Go on. Explore!

lvl 0 • 0 xp

lvl 1

Home Market Decks Interests

Genetics, Exam 2 chapter 12

memorize.ai (lvl 286)

(0)

38 cards

()

Section 1

Preview this deck

Difference between nucleoside and nucleotide

Front

1 / 38

0.0

0 reviews

5			0
4			0
3			0
2			0
1			0

Active users

All-time users

Favorites

Last updated

6 years ago

Date created

Mar 14, 2020

Cards (38)

Section 1

(38 cards)

Difference between nucleoside and nucleotide

Front

Nucleoside: base + sugar Nucleotide: Base+ sugar+ phosphate

Back

Define the following: primer, OriC, replicon, replication fork, replication bubble

Front

Primer: 10-12 nt long, start or prime of DNA synthesis oriC: single origin of replication Replicon: a seg, of DNA that undergoes replication ( each has an origin of rep) Replication Fork: where two stands separate Replication Bubble: unwinding of Double stranded DNA creates a loop

Back

In what kinds of cell do you have telomerase activity? (germ cells)

Front

skin, germ cells

Back

Steps of Replication:

Front

-Initiation: oriC, initiator protein binds to oriC, causes shot stretch of DNA to unwind, -Unwinding: the unwinding allows helicase and other ssb proteins to attach, allows gyrase to go ahead of helicase to alleviate coiling -Elongation: RNA primers ( 10 -12 NT) produced by primase, DNa pol 3 and 1, DN ligase

Back

Single strand binding protein (SSBP)

Front

-Binds to and stabilizes single-stranded DNA until it can be used as a template. -keeps them from winding - breaks the hydrogen bonds ( moves from 5' to 3')

Back

How does a phosphodiester bond form (what are the two partners?)

Front

DNA is made from Deoxyribonucleoside triphosphates (dNTP's ) In Replication the 3' OH group of the last nucleotide on the strand attacks the 5' phosphate group in the incoming NTP 2 phosphates are cleaved off and a phosphodiester bond forms between the 2 nucleotides.

Back

Primase:

Front

synthesizes RNA Primers

Back

DNA Pol III:

Front

-5'-3' polymerase activity: responsible for most DNA replication adds nt to 3' end end growing strand -3' -5' exonuclease activity proofredaing ablity , removes incorrect nt 3' -5'

Back

What is the relationship between telomere length and cancer/aging

Front

-telomeres shorten in actively dividing cells -telomaerse activity decreases( senescent ), cells ability to divide - Cancer cells commonl carry mutations increasing activity of telomerase

Back

DNA Helicase

Front

-breaks h bonds and separates DNA strands -moves 5'-3' - binds to the lagging strand template at each replication fork

Back

endonuclease

Front

makes internal cuts in nucleic acids molecules

Back

What are the two types of chemical bonds found in a DNA molecule?

Front

nucleotide- hydrogen bonds back bone- covalent ( phosphodiester)

Back

Experiment of Meselson and Stahl: semiconservative model is the right model

Front

14N- common 15N-rare heavy E.coli were grown first in 15N media, then transferred to 14N media A) E. coli was grown in 15N and when centrifuged it showed up as a single band in the bottom of the test tube (Original DNA) -100% B) 15N E.coli (Original DNA) was transferred into 14N and then centrifuged ( 1st round of Rep.) and it showed 1 band in the middle meaning that replication happened (Original DNA stand + New DNA strand) 100% C) Then was centrifuged again ( 2nd Round of Rep) in 14N media and was then centrifuged and it showed 2 bands. 1 was the intermediate (Original DNA stand + New DNA strand) and the lighter meaning new DNA stands (New DNA stands) 50% : 50% D) additional rounds of Rep. in the 14N media was Centrifuged and 2 bands showed up. 1 was the intermediate (Original DNA stand + New DNA strand) and the lighter meaning new DNA stands (New DNA stands) 25% : 75% Conclusion: DNA is Semi- conservative

Back

Accuracy vs speed of DNA replication

Front

- replication has to be accurate( 1 error / million bp leads to 6400 mistakes every cell division - Replication has to take place at high speed ( E.coli 1000 nt/sec)

Back

What are Okazaki fragments?

