaches the
termination signal.
Transcription completes with
a new messenger RNA molecule being released the the DNA template called transcript.
The mRNA moves through the
nuclear pores to the cytoplasm to the ribosomes.
Protein Synthesis is
making proteins
Proteins are significant because they
determine the structure and function of cells.
Structure of Protein
- Polymer
- 20 Amino Acids (possibly hundreds to thousands).
- Sequence influences shape which influences function of the protein.
What is the Genetic Code?
Exact sequence of bases for instructions.
What is a Codon?
Series of 3 nucleotides on mRNA.
What is the maximum number of 3 letter codons?
64
How many possible bases do codons have
4
Each amino acid has
2 or more codons.
Translation is the process
of assembling polypeptides from information carried on mRNA.
Translation takes place
at Ribosomes
During translation, amino acids in the cytolplasm
are transported by Transfer RNA
The anticodon is
a sequence of three nucleotides that fit to corresponding mRNA codon
Amino acids possess
a specialized region for attachment of specific amino acids.
Final stage of translation
Ribsomes move along mRNA transcript and each codon is paired with its anticodon.
