The document summarizes key concepts about DNA, RNA, and protein synthesis. It describes Griffith's experiments which discovered genetic transformation through DNA and Avery's experiments identifying DNA as the transforming factor. It also discusses Hershey and Chase's experiments confirming that DNA is the hereditary material in viruses. The structure of DNA and how it replicates is outlined. Finally, the document explains the flow of genetic information from DNA to RNA to protein and the major steps in transcription and translation.
3. Griffith’s Experiments
• Fredrick Griffith studied bacteria that
cause pneumonia
– Some strains, or types, were harmful and
caused pneumonia in mammals (smooth)
– Other strains were harmless and did not
cause pneumonia (rough)
4. Griffith’s Experiments
• Used the two strains of bacteria in four
experiments
• Discovered that genetic material can be
transferred from one cell to another and
change those cells
• He called this transformation
6. Avery’s Experiments
• Oswald Avery wanted to find out what
factor caused the transformation in
Griffith’s experiments
• Discovered that the factor was DNA
10. DNA Double Helix
• Structure of DNA discovered in 1953 by
James Watson and Francis Crick
• Used Maurice Wilkins and Rosalind
Franklin’s x-ray picture of DNA to help
11. DNA Nucleotides
• Made of two long strands of nucleotides
– Each nucleotide contains three parts
• Five-carbon sugar (deoxyribose)
• Phosphate group
• Nitrogenous base
13. Bonds Hold DNA Together
• Structure is similar to
a spiral staircase
– Alternating sugar and
phosphate molecules
= side handrails of the
staircase
– Base pairs = steps of
the staircase
18. DNA Replication
• DNA replication is the process by which
DNA is copied in a cell before a cell
divides
19. Steps of DNA Replication
1. Enzymes called
helicases separate
the DNA strands
20. Steps of DNA Replication
2. Enzymes called DNA
polymerases add
complementary
nucleotides to each
of the original
strands
21. Steps of DNA Replication
3. DNA polymerases
finish replicating the
DNA and fall off
– Result is two separate
and identical DNA
molecules
22. DNA Errors in Replication
• DNA replication is usually very accurate
– Only about one error occurs for every billion
nucleotides
• When mistakes occur, a change in the
nucleotide sequence results in a mutation
25. RNA Structure and Function
• RNA is very similar to DNA – long strand
of nucleotides
26. RNA Structure and Function
• RNA is different from DNA in the following
ways:
– Contains the sugar ribose instead of
deoxyribose
– Contains uracil instead of thymine
– Single-stranded
– Much shorter than DNA
27. Types of RNA
• There are three major types of RNA that
each play a different role in protein
synthesis
28. Types of RNA
• Ribosomal RNA
(rRNA) – makes up
part of the ribosome
29. Types of RNA
• Messenger RNA (mRNA) – carries the
message from DNA in the nucleus to the
ribosomes in the cytoplasm
30. Types of RNA
• Transfer RNA
(tRNA) – transfers
amino acids to the
ribosome to make a
protein
31. The Genetic Code
• The genetic code is the rules for how a
sequence of bases codes for a particular
amino acid
• Each group of three nucleotides is called a
codon and codes for an amino acid
