1. Nucleic Acids and Protein Synthesis
Chapter 12
Nucleic Acids
and
Protein Synthesis

2. DNA: Structure and Shape
Composition: a nucleotide has these 3 things:
Deoxyribose (a sugar)
Phosphate Group
Nitrogen-containing bases
(N-bases)
Purines:
Adenine (A)
Guanine (G)
Pyrimidines
3. Thymine (T)
4. Cytosine (C)
Shape: Double helix

3. Replication: DNA copies itself
Steps:
The nucleotide chain separates and unwinds
Each chain serves as a template for the next step
The enzyme helicase helps the process
Complementary nucleotides that are free-floating in the nucleus, assemble
Nucleotides join by Hydrogen bonds
Products: Two new DNA strands (this occurs before a cell divides).

4. RNA: Composition and Shape
Ribose (a sugar)
Phosphate group
--N-base: Adenine(A),
Uracil(U),
Cytosine (C), and
Guanine (G)
Shape: single-stranded

5. RNA: Types
mRNA – messenger RNA carries info from DNA in the nucleus to the cytosol.
tRNA- transfer RNA takes info from the mRNA and binds to amino acids.
rRNA- ribosomal RNA exists where proteins are made.

6. Transcription: DNA makes RNA
Steps:
DNA unwinds
Complementary RNA nucleotides assemble
Nucleotides of RNA join and separate from DNA molecule
Results:
DNA passes info (transcribes) onto RNA.
RNA molecules exit the nucleus and go to ribosomes for protein synthesis.

7. Translation – Protein Synthesis
Composition of Proteins: chains of amino acids
Each of the 20 amino acids are coded for by a specific sequence of 3 mRNA nucleotides (p 303)
Steps of Process: codes from mRNA are translated into making proteins (p 304)
mRNA leaves nucleus and goes to ribosomes
Amino acids are carried to the ribosomes by tRNA
tRNA carries anticodons complementary to the codons of mRNA and in joining, the amino acids are connected in a certain sequence to produce proteins.

8. translation:

9. Summary – from replication to translation

10. More . . . DNA composition Quiz DNA replication quiz
Transcription Quiz
RNA Types Quiz
Translation Quiz

11. 12.4 Mutations: changes in genetic material
Gene Mutations: changes in one or a few nucleotides affecting one gene
Point mutations
Frameshift mutations
Chromosomal mutations: involves changes in the number and structure of chromosomes
Significance:
Neutral effects
Disorders
Genetic variability among species
Polyploidy in plants

12. 12.5 Gene Regulation
Terms:
Operon
Differentiation
Hox genes