Class Notes (836,517)
United States (324,533)
BIOSC 0160 (72)
All (16)

DNA as Genetic Material Notes

7 Pages
Unlock Document

Biological Sciences
BIOSC 0160
All Professors

2/6 Chapter 14: DNA as Genetic Material Deoxyribonucleic Acid • Structure o The Double Helix  Consists of two strands  Each has a backbone of sugar and phosphate  Each sugar has a nitrogenous base attached to it • A, adenine (purine) • C, cytosine (pyrimidine) • G, guanine (purine) • T, thymine (pyrimidine)  Complementarity and Antiparallel Strands • Two strands are held together by hydrogen bonds between bases • Bases pair in a way that is most energetically favorable (purine with pyrimidine) o Adenine bonds with thymine o Guanine bonds with cytosine • Antiparallel o Refers to the strand directionality o Each strand has two ends  5’ end with free phosphate  3’ end with free hydroxyl on ribose o Phosphodiester bond forms between phosphate and hydroxyl o Always synthesized 5’  3’ 2/6 o Strands are parallel but run in opposite directions • Replication o Copying DNA o Uses enzymes called DNA polymerases o Begins at the origin of replication  There are several along the length of the DNA strand  At each one, strands separate and yield two replication forks  One bubble, to replication forks moving in opposite directions 5’ Replication Site 3’ 3’ 5’ Replication Site 5’ Replication Replication 3’ 3’ Bubble Forks 5’ • Replication cont. o Complementarity of strands is key to accurate replication  Semiconservative model • Each original strand acts as a template for the new strand • Meselson-Stahl Experiment o Hypotheses:  Semiconservative: One new strand, one old  Conservative: Parental DNA, offspring DNA  Dispersive: Segments of each are interspersed 2/6 o Leading and Lagging Strands  Nucleic acids are always synthesized 3’  5’  Thus, template is always read 3’  5’  Requires RNA primers, which are inserted to temporarily create the double strand construct  Leading Strand • Grows continuously because replication leads (is in front of) new DNA strand 2/6 • Direction of synthesis is the same as direction of replication fork  Lagging Strand • Grows in short pieces (Okazaki fragments) because the fork lags behind (is in back of) new DNA strand o Direction of synthesis is opposite the direction of the replication fork = RNA Primer 5’ 3’ 3’ 5’ Leading
More Less

Related notes for BIOSC 0160

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.