Name _________________________________________
Chapter 10 Section 3 and 4– Notes
Zoology
DNA Replication and Protein Synthesis
I.
II.
Objectives a.
Summarize the process of DNA replication b.
Identify the role of enzymes in the replication of DNA c.
Describe how complementary base pairing guides DNA replication d.
Compare the number of replication forks in prokaryotic and eukaryotic cells during DNA replication e.
Describe how errors are corrected during DNA replication
How DNA replication occurs a.
DNA replication is the process by which DNA is copied before a cell divides b.
Steps of DNA replication i.
Replication begins with the separation of the DNA strands by helicases ii.
Then, DNA polymerases form new strands by adding complementary nucleotides to each of the original strands c.
Each new DNA molecule is made of one strand of nucleotides from the original DNA molecule and one new strand. This is called semi-conservative replication.
III.
DNA errors in replication a.
Changes in DNA are called mutations b.
DNA proofreading and repair prevent many replication errors. c.
DNA replication and cancer i.
Unrepaired mutations that affect genes that control cell division can cause diseases such as cancer
IV.
Section 4 – Protein Synthesis a.
Objectives i.
Outline the flow of genetic information in cells from DNA to protein ii.
Compare the structure of RNA with that of DNA iii.
Describe the importance of the genetic code iv.
Compare the role of mRNA, rRNA, and tRNA in translation
V.
v.
Identify the importance of learning about the human genome
Flow of Genetic Information a.
The flow of genetic information can be symbolized as DNA – RNA – Protein
VI.
RNA Structure and Function a.
RNA has the sugar ribose instead of deoxyribose and uracil in place of thymine

b.
RNA is a single strand and is shorter than DNA c.
Types of RNA i.
Cells have three major types of RNA
1.
Messenger RNA (mRNA)
2.
Ribosomal RNA (rRNA)
3.
Transfer RNA (tRNA) d.
mRNA carries the genetic “message” from the nucleus to the cytosol e.
rRNA is the major component of ribosomes f.
tRNA caries specific amino acids, helping to form polypeptides
VII.
Transcription a.
During transcription DNA acts as a template for directing the synthesis of RNA
VIII.
Genetic Code a.
The nearly universal genetic code identifies the specific amino acids coded for by each
IX.
three-nucleotide mRNA codon
Translation a.
Steps of translation i.
During translation, amino acids are assembled from information encoded in mRNA ii.
As the mRNA codons move through the ribosome, tRNAs add specific amino acids to the growing polypeptide chain iii.
The process continues until a stop codon is reached and the newly made protein is released
X.
The Human Genome a.
The entire gene sequence of the human genome, the complete genetic content, is now known b.
To learn where and when human cells use each of the proteins coded for the approximately 30,000 genes in the human genome will take much more analysis