Chapter 13: DNA Replication and Repair Flashcards Preview

Molecular Cell Biology > Chapter 13: DNA Replication and Repair > Flashcards

Flashcards in Chapter 13: DNA Replication and Repair Deck (95)
Loading flashcards...

What are the four bases in DNA replication?

- Adenine (A) and Guanine (G)= purines
Thymine (T) and Cytosine (C)= pyrimidines


How many hydrogen bonds are present between G and C vs A and T?

- GC = three hydrogen bonds
- AT= two hydrogen bonds
L> less energy to break


What way is DNA read by DNA poly?

- 5' to 3'
**opposite polarity***


What does the 3' end of DNA possess?

- free OH and it is important when it comes to adding bases (nucleotides)


DNA stands for?

-deoxyribonucleic acid


Describe DNA

- two long polynucleotide chains
- four chemically similar sub unites (nucleotides/bases)
- hydrogen bonding between bases form double stranded DNA


When is uracil present?

- only in RNA....if it shows up in your DNA it is an indication that there is a mistake going on ....


What can denature DNA?

- helicase and temperature ..making dsDNA nto ssDNA


What makes up a nucleotide?

- 5 carbon sugar
- phosphate group
- nitrogen contaiing base


What are the two nucleotides?

- DNA --> deoxyribose sugar, nucleotides: GACT
- RNA--> ribose sugar, nucleotides: GACU



- without a phosphate group


What makes up the backbone of DNA?

- sugar-phosphate


Where will a DNA nucleotide come in?

at 3' free OH end


Describe Base pairing of DNA.

- Complementary pairing
L> G with C
L> A with T (or U in RNA)


DNA strands run in what type of direction?

- antiparallel bc of polarity
-always read 5'-3'


What two types of grooves are there in DNA?

1. Minor groove
2. Major groove -
*they are important for the interaction with DNA
**major groove -->interaction occurs more easily within these groups...molecules can non-covalently bond with the DNA to affect its regulation for replication...protein synthesis


Primary Functions of DNA?

- storage of genetic information
- replication and inheritance
- expression of genetic information
**genetic info is stored via base pairs
- near identical replication bc of its organization and complimentary base pair interactions
- passed on
- expression of genetic information = proteins


What is a genome?

- complete set of organism's DNA
- found in every cell
- a genome contains the information to make every protein required by the body


What type of cells do not have a genome?

- red blood cells.... they do not have a nucleus..they are enucleated


How is the genome duplicated in the cell cycle?

- semi-conservative replication


What does IPS stand for?

- induced pluripotent stem cells


What has IPS disproven in terms of our though on genes?

-we use to believe when a cell terminally differentiated they lost all genes not necessary for their functions but this is not the case...they maintain them regardless


Explain the two types of replication DNA was thought to undergo - which was actually proven correct?

1. conservative or dispersive replication - disproven. DNA seems to be a mix of original and new DNA that is not identical to the original parental replication occurs again and again it becomes less and less identical to the original parental DNA molecule
2. semiconservative replication(correct): conserve one of the original parent strands...daughter strand is produced via this...1/2 parent and 1/2 newly synthesized DNA
**the reason this works is bc of the complementary base pairing..once the parent molecule separates into ss they contain every base needed to be returned back to an identical double helix of the original parent strand


Initiation of Prokaryotic Replication:
-origin of replication in E.coli??

-specific site on the chromosome where replication occurs there ...due to high concentration of A and T bonds
**circular chromosome in prokaryotes


Initiation of Prokaryotic Replication:
- what kind of direction is it?

- bidirectional


Initiation of Prokaryotic Replication:
-What happens at the oriC?

- DNA needs to be denatured and plot into single strands...30 enzymes are involved in this via semi-conservativer explication...replication roles directly through until they pop into two separate chromosomes


Initiation of Prokaryotic Replication:
-replication forks?
L>how many?

- strands separating
-nucleotides are being added
-two forks ...opening it up you get two forks going in BOTH directions


DNA Supercoiling:
- what are the states DNA can be found in?

- relaxed DNA
- supercoiled DNA
- negatively supercoiled
-positively supercoiled
**can cause trouble


DNA Supercoiling:
- Relaxed state?

- what they want to be like..natural state.. proteins etc don't always let it be this way...but it is the regular helical strand


DNA Supercoiling:
-negatively supercoiled?

- the DNA is under wound..a part of it is actually able to come apart...youd find this sort of at an origin of replication