Unit 10-Molecular Genetics Flashcards
(60 cards)
DNA structure
nitrogenous bases
- T,G,C,A
backbone
- sugar phosphate
What type of polymer and monomer is DNA and RNA
Polymer = nucleic acids Monomer = nucleotides
The nucleotides are joined together by what
Covalent bonds between the sugar of one and the phosphate of the other
This creates the sugar phosphate backbone
Along a strand of a double helix is the nucleotide sequence GGCATAGGT. what is the complementary sequence for the other DNA strand
CCGTATCCA
Define semi conservative model
A model of DNA replication that half of the parental molecule is maintained (conserved) in each daughter molecule
The DNA double helix separates and each half acts as a template while free nucleuotides come in and attach in the appropriate sequence to the new daughter strand (synthesis of the complementary stand!)
How does complementary base pairing make possible the replication of DNA
When the two strands of the double helix separate, free nucleotides can base pair along each strand leading to the synthesis of new complementary strands
Replication of a DNA molecule begins at _______
Special sites called origins of replication
What enzyme is used to create replication bubbles (separate the parental strands)
DNA helicase separates the the parental strands to create two forks
DNA replication proceeds in two directions at many sites simultaneously how does this work
The leading strand opens in the 3’ to 5’ direction (top strand)
Lagging strand opens in the 5’ to 3’ direction (bottom strand)
On the leading strand in what direction do you read to form the daughter strand
What direction is it synthesized
3 to 5 direction
5 to 3 direction
What is the overall direction of replication
To the left
From the tip of the fork to the point where it closes
What is DNA polymerase
The enzymes that link DNA nucleotides to a growing daughter strand
Where does DNA polymerase add nucleotides
ONLY at the 3’ end of the strand!!
Never the 5’
Therefore!
A daughter DNA strand can grow only in the 5’ to 3’ direction
Which daughter strand can be synthesized continuously
Which daughter strand cannot and why
The daughter strand that starts at the 5’ and goes to the 3’ TOWRDS the point in which the fork meets
(Continuous)
The daughter strand that starts at the 5’ and goes to the 3’ away from the point the fork meets needs to be synthesized in short pieces
What is DNA Ligase
An enzyme that works to link the pieces together of the second daughter strand that was NOT done continuously
These fragments are called Okazaki fragments
DNA strands are ___
Antiparallel
On the lagging strand in what direction do you read the DNA
In what direction is it synthesized
3’ to 5’
5’ to 3’
What is the function of DNA polymerase in DNA replication
As free nucleotides base pair to a parallel DNA strand the enzyme covalently bonds them to the 3’ end of a growing daughter strand
What is the 3’ prime and 5’ prime
The primed numbers refer to the carbon atoms of the nucleotide sugars
At one end of each DNA strand the sugars 3’ carbon atoms is attached to an -OH group and at the other end the sugars 5’ carbon is attached to a phosphate group
What are the two main stages of DNA replication and synthesis
Transcription
- the synthesis of RNA under the direction of DNA
Translation
- the synthesis of protein under the direction of RNA
What are the functions of transcription and translation
Transcription is the transfer of information from DNA to RNA.
Translation is the use of the information in RNA to make a polypeptide
Are both stands of the DNA transcribed
No! Only one is transcribed
The template strand
The DNA template strand AAACCGGCAAAA is transcribed into what code for RNA
UUUGGCCGUUUU
What is a triplet code
The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of non overlapping three base “words” called codons!