Front

- DNA + RNA -discontinuously synthesized short DNA fragments forming lagging strand

Back

DNA ligase

Front

-binds by forming phosphodiester bonds

Back

Leading and lagging: what are the differences

Front

-Leading: continuous, 1 primer, no okazaki fragments, moves toward fork -Lagging: discontinuous, many primers, has okazaki fragments, moves away from fork

Back

What is the function of the exonuclease activity of DNA pol I?

Front

5'-3' exonuclease activity removes RNA primers and replaces them with DNA

Back

List the three possible models for DNA replication

Front

conservative: both parental strands stay together dispersive: Parental and daughter DNA segments are mixed in both strands following replication semiconservative:-The double-stranded DNA contains one parental and one daughter strand following replication

Back

Synthesis of RNA primer

Front

- produced by primase ( 10-12 NT) - provide a 3'- OH group - lagging has many -leading has 1 - removed and replaced by DNA by Pol 1 ( 5'- 3' exonuclease )

Back

Telomerase (eukaryotic)

Front

-catalyzes the lengthening of telmerase in germ cells( they never shorten)

Back

What is required for DNA replication?

Front

-Template strand -Raw Materials: dNTPs ( dATP, dGTP, dCTP, dTTp) - Enzymes and other Proteins( DNA polymerase, RNA primers)

Back

Directions

Front

-Can growth DNA synthesis for 5' to 3' -read 3' to 5'

Back

Tus

Front

- binds to Ter - inhibits movement of helicase

Back

DNA gyrase or Topoisomerase

Front

- travels ahead of helicase to alleviate supercoiling

Back

What is the direction of DNA synthesis?

Front

5' to 3' for synthesis

Back

Telomerase (process, function)

Front

- al teleomore have a G-rich 3' overhang -The Rna part of Telomerase ( 15-22 NT) is complentary to teh G-rich stand and pairs wit it, providing a template for the synthesis of copies -nucleotide are added to the 3' end of G-rich strand -RNA moves along the DNA and adds more nucleotide

Back

What is the difference between theta replication and eukaryotic replication

Front

Theta replication is for bacteria DNA - One bubble - One Origin of Rep. site - Unidirectional - Bidirectional - it replicates in both directions because it circular Eukaryotic replication is for us -Large Chromosomes -Bidirectional -Multiple Origins of Replication because its Linear

Back

Chargaff rules imply a double stranded DNA molecule. Define complementary base pairing rule

Front

Pyrim(Y)- C,T Purin( R)- A,G pairing: A+ T, C+ G

Back

Why do you have 3' overhangs in telomeres? How is that a problem?

Front

to prevent teleomeres from shortening and becoming senscent, causing us to get old or cancer cells to appear frm over activation of Telomerase

Back

Give 3 reasons why DNA replication in eukaryotes is more complex

Front

-linear -many origins for replication -larger

Back

During what phase of the cell cycle does DNA replication occur?

Front

'S "phase of mitosis

Back

DNA pol I activity:

Front

Pol I: All pol III activity, -5'-3' exonuclease activity: ( main function) removes RNA primers and replaces them with DNA

Back

What happens to the telomeres in somatic cells as you age?

Front

they shorten and become senescent

Back

Bonds formed during DNA replication

Front

A. Hydrogen bonds between bases of two strands (A-T and C-G) B. Covalent phosphodiester bonds between nucleotides (backbone): 3'OH of sugar and phosphate of nucleotide triphosphate (nucleophilic attack): growth 5' to 3'

Back

Give two unusual features of DNA polymerases

Front

1. Cannot initiate DNA synthesis so it uses RNA primers ( gets removed with Pol 1) 2. Can attach NT only in the 5' to 3' direction causing okazaki fragments

Back

Eukaryotic - DNA Polymerases

Front

Alpha: starts DNA replication in conjunction with primase Delta ( δ): replication of the lagging strand during s phase Sigma: replication of the leading strand during S phase Gamma (Y): replication of mitochondrial DNA

Back

DNAa

Front

an initiator protein in E.coli

Back